OBDI Code 33

[twiget]

I recently got my 'burb back up and running after a couple months as a paperweight. The distributor failed and I had to replace it. I set the timing at 0* TDC when I installed the new distributor. Now the truck starts up, but it idles rough for a few seconds, and occasionally it will die. If I give it a little gas, the idle will smooth out and the CEL comes on and my reader tells me it is code 33 for the MAF/MAP. It will also stall when I come to a stop if I dont keep my foot on the gas, and it also hesitates and almost stalls when I try to accelerate.

The truck is a '90 454 TBI, and after doing some research on code 33, I think the problem the timing. I found a reference indicating that the ECU needs to be disconnected from the distributor when setting the timing. When I unplugged the ECU connector from the distributor, the motor would crank but not fire up.

Is there a connector I am missing that disconnects the ECU from the distributor? Is the timing even a viable culprit for my fault?

 

[BoondocK5]

Are you talking about the brown w/white stripe wire with a plug near the steering column, on the wiring harness under the hood?
That must be disconnected while setting base timing.
One of you high speed mechanic types that are still in the business can chime in and correct me.

 

[Keitha]

That is correct. You MUST disconect the spark controll wire as Boondock5 mentioned. It is a single plug wire that should be on the left side (driver side) of your brake booster. Without disconnecting that wire, you are probably around 10 degrees retarded (your spark timing, not you).

good luck,

 

[zombie1969]

33 should be for the map having a high voltage reading and I think a high reading will cause it to run rich at idle.You can check the map with a volt meter and vacume pump.Also check the wiring and conections.

 

[DizturbedOne]

Is this truck a speed density truck (MAP) or MAF?

Truck won't fire if you disconnect the connector at the base of the dizzy. As others said, it needs to be the brown wire w/white stripe to set the base timing.

I hope that's your problem, but it sounds like your MAP or TPS is bad by the way it is running and driving. MAF's tend to act a bit differently.

 

[DeviousK5]

It is a MAP sensor , check to make sure the vacuum line isnt pinched severed or clogged. Then electrical PinA at the map is ground(black/red or purple wire) make sure its a good ground. Pin c is 5volt reference(gray) make sure its got that 5volts(key on engine off) and pin b is signal and should read .5-1.5volts at idle . if you've got good vacuum and the signal signal is off replace the MAP

 

[twiget]

I checked the MAP sensor when I got home from work, and sure enough the vacuum tube had come off the back. I must have hit it with my elbow when I was installing the distributor. Plugging that back in took care of my Code 33 problem. After that it was easy, reset the timing with the spark control cable disconnected, put everything back together and went for a test drive. 28 miles later and everything is peachy. Now I just need to get it smogged and registered tomorrow and I'll be all legal. Thanks for the help guys.