[SOHCSports]

Slowly ironing out the bugs on my next project (1994 Chrysler Lebaron LX 3.0). Have a couple of issues, during the first start of the day the car cranks up instantly but after that it takes multiple attempts to get her started. I am also throwing codes 21 and 52 after idling for a bit. I am pulling almost 20hg of vac at idle, so I do not believe it is vacuum related. Can someone give me a good vicinity on where to start? I believe I am going to start out with a tune up first and see where that takes me, I am also suspecting a bad fuel pump maybe? Any help/tips would be appreciated.

 

[Wiscoballer]

Fault Code 21

Synopsis

Description: Oxygen sensor signal stays in neutral region too long
Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented from running lean

Possible Causes

Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Look for melted wire insulation near the exhaust manifold. An open connection will cause this fault code.
Bad oxygen sensor - Replace the sensor which is located on the turbo housing near the down pipe (for turbo) or on the down pipe near the exhaust manifold.


Diagnostic Method

Trigger Parameters

- In closed-loop for 718 seconds (11 minutes, 58 seconds)
- Sensor output stays in the neutral region for more than 21 seconds
Results If Component Fails

A fault code 21 is stored. The circuit stays in closed-loop and the logic module will still monitor the oxygen sensor signal and allow the engine to run rich, but prevent it from running lean.

Fault Code 52

Synopsis

Description: Oxygen sensor output indicates rich too long
Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented from running lean

Possible Causes

Bad oxygen sensor - Replace the sensor which is located on the turbo housing near the down pipe (for turbo) or on the down pipe near the exhaust manifold.
Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Look for melted wire insulation near the exhaust manifold. A shorted connection to any positive source will cause this fault code.

High fuel rail pressure - See the Diagnosing Your Fuel System page.


Diagnostic Method

Trigger Parameters

- In closed-loop
- Sensor output indicates rich for more than 715 seconds (11 minutes, 55 seconds)
Results If Component Fails

A fault code 52 is stored, the circuit stays in closed-loop, and the logic module will still monitor the oxygen sensor signal. If the condition persists for four times what it took to set the code, the logic module will allow the engine to run rich, but prevent it from running lean.

from: Fault Codes - Mini-Mopar Resources

Looks like both are O2 sensor issues, replace/grab from junkyard, and retry.

 

[SOHCSports]

Fault Code 21

Synopsis

Description: Oxygen sensor signal stays in neutral region too long
Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented from running lean

Possible Causes

Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Look for melted wire insulation near the exhaust manifold. An open connection will cause this fault code.
Bad oxygen sensor - Replace the sensor which is located on the turbo housing near the down pipe (for turbo) or on the down pipe near the exhaust manifold.


Diagnostic Method

Trigger Parameters

- In closed-loop for 718 seconds (11 minutes, 58 seconds)
- Sensor output stays in the neutral region for more than 21 seconds
Results If Component Fails

A fault code 21 is stored. The circuit stays in closed-loop and the logic module will still monitor the oxygen sensor signal and allow the engine to run rich, but prevent it from running lean.

Fault Code 52

Synopsis

Description: Oxygen sensor output indicates rich too long
Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented from running lean

Possible Causes

Bad oxygen sensor - Replace the sensor which is located on the turbo housing near the down pipe (for turbo) or on the down pipe near the exhaust manifold.
Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Look for melted wire insulation near the exhaust manifold. A shorted connection to any positive source will cause this fault code.

High fuel rail pressure - See the Diagnosing Your Fuel System page.


Diagnostic Method

Trigger Parameters

- In closed-loop
- Sensor output indicates rich for more than 715 seconds (11 minutes, 55 seconds)
Results If Component Fails

A fault code 52 is stored, the circuit stays in closed-loop, and the logic module will still monitor the oxygen sensor signal. If the condition persists for four times what it took to set the code, the logic module will allow the engine to run rich, but prevent it from running lean.

from: Fault Codes - Mini-Mopar Resources

Looks like both are O2 sensor issues, replace/grab from junkyard, and retry.

Checked the fpr, looks good. I am leaning towards o2 sensor and fuel pump, since the car cranks up instantaneously after it "rested" for a while. Thanks for your help. I will try these and let you know what happens.

 

[c2xejk]

Curious how you checked the FPR. Fuel pressure in the rail? Presence of fuel in the vacuum line?

I might also check for a leaky injector.

 

[SOHCSports]

Curious how you checked the FPR. Fuel pressure in the rail? Presence of fuel in the vacuum line?

I might also check for a leaky injector.

I checked for the presence of fuel in the vacuum line.

 

[6g72 acclaim]

I would start with replacing the o2 and checking the wiring. Both codes point to bad o2 or wiring.

 

[SOHCSports]

Changed the o2 sensor. Code 21 went away, code 52 returned. Starting to suspect the FPR again. Any other tips?

 

[Wiscoballer]

are you running a AFPR? the other part of 52 is high pressure, so turn down an AFPR, or get a new FPR, preferrably a AFPR

 

[SOHCSports]

I am running a stock regulator. looked at the price of a new one. it is 80 bucks ouch. I am starting to think the fuel pump is not bad as the car will sputter then die and priming the pump seems to make starting the car worse while simply turning the key without cycling the key seems to have better results. so I am thinking the car is flooding itself out. can a regulator be bad while still not seeing any fuel in the vacuum lines? Thanks again.

 

[Wiscoballer]

im confused. By cycling the key, but not turning the engine over (off to on, not start) you prime the pump. So you prime the pump and it works? Either way, if a new stock regulator is $80, someone on the other site is selling a AFPR for $100, and 6G72Sundance has a spare rail I think. Wouldn't take too much to go to an AFPR and dial it in better.

 

[SOHCSports]

im confused. By cycling the key, but not turning the engine over (off to on, not start) you prime the pump. So you prime the pump and it works? Either way, if a new stock regulator is $80, someone on the other site is selling a AFPR for $100, and 6G72Sundance has a spare rail I think. Wouldn't take too much to go to an AFPR and dial it in better.

Sorry for the confusion lol. I meant simply turning the engine over (without doing key on engine off repeatedly) several times starts the car. it will however sputter as if the car is recieving too much fuel. after a while the idle will smooth out. after a period of time code 52 will return.

 

[Wiscoballer]

id say the code is right then, that it is recieving too high of fuel pressure, and therefore too much fuel. Nothing else to do but see if you can get an in line AFPR cheaper, and regulate it before the FPR, or just go to a single AFPR.

 

[SOHCSports]

Found one at Autozone for around 70 bucks going to try it out and post results. I do not want a AFPR until I get ported heads. At that point I will add a Greddy Emanage and FMU to compensate where the stock fueling runs out. Oh yeah this is going to be an N/A build by the way. :nodding: There is a N/A A604/3.0 Shadow around here that bracket races 14.7 consistently naturally aspirated.

 

[Wiscoballer]

sounds good, I understand your hesitation on the AFPR now. Good luck, and let us know if it fixes it.

 

[SOHCSports]

Turned out to be an injector stuck open, replaced it with a new one. Regulator is fine. Upon further diagnosis it did not add up to me that there was no fuel in the vacuum lines or throwing map codes (FPR symptoms). While I had the fuel rail off I went ahead and installed new o-rings on the rest of the injectors. Thanks again.