The Service Engine Soon light on my 89 Trans Am GTA has been coming on. The stored trouble code is 33 - the FAQ section indicates that is a High Voltage (low vacuum) at the MAP sensor. If the car is at idle or low RPM, it may run very roughly or even stall. The idle/stall problem doesn't seem to occur if the car is at a crusing speed. Before I could get a valid trouble code, I had the spark plugs, plug wires, and O2 sensor replaced. Is there a common cause for this code or is it one of those codes that could be caused by a thousand different things? Thanks!

John

 

even the slightest crack in a vacuum hose for map will **** it off triping a code check ur hoses for heat rot or cracks specially hoses under the TPI pendlium

 

At first glance, the vacuum hose looks fine. I guess there might be a pin hole or smething but there's nothing obvious

 

Your car is an 89, it does not have a map sensor. Code 33 is a mass air flow sensor code. First thing I'd be looking at is the maf power and burn relays. Thier located on the firewall between the d/s fender and brake booster (the 2 oval ones).

 

What do I need to look for on those relays?

 

The relays are about 12 dollars at most parts stores I'd replace them both, also inspect the condition of the wiring on the connectors, any bare spots should be wrapped with elec tape.

 

I replaced the relays - cost me $15 and took 10 minutes. The first results are encouraging. I drove it all afternoon in 95 degree heat with A/C blasting and lugging it to the mall, Target, etc. without any sign of the Service Engine Soon light.....

Keeping my fingers crossed

John