AF: 2002 Dodge Grand Caravan, no codes but engine running rough and will not go over 4500 rpm... | Allpar Forums
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

2002 Dodge Grand Caravan, no codes but engine running rough and will not go over 4500 rpm...

Discussion in 'Minivans · Pacifica' started by Rick Anderson, Feb 8, 2020.

  1. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    2002 Dodge Grand Caravan eL, 3.3L Engine, A-604/41TE Transmission
    4th Generation, RS Platform...
    I keep it as beater pick-up truck, its only driven every other week...

    Engine Started running rough, very rough, loosing power, when the engine is cold you can smell fuel from the exhaust.... .....after warming up, it runs smoother, but if I floor the accelerator (while moving) it won't got over 4500rpm....

    Its intermittent, sometimes very rough start and rough running cold, sometimes not, the passing maneuver at WOT, the rpm where the engine power decreases and the vehicle slows vary's, between 4200 and 4700 rpm, sometimes I get to 5000 rpm before power tapers off and the vehicle slows down and if I lift off the pedal and let the trans upshift and rpm decreases I accelerate again, but at only partial power....

    No Check Engine Light (CEL) and no codes, other than the typical P1684 (Battery Disconnected in the last 50 engine starts; and I have disconnected the new battery within that time).....

    What I've done....
    • Inspected the Wire Harness, yea its pretty rough looking, but nothing melted or chafed....
    • The Fuel Injector Harness look the most grimey, and lots of stuff on the internet about this one shorting from wires melting together. I removed it, cleaned and separate the wires that insulation fused together, but not enough to melt through and short. I could only find a single tiny spot with exposed wiring, and the adjacent wires didn't have any missing insulation. Still wrapped them individually with electric tape and re-wrapped the entire harness.
    • Checked the injectors all 6 are between 11-12 ohms.
    • Cleaned the connector ends with Electronics cleaner.
    • Tune-Up, new air filter, new plugs, old plugs were eroded an additional 0.010" greater than the original gap, they were also black and damp/oily, not wet, but a black gummy coat, like its been running really rich....
    • New MAP Sensor and TPS sensor....
    • Cleaned the Throttle Body....
    • The Tail Pipe behind the muffler has rusted through and fell off, I replaced it....
    No change, other than the more often I drive it, the less rough it runs, but it only takes it sitting 3 days and its running like only half the cylinders are firing until it warms up... ...still have yet to throw a misfire code.... ...and I've gotten misfire codes in the past for misses barely detectable..... Power tapering off and the engine/vehicle slowing down when I hit between 4200-4700 rpm hasn't changed, it always does it....

    Never a CEL the whole time its being doing this, I've checked with the Key Dance and readout in the odometer and using an OBDII Scanner through the OBDII port, no codes other than the P1684, that has nothing to do with the problem...

    I've ordered from RockAuto;
    • New Crank Position Sensor
    • New Cam Position Sensor
    • New Coil Pack (I had misfires years ago, the coil pack had carbon tracking on it, instead of replacing it, I cleaned the coil pack thoroughly and removed them, and never had the misfires again. So the coil pack is less than perfect, but again I get no misfire codes.
    After trying these, the only thing I can think of is an O2 sensor and removing the entire engine wire harness and unwrapping, inspecting/fixing and re-wrapping it, other than that I'm at a loss....

    Anyone experience this, found a fix?
     
  2. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    I believe the comment about the spark plugs being black which is an indication of an overly rich fuel mixture is the clue. And at WOT / wide open throttle you have the stumbling and rough running indicates that the problem is NOT with the oxygen sensor. At WOT the engine fuel management system goes into OPEN LOOP mode and ignores the reading from the oxygen sensor.

    Connect an appropriate scan tool and monitor the short term and long term fuel trim values after the engine is thoroughly warm and reaches operating temperature. It the fuel trim values are excessively negative and never briefly go to a positive value, that indicates the fuel injector(s) are sticking and dumping excess fuel into 1 or more cylinders. The oxygen sensor reports a rich air-fuel mixture to the PCM (powertrain control module) and it tries to lean the air-fuel mixture to attain a stoichiometric / cheically balanced value but cannot attain it.

    Another possibility is the EGR (exhaust gas recirculation) valve is defective and leaking exhaust into the intake air stream and skewing the air-fuel mixture and causing the rough running situation.

    The spark plugs have been replaced. Did you check the inside of each spark plug boot for carbon trace arcing? That can cause a spark misfire. Just some things to check.
     
    tomit likes this.
  3. ImperialCrown

    ImperialCrown Moderator
    Level III Supporter

    Joined:
    Jun 8, 2008
    Messages:
    21,196
    Likes:
    4,399
    Plug wires may fail before the platinum spark plugs at 100K miles. You want a nice blue, white spark. A yellow/orange spark may indicate low voltage.
    The spark plugs should be replaced with the OEM double-platinum Champion RE14PLP5.
    Short trips, idling and cold weather may not let the spark plugs burn off the carbon fouling very well. A warm-up and road load drive may help.

    It may not throw codes if the values are off, but still believable to the PCM. Some codes like catalytic converter efficiency take a long time to set.
    It may take awhile to set a misfire, fuel system rich or O2 sensor code because the vehicle isn't driven often.

    I agree that a scan tool should be the next level of investigation. Once warmed to closed-loop operation, the O2 sensors should be switching high/low. The upstream should be switching about twice as rapidly as the downstream sensor. Using OEM sensors may be important here as well, if replacing them.
    The fuel trim (mixture) should be within +/- 10% on the scan tool display.
     
  4. chuzz

    chuzz Well-Known Member

    Joined:
    Apr 3, 2004
    Messages:
    7,986
    Likes:
    1,073
    I'm not a mechanic, so take this comment as you will. Since you don't drive it very often, I suspect that you have more of a fuel related problem than anything else. Try a bottle of Techron Fuel System Cleaner and put some FRESH gas in it. It sounds to me like your gas is building up varnish.
     
  5. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    Thanks guys.... ...a couple things I didn't mention....

    Bad Fuel: I just filled the almost empty tank with new fuel a week ago, adding a bottle of Chevron Techron... ...yes thinking perhaps its bad fuel or dirty fuel injector.... ...I've burned through half a tank since the problem.... ...the rough running could be water in the tank, but I wouldn't think the stumbling that prevents going above ~4500 rpm, would be water, suppose its possible....

    Ignition Cables: I've replaced the ignition cables less than a 100k miles ago, I remember thinking it was a waste of money, since the OEM and the Mopar Replacement are Suppression Cables, meaning they are a solid metal wire wrapped in a coil through the cable, forming an inductor to suppress EMI/RFI instead of being a carbon impregnated latex to make a flexible resistor to reduce EMI/RFI. In short, these Ignition cables don't wear out anymore than the regular wires in the vehicle. BUT, you may have a point, because of this I have ruled the cable out and they should be on my list to check/confirm. I put dielectric grease in the boots when replacing the plugs, I didn't do more than a causal look, so perhaps a resistance check and closer look for carbon tracks is in order. The vehicle has gotten carbon tracks on the coil pack before... ...I cleaned the carbon tracks off, that is why I'm replacing the coil pack when it comes in the mail.

    BTW, the '02 3.3L has double platinum plugs, since it's a wasted spark DIS ignition, half the plugs have reverse current flow. The recommended Change Interval is 60k miles.

    O2 Sensor/Running Rich:
    Stumbling Occurs at part throttle and idle (when cold) also.... ....the only way I can get the motor up to 4500 rpm and not be driving 90mph, is to do a passing maneuver, i.e. WOT.... .....perhaps I'll try setting the trans to low gear and see what happens?

    I haven't checked fuel trims yet, but I am putting it on the list of things to do....
    But how do fuel trims get corrupted with erroneous data? A bad O2 Sensor or an exhaust leak sucking oxygen into the exhaust to trick the O2 sensor.... ....WOT may be open loop, but the open loop operation is trimmed by data from the O2 sensor while in closed loop operation... ...correct me if I'm wrong but it is possible for a bad O2 sensor to affect closed loop operation by causing erroneous stored trim values....

    No EGR on this M/Y 3.3L, the port into the upper plenum is blocked off. I had the upper plenum off to get to the fuel injector wire harness, I can find no EGR, and I would have seen some sort of plumbing into the intake if there was an EGR. Some years, they accomplished the EGR function with valve overlap, sucking back in a small charge of exhaust with the intake...

    Read above, since the Ignition Cables are suppressive and replaced previously, I was probably a bit to casual about checking them while changing the plugs because of that. I'm going to go back and double check those.....

    Codes needing some time to set: True, but they have had more than enough time to set a code. I've had misfires in the past with this vehicle, not nearly as bad and not nearly as long, and misfires codes with a CEL were set. Its not doing it now. And the way the PCM detects misfires is a change in crank speed between cylinders firing.... ....so a misfire for any reason should be detected, so is the stumbling not misfires, but instead the all the cylinders slowing down? Only thing I can think causing that is A/F ratio? And I do have multiple symptoms of running rich...

    Fuel Pump:
    There is no pressure test port on my 3.3L, I don't have an adaptor to connect between the quick disconnects to check fuel pressure. I see it being very rare a fuel pump would fail in a way to cause this, and not die shortly afterward......

    Crank/Cam Position Sensor:
    I have read and experienced the Crank/Cam Position Sensor failing and not setting a code, it didn't cause this kind of operation, but I suppose its possible. I have a new Crank/Cam Position Sensor on the way in the mail and will replace them.
     
  6. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    I agree and believe you have eliminated poor fuel quality or fuel contamination as a possibility.

    As a quick fix I have take some fine sandpaper, formed into a roll and scratched the inside surface of the spark plug boots to remove carbon tracking.

    Since stumbling occurs at idle when cold I would tend to eliminate the oxygen sensor as the culprit. It takes 1 - 2 minutes after cold engine start for the oxygen sensor to heat to 600+ deg F and start functioning and provide feedback air-fuel mixture data to the PCM.

    Try this test. Unplug the oxygen sensor. You should generate a diagnostic code for open electrical circuit to the oxygen sensor. Start engine and run. Do you experience the same stumbling and engine rpm limitation. If YES then the oxygen sensor is NOT the issue. If NO and the engine runs better then suspect an erroneous signal from the oxygen sensor to the PCM or a problem with the oxygen sensor wiring.

    An oxygen sensor works by comparing the amount of oxygen in the exhaust stream to the amount of oxygen in the ambient / surrounding air. If you look closely at an oxygen sensor it has perforations in the body outside the flange mounting on the exhaust pipe. It has to breathe so to speak for this comparison to happen. If there is an exhaust leak the exhaust stream has outside oxygen enter the stream. That skews or decreases the delta or difference value between the oxygen content in the exhaust and outside air. This results in a lean air fuel voltage value (less than 0.45 volt) reported to the PCM. The PCM increases the fuel injector pulse width to add more fuel so as to drive the air - fuel mixture rich as reported by the oxygen sensor. But if the exhaust leak is sufficiently large the PCM increases the air - fuel mixture but never can get it to a rich value as reported by the oxygen sensor. An overly rich fuel mixture can cause engine stumbling.

    As I C mentioned in his post #3 ideally you want the air fuel mixture / fuel trims to oscillate between +- 10%. It should fluctuate between lean and rich fuel mixture constantly. This is the design goal for all engine fuel management systems.

    Yes. That is why I suggested to disconnect the oxygen sensor and run the engine. With the oxygen sensor disconnected does the engine run better?

    Very good. One more possible failure to eliminate.

    There is a fuel pressure regulator integrated into the fuel pump module at the tank. If it has failed and is allowing excessive pressure in the fuel delivery system, you will get overly rich fuel mixtures. But I would tend to agree with you this is probably lower on the list of possible culprits.

    Firing the "parts cannon" can get expensive and frustrating. Keep us updated on this diagnostic journey.
     
  7. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    Its 20°F warmer today than yesterday, in the 50's, just got back from a test drive...
    I tried switching around Relays for Relays used during engine operation (Fuel Pump, EATX, etc) in case a bad relay was cutting in or out, introducing resistance, etc.... ...no change...
    It was even harder to start, stumbling, cranked for a long time,needed a ton of pedal/throttle opened before it started and spewed a ton of smoke (likely the raw gas from the long cranking)....

    The engine was stumbling so bad off idle, I couldn't get the vehicle above 25mph.... ....I pulled over and let it warmed up more, when the temp gauge got up to 1 tic above cold (where it might go into closed loop operation) the engine smoothed out and I was able to smoothly get up to 60mph at part throttle.....

    I tried part throttle in low gear, the engine stumbles at ~4500 rpm and won't get over that rpm... ...it varies what rpm a few hundred rpm each time I try it....

    So this is not a "switch over to open loop at WOT" situation, it's the engine "can't sustain RPM above a 4500rpm) issue....

    But on my way back, multiple time the engine was able to get above 5k rpm, 5300 rpm at one point, again it's warmer today.....

    While it costs nothing to disconnect the O2 sensor, I will give this a try....

    After today, I'm convinced the situation is worse in Open Loop, than closed Loop, so I suspect this would make the situation worse, as it will force it into open loop.... ....might still be valuable info, I will know the problem is Open Loop and simply not a Cold Engine make the problems worse.... ....if there is no change, than it might not be open loop, it's simply the problem is such, a cold engine can't deal with it until warmed up....

    Yes, a switching O2 sensor's voltage range is so narrow at Stoichiometric, it can't be accurate, the whole A/F ratio management system is to use the very clear and broad switch over between lean and rich and bracket that, just shooting for the narrowest switch over, going lean/rich at the greatest frequency.....

    See, where we disagree, and I might be wrong.... ...since the system is adaptive, it stores correction values to correct the base tables the next time the condition is encountered... ...and these corrections values are used while in open loop... ...this is where I'm thinking, something is feeding incorrect info to the system, causing awful correction values that make the engine run horribly in open loop.....

    I'll try this soon. After driving today, its clear the problem is far worse while cold and in open loop.... ....while the engine smooths out and seems normal once warmed up and only using part throttle, it won't go over 5300 rpm, part throttle or WOT, lots of signs running rich either smooth or stumbling at high fuel demand for high rpms.... ....there is something going on with either Ignition or fuel supply (and injector pulse width could be part of that)....

    There is a cylinder module on top of the fuel rail, I was thinking that was the pressure regulator, but there is no return line. My Neon had the same thing, it was a Hydraulic Damper/Accumulator in the rail, not the pressure regulator, it's mounted on the fuel pump like you say.

    I did a quick search for a cheap adapter, didn't find one for Chryslers, I might keep trying and see if I can find one cheap online, so I can check fuel pressure.

    I agree, I have often warned others about this.... ....this is why I'm waiting for them coming in the mail from RockAuto at a significant savings, over retail.... ...in the case of Crank Position Sensor, I have seen this way to often create enormous amounts of problems and never set a code and I don't have an Ocilliscope to test it properly..... ....for $11, I'm not taking much of a risk...

    My cheap scan tool is of no use, it can only repeat any freeze frame data from the PCM, and the PCM sees absolutely nothing wrong....
    I've had shorted fuel injector circuits in other Chrysler vehicles, and that set a code for faults in the injector circuits, and this seems like that, except it gets better and worse according to conditions, while a true short was constant....

    I have AutoEnginuity on a laptop, its a pain to get it out and in the car and all setup, but its time to go through this and start reading data fed from the PCM.....
     
  8. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    Do you have the correct spark plug specifications? See I C post # 3. I have seen a different retail brand of spark plug cause all sorts of stumbling and driveability issues with Chrysler engines.

    Correct.

    The closed loop fuel trim adjustments, either positive or negative (adding or subtracting fuel) are NOT used during OPEN LOOP operation. So in OPEN LOOP no updating of the calculated fuel trim values are used based upon input from the oxygen sensor. So that makes me think something else is causing an enrichened air - fuel mixture or incorrect spark plugs that are not firing properly.

    I did an internet search and found an image of a 2002 Grand Caravan with 3.3 liter V6 engine. The fuel rail pressure test port is under the air cleaner box and flexible intake tube to the upper intake manifold. You probably need to remove the air clean box and intake tube to see it. Attached image.

    2002 Caravan 3_3 V6 fuel rail port.jpg
     
  9. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    I did use the exact OEM Plugs, the same as ImperialCrown listed. Double checked the gap, the same as listed on the Emissions Decal, 0.050"...
    The same plugs were in the engine before, when this started and nothing's changed after replacing them....
    The old plugs gap had grown 0.010" to be 0.060" they were coated dark black, but it wasn't powdery, gummey, not wet or oily either, more like a soft gummy coat of varnish.... ....I took that as a sign its running very rich....

    The vehicle has only been used for short trips, which doesn't help burn off.....

    I've read the closed loop corrections are applied to the open loop operations. Perhaps not "trim" adjustments, but perhaps other adjustments. I seem to remember tables for volumetric efficiency....

    That's the plastic line/hose between the fuel line in the body and the lead-in line to the fuel rail.....
    It's below the Intake Tube between the Air Filter Box and Throttle Body....
    That is odd, because mine is a stiff plastic line/hose with quick disconnects on each side....
    I just went out and double checked it, no pressure take-off on my hose/line, the entire length from metal line to metal line....
     
  10. ImperialCrown

    ImperialCrown Moderator
    Level III Supporter

    Joined:
    Jun 8, 2008
    Messages:
    21,196
    Likes:
    4,399
    The fuel line adapter can be made or purchased. It is Chrysler (Miller) tool # 6539. It goes in-line with the 5/16" supply line.
    If the f/p regulator is delivering a very high pressure, this can make it run rich, even if the injector pulsewidth is backed down to almost always closed.
    Part of the problem is the short trip/cold weather operation. The vehicle should be taken out for an occasional highway cruise.

    [​IMG]
     
  11. chuzz

    chuzz Well-Known Member

    Joined:
    Apr 3, 2004
    Messages:
    7,986
    Likes:
    1,073
    Okay Guys, I'm by no means what you'd call a mechanic and the more computerized cars get, the more confused I get. I'm going to ask what to a couple of you guys may be a very stupid question. But here goes. Is there any chance that a faulty Coolant Temp Sensor could be causing some of these problems? I haven't noticed that it's been replaced or checked, but may have overlooked that tidbit of information. If so, I apologize and will not throw any more monkey wrenches into the quandary.
     
  12. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    I should add, last night I fired it up again and took a drive, the vehicle sat long enough the motor was cold, but NOT cold soaked, i.e. sat for a 4-5 hours, not 24 hours....
    It started totally normal, but idled a bit rough, part throttle performance is ok, WOT and part throttle near WOT, is down on power, and still has the engine stumbles and won't go above ~4500, +/- a couple of hundred RPM, each time I try it.... ....it seems to vary with speed and load...

    I filled up on gas, adding Techron Fuel Injector Cleaner and HEET additive that removes water.... ...I have burned 12 gallons since starting this troubleshooting... ...didn't note the mileage, but doubt I drove more than 50-60 miles, so the mileage has gone in dumper....

    I'm starting to believe the root problem is the engine is running excessively rich......
    The black plugs, gasoline smell and smoke from the exhaust support it, mileage way down, like 1/4th of normal is more confirmation....
    The Stumble at high rpm may simply be the A/F mixture is too rich for that rpm....
    It would also explain why I get no Misfire Codes, the engine isn't missing as the PCM sees it... ...the PCM looks for an individual cylinder slowing down inbetween firings.... ....my engine may feel like its missing, but its all the cylinders slowing down because the A/F mixture is so rich.....
    Thanks IC!
    Yea, I was looking at these last night online, saw one that was not the Miller Tool but was for Chrysler 5/16" fuel lines...
    The same thought had occurred to me, the fuel pressure regulator failed, the fuel pressure is excessive, more than the PCM can adapt to with injector pulse width, thus the vehicle runs excessively rich.....

    Only other thing I could imagine causing this, since I've replaced the MAP sensor already, is the circuit for the MAP sensor has a partial or full short and providing erroneous data that the Manifold Pressure was much higher than actual, that would cause the PCM to pour in a lot more fuel by opening up the fuel injector pulse width..... ....I'd think this would also trip a code....

    I've cleaned up the Fuel Injector Wire Harness, that includes a length to the MAP sensor, but that is just a segment of the larger Engine Wire Harness, which I've only looked over and although its pretty weather, there is no obvious signs of heat/chaffing damage that could cause a short. Pulling that whole harness out and cleaning it up and re-wrapping it is the last item on my list.... ...just before it, checking continuity pin by pin.....

    Since there is nothing monitoring fuel pressure AFA the PCM is concerned, so a pressure regulator going bad and sending fuel pressure through the roof wouldn't trip a code.... ....I'd think I'd get a code for running rich, but its possible the PCM needs to monitor it longer than I have driven it (reseting the PCM several times as well by pulling the battery cable) before tripping the rich mixture code.....

    I have to get my AutoEnginuity on a laptop up and running, plugged into this vehicle, do some live monitoring of data...
    If its the fuel pressure regulator, I suspect I'll see:
    Fuel Injector Pulse Width shortened to min...
    Fuel Trim negative as possible...
    O2 Sensor not/barely switching, staying at Rich....
    MAP sensor / Manifold Pressure at expected vacuum/pressure....

    If its the MAP sensor, or its circuit shorting it, I should see a Manifold Pressure/Vacuum way off....
    Judging from how bad I suspect its running rich, the MAP would be at its max pressure possible, it it is the root cause of this...

    It could, and someone correct me if I'm wrong, but the Temp Gauge in the Dash gets its signal from the Coolant Temp Sensor also.....

    If the Temp Gauge in the Dash's reading was way off, I would have replaced the sensor already.....

    It is possible the Coolant Temp Sensor could be off/out of calibration enough to affect engine operation and the Temp Gauge in the Dash seems normal, true.... ....but a bad Coolant Temp Sensor alone I doubt could cause a problem this severe, as well, if it was off far enough to affect engine operation as bad as mine is running, the Temp Gauge in the Dash would have to be noticeably off as well....

    You can check the Coolant Temp Sensor with a Ohm Gauge, you'd need a reference for its resistance vs temp, its on my list to try if more likely things don't work.... ...its lower on the list, because I just don't see it as likely to be the cause....
     
  13. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    No need to apologize for suggesting ideas to help resolve the problem. Brainstorming is welcomed.

    I would tend to think that a coolant temperature sensor that skews valid data input to the PCM would make the engine go into a no start mode. Also there are rationality checks that will set a diagnostic code if the coolant temperature sensor gets out of range. And I believe there is a logic check that compares the input from the coolant temperature sensor against the intake air temperature sensor input value and sets an appropriate code if the correlation between the two get out of range. There has been no indication of a diagnostic code associated with the coolant temperature sensor.
     
  14. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    Exactly, Chuzz you're on the right track, but as you learn/understand the system better, you'd see this would be low on the list of possible causes.... AllanC brings up a good point, if this was the cause the PCM could tell and would trip a code for it.....

    I'm becoming more convinced this could be the fuel pressure regulator, and the PCM has no way to tell what the fuel pressure is... ...so having a pretty severe problem, with the PCM not setting any codes, plus symptoms of a rich mixture, bumps the fuel pump and pressure regulator up on the list of likely causes. I'm going to order the "T" tap tool to check fuel pressure.

    What is the Fuel Pressure that I should see for a 3.3L? The typcial 50PSI +/- 5PSI?

    And of course, just checking prices, the only pressure regulator available is just $5 less than a new Carter Fuel Pump Assembly.......
    Of course, check pressure first... ...but if the fuel pressure checks bad, which to purchase?o_O I'll probably go with a new aftermarket Carter Fuel Pump assembly.... ...knowing my luck after replacing the pressure regulator, the pump will go out a week later.... ....this vehicle doesn't have enough life left in it to outlive a new aftermarket pump, I'm not springing for an OEM pump.... ...as well, what caused the regulator to fail, might have been corrosion or failed internally, or its valving could have clogged from debri coming from a pump about to fail? But I'm getting ahead of myself, I have to check fuel pressure first to confirm this......
     
  15. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    Service manual description of fuel pressure regulator 2002 Dodge Grand Caravan 3.3 / 3.8 V6

    OPERATION
    The fuel system uses a nonadjustable pressure regulator that maintains fuel system pressure at
    approximately 400 ±34 kPa (58 ±5 psi). The fuel pressure regulator contains a diaphragm, calibrated
    spring and a fuel return valve. The spring pushes down on the diaphragm and closes off the fuel return
    port. System fuel pressure reflects the amount of fuel pressure required to open the return port.
    The pressure regulator is a mechanical device that is NOT controlled by the PCM or engine vacuum.


    It is good to think "outside the box" and ponder all possible culprits in this poor driveability situation. And I can throw another factor to consider as a cause. It is possible to have a catalytic converter that is partially plugged / restricted. This will cause the engine to not breathe properly and you will get poor performance and stumbling as noted.

    But enough with the guesswork. Observe the behavior of the upstream oxygen sensor and short term and long term fuel trim values. That will give direction as to the path way to take for solving the problem.

    Have you detached the electrical connector at the upstream oxygen sensor and noted how the engine runs?
     
    Rick Anderson likes this.
  16. Rick Anderson

    Rick Anderson Well-Known Member

    Joined:
    May 28, 2002
    Messages:
    5,412
    Likes:
    2,042
    No, not yet, and its raining tonight, so it might not happen till another night.....

    I'm setting my priorities as:
    Order a cheap Fuel Pressure Test Adapter....
    Use my AutoEnginuity to monitor the parameters we've spoke about....
    Perhaps check electrical continuity, reference voltage on the MAP sensor plug....
    Disconnect the O2 Sensor....
    Test the Fuel Pressure when I get the Fuel Pressure Test Adapter....
    Since I ordered an inexpensive Crank Position Sensor, I'll probably install that when it arrives...

    Then I'll start looking at the CAT, but like the others, the OBDII tests the CAT, if it was clogged, I think I should be getting a code for that....
    I just replaced the rusted tail pipe and resonator that rusted through and fell off, the exhaust sounds the same as it always had, not loud, but near the tail pipe outlet, there is certainly a bit of raspy sound you'd expect from a performance car, not a Mini-Van, which is something I noticed while it was new....
     
  17. AllanC

    AllanC Well-Known Member

    Joined:
    Jan 6, 2003
    Messages:
    4,536
    Likes:
    1,125
    The only diagnostic code that the PCM will set for the catalytic converter is P0420; catalyst efficiency below minimum threshold. A plugged / restricted may NOT set this code. There is no sensor that measures the pressure differential between inlet and outlet of the converter.
     
    Doug D likes this.
  18. Doug D

    Doug D Virginia Gentleman

    Joined:
    Aug 10, 2000
    Messages:
    14,541
    Likes:
    4,021
    If you have to replace the fuel pump, definitely go with the Carter. At a local shop that's about all they will warranty. The rest are either junk or cost way too much.
     
  19. chuzz

    chuzz Well-Known Member

    Joined:
    Apr 3, 2004
    Messages:
    7,986
    Likes:
    1,073
    #19 chuzz, Feb 11, 2020
    Last edited: Feb 11, 2020
  20. valiant67

    valiant67 ...

    Joined:
    Jan 7, 2003
    Messages:
    36,678
    Likes:
    19,424
    By 2002, it should be in the tank. A pressure regulator under the hood went away with the returnless fuel systems Chrysler started using around 1994. I’m not sure when the vans changed over, but I’m sure it was in place by the 1996 redesign.
     

Share This Page

Loading...
 We are not affiliated with FCA. We make no claims regarding validity or accuracy of information or advice. Copyright © VerticalScope Inc. All rights reserved.