Engine Performance problem
1997 Oldsmobile Aurora V8 Front Wheel Drive Automatic 151000 miles
I replaced my air filter 2 weeks ago with a K& N. Since then my check engine light has been going on and off. Both o2 sensors heater low voltage and slow response, p1139 p1140 manufactured controlled codes whatever that means, (Fuel and Air Metering). EGR Flow, p101 MAF. Now I cleaned the MAF sensor and its still acting up, bbut only at low RPMS, highway driving is fine. I was told O2 sensors would not cause this because the computer would compensate to a preprogrammed setting if it detects a malfunction in O2 sensor. Samer thing with MAF. They said computer would compensate if it sensed a problem with sensor. Is this true and if not what do I replace first O2 sensor or MAF sensor. Car is really running hot (250 degrees) but was told that normal for that vehicle. Really Loud clanging noise under heavy load mainly during takeoff. (Possible detonation?) I guess my question is, can one sensor cause the other sensors to throw codes or are they all bad, I dont want to fix somethinf that isn't broken.
A bad mass air flow sensor can cause several other codes to set, especially slow response o2. I would replace mass air flow first, its the easiest and most common. 250 is too high to bew running. Anything above 228 is when you need to take action. The engine will boil over at 257 degrees. Are the fans coming on?
February, 26, 2009 AT 6:42 AM
Thanks for your prompt response, just to give you and update before I answer your question, I replaced fuel filter, cleaned EGR and Throttle Body, as well as the MAF sensor a second time but thouroughly. I cleared the codes since then and so far so good. Now to answer your question first the MAF did'nt malfunction till I installed the K& N but since I cleaned it that may have been the problem, (wait and see), secondly the car doesn't constantly run at 250 maybey for a minute or two, (need to check fans) i've never had a V8 so didnt know if that was normal, now I called Cadillac (cause oldsmobile no longer exsists), and they tell me that anywhere between 180- 220 is normal operating temp for that vehicle but not uncommon to temporarly exceed that. Thats what the aurora forums are telling me too. But I thought the same with the boiling boint, it doesn't make sense, but their telling me that Northstar Engines always run hotter than normal v8's. What do you think should I replace the Thermostat or start looking further?
February, 27, 2009 AT 4:58 PM
First of all your driveability problem has probably been resolved by cleaning the mass air flow sensor since you say it started right after the k and n, because the oil from the filter most likely caused the malfunction of the mass air flow sensor. There are big warnings not to over oil the filters because the y will damage mass air flow sensor. As for the running temp, I actually worked for oldsmobile when there was a oldsmobile and worked on a lot of auroras. The coolant fans come on at 228 degrees and the high speed fan comes on at I think its 235 so it should not go over that hot. If it reaches that temp and the fans come on and the temp falls down then this is normal but 250 is definitely too high.