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Interesting. I've never read that article, and I'm surprised it would take that long to monitor the O2 sensor. Back then, they were not heated. Newer, 4-wire sensors have a heating element to bring them up to 600F as fast as possible, so that they can be used earlier (as in, two minutes after start). Maybe it really does take 12 minutes for the older sensors. In that case, you might have an O2 sensor problem. Are there any fault codes?

The exhaust is just a big safety issue. Yes, it would chug anytime.
 

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I'm not worried about when the 02 sensor kicks in so much, as is it the correct one and IS T working correctly? I have have wrong sensors installed by customers come into the shop not running right and after checking voltage from sensor with analog or digital voltmeter while engine running, found sensor calibration not right. Replaced with Bosch or Mopar sensor and car cured. It sounds to me that once the sensor kicks in is when the bad idle starts.
 

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Bad O2 sensor will drop gas mileage anywhere from 4 to 10 mpg, and often will buck/jerk like someone slamming the clutch in and out.
 

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Discussion Starter #24
Ok, thanks for the clarification. No, unfortunately, no codes. This car is an 86, so it's just got the single wire non-heated O2 sensor.

Yeah, the problem definitely seems to present itself once it warms up. I'm not sure on the brand that was in there previously (I still have it, but all it says on it is "0089"), but the replacement I used was a Denso #234-1000 universal upstream sensor from Advance. Their parts lookup showed this Denso and a Bosch #11027 as compatible with my car. Maybe I have the wrong one or maybe this car needs the Mopar specific sensor? How could I tell if it's calibrated correctly for this car? I have a meter and a scope.
 

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I got rid of all my manuals when I retired but there is a certain voltage scale that the sensor must work in. If the sensor does not. it will cause driveability problems. If I can remember back long ago, I think the 02 sensor was : .01 volt, lean-1.1 volt being full rich. A good digital voltmeter tapped into the sensor running will see this. Some sensors start at .5 volts, which is no good for you.
 

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The scale ranges from 0.1V to 0.9V. Denso is a good brand, OEM quality. So is NGK.
 

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The O2 sensor doesn't put out a steady voltage, it's a waveform. Should be a steady oscillation, like this: http://www.aa1car.com/library/o2chart.gif. The failure mode they show (low peaks) is due to degradation of the catalyst in the sensor tip; an O2 sensor is actually a tiny fuel cell. If you put in an incompatible sensor, problems would have showed up as soon as you tried to start the car.

I've heard that Bosch O2 sensors can cause issues, but I've been using one for over three years now with no problems whatsoever.

I agree with Bob that the carbon monoxide hazard from the exhaust is a serious issue, but I don't think that'll cause something like this.
 

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That's not quite how an O2 sensor works. It is not a catalyst, although it is platinum-coated. Its active element is zirconium, which is a piezoelectric material - in the presence of oxygen, it generates a tiny voltage inversely proportional to the O2 content in the air around it. It's not a fuel cell.
 

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Huh, I had heard it was a fuel cell somewhere, never knew that piezo worked without physically stressing it somehow. But you learn something every day!
 

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Excuse me, it's the anti-knock sensor in turbos that's piezoelectric. The zirconium is not, but neither is it a fuel cell. Resistance changes with exposure to oxygen, which changes the voltage signal.
 

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Discussion Starter #31
So after an aftermarket egr valve, TPS, Champion plugs (.035), Autolite wires, OEM coil, new timing belt+tensioner, new resonator, new donut gasket and Mopar o2 sensor, the engine runs about the same. Most of the symptoms present themselves when the engine is idling or coming off idle. The idle hunts, it idles a little high (around 800rpm), misfires and shakes. The engine also stumbles when accelerated from a stop and then recovers, almost like a carb with a bad accelerator pump. Once the car gets moving, it runs good.

I did a compression check and that seems ok. I did get a code 44 (battery temp out of range) that seemed to come and go over the past several months, but after reseating the black connector at the logic module, it seems to have gone away. I noticed that the hot restart issue I had mentioned previously seems to happen only if I immediately turn the key through to the start position, without waiting a second for the fuel pump to prime. If I wait a quick second, it hardly ever stalls out.

There's also something mechanical going on. The valvetrain gets pretty loud when warm, especially when it's revved, and there's some ringing noise that sounds like it's coming from the lower passenger side of the engine. The crank pulley has some weird jagged lines in one of the belt groves...almost looks like a crack, but I'm not sure. That might be where the ringing noise is coming from, but if that were the case, i'm not sure why it would happen only when it gets hot. Tried to find another crank pulley in a bone yard to try and swap on, but no one seems to have the four bolt version.

It's also got either got a vacuum leak at the manifold or an exhaust leak, as I can hear a pretty loud hissing noise on the passenger side - I haven't been able to pinpoint a vacuum leak, even with a hose held to my ear. It doesn't sound like it's coming from inside the throttle body because the noise doesn't change with the filter covers on or off. When I'm driving the car I can also hear what I think is an exhaust leak, but only when I'm on the gas. It goes away when I let off and sounds like a clicking noise. I had another car that made the same noise and it turned out to be a leaking exhaust manifold gasket. I'm planning on checking that out...any tips on getting the manifold off? Do I have to remove the intake and/or power steering pump/bracket in order to get at it?
 

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My guess is one or a combination of two things.

!) the base plate you replaced is most likely a source of a vacuum leak. The replacement ones are not very well made and when torque (even when torque correctly) tend to crack causing leaks and rough starts and idling - if it will start at all. What did you torque the TB to?

2) check the electrical lines on the fuel injector cap, the connecting wiring from the fuel injector cap connector to the wiring outside connector. Follow the wiring several inches down for missing insulation.

3) the Fuel Injector is a bear to seat properly. I had to use a flat nose plier and had to use considerable force to get the FI down into the throat. The cap, when replaced on top of the FI should not show any signs of resistance when screwing it back on. If it does, the FI is not seated correctly.

There are different designs to FI. The newer ones have only one oring. The original Mopar have a different design and two orings. If you replaced the FI be sure no orings were left in the throat and sitting on the bottom before replacing with a new FI.
 

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Manifold vacuum leaks generally cause a fast idle. An OEM PCV valve is important for correct vacuum metering.
I have had aftermarket TPS sensors cause idle fluctuation issues. Watch the signal voltage, it should sit rock-solid at a value and not wander up or down at idle.
A P/S pump can 'hiss', it may be helpful to remove the drive belts and listen again.
What is your current fuel injector part #?
A perforated fuel pressure regulator diaphragm can make it rich, so that the O2 sensor will tell the PCM to drive the injector pulsewidth lean.
Do the symptoms appear right after starting the car cold or does it have to enter closed loop first for the issues to appear?
Did you set ign timing with the 2-wire CTS unplugged? The single-wire (violet) CTS is for the dash gauge only.
Engine knock isn't good. These had piston wrist pin issues and could scuff the cylinder walls in the affected cylinder. This could reduce compression in that cylinder which would show up more at idle and lower engine speeds than down the road. A compression test can miss this and a cylinder leak-down test is much more accurate for diagnosis.
The battery temperature sensor is used for an ambient (outside air) temperature reading for the PCM. The sensor may be inside the PCM itself or down by the lower radiator support where it could be struck by curbs, etc.
 

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Discussion Starter #34
Thanks for the responses!

dc8flyer - I torqued the TB bolts to 200 inch pounds. The base gasket I bought was seperate from the TBI repair kit. It was as thick as the original one I removed and I decided to use that one instead of the one that came with the kit, which was a little thinner, but not by much. Will have a close look at the injector wiring harness tomorrow, but when I changed the injector, I didn't notice anything obvious with the insulation missing from the wiring. That replacement injector I bought WAS a real pain to get in, but it ran the same after as it did before so I'm thinking I got it in there OK. I made sure there weren't any old orings laying in the pod before I installed the new one.

ImperialCrown - Thanks for the tip on the TPS. I will check the signal voltage and see what it looks like. The service manual says it should be 5V from the logic module. How about the output voltage? That voltage should remain steady while at idle too right? I'll take the PS belt off and see if the noise changes. The injector I used was a Bosch 4418553. For a perforated FPR, is there anything I can check to look for symptoms of that? As for when the symptoms start, they seem to be most noticable while in closed loop, right after the idle drops down to it's lowest speed. Ignition timing was set with the 2-wire CTS unplugged. I don't think the engine is knocking. The chattering noise seems to be coming from the valvetrain and really only when it's revved. Maybe it's a sticking valve or lifter? This car sat for a long time before I got it. You can hear a popping noise from the tailpipe, almost as if a valve was sticking. There is some kind of a ringing noise coming from the lower end of the drivebelt area, but I think that may be a possible cracked crank pulley or it could be that the bearing in the new timing belt tensioner I installed went bad. That particular sound definitely seems to be something external to the block. I think my 86 has the sensor in the computer. When I had the black logic module plug out, I checked resistance to ground on the battery temp sensor wire and it was within spec. The service manual said that if it was, there could be a problem with the logic module, but so far, I haven't gotten the code since reseating the connector.
 

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Tha base gasket may be the same thickness but I've noticed the material is more a hard foam and not as dense.as the original. I also thought the torque was closer to 175?
 

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Discussion Starter #37
dc8flyer - The factory service manual said it was 200 inch pounds, so I went with that figure. You're right about that gasket though - it kind of looks like some weird layered foam that is compressed together. Not sure how well that works compared to the factory one, but the old gasket looked like the same material as the replacement.

ImperialCrown - The TPS holds steady at idle. I get 4.98V in and 0.81V out at idle. I also checked the MAP sensor voltages with the key on and the vac nipple hooked to my vacuum pump. Maybe you guys can tell me if there's a problem. Here are the results:

0 in Hg = 4.68V
5 in Hg = 3.87V
10 in Hg = 3.02V
15 in Hg = 2.2V

While probing the MAP signal and ground wires with the engine hot and running at idle, my meter jumps around between 1.5-1.6V. Idle is about 800 rpm.

I also listened to how the engine sounds until it fully warms up. It sounds smooth until just before the cooling fan kicks in and then the missing starts, which is about the time it makes it's final drop down to curb idle speed.

As far as that ringing noise is concerned, it's not present when the engine is cold, while warming up or at the time the engine drops down to curb idle speed, but shortly after that, it slowly comes on and gets louder as the engine gets hot. It sounds like it's coming from the area behind the cam pulley. I'm thinking that this noise might have something to do with the engine oil getting hot and the pressure drops down. Isn't the bearing behind the cam pulley the last one that gets lubricated in the head? Guess I'll have to pull the valve cover and take a look and see what it looks like.

Can anyone tell me if I have the red and blue orifices in the right places? Currently, the red (small orifice) is in the line that tees off from the vapor canister and goes towards the PCV and the blue (large) orifice goes from the other end of that tee (from the canister) to the check valve next to the throttle body. Is that right?
 

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Discussion Starter #38
Update: Borrowed another MAP sensor (part # 4419315. Original was part # 5227323) and tried it, but it's still running the same. Interestingly after the MAP swap, two codes popped up - a 47 and 24. I don't understand why the 24 came back, as the TPS was recently replaced. The 47 may have had something to do with having the AC on. Whenever I have it on, the voltmeter drops below the midway dot on the gauge at idle, unless I am driving. Very weird. At least the code 44 seems to have disappeared.

Can anyone confirm the red and blue orifice locations please?
 

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The MAP signal voltage will jump around as vacuum varies. The MAP voltages that you posted look OK and will change inversely with vacuum (negative pressure).
The TPS should follow the throttle opening smoothly. If the throttle is sitting still, so should the signal voltage.
Have you erased the codes and they came back?
I would be careful about swapping parts and only use the OEM part # that is called for. Otherwise the results can be misleading if you trying to diagnose a problem.
 

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Discussion Starter #40
Ok thanks for verifying the MAP signal.

I cleared the codes yesterday and after checking codes again after 200 miles, I only have the 47. With the A/C on now, the voltmeter always drops below the midpoint when I'm idling, so it's possible that maybe the voltage regulator and/or battery temp sensor circuitry may be faulty which is causing the 47 to appear. I haven't gotten the 44 back yet, but that's something I'll have to look into. To my surprise, the engine idles GREAT as long as the A/C is on, but once it's off, it starts missing.
 
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