ok, I know, millions of posts on this before. Anyway, About 2 months ago my 87 IROC has been refusing to stay started when I turn the key. It'll turn over for about 2 secs, then just die. After a few attempts it'll finally stay started. It's been doing this on and off ever since. Sometimes I can go a few days without the prob, then it magically appears. WHen it does, the computer registers code 33. According to the repair manuals this can be 3 things: MAF, MAP, or faulty ECM.

Now, my questions to u guys are: Is it possible for a computer to just go bad out of the blue and cause intermittent probs or would it cause this prob all the time if it was bad? I ask because exactly 1 year ago I purchased a computer chip from FastChips and it worked perfectly ever since.

If its the MAP sensor, is it just a matter of unplugging the battery, replacing the old sensor and then just plugging the wires back into it and reconnecting the battery?

I really hope its not the MAF cuz those things are pretty damn expensive. I'm really hoping this is a simple fix cuz I really don't have the money to take it somewhere and get raped for repairs.

Any thoughts would be greatly appreciated!!

BTW, the car has a LB9 TPI V8, FastChip Stage 2 chip, 160* thermo, 3" from the cat-back, Flowmaster 80 series (I think), T-5 tranny, and 3.73 9-bolt rear

 

To test the MAF is easy. Unplug it and see if your starting problem goes away. If it does, it's the MAF. And I gotta tell you that your symptoms are exactly those of a bad MAF. Dies almost immediately after startup.

 

anyone else?? Oh, btw, I was wrong about the code....its 34 not 33

 

If it's stock 87 you have MAF not MAP.
When my ECM starting to die, it would work on and off, I would get the check engine light and the speedo would stop working.

 

so if the ECM is faulty, it would be the actual chip (In my case, the aftermarket chip from FastChip) and not the entire box that houses the computer circuitry? Also, can anyone else confirm the MAF theory of unplugging it? Wouldn't unplugging it make the car run like Sh*t? Thanks

 

Replacing the relay fixed the code 34 problems for me.

 

where is this relay located?

 

Why don't you jsut try (temporarily) unplugging the MAF? It's not going to hurt anything. You'll get a solid check engine light, but if it solves the cold-start problem then you've nailed it dead-bang. I swear it won't hurt anything. I wouldn't post it if I hadn't tried it myself on various occasions.

MAF relay is on the firewall near the brake booster, along with several other very similar looking relays.

 

ah ha, that explains what that module thing is on the firewall, when I looked in a service manual, it said it was the MAP sensor. And like someone else already pointed out (which I was confused about) is that there wasn't a MAP system pre 1990. Anyway, I'll try unplugging the MAF. The car hasn't stalled at startup in the last few days but has run pretty erratic and usually trips the SES light after about a minute or so of operation.

 

When you unplug the MAF it causes the SES and a code. How ever it will continue to run but it is in "limp home mode". You haven't fixed the problem. The 2 MAF relays "Power Relay and Burn Off Relay" cost like $11.79 each at a GM dealer (atleast the one near me) try replacing them first. It is cheap and easy and if the car has over 70,000 miles they should be replaced, just good general maintance along with other sensors and relays.

But if it doesn't fix it then it could be the MAF itself.

 

thanks for the info, hopefully that does it. If I remember correctly, new MAFs are $300+. The car just turned 109,000 miles so, like you said, the relays should be replaced anyhow.

 

well, I unplugged the MAF and the car started up but was idling erratically. After a few mins I turned it off, plugged the MAF back in and started her up and she started up just fine. I drove to the grocery store and the car ran fine all the way there, didn't even trip the SES light while driving. Get back in the car after finishing my shopping and she doesn't want to start up like usual. I whip out my trusty paperclip to display the codes and now I'm getting 33 & 34. Before it was just 34.

According to thirdgen.org, 33 is high voltage at MAF & 34 is low voltage at MAF. But, in the service manual I looked in, it said that 34 meant either a bad MAF (or MAP) or bad ECM. And I think 33 was the EGR.

 

Change your relay(s). They are only about $10 each.

 

This may be a stupid question but, what are relays and where are they located for the MAF?

 

There are 3 relays on the firewall - Fuel, MAF burn-off and MAF. They are located between the brake booster and the fender. 2 of them look alike - the MAF burn-off and the MAF. These are the 2 I would replace.

I had to order the MAF (or was it the MAF burn-off) relay when I got it from Autozone - they only listed one of them - but - they are both the same.