Code 33 Problems

[omega1940]

I'm at my wits end and so is my mechanic. I have a completely rebuilt 88 L-98 with 383 stroker (cam, rollers, roller assembly, four bolt main, etc. etc._), and enormous power/torque.

About 2 months ago, I started "throwing" a code 33. I would get a slight "stutter" in the throttle, then the code would show up and the car ran like it had 2 plug wires pulled. I could turn if off for a couple of minutes, fire it up and drive for a couple of days with no problem. It has continued to this day, when it did it 3 times just today. I replaced the MAF with an adjustable high flow MAF, and it would work for 2 days then it would set-off again. My mechanic suggested I reinstall my OEM PROM chip and I did that. Still did it. I have a 52 MM Throttle Body that is about 2 years old and have no reason to suspect anything there. I replaced the burn-off and power relays Tuesday night (for the second time) and it ran all day yesterday without a problem. I thought I had found the problem. Then today it happened 3 times. When my mechanic plugged his digital reader into the plug-in under the driver's side dash (can't think of what they call it) he said it appeared that the MAF was showing the right amount of air density, then suddenly it would go up very fast and set off the code 33. As I said I replaced the MAF. I even went back to the OEM MAF I had (actually it was slightly modified, but wasn't adjustable) the code 33 problem still occured. We have checked the wiring to see if there is any problem and there is none, including the connector to the MAF. Timing is perfect. I just can't believe that with a pretty straightforward system like the MAF, relays, etc. that we can't find out what's going on. When it dumps the 33 it runs so bad I have to keep revving the engine until I can pull over and turn it off or it dies on me. PLEASE, PLEASE PLEASE HELP!

Anyone reading this from the Phoenix area I would like to get a referral on a Vette mechanic. Mine is great for the regular stuff, but not like this problem.

Mike

PS: Jeff DeBur is reprogramming my PROM for the stroker right now. I'm holding out hope that this could solf the problem, but I'm pretty pessimistic right now.

 

[nyernga]

Check the simple things at this point. The air intake tube to the throttle body could have a slight crack in it. Mine did that 2 years ago and had the same symptoms.

Sometimes you get so close to the forrest you can't see the trees.

Len

 

[redc4corvette]

If no leaks around the airfilter or the MAF ,TPS set correctly then the book say's replace the ECM.

 

[WhalePirot]

Googled on GM and Code 33 to find:

Found:
Code 33 MAP sensor voltage too high (> 4.00 v). Possible vacuumleak to sensor or faulty sensor.Also: http://www.google.com/search?q=GM+%22Code+33%22&sourceid=firefox&start=0&start=0&ie=utf-8&oe=utf-8

which states, "Apparently when a code 33 reveals itself, these cars normally go into a limp mode, locking the car at 22-degrees of timing, which causes terrible driveability." and "Through the use of modern technology, the Diacom identified several codes and helped us eliminate all but one. This could be caused by a marginally failing device, or a fault somewhere in the wiring harness itself. At this point you should consult a factory service manual, which contains step-by-step diagnostics for isolating the fault causing the code. Usually all that’s required is a multimeter, test light, and jumper wires. In our particular case, Myron believes it’s just a bad connection somewhere, and told us to replace the Burn off and MAF Power relays first, then to look into replacing the Mass Air Flow sensor. After all, spending $20 on a couple of sensors is a lot cheaper than handing over $300 for a new meter!

 

[omega1940]

Thanks for your feedback. I did replace the "accordian" style tube with one of the heavy rubber smooth tubes. No change. I'm using the accordian-style again.

Mike