P0172-final plea for help

OBDII

OBDII (1996 and up)

profile | register | preferences | faq | search

UBBFriend: Email This Page to Someone!

next newest topic | next oldest topic

Author	Topic: P0172-final plea for help
gbrand Member	posted 02-14-2003 09:50 PM 96 2.4L Pontiac Sunfire 5spd-Been getting an intermittent code P0172(running rich) for over a year-at inspection last fall took to state certified emission shop, said fix it. They said there is nothing wrong, and passed it. code has come and gone since. about 1 month ago it came up solid-along with P0420 catylast low effeciency. So I took back to them, said fix it. They said oh your cat is bad. I said the cat is full of crap because the car is running rich, that is the root cause problem and must be solved before replacing cat. So they replaced front o2 sensor-which I had replaced just before inspection-and the codes cleared-(or were cleared). When I told them I didn't think the root cause had been found, as the O2 sensor had been recently replaced they yuk-yuked "well I hope you kept the reciept so you can get your money back on the O2 sensor. WEll, 3 days later the P0172 came back, and then a week later the P0420 came up-I took it back and told then "I hope you have the receipt for the sensor" they checked all over and gave up-gave me my money back on the sensor(but not the labor). I have checked compression, replaced coil packs, housings and boots, fuel filtercleaned IACand throttle body,. They said the fuel pressure and all sensor readings during live monitoring looked good. Teh car runs good, may have a little stumble at idle. I am suspecting maybe a leaky fuel injector-or a trip to dealer. Anybody had anyhtng like this? IP: Logged
KAP1014 Member	posted 02-14-2003 11:00 PM Do you have any obvious signs of the car running rich other than "maybe a little stumble at idle" that occurs? Any smoke out the exhaust? Does it smell like it is running rich? The first thing that I would like to see is the Freeze Frame and Failure Records for the codes when they were stored and how many times they have occured. That can provide some insight into what is happening when it sets the code. An intermittent MAF or MAP sensor or a CTS reading bad can make it run rich. A bad ground to the HO2S can do the same thing. If the codes are there, don't clear them, leave them there and get the FF and FR data and post what you can from that. I'm sure there will be a good hint in them as to what is causing your problem. IP: Logged
gbrand Member	posted 02-15-2003 08:51 AM Thanks fro the help-There is some carbon on the exhaust tips, the plugs had some light carbon on them, and with the cat code coming up I think the car is running rich at times. Also in hot weather it sometimes dies or bogs after sitting at a stop light for a while. Like an old carbed car with the choke not fully releasing. Can't test that behavior until summer though.. There is no MAF sensor on this car, and the Throttle body cleaning and Super fuel injector cleaner I ran thru the tank seems to help in the short term to reduce the frequency of the P0172. This is why I am thinking possibly the injectors. I cannot pull the freeze frame data, but I know a dealer or real shop can can, so I will not clear codes. MY cheap code reader will only pull/clear codes and give moniter status, but has already paid for itself to on the preliminary work or these guys would have put a cat on my car for 800-1200 bucks and not solved the real problem. Also pinpointed several other problems on my truck. IP: Logged
KAP1014 Member	posted 02-15-2003 02:16 PM The best way to check the injectors is to use a labscope with a low amps probe to see how the injector is working. Getting a good waveform from one can tell you the condition of the coil inside the injector, but looking at the pattern from an amp probe tells you the working condition. Another possible way to see if your injectors are bad is to do a resistance check on them. Unplug the injectors and check the resistance between the terminals on each one. They should be 1.9 to 2.1 ohms for this engine. If any are out of spec, they need to be replaced. Many times they will be within specs and still be bad, the electrical condition of one doesn't help determine whether it is clogged or dirty. Even with an amps probe on them, you can't see how the spray comes from one. It can be releasing the right amount of fuel incorrectly and cause a rich condition. The fuel pressure regulator is a common problem on these engines also. With the engine running, the fuel pressure should increase about 5 psi when the vacuum line is disconnected from the regulator. Another thing to check is for gas coming out of the regulator when the vacuum is removed. If it is, the regulator is bad. IP: Logged
gbrand Member	posted 02-15-2003 11:20 PM Thanks again for input, No gas coming from regulator vac line, had checked and it holds vac.as well. The shop claims they tested fuel pressure and it was in spec. Virtually impossible to get to connectors without disassy of rail/injectors on this motor. Thsy claim there was a siganl to all injectors-I believe as car basicly runs OK most of the time. But if one is leaking there is no electrical way to determine that. IP: Logged
KAP1014 Member	posted 02-16-2003 03:05 AM Check the fuel pressure with the key on, engine off. Pressurize the line by cycling the key a couple of times and watching the pressure gauge, if it drops more than 5-10 psi in 2 minutes or so, you have a leakdown problem. It might also be that the injector spray pattern is bad, which creates a nightmare to diagnose. The fuel spray is more like a stream and doesn't atomize with the air and causes a rich condition that doesn't get corected by the computer fuel trim. IP: Logged
gbrand Member	posted 02-17-2003 09:11 PM OK, Sunday disaasy of fuel rail-injectors all looked and tested good, no leakage. very little dirt. Put back together with new Orings, we'll see IP: Logged
gbrand Member	posted 03-06-2003 08:57 PM OK, took to dealer(had a recall on a steering part to fix too)-told them to fix it. Told thenm history. They called me back and said I had a vac leak near the #1 injector and the Cat is bad. I told them fine, fix the vac leak and the P0172 code, ther was no point in fixing the cat until the rich running problem was fixed. Tehy argued and argued that they could not do anything until the catwas fixed, that the"GM waY" the mechanics could not work on a car unless they fixed everything first. Even thought the cat was not the cause of the problem. I told them to fix what I asked and that once the P0172 problem was fixed then I would fix the cat/ I told them as a agent of the manufacturer they had an obligation to fix the car when oterhs couldn't they refused and told me to pick up my car. I am going to complain to the the general manager and find another dealer if need be, GM has trained thier service dept to generate revenue, not fix cars Or this dealer is crooked. IP: Logged
carfixer Member	posted 08-07-2004 08:56 AM OK, Can you tell me under what conditions the P0172 code sets? What's the ECT read? How long from start up? It would be a BIG help if you could get a scan tool that will allow you to monitor the short term fuel trims from a cold startup? This might be a ground issue! [This message has been edited by carfixer (edited 08-07-2004).] IP: Logged
sonny Junior Member	posted 08-08-2004 03:19 PM Could this problem be caused by a "stuck open" EGR valve? sonny IP: Logged
gbrand Member	posted 08-22-2004 09:22 PM Thanks for the responses and sorry for the dealy in responding. Was on a 2000 mile trip with the sunfire and then up return needed to get another car,91 Legacy, ready for a tailpipe test-it passed! On the trip the CEL went on and off several times, and now is stuck on again. I read the codes upon return and both the P0172 and P0420 are back, both indicating they are illuminating the CEL. As far as the EGR, I had removed it and it seemed to be freely operating and relatively clean. Yes, a more sophisticated scan tool would help, that is what I thought I was paying the dealer and the repair shop to use. The repair shop said they used the Autotap and everything was fine, (but didnt see the code GET thrown) and the dealer flat refused to do any diagnosis until the cat was replaced. I am going to replace the plugs and the coil housing in the car-at an earlier time(may 2002) the dealer replaced the coil packs, plugs and coil housings and over xmas(2003) the car developed an intermittnet miss-sthrough trial and error I narrowed it down to the coil housing, and since the repair was under lifetime warrenty I want a new one-I had them save the old parts so the old housing is now on the car. Also they told me a line of crap that the new autolight plugs I had just installed 100 miles prior to failure may have caused my coil packs to burn out, I sent the plegs and all defective parts back to autolite and they said that was a crock of crap. If this helps at all almost on a regular basis the CEL would be off, then I would drive to work, about 52 miles on some freeway but mostly 4 lane stop and go traffic at about 45 to 60 mph between lights. Then i would leave work, drive about 4 miles and at the second stop light i came to the CEL would come on and the code was the P0172. it would stay on for a day or 2, usually go out while i was driving around home and then caome on again at the same light. Again, thanks for your help all, i will post updates as I work on this and inspection time gets closer IP: Logged
BMasterjerry Member	posted 08-23-2004 07:04 PM ...And WHY can't the Catalyst be bad? IP: Logged
WILD BILL Junior Member	posted 08-23-2004 08:38 PM quote: Originally posted by gbrand: Thanks for the responses and sorry for the dealy in responding. Was on a 2000 mile trip with the sunfire and then up return needed to get another car,91 Legacy, ready for a tailpipe test-it passed! On the trip the CEL went on and off several times, and now is stuck on again. I read the codes upon return and both the P0172 and P0420 are back, both indicating they are illuminating the CEL. As far as the EGR, I had removed it and it seemed to be freely operating and relatively clean. Yes, a more sophisticated scan tool would help, that is what I thought I was paying the dealer and the repair shop to use. The repair shop said they used the Autotap and everything was fine, (but didnt see the code GET thrown) and the dealer flat refused to do any diagnosis until the cat was replaced. I am going to replace the plugs and the coil housing in the car-at an earlier time(may 2002) the dealer replaced the coil packs, plugs and coil housings and over xmas(2003) the car developed an intermittnet miss-sthrough trial and error I narrowed it down to the coil housing, and since the repair was under lifetime warrenty I want a new one-I had them save the old parts so the old housing is now on the car. Also they told me a line of crap that the new autolight plugs I had just installed 100 miles prior to failure may have caused my coil packs to burn out, I sent the plegs and all defective parts back to autolite and they said that was a crock of crap. If this helps at all almost on a regular basis the CEL would be off, then I would drive to work, about 52 miles on some freeway but mostly 4 lane stop and go traffic at about 45 to 60 mph between lights. Then i would leave work, drive about 4 miles and at the second stop light i came to the CEL would come on and the code was the P0172. it would stay on for a day or 2, usually go out while i was driving around home and then caome on again at the same light. Again, thanks for your help all, i will post updates as I work on this and inspection time gets closer IP: Logged
WILD BILL Junior Member	posted 08-23-2004 08:43 PM SOUNDS TO ME LIKE YOU HAVE A DIRTY OR STICKY INJECTOR. YOU WOULD NEED TO READ TO FUEL TRIM WHILE THE CODE IS A HARD CODE. IF IT IS THE MINUS THAT MEANS THE PCM IS TRYING TO TAKE FUEL AWAY DUE TO A RICH MIXTURE. INJECTOR BALANCE TEST WOULD BE INLINE AND AN INJECTOR CLEANING ALSO, SOMETIME TIMES IT NEEDS TO BE DONE TWICE TO BE EFFECTIVE. HOW MANY MILES ON THIS THING ANYWAY? quote: Originally posted by gbrand: Thanks for the responses and sorry for the dealy in responding. Was on a 2000 mile trip with the sunfire and then up return needed to get another car,91 Legacy, ready for a tailpipe test-it passed! On the trip the CEL went on and off several times, and now is stuck on again. I read the codes upon return and both the P0172 and P0420 are back, both indicating they are illuminating the CEL. As far as the EGR, I had removed it and it seemed to be freely operating and relatively clean. Yes, a more sophisticated scan tool would help, that is what I thought I was paying the dealer and the repair shop to use. The repair shop said they used the Autotap and everything was fine, (but didnt see the code GET thrown) and the dealer flat refused to do any diagnosis until the cat was replaced. I am going to replace the plugs and the coil housing in the car-at an earlier time(may 2002) the dealer replaced the coil packs, plugs and coil housings and over xmas(2003) the car developed an intermittnet miss-sthrough trial and error I narrowed it down to the coil housing, and since the repair was under lifetime warrenty I want a new one-I had them save the old parts so the old housing is now on the car. Also they told me a line of crap that the new autolight plugs I had just installed 100 miles prior to failure may have caused my coil packs to burn out, I sent the plegs and all defective parts back to autolite and they said that was a crock of crap. If this helps at all almost on a regular basis the CEL would be off, then I would drive to work, about 52 miles on some freeway but mostly 4 lane stop and go traffic at about 45 to 60 mph between lights. Then i would leave work, drive about 4 miles and at the second stop light i came to the CEL would come on and the code was the P0172. it would stay on for a day or 2, usually go out while i was driving around home and then caome on again at the same light. Again, thanks for your help all, i will post updates as I work on this and inspection time gets closer IP: Logged
gbrand Member	posted 08-24-2004 05:28 AM Of course the Cat CAN BE and prolly is bad by now-but putting a new cat on a car that is running rich will only ruin it as well. My request was to fix the running rich problem first and then replace the cat. Also for quite a while after clearing the codes only the P0172 code would come up, not always the cat code. As far as the injectors go,i did take them out , clean and ohn and test themm-all seem to be fine. I have also used fuel injector cleaner on a regular basis and Seafoam also. Because of the physical wiring on this car an injector balence test would be impossible to perform with contructing some type of a break out harness to selectively tuen off the injectors one by one. And if the problem is intermittent it may not show up. I wne tback to the dealer yesterday, one of the times replaced under a lifetime warrenty repair in may 2002 ws a coil housing, after an intermittent miss(after the code problem had come up) turned out to be a defective coil housing(I had then save my old parts) , i solved by lots of trial and error trouble shooting. The dealers take on replacing the ne coil housing is that he will not do it even as it is not on the car even though they-A) replaced a part that ewas not defecive B) I have saved them the diagnosis and time to bring a car into their shop for warrenty repair. i think this delaer's service dept is a borderline fraud. They are calling the cfactory to see if the will authorize giving a part wiwthout me putting the defective housig back on the car and taking it in for a diagnosis. My nest step will be to get this hassle with the coil cover straightened out, as a matter of principle, put in a new set of plugs and look at again. Thanks again for all your help. Unfortunately I know thier is not going to be an easy solution for this problem IP: Logged
carfixer Member	posted 08-24-2004 08:28 AM quote: Originally posted by gbrand: Thanks for the responses and sorry for the dealy in responding. Was on a 2000 mile trip with the sunfire and then up return needed to get another car,91 Legacy, ready for a tailpipe test-it passed! On the trip the CEL went on and off several times, and now is stuck on again. I read the codes upon return and both the P0172 and P0420 are back, both indicating they are illuminating the CEL. As far as the EGR, I had removed it and it seemed to be freely operating and relatively clean. Yes, a more sophisticated scan tool would help, that is what I thought I was paying the dealer and the repair shop to use. The repair shop said they used the Autotap and everything was fine, (but didnt see the code GET thrown) and the dealer flat refused to do any diagnosis until the cat was replaced. I am going to replace the plugs and the coil housing in the car-at an earlier time(may 2002) the dealer replaced the coil packs, plugs and coil housings and over xmas(2003) the car developed an intermittnet miss-sthrough trial and error I narrowed it down to the coil housing, and since the repair was under lifetime warrenty I want a new one-I had them save the old parts so the old housing is now on the car. Also they told me a line of crap that the new autolight plugs I had just installed 100 miles prior to failure may have caused my coil packs to burn out, I sent the plegs and all defective parts back to autolite and they said that was a crock of crap. If this helps at all almost on a regular basis the CEL would be off, then I would drive to work, about 52 miles on some freeway but mostly 4 lane stop and go traffic at about 45 to 60 mph between lights. Then i would leave work, drive about 4 miles and at the second stop light i came to the CEL would come on and the code was the P0172. it would stay on for a day or 2, usually go out while i was driving around home and then caome on again at the same light. Again, thanks for your help all, i will post updates as I work on this and inspection time gets closer The cat is most likely bad. Can't you get the FF (freeze frame) with your scan tool? If a scan tool can't give you the FF data I would sell it and buy something different. IP: Logged
joe4 Junior Member	posted 08-24-2004 12:19 PM >>I am going to replace the plugs and the coil housing in the car-at an earlier time(may 2002) the dealer replaced the coil packs, plugs and coil housings and over xmas(2003) the car developed an intermittnet miss-sthrough trial and error I narrowed it down to the coil housing, and since the repair was under lifetime warrenty I want a new one-I had them save the old parts so the old housing is now on the car. Also they told me a line of crap that the new autolight plugs I had just installed 100 miles prior to failure may have caused my coil packs to burn out, I sent the plegs and all defective parts back to autolite and they said that was a crock of crap.<< The new ignition systems are very sensitive to secondary resistance so that statement that the plugs burned the coils could be true, I myself have trouble keeping up on the latest. From reading a lot of posts on the problems people have going with non OEM plugs I am going to stick with OEM, what ever it comes with from the factory is going back in. IP: Logged
BMasterjerry Member	posted 08-24-2004 10:01 PM quote: Originally posted by gbrand: Of course the Cat CAN BE and prolly is bad by now-but putting a new cat on a car that is running rich will only ruin it as well. My request was to fix the running rich problem first and then replace the cat. Also for quite a while after clearing the codes only the P0172 code would come up, not always the cat code. I don't know the complete history of your car but if the Cat is partially restricted, it can be throwing the rich code (PO172) because the exhaust system isn't "breathing" correctly. Could be damaged from an earlier problem. Just a thought... IP: Logged
carfixer Member	posted 08-25-2004 05:48 PM quote: Originally posted by BMasterjerry: I don't know the complete history of your car but if the Cat is partially restricted, it can be throwing the rich code (PO172) because the exhaust system isn't "breathing" correctly. Could be damaged from an earlier problem. Just a thought... Exactly, That's why I like to look af fuel trims. They can tell you a lot. IP: Logged
YardMech Junior Member	posted 09-09-2004 09:31 AM Side note: I have exactly the same car (96 Sunfire 2.4L) with very close to the same symptoms (P0172 and P0420)- not solved yet, but my current suspect is the MAP sensor, leading to poorly timed firing. I'd gone through the coil packs and ICM checkouts without finding anything wrong - and as a comment, I can't beleive that non-name brand spark plugs can destroy coil packs! IP: Logged
gbrand Member	posted 09-09-2004 06:28 PM YardMech, finally someone with the same car, same problem! in last 2 weeks I have driven almost 2000 miles and read the codes today, still P0172 and P0420. I have not done anything to the car, and prolly will not for a week or so at least due to other things I need to work on. As mjfeeney stated in the post on the 98 ford, http://www.obdii.com/ubb/Forum1/HTML/001408.html simply replacing O2 sensors and cats does not attack the root cause problem that is makeing the vehicle run rich. The links to the Wells pages is great, and OMG use an actual gas analyser to supplement the OBD2 reading to pinpoint the problem. I THOUGHT that was the type of expertise i was going to get by paying big bucks at a state emission shop and a dealer, but got monkeys instead. I will get back on this and let all know any updates, YardMech if you find anything let me know. Thanks again for all help IP: Logged
holstdb Member	posted 09-14-2004 02:15 PM gbrand, one other thing I'll toss in. When you do decide to get the catalytic convertor replaced, I wouldn't go to the GM dealer! It will cost you a fortune. The 2.4 LD9 Twin Cam from 96-98 uses a downpipe and cat that is one piece, and the flange where it bolts to the manifold has this accordion flex joint that is very prone to cracking. If it's original on your car you probably need a new one anyways. My advise is to check around, that whole assembly is less than $200 from Summit Racing (stock OEM replacement) http://store.summitracing.com/default.asp?target=esearch.asp&N=100&Ntk=PartSearch&Ntt=CTO-4107&x=8&y=5 It's part number CTO-4107 mfg by Catco, you can get it other places too. Trust me, I've been there, I just swapped a 2.4 TC engine and 5spd trans into a 96 Beretta. GM dealer wanted $500 bucks for the downpipe/cat I believe, and I get parts for "trade" which is a discount price. IP: Logged
micronot Junior Member	posted 08-02-2006 05:08 PM I have a friend with a Ford Escort with similar issue. He took his car to a local mechanic where they tried to replace the cat and the O2 sensor but the same codes came back. He took the car back to them and they just wanted to replace the same parts again, so instead this time he took the car to the dealer... and I was real surprised what the dealer replaced... they replace the PCV valve! Thats all and the codes havent been back since. I found that hard to believe, but I can't see why the dealer would lie to him about doing a repair that was so cheap and it did make his problem go away. IP: Logged
gbrand Member	posted 08-08-2006 09:15 PM Thanks for your suggestions, i hadnt been on this forum as oftern as I like to recently. Last year(Fall 2005) I was able to clear the codes, and get the monitors to run-all but the Cat-but here you can have 2 monitors unready and still pass as long as the MIL is not lit. So I passed inspection, and the light came on and has stayed on since. Last night I cleared the codes, and after driving to/from work, 25 miles each way, and read them tonight-no pending, and all monitors set except the cat-so could pass isnpection if it was up today. I did putin new plugs this summer, and also hosed out the external surface of my radiator-was getting to upper end of normal range(220) when stuck in traffic w/AC on(fan was on) and 100+ outside. Now goes up to 200. I will monitor thsi as time goes on, BTW there is no PCV valve on this car. IP: Logged

All times are CT (US)	next newest topic \| next oldest topic
Administrative Options: Close Topic \| Archive/Move \| Delete Topic
	Hop to:

Contact Us | OBDII Home Page

The OBD-II Home Page is hosted by B&B Electronics of Ottawa, Illinois