Question Hi Roland, I am a 30 year ASE Master Tech. with zero exreience on Chrysler. (Foreign specialist) I earned this vehicle FREE or she would be driving a Jetta.
After engine replacement, and upon startup, (10 seconds) the check engine light comes on and stores PO171. How is this possible? We are still in open loop and none of the monitors are even set. It only happens first COLD start. If I clear it, it will not occur the rest of the day. Only AM cold. Almost always.
STF, LTF, Map all look good. No leaks. (Smoked it) No degradation of performance whatsoever. Light on or off. How can that code set in the first 10seconds of operation?
I appreciate any ideas/help.
Regards,
Mark
AnswerHi Mark,
The monitoring doesn't occur until closed loop mode, as you surmise. However the elevation to code status, light 'on' etc. doesn't occur until the second consecutive trip and a freeze frame is stored. Perhaps it has "matured" at the close of the previous day, but it isn't going to alarm until the next start-up (cold or hot). You didn't mention whether you are clearing the code with DRB III or equivalent or by battery disconnect which might be a factor. I would look into the 02 sensor as the cause rather than ponder too much longer. If you want to discuss this some more use the "thank and rate" tab which has a section for comments. You don't have to wair for my "availability" that way. I would appreciate a translation of STF and LTF.
Roland
PS Please don't "dis" Chrysler-products. We have a '75 Westfalia in our garage about which I can't say too much, but on the otherhand our experience with a '91 Jetta was frustrating to say the least. You may find the Stratus to be OK after this is cleared up.
Roland, thanks for the RE: I abbreviated. STFT and LTFT. (Short and long term fuel trims) Clearing with a Snappy. Westfalia? That's your own fault.VBG Do you have a Type 4 next to it? I'm curuious though, how could you have a tough problem on a 91 Jetta? They are pretty straight forward. E-mail me if you need any help on the Euro's. in the future. I took a quick peek at the O2's waveform and it looked slightly lazy, but not out of parameters hot. I do not see how the ECU expects any signal from an O2 in the first 10 seconds. Even if it is a heated one?
Hi Mark,
Just a conjecture that because the code doesn't 'mature' until there are two consecutive failures, might it not wait to display until the third key cycle? I agree with you otherwise about the open loop not being relevant, unless the coolant sensor is off-value and it thinks it is time for closed loop operation. Maybe check for codes immediately after the second trip and see if it shows up on the third key, when its hot.
Fortunately the '91 Jetta is gone. It has the RX (or R something, 1.8L engine) and an automatic trans and A/C and it was hell to work on, no space in the engine compartment for most jobs like the starter, the exhaust manifold bolts, even changing the oil filter was a knuckle-bruiser. I was glad to be able to sell it when another car became available from a family member. I have to beg ignorance of the specifics of the type 4 engine, is that the water-cooled? But the type 2, 1.8L FI 'loaf' has been totally reliable. Thanks for the offer of help in the future.
I hope you can sort out the 0171 situation
