Hello every one I am new to this web site but it seems very helpful. I recently bought an 86 trans am 5.0 vin F. TPI. I've always wanted an f-body and finally picked this beauty up in florida and drove it back to cleve. I have done alot to make this motor run perfect and I thought I was finally done when the car (while driving) started to studder at crusing speed of 30mph then the engine light came on and ran a code 33. (MAF sensor) so I replaced the sensor(150$) and the relay. Still this code pops up either right away or after about 10 mins of driving, and the car chuggs and runns rough. Mostly when accelerating. I took it to the dealer when the engine light was not on and the couldn't find the problem. I've heard of a possible "bugged prom chip" that would cause this problem. Any suggestions before I throw in the towel. Please Help......Love the car hate to give up...Andy akobak@kent.edu

 

First off-welcome!
There are two maf sensor relays-did you change them both?
Unless you've done a lot of mods-cam/heads etc. the stock program shouldn't need to be changed. If you do mods then the maf high diag error 33 threshold under ecm constants needs to be increased.
Also try adjusting the minimum idle air on the tb; lot of times that'll solve it.

 

welcome. Hows the seal around the MAF unit itself. That was the case w/ mine. All I did was put some electrical tape around the edge to make a makeshift gasket. Solved my problem

Jason

 

Thanks for the replys. I just took the car to the dealership and they thought my problem was solved when the disconected the maf harness and reconected it. But some money later, pulling out of the parking lot the code 33 reappeared and once again the car was running horible. And the dealer had no idea what the problem was because the code was so sporadic. (comes and goes) not always on or stored for that matter. Any other suggestions. Everyone is stumped...????

 

Get a voltmeter and adjust the TPS, its on the side of the TB.

My TPS on my '87 is adjustable by just loosening the two screws and rotating the TPS body. Check out the FAQ about adjusting the TPS.

If you are in closed loop mode, typically on the highway at 50 to 60 mph cruise, you will set the 33 error code when the MAF reads a low value while cruising at a moderate speed. I got good enough at this that I could predict when I would set the 33 error code.

Also, do a search on this, beacuse this idea of setting the 33 error code was written up about 2 years ago. Setting the 33 error code has nothing to do with the switches (burn off and relay) that everybody changes. I did that same thing, it did not get rid of the 33 error code.

Do the TPS adjustment, then disconnect the ground (black) wire on the battery for 1 minute, then reconnect the wire. This will erase all error codes and reset the ECM.

 

I did a search and found this:

The 33 error code will be set if the ECM sees over 45gms/sec @ less than 2000RPM and the throotle is less than 1/4 (this would be the TPS value).

This was a long time ago for me, but I remember that while I was on the xway, when I felt the engine booble, the engine rpm was under 2000RPM, @ light throotle, and in overdrive with 700R4 tranny. About 5 seconds (or maybe less) after a felt the booble, the check engine light would come on and the engine would run like crap.

I have a 52mm TB, 3.70 rear gears, 700R4 tranny, descreened MAF. This set of mods apparently sets up the above conditions and the 33 error code can be set. I would never set the 33 error code if I drive the car in 3, as opposed to OD. Having the tranny in OD put me into the condition to set the 33 error code. You can avoid the 33 code if you go into OD above what ever speed keeps the engine above 2000RPM.

Repeat: This has nothing to do with faulty relays. Buy a new relay and you have wasted some money.

 

Thanks for the info. My engine light comes on either Right when i leave my drive way and accelerate lightly or after driving on the highway for about 10 mins in overdrive. But just like you said, I bobbles a little then within 5 seconds it runs horrible. I will try the tps ajustment. (did this adjustment work for you?) I read that it could have been a "bugged chip" causing this problem so i bought an aftermarket hypertech street runner chip and the problem seemed to go away untill driving the car for the second time after the chip. Then the problem sprang up again right out of the driveway, once again. I'm loosing my mind over this. I have another ECM on its way. (Dealer suggested). This is turning into a big money problem, but we will figure it out!!!!!!Wonder if this problem is caused by the K&N air filter I put in. I will yank it out and try the stock one again too. ahhhhhhhhhhhh!!!!!

 

Code 33 / 34 tests.

First check air ducts for cracks, holes and tighten clamps.

With the ignition off, unplug the MAF and apply power to ALDL terminal
"G". Check the red wire on the MAF connector for power. If no power,
verify 12v on relay connector orange and white/tan wires. Verify the
connector black/white wire is grounded. Verify black wire from MAF
connector terminal B to ECM connector A11 with an ohm meter. Verify
red wire from relay connector to MAF connector with an ohm meter.
If all is good replace MAF power relay.

Turn ignition on, Check MAF connector dark blue wire for 12v, if so,
unplug MAF burn off relay and check again. If so, check relay
connector black wire for ground. If so, the black wire is shorted to
ground or the ECM is bad. If not, replace MAF burn off relay.

If the dark blue wire at the start of the above test had no voltage,
check the MAF connector dark green wire with ignition on for a 5v
reference signal. If so, and all connectors are good, replace MAF.
If no 5v reference on dark green wire, verify it from the MAF connector
to ECM connector B12 with an ohm meter. If the wire is good replace the
ECM. If the dark green wire has 12v on it, turn ignition off and unplug
the ECM connectors. Turn ignition back on and check again, if so,
it is shorted to power somewhere. If not, and all connectors and
grounds are good replace ECM.

 

You should check the stuff shown above, but I know that if all systems are OK, the 33 error code is simply caused by a specific driving mode. IT IS NOT THE CHIP OR THE ECM. Its just inherit in the ECM program logic.

Do you like the way your car runs with the hypertech other than the 33 error code? If yes, I can use your hypertech Eprom and remove the 33 error code if you will ship me the Hypertech. I think that this is possible. I think that the only sure fire way to get rid of the 33 code is to get a custom burned Eprom. I woulndnt mind doing this for you, we can both learn from the experience. In fact, you are in Cleveland, its only a 2 1/2 hour drive to Monroe, Mi. (I use to live in Akron for 52 years.)

 

Thanks Doc, I am going to try all the checks i can with the voltmeter. Problem is my dad just moved to michigan with my meter. So once i get ahold of it ill check everything if problem still persists I'll let you know. Thanks for the offer. I would drive down to meet up with you if this doesn't work. Would erasing the code from the chip get rid of the problem? Are you capable of burning the factory chip to make the car perform better? That would be sweet. Let me know. Thanks, Andy


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Do you have a stock throttle body? Have you de-screened the MAF?

The only way I could get rid of the code 33 after changing to a 58mm throttle body and taking out the MAF screens was to change this setting in my 165 32B code PROM.

MAF High Diag Err. Threshold

Factory set at 45, changed mine to 55. Errors went away
and ECM tuned fine. I was running a 383 with 30# injectors and actually got the tune fairly close. Then I changed to speed density and haven't looked back at a MAF since.

The biggest problem with this error was once it was set the engine would run awful until it was shut down and restarted.
I set idle air, timing, tried two different known good MAF sensors, etc. I just assumed it was the 58mm TB or the 383, or the screens.

Hope this helps! I never did find any other reason other than the mods I had made and like I said, after getting rid of the error I actually got the thing to run pretty good.

 

If you like the Hypertech chip,, if you feel that makes your car run better except the the 33 code stuff, I had in mind to simply copy the Hypertech chip into a file, turn off the 33 error code (in this manner, I think that you will never get a 33 error code again) and then erase the chip,, then burn back the same file but with the erased 33 code version. You might have to buy a new Eprom chip because the one in the Hypertech may not be an erasable/rewritable type, but the Eprom chip in Hrpertech units I believe are removable which is very important.

Also, it would be a good experiment for us. So yes, I have the capability of burning Eproms, but to do it right for your specific car, it would take alot of street runs doing scans burning a new chip, and starting the process all over again. Its a very tedious job. However, what I propose is a one time thing and we can see if it works. I do not get the 33 error code anymore for my '87.

I know from personal experience that the 33 error code is very very fustrating thing. The only way to get rid of it for good is a custom chip because what sets it off is in the programming. Send me email if you want to go this route.