Hey all, I know there have been many posts dealing with code 33, but I did a search and couldn't come up with anything quite like my problem. So, I'll post it here, in the hopes that someone knows...

First off, my car is an 88 Trans Am GTA with the L98 TPI motor. On my way to work today, my car gave me a code 33, MAF sensor. It seems to accelerate fine, but I couldn't really tell cause there was nowhere to really stomp on it in rush hour traffic. When I let off the gas, it seems to "grab", almost like a manual trans car when you let off the gas and leave the clutch out. When I got to work @5:00 PM, the idle seemed stumbly and kind of low in park - acting almost like it was gonna stall. Then, when I left work @10:00 PM, no code, no problem, nothing.

I haven't had a chance to look at it yet, because it was dark when I got off work, and this is the first time this has happened. I'm gonna look at it tomorrow, but in the meantime, does anyone have any ideas? Or had this problem before? TIA for any replies, I'm really hoping I don't have to replace the stupid expensive MAF sensor...

 

Probably the best thing to do is to start by eliminating all the usual suspects. The '33' is caused by a higher than expected intake air flow at a given engine RPM and throttle opening. Since the HEI module in teh distributor reports engine RPM, we can presume that is working correctly if you don't have any ignition miss. The throttle angle is reported by the TPS, so checking the TPS base position might be a good idea. As long as the TPS voltage is below 0.6 VDC in the closed throttle position, the ECM should be able to understand the signal. If the base voltage is at or above 0.60 V, or there are places in the travel of the TPS that the signal just falls off (intermittent contact), you may have a TPS issue. The preferred setting is 0.54VDC.

 

Vader, thanks for replying...I drove the car around today for a while, but I can't get the problem to reappear. My car is acting like nothing ever happened! No code, no driveability problem, nothing! When a TPS sensor goes bad, is it possible for it to be intermittent, and only act up sometimes? It was only that one time that it happened. I'll post again if it happens again, but right now I am stumped! Any other ideas on what it could be?

 

I had a vacuum leak which seemed to cause a code 33. Nobody had any clue what caused it. Same type of strangely intermittant problem. Only mine always started bucking around and flashing the SES light when i gave it throttle sometimes, then it stopped flashing the SES and stoped bucking, go figure. Code 33 was still in the computer when I dumped the codes. The problem would go away for a few days and then come back. It was really weird. I found a small vacuum leak under my TB, I fixed it and the problem hasn't been back since. I can't say for sure that was the source, but it sure seems like it was. Does your light stay on or just flash when it malfunctions. Check around for vacuum leaks especially those little brittle lines. Also, with the car running, tap on the MAF. Yeah it sounds silly but give it a few taps. If the idle starts stumbling its time for a new unit. Let us know how it goes.