Can't find the problem

[cobraboy169]

I have a 98 Cobra that is giving me hell. I keep getting check engine lights for the System too lean on both Bank 1 and Bank 2. The DTC codes are P0174, P0174. I have gooten two different tunes but eventually the check engine light keeps coming back. I am now thinking that I have a vacuum leak somewhere the only problem is I can't seem to find it. I have used carb cleaner around the entire engine and I can't seem to find the problem.

I thought the problem could be not changing the intake gasket when I swtiched out my lower intakes. I am thinking that may be it but when I was spraying the carb cleaner the rpms never jumped or smoothed out. I can smell what seems to me like a little bit of fuel coming from the backside of the enigine on the driver's side but again I cannot see any fuel puddles or leaks anywhere. The car is running through gas extremely fast and I just can't seem to figure out why. Does anyone have some suggestions about what might me going on? Other techniques to find the problem are welcomed.

 

[Toasty]

take it apart, clean the intake gaskets, and the imrc gaskets, let them dry thoroughly and then reinstall everything carefully. Some of the intake gaskets have a rubberized insert - check to see that yours is not torn.

The intake to imrc and imrc to head gaskets are reuseable. I think I sprayed mine down with brake cleaner and carefully cleaned them, let them dry, and then reused them. Zero issues with 6# of boost.

HTH

 

[SNAKEYE]

Do the O2 sensors have more than 50K miles on them? If so they may be due for replacement.

 

[Slow95Cobra]

its buring more fuel because the PCM is adding fuel for the lean condition. P0171 and P0174 codes are not normally o2 concerns. the o2's are picking up more oxygen than the MAF is reading on the intake side... so the pcm starts adding fuel, untill the Long Term Fuel Trims go over 10%, then it sets a code for the bank, or banks running lean. do you have a way to datalog the Short Term & Long Term Fuel Trims? and can you datalog the Baro. on the MAF?

 

[Tx_Diablous]

Your code says you are running lean but if you are flying through fuel that can not be true unless you have a leak and a vaccuum leak would most screw with your Idle. If no fuel leak I would say you have a bad O2 somehere and with no way to monitor the O2 I would just change them. If you can monitor what the PCM sees then that is a horse of a different color. I can help you out with what it shoud be seeing if you like but I need some O2 numbers.

 

[cobraboy169]

Thanks everyone. I changed my O2 sensors less that 1K miles ago so that can't be the problem. I have heard that when the vehicle is running too learn the computer automatically compensates for that and adds fuel. I have also heard the same for when the vehicle is running too rich. Is that not right? My idle is a little irratic but aht is because the TPS is a little loose. For some reason when I changed the T/B the TPS wasn't on it so I had to take the stock one off and the screw it onto the new T/B. For some reason the screws wont go in all the way without stripping so it is a little loose but it only jumps every once in a while.

I also have an IMRC delete kit so I don't have the IMRC gaskets. (At least I don't think I have them on the vehicle any more). I put the delete kit on years ago so I dn't remember. I am thinking of getting an extra Intake gasket just in case and then take it apart like Tosty mentioned and see what I can find.

do you have a way to datalog the Short Term & Long Term Fuel Trims? and can you datalog the Baro. on the MAF?

I am not too sure how I would do that. I have an SCT Xcal2 tuner but I am not sure if I can check the Short Term & Long Term Fuel Trims. If you let me konw how to do this I will give it a shot and see what comes up. Thanks again everyone.

 

[coolguy10786]

What kind of injectors are you running?

 

[cobraboy169]

They are the stock injectors. They have not been replaced since I have owned the vehicle. I have been thinking about changing them but I didn't think it was necessary.

 

[STAMPEDE3]

Could be exhaust leak.

Could it be that the TPS voltage is off from being loose and isn't matching what it should compared to what the MAF and O2s are saying?
I'm not sure if the TPS is figured into that but I think it is.

 

[Cookieman00x]

try reverting back to the stock tune, reset the ECU and see if the problem goes away.

 

[cobraboy169]

Could be exhaust leak.

Could it be that the TPS voltage is off from being loose and isn't matching what it should compared to what the MAF and O2s are saying?
I'm not sure if the TPS is figured into that but I think it is.

I have a slight exhaust leak due to the BBk LTs not matching up properly with the EGR tube going into the driver's side header underneath the driver's side head. It is very secure but it has a very small leak due to the small amount of space to get the wrench down in there to tighten it up more. I am not too sure about the TPS sensor either. It seems to have all started since I changed the lower intakes. Im going to start where I last left off then go down the list of suggestions from everyone here. Thanks all.

 

[theHumP]

Your running lean, you smell gas toward the rear of the motor, you are burning through gas... Check the o-rings on you injectors or verify that they are seated firmly, maybe your leaking fuel that should be going into the cylinders which would present the smell, and cause the codes.

 

[97cobraheaven]

Your running lean, you smell gas toward the rear of the motor, you are burning through gas... Check the o-rings on you injectors or verify that they are seated firmly, maybe your leaking fuel that should be going into the cylinders which would present the smell, and cause the codes.

Agreed, check your injectors. Make sure they are all plugged in. I had one come loose and was burning through fuel and just wasnt running right. Sure enough the injectors electric plug-in came loose so it wasnt spraying any fuel in that cyclinder at all

 

[fordvicious32v]

guys its funny because i have the same ****ing problem but my car has aftermarket injectors i think they are 30lbs, i replaced the rear o2's only should i replace the fronts also? i need to do plugs and wires, i replaced the fuel filter and it feels a lot better but it keeps giving me the P0174 & P0172 codes

 

[mwolson]

Did you get a tune for your long tubes?

The PCM is sensitive to the amount of time that the exhaust gasses take to get from the combustion chamber to the O2 sensors. The PCM correlates the O2 sensor readings to the combustion events that caused the exhaust gasses at the O2 sensor at that time.

If your tuner does not adjust a table called "O2 Transport Delay in Revs", the PCM will be trying to hit stoich based on fuel data from the wrong combustion events. FYI, the delay for stock exhaust manifolds is 8 to 15 revs, depending on Load and RPM. If the distance to the O2 sensors on your long tubes is 50% longer than stock, then that table should be increased by about the same amount for you to have a proper tune for your particular engine, including your long tubes.

 

[cobraboy169]

guys its funny because i have the same ****ing problem but my car has aftermarket injectors i think they are 30lbs, i replaced the rear o2's only should i replace the fronts also? i need to do plugs and wires, i replaced the fuel filter and it feels a lot better but it keeps giving me the P0174 & P0172 codes

It depends on what type of exhaust you have on your vehicle. If you don't have any cats on your vehicle then it is point less to change them. The rear ones are called Cat monitors so if you don't have any cats on the vehicle then it will not matter how old or new those are. You need to change the front o2 sensors if anything. Those are my thoughts. I just had that talk with my father about the o2 sensors and changing them.

yes, I did have the vehicle tuned for the LTs i am going to try a couple different things and have my dad run a Diag test on my vehicle and he said he should be able to identify the problem. I had Rick from Amazon Tuning Solutions tune my car and he tried a couple different things. I know it is not the tune it is something with the vehicle, a leak of sum sort, or a fuel leak, or both.