87 IROC 305 TPI Auto (stock)
Here's what has started. I drove home from work today and the car has been driving great. When I back onto the driveway and put the car in park the idle feels rough and it starts to search a bit from normal 600 to 800. I also notice smoke coming out. I checked a bunch of things since I recently changed plugs, wires, cap and rotor. All good.

I finally unplug the MAF sensor and crank it back up and it is back to normal, no smoke and good idle. I know it refers to back up tables when not plugged in. My question is can this be anything else but the MAF sensor, since it is only about 2 months old and it's a Wells (SU145) is the # I think. I checked the relays by swapping them into the fuel pump relay and made sure the pump would prime.

Any suggestions would be greatly appreciated. The car has been running great with zero problems until now. Can a MAF sensor just go out that sudden?

Thanks
Tim

 

I reset the computer after checking all connections. Started it up and still have a rough idle and it is running incredibly rich (smell) of the smoke. There is no SES light. I took it for a short drive and it seems to have a slight hesitation but all power still there. I don't know if the MAF has anything to do with it now sense there have been no codes since the start. I checked for vacumm leaks with some carb cleaner.

Please help..I running out of ideas. I'm going through some trouble shooting guides now, but need help if there are any suggestions on things to check. I also don't understand why it runs close to normal (not rich) with the MAF unplugged.

HELP

Tim

 

what kind of smoke are you seeing?


and what made you replace the MAF the first time?

 

It's dark smoke....really rich exhaust.

And I bought the car and it had an intermintent code 33. I didn't really know for sure it needed a MAF but just to make sure since it was a used car. I also replaced the TPS and the code has not returned.

I replaced plugs, wires, cap and rotor which looked to be original and the car has ran like new since.

But as always something has knocked me off my high horse and I'm stumped. This is my 3rd IROC and I've gotten pretty good at trouble shooting, mostly because of this board.

I'm just out of ideas since this just happened out of the blue with no other indications and no SES.

Any help??

Thanks

 

^^^^

 

HELP.....

Suggestions?

I know someone has a clue about this.

 

im guessing either bad injectors or a faulty o2 sensor.

 

Well here's what's been going on for anyone trying to help.
I ended up getting a code 33. I hooked up a scanner to it today and the MAF is reading about 25 g/s at start up and then goes down to about 6-9, then SES sets. The O2 cross counts look as if they are working but at some points it stays at zero. I just replaced both MAF relays a few minutes ago here at work and no change.
My question is can a bad O2 sensor set the MAF code and cause the MAF to read low. TPS is .56 running. I'll write down some other numbers to see if anyone can figure this out.
I have a PathfinderII but as soon as the code 33 sets it will end the program thinking that must be the problem. The MAF is only 2 months old (SU145) Wells. The car has become hesitate to start. Usually starts right up, now it takes a second but still first turn.
Again can anyone answer the O2 sensor question?

Up at speed the car seems to run fine, but when yoiu let out of the gas it lugs down like the TPS is not right but it is. If that helps any troubleshooting.
Thanks

Tim

 

Your TPS is .56 at idle, what about at WOT? Make sure it isn't sticking. That could casue the condition you are describing

 

The TPS is new and I re-adjusted it just to make sure. And it flows smoothly to over 4v at WOT.

I posted my scantool info in another post, if you're any good at looking at the info and determining what's going on.

Thanks again.

Tim

 

Have you checked your fuel pressure at all? a bad O2 sensor can cause rich/lean conditions. A code 33 COULD be caused if the O2 sensor is bad, making the MAF work a little harder. I'm not sure on that one but it sounds good in theory. But you would have a code 45 to correspond, I would think.

Anyways, back in earth... have you checked your IAC valve at all? it could need cleaned. I know this doesn't relate to the code 33, but you'd be surprised at how one thing can cause another to malfunction.

 

i would first start by replacing the 02 sensor. it's cheap and good insurance. then clear out the computer again and give a whirl. also try to check you fuel pressure as previously metioned.

 

The IAC passages were clean about a month ago when I put in a new IAC valve.

I'm hoping the O2 sensor is the culprit but I'm just not sure if that would cause the immediate code 33 I'm getting.

And I also don't know how I'm running like new for months and then within seconds with no signs of anything going south, the car runs like crap and code 33 shows up. Unless my MAF crapped out, but it still shows flow on the scanner.

Can any of you guys look at my other post with the Scantool info and see what you think?

Thanks again and keep the suggestions going...

 

if you disconnect the maf and it runs fine, then my money is on the maf. I'd replace the 02 first because it is so cheap, and if that doesn't fix it, tell whoever you got them maf from its faulty and you want one for free.

im haveing the same rich, rough idle problem, i just got my injectors cleaned, new egr valve, and a new 02 sensor and if they dont fix it, its gotta be the iac, maf, or tps.

 

It did turn out to be the 1 month old MAF!! I got it from the guy that was selling a bunch of them. I found him thru this site. Stockcar99 or something like that. It was the Wells Maf also, guess that's $80 down the drain.

Thanks for all the help from everyone. It helps to have a buddy with a MAF car that you can swap in his MAF to check yours....

Car is running like new again!!! And has been for a month or so now!

Tim