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Hesitation on Accelleration & Rough Cold Idle/Running

Discussion in 'L: Horizon/Omni, Rampage, etc' started by cadman777, Aug 4, 2016.

  1. cadman777

    cadman777 Active Member

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    Back again w/this 88 Horizon 2.2L A/T Americana.

    I'd appreciate any assistance, tips or whatever to help me figure out what's wrong w/this car.

    The guy has 2 complaints:

    1. It idles and runs rough when cold, and

    2. It stumbles/hesitates on acceleration, when starting from a complete stop.

    What things can I look at to do the 'process of elimination' diagnostics to narrow-down the CAUSE of the problem, and finally pin-point it?

    Thanx!
     
  2. ImperialCrown

    Level III Supporter

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    Any fault codes or POWER LIMITED/LOSS light?
    Start with the basics like distributor/cap, rotor, wires and spark plug health. Is the inside of the the distributor cap clean? Is the carbon rotor contact button shiny? Is the timing set correctly by first disconnecting the 2-wire coolant temp sensor? (This will turn on the POWER LIMITED light, but the ECT code can be erased afterwards). You can remove the cam sprocket circular plug and see the cam timing mark in line with the engine center line with your advance timing light? (Tilted slightly rearward).
    Are the wires plugged all the way into the cap? Are they the correct Champion CopperPlus RN12YC? Are the old plug tips normal or carbon fouled (rich)?
    Has the O2 sensor ever been replaced (and with an OEM part)? I have had issues with Bosch plugs and 'universal' O2 sensors.
    Is the (OEM preferred) PCV drawing correctly and not leaving an oil splotch on the air filter?
    Although scan tool diagnostics are quick and easy, you can test each component manually with a multimeter. The Chrysler Powertrain diagnostic test procedures manual gives you the steps to follow to find the problem. In some steps it may call for the DRBII, but you can test most everything with your multimeter.
    In some ways, the old TBI system is simpler which is a blessing. It just doesn't have the deeper self-diagnostics as found in new cars.

    Some resources:

    Chrysler 1988 2.2L/2.5L E.F.I. Powertrain Diagnostic Test Procedures Manual

    http://buy1.snapon.com/products/dia...icVCS(EAZ0025B01CRevB)/07 ChryslerTesting.pdf
     
  3. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Fault codes are definitely the first step, but this sounds like it could be an EGR valve stuck open. It will cause stalling and/or rough cold idle, and loss of power when warm and accelerating from a stop.
     
    Doug D likes this.
  4. ImperialCrown

    Level III Supporter

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    A quick check of a stuck open EGR would be to remove the air cleaner from a cool engine. Then locate the metal tube (or pipe) that runs from the EGR valve to the intake 'floor' underneath the intake manifold:
    http://repairguide.autozone.com/zne...0c152/80/21/5e/cb/medium/0900c15280215ecb.gif
    Remove and plug the vacuum hose from the EGR valve diaphragm.
    Start the car and feel for the metal EGR tube temperature. It should remain 'cool'. This indicates that there is no EGR flow. If the tube warms rapidly, that would indicate that exhaust gases are flowing through the tube which would be wrong with the vacuum hose off of the valve.
    If there is suction present at the end of the vacuum hose, that might indicate that the EGR transducer (black, plastic round valve in line with the rubber hose) is leaking when it shouldn't be.
    EGR should only be present with a warm engine with the engine under some load and an opened throttle.
     
  5. cadman777

    cadman777 Active Member

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    Hey guys, thanx for all this info.

    No fault codes.

    Timing is good, b/c I set it last year according to the manual (ECT unplugged).

    All plugs are pretty tan color, correct gap, etc.

    I just got done w/changing the injector.
    I did that b/c it was getting real bad gas mileage, and figured 'why not', it may be dripping.
    The 'cone' spray pattern is fairly good, but it did have some blank spots shifting around (using the timing light to watch it).

    I did DRB II readings and they all looked pretty good except the Idle Adap = +40 ms, and LT Adap = +5%.
    Then I cleared the memory, and after idling hot for a while, the Idle Adap = 0 ms, and LT Adap = 0%.

    Can't change the plugs, wires, cap & rotor until the parts come in.
    I decided to do that b/c the wires are showing cracks on the rubber and the rotor is at least 2 years old.
    The scope shows a lot of 'spikes' on the screen at the point of discharge, plus the fire pattern is weird: 3 consistent and 1 very high on every wire tested.

    The EGR valve is new. I changed it a few weeks ago, b/c it was causing rough idle.
    The test I did to determine it was bad is disconnect the vacuum hose and run the car.
    Result: the idle smoothed out. So I just changed it.

    The MAP sensor is relatively new, and so is the TPS.
    I determined that both were bad after proper diagnostics (bad MAP calibration and dead spots on TPS).
    That was about 6 months ago.

    O2 sensor is OEM & new last year. that's why it runs much better. The O2 DRB II sensor data readings are good.

    On-going complaints:

    1. When you take-off from a stop (hot engine, a/c on 'Max'), after a few seconds, you feel a noticeable 'hiccup' for about a second. Doesn't matter if you 'feather' it or 'stomp' on it.
    What can be causing that?

    The thing idles perfectly when hot, both a/c on and off. It's rock steady.
    It ran rough cold before today, not sure how it'll run cold now, but will find out tomorrow after a night of cooling-down.

    2. When you're cruising, after about a minute of steady gas pedal, you feel the same 'hiccup' for a second. That happens from time to time, but not repeatable on demand.
    What can be causing that?

    I have the 2.2L Diagnostics manual, and it's not much help.
    It's written for a DRB II menu that mine doesn't have, and it's a PITA to adapt to the DMM. Also, I don't have the Snap-On tool, but thanx for the intel on their diagnostics procedures.

    I have an OTC Pegisys, and that's what I used to do the scope tests.

    Any other ideas?

    Thanx for helping!
     
    #5 cadman777, Aug 5, 2016
    Last edited: Aug 5, 2016
  6. ImperialCrown

    Level III Supporter

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    That brief 'hiccup' may be the A/C compressor cycling on? At times with a 4-cylinder, you can really feel the compressor kick on and off. Newer 4-cyl cars have software to help minimize the compressor 'kick'. A ∽5 horsepower drop can also be noticeable when the compressor is running.
    Try it with the A/C off for diagnosis.
    Lets wait and see what the tune-up does for it.
     
  7. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    I'm betting it just needs the tuneup. I have owned these cars for 31 years, and I never get more than 15K miles out of an ignition rotor before the tip chars. Once I pushed it to 20K miles, and one day it worked, the next it would not start. Took me two days to determine that it was the rotor. I do a mini-tuneup every 15K miles (plugs, rotor, air filter, PCV, breather filter. I turn the tips of the wires around 180 degrees in the cap and use the back side of the prongs. At 30K miles I also do the cap, wires and gas filter.
     
  8. 88horizon5speed

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    when I had my horizon I had a few months where I had similar symptoms as you do. It finally went away after I changed the MAP sensor. I know it wasnt anything else I did because I only changed one possible part at a time until it was fixed to isolate the source.

    I realize you shouldnt just throw parts at a problem because you can definitely spend more that way on the other parts you didnt really need but its a cheap sensor and it might be worth looking into if your problem persists and doesnt seem to be anything else mentioned. Who knows it my be your problem, it may not be.
     
  9. cadman777

    cadman777 Active Member

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    Hey guys, thanx for all the help!
    The MAP sensor is new, so I ruled that out.
    It turned out to be Bob's suggestion.
    Actually, I changed the injector and that fixed the bad running when cold.
    Then I changed the plugs, wires cap and rotor, and the hesitation disappeared.
    The wires were cracked and the rotor was 'charred', while the wires were already used-up on both sides.
    The plugs were pristine, but since they were Autolite, I changed them to Champion.
    So basically, I will take Bob's idea and tell my neighbor to change the rotor every 15k miles and flip the wires around at that time, as well as check the plug gaps.
    Again, thanx for helping.
    Now onto rebuilding his suspension (boy is it BAD!).
     

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