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Topic
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1996 Doge Neon
287,??? miles
DOHC 4 cyl
5 spd manualLooking for SECOND opinions as to what should be the first step to take.
Wife has been complaining that when going at slow speeds only, and when putting the CLUTCH IN (not shifting to Neutral) to stop at a stop sign or traffic light, the idle goes low, almost to the point of the car stopping (engine not running stopping that is). This seems to have been happening for some time now and there has been no CEL. Yesterday on her way home the CEL came on and a P0172 code has been stored.
Trouble Code Conditions:
Engine running in closed loop, IAT (Intake Air Temperature) Sensor signal over 20ºF, altitude less than 8,000 feet, and the PCM (Power Control Module) detected too large an amount of Fuel Trim correction due to a rich A/F (Air/Fuel) condition.
Possible Causes:
Base engine fault (i.e., cam timing incorrect, oil level too high)
EVAP vapor recovery system failure (e.g., canister full of fuel)
Fuel control Sensor is out of calibration (e.g., ECT, IAT (Intake Air Temperature) or MAP (Manifold Absolute Pressure)
Fuel delivery component fault (injector leak, high fuel pressure)
O2 element is contaminated, deteriorated or it has failed
O2 heater is damaged or it has failedDidn’t get all the information last night from the scanner but will try to get it tonight when wife gets home (if the CEL is still on and the code is still stored) I did not reset the code. I believe it will extinguish the light if it does not detect the problem again within ? cycles.
Cam Timing ? If sensor says yes should it be OK
Oil level if anything was a little low was just changed 5 days ago.———————————————————————————-
With engine running at idle in neutral Parking Brake on.
Using Snap On MT2500 scanner.*EVAP – Don’t know, I think I can purge it with the scanner. Will update
IAC (Idle Air Control)- Could easily move the idle up to 2000 RPMS + and back down smoothly and without problems.
CAM Sensor – Yes Crank Sensor – Yes
*ETC – ? What is it?
*IAT/MAP (Intake Air Temperature / Manifold Absolute Pressure) – TBD (To Be Determined) I think I saw +5V there with the scanner last night will check and verify tonight).STFT (Short Term Fuel Trim)- varied from +2 to -2 (mostly between +1 and -1
*LTFT(Long Term Fuel Trim) – will update (but think it was around 12 don’t know whether + or –
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Fuel injectors did not seem to be leaking.
Fuel Pressure – will check tonight if possibleO2 element – has never been replaced since I’ve owned the vehicle (from 130,000 to 287,??? miles).
O2 heater – has never been replaced since I’ve owned the vehicle (from 130,000 to 287,???miles).Will update this thread as I find the missing info to post here.
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Replies
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P0172-the oxygen sensor has picked up a rich condition.
Try cleaning the Maf. You could have a vacuum leak.
also check for an exhaust leak before the o2 sensor;)
IAT- Intake air temp sensor[quote=”college man” post=32745]P0172-the oxygen sensor has picked up a rich condition.
Try cleaning the Maf. You could have a vacuum leak.
also check for an exhaust leak before the o2 sensor;)
[/quote]Thanks, I’ve watched every one of Eric’s videos.
No MAF (Mass Air Flow) sensor on this vehicle.
The MAP (Manifold Absolute Pressure) / IAT (Intake Air Temperature) sensor is a single sensor with a 4 pin connector that is located in the intake manifold plenum. It has a common ground pin, a +5V reference voltage pin and output pins for the MAP and IAT. Could it be dirty enough to need to be cleaned? With KOEO (Key On Engine Off) the supply voltage is supposed to be +5V (+-.5V). With engine hot and in neutral at idle it should be 1.5V to 2.1V. Will try to check that tonight with the scanner.
Could a bad gasket between the TB (Throttle Body) and the IM (Intake Manifold) cause this code to be set?
I would start with cleaning the IAT it should be located
in the clean air duct.clean as you would a maf. you could also
clean the map sensor.The throttle body gasket would be a vacuum leak
source.which will make the computer richen up the mixture.when you do
clean the above sensors. do one at a time.clear the trouble light and see
if the symptoms improve.For that P0172, i would be looking at your pre-cat o2 voltage on your MT2500 and see if its pegged high. If it is, create a vacuum leak and see how the o2 sensor responds.
You could also do a injector leak down test if you suspect a leaking injector. Also ohm’ing each injector at room temperature may be somewhat beneficial. You have high impedance injectors so expect to see readings around 12k to 16k ohms.
However, if it was a fuel issue, your LTFT numbers would be very negative.
Another test would be of the MAP sensor with a vacuum pump and a DVOM or just a vacuum pump with your MT2500 as the voltage readings so be preset on your PID data.
Keep us posted.
O2 sensor seems to be working properly as it changes when I change the EGR with the MT2500 from NORM to FLOW to BLOCK. NORM it goes above and below about 4.5V down to 1.?V and up to 9.?V On the FLOW and the BLOCK one stays between the low to middle and the other stays between the middle and the high (I don’t remember which did which, other than NORM, so I won’t state definately FLOW did this or BLOCK did that). My assumption is that the O2 sensor is good.as it is changing with conditions changing.
EVAP tested with the MT2500 as working properly through its 3 cycle choices.
On Saturday I’ll clean the MAP/IAT sensor that’s in the intake manifold plenum and replace the gasket between the throttle body and the intake manifold and the gaskets between the EGR tube connection at the throttle body and its connection to the EGR valve (gasket at each end).
[quote=”dreamer2355″ post=32782]For that P0172, i would be looking at your pre-cat o2 voltage on your MT2500 and see if its pegged high. If it is, create a vacuum leak and see how the o2 sensor responds.
You could also do a injector leak down test if you suspect a leaking injector. Also ohm’ing each injector at room temperature may be somewhat beneficial. You have high impedance injectors so expect to see readings around 12k to 16k ohms.
However, if it was a fuel issue, your LTFT numbers would be very negative.
Another test would be of the MAP sensor with a vacuum pump and a DVOM or just a vacuum pump with your MT2500 as the voltage readings so be preset on your PID data.
Keep us posted.[/quote]
The reason he said to check the O2 readings was to confirm it’s operation AND verify the rich condition. This may not have anything to do with a vacuum leak. I think we had someone a while back with an issue with a similar vehicle and it had something to do with the fuel pump. If it were me I might be looking for a leaking injector or something or perhaps a problem with the fuel pressure regulator.
Keep us posted.
Replaced the EGR tube gasket (pictured) with a new one and put a new gasket between the throttle body and the intake manifold (which was missing, no gasket there) on Saturday. I also cleaned all the black sooty slimy crud from the throttle body again (just cleaned it about 4 months ago and it seems like it had more crud on it than the last time, which was the first time it had ever been cleaned). Had to disconnect the battery so everything that gets reset when the battery is disconnected for a couple hours was reset including the P0172 code. Wife just drove it to work this AM so we’ll see whether the code comes back with the computer thinking it’s running lean and thereby making it run rich and setting off the P0172 Rich code.
“At work. No check engine light. Feels like it is running well. No low idles at stops so far. I LOVE YOU!”
Just got this text and so far the CEL/MIL has not come back on. It’s running great, no low idle about to stall condition for the first 75 mile to work run. Hope it continues. Will update.
Well, another 75 miles on the odometer for the return trip home. No CEL(Check Engine Light)/MIL (Malfunction Indicator Lamp) or any indication of at low idle coming to a stop and wondering if it is going to die. She says it even runs smoother and not so jerky on acceleration. So far so good. Will update again at the end of the week.
[quote=”johnbkobb” post=33063]”At work. No check engine light. Feels like it is running well. No low idles at stops so far. I LOVE YOU!”
Just got this text and so far the CEL/MIL has not come back on. It’s running great, no low idle about to stall condition for the first 75 mile to work run. Hope it continues. Will update.[/quote]
Awesome!
Keep us posted!
I changed my thread icon back to yellow traffic light from the happy face I had changed it to yesterday, when I thought I had it fixed, because I just got this text this AM “At work. Car seems ok but check engine light came on before I even left the subdivision!” Will have to check it tonight when she gets home and update.
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