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3100 TPS, MAF, O2 issues?


nebojsa_o

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Hey all. Not sure how long this will turn out to be once I'm done typing, so sorry in advance, but please give it a read... :laugh:

 

Alright, '96 Cutlass, 3100... For the last year or two, if I got WOT for a bit, like 0-120ish km/h, or 50 to about the same, I would get a CEL, code P0131. It goes off after a few normal driving cycles, and doesn't come back until I do the same thing again. So a few months ago, I did the LIM and headgasket, and while I was at it, I replaced the Oxygen Sensor, and when it was all back together, I tried a WOT run, and the same code came, so I said fuck it for now.

 

I didn't drive the car in a while, my mom's been using it for work and back. And the few times I drove it, there was no bagging of any sort, and no issues.

 

Then one time I was merging, and stepped on it, and the car felt a bit sluggish, hesitant to go, and accelerated slowly (slower than the usual slow).:laugh: And it didn't wanna downshift.

 

So a few days ago I did the LIM again since I fucked up the silicone process last time, and it was leaking oil a bit. All went well, no more oil leak, so I drove it around for a bit to make sure all was well. The hesitation is definitely more noticeable than the first time I noticed it, about a month or so ago.

 

No CEL, but I assumed TPS. I checked the resistance on the TPS, and it would gradually go up until the throttle is half open, and then anything after half reacts the same as closed throttle. So I went to the J/Y and checked a TPS there, went nice and gradual from closed to WOT. I brought it home, and installed it.

 

Start the car and CEL is on. I check the code and it's P0121. The car defenitely drove better, but the light was on. So I turn the CEL off, and go for a bit of a cruise. Went WOT a couple times, and it downshifts every time, and is much better than it was, but one WOT run was slower than the other... Rpms climb slower as well as the speed. Pulling into the crescent, the CEL comes on again.

 

I park on the driveway, and scan for codes, 2 of them this time. P0101, and P0131...

 

P0121 - Throttle Position Sensor circuit, range, or performance problem

P0101 - Mass Air Flow sensor circuit, range or performance problem

P0131 - Oxygen sensor circuit, low voltage (upstream sensor)

 

So until I replaced the TPS there was no codes at all, and now I'm getting TPS and MAF, and that Oxygen sensor code that's "normal" after a longer WOT run...

 

Can the TPS cause MAF to go bad? The TPS was most likely messed up for a some time now, but it drove perfect unless you went WOT, and no one did, so who knows how long it's been bad. Any ideas, pointers? Try another TPS, clean MAF, undo the battery, reset the shit, anything?

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The P0131 is not normal at all after a long WOT run.. Thats indicating that you are prolly running lean as fuck. The PCM expects the O2 voltage to be around the .7-.9v range when WOT.

 

I would be willing to bet the MAF is failing or extememly dirty.

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I second the MAF issue. If the MAF isn't reading the correct volume of air at WOT (aka lots of air) then the computer is going to pull fuel and as soon as that happens the O2's swing wildly lean, next thing you know the computer has no idea what's going on because one major sensor is telling it to reduce fuel while another less important sensor is telling it to add fuel.

 

Take the MAF out and clean it with cleaner and a Q-tip. Make sure you don't leave any residue on the wires.

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Wouldn't the MAF code come up at some point earlier? Is it just a big coincidence that it came as soon as I replaced the TPS? Thanks for the advice, keep it coming. :thumbsup:

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No, and heres why.

 

When the TPS failed, the PCM set the P0121 DTC, at which time the PCM defaults to the MAP sensor and ignores the MAF readings to a certain point.

 

Theres a chance after if was fixed and it started reading off the the MAF again and realized it didnt correlate with the MAP readings (Your fuel trims were relearning which needs the MAF and MAP to be working properly) so it assumed the MAF was not reading right based off the O2 voltages..

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Like you're doing or already did with the Lumina? :bonk:

 

Well I took the MAF out the same evening, and cleaned it up, and was gonna install it in the morning, but it's been snowing all fucking day... Tomorrow should be alright though so I'll put it back, and see if it's any different. If it's still the same, I'll try 1 more TPS, and after that another MAF. Are MAFs from 3400 engines the same, or do they have to be w-body 3100 specific? My dad has a 3400 in his '01 Silhoutte, and I could borrow the MAF for testing if it's the same. I'll let you guys know what happens. :cheers:

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Alright, I cleaned the MAF, and put it back in. It drove normal until about 1/2 or 3/4 throttle. Then sometimes it accelerates normal, and other times turns into a dog. No CEL during the 30 minute drive, until I went on the highway to do a WOT run. It accelerated decent, but maybe a bit too slow, then slowed down, so at 100km/h, it probably took about 5-7 seconds to climb up to 110km/h.:willy_nilly: With the pedal all the way down, it got to about 115-120 km/h and then the CEL came on, and that instant it started picking up speed like it's supposed to, until I let off. I slowed down, and tried accelerating again, and it's all sluggish again. I checked the codes, P0101, and P0131 again.

 

So, will a '01 Silhoutte 3400 MAF work or no? If I go to the J/Y for a MAF, can I look at anything 3100 equipped, or does it need to be ODBII w-body? Thanks guys.

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So, will a '01 Silhoutte 3400 MAF work or no? If I go to the J/Y for a MAF, can I look at anything 3100 equipped, or does it need to be ODBII w-body? Thanks guys.

 

I wonder if you could cross reference parts numbers on a car parts website to check...:thinking:

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You can for some things, but I'm not sure if MAF is one of those. I'd rather confirm with someone, then go and buy a wrong one. But thanks anyways.

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I meant to just see if the parts numbers are the same, to see if you could borrow the one out of the U-body.

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http://www.w-body.com/showthread.php/46087-Mike-s-Official-Nexpart-Wrenchead-Request-Thread

 

:thumbsup:

 

Through the catalog I find out that the part number for a '96 3100 CS is a Standard brand S-656. And from there I run a Buyer's Guide Search...

 

minus.gifSILHOUETTE (OLDS) (4) 1992-1995 leaf.gif1995 V6-231ci 3.8L F/I Vin L leaf.gif1994 V6-231ci 3.8L F/I Vin L leaf.gif1993 V6-231ci 3.8L F/I Vin L leaf.gif1992 V6-231ci 3.8L F/I Vin L

 

 

So the short answer is, no.

 

S656_CONNECTOR.JPG

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I tried to post the whole buyers guide, but it is far too big for this forum's text limits.

 

Basically, it seems to fit various V6s from 1999 and before. LMK what you are planning to get one out of a junk yard, and ill let you know if it should work.

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I was hoping you would chime in here Mike. Thank you sir :)

 

Sorry Neb.

 

Yeah, it kinda seemed like you were hinting at me to look it up in Nexpart haha

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Well, I got a MAF out of a '96 or '97 Lumina with 252,000 kms which is more than mine. That was the only 3100 w-body with a MAF, the others were '94 and '95 with no MAF... Anyways, I got it home, cleaned it, replaced my old one, and went for a drive, and it drove like a whole new car. It did idle a bit rough, kind of like it was missing, but that went away after about 20 seconds of normal driving, and hasn't come up since. Thanks for all the help everyone!:thumbsup:

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