amcdude Posted August 20, 2003 Report Share Posted August 20, 2003 I've got a '90 TGP that I recently acquired. Some hack supposedly thought that the timing chain was the cause of the no-start condition, and had partially dissasembled the motor. Once I reassembled the engine and unplugged the aftermarket security system, it started right up and ran great. The only problem now (and it's a big one unless your a granny and don't use the accelerator) is the fact that the computer seems to cut fuel antime the engine sees boost. The boost level that it reaches before fuel cut-out varies somewhat, but is usually around 2-5psi indicated on the stock guage cluster. It cuts out almost imediatly once manifold pressure goes positive. The computer has set no trouble codes, the check engine light hasn't come on, and all the wiring an hoses seem to be in good condition. I'm completely stumped on this one. The only thing I can think of is that the MAP sensor is giving a incorrect reading to the computor, so the ecm is thinks that the engine is seeing overboost, and then cutting fuel. If this is the case, the only plausible explanation is that someone installed a one-bar MAP sensor, since I'd doubt that the correct two-bar MAP sensor would only read inaccurately in positive pressure, yet work perfectly fine under vacuum. Any thoughts would greatly be apprecieated on this. Thanks. Quote Link to comment Share on other sites More sharing options...
amcdude Posted August 20, 2003 Author Report Share Posted August 20, 2003 Supposing the it is the incorrect MAP sensor scenario, how could I easily tell the difference between the one and two-bar MAP sensor? Quote Link to comment Share on other sites More sharing options...
idbeast Posted August 20, 2003 Report Share Posted August 20, 2003 Replace your plugs and wires, The heat is rough on the wires. But what do I know. :read: Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted August 20, 2003 Report Share Posted August 20, 2003 Well I noticed that the GM 2bar map has an orenge plastick inside where the wireharness goes into...the 1bars have either black, white or blue. Those other 1bars shouldn't even fit without messing with the wireharnesses plastic pin cover. Also with a volt meter when the mapp is connected but with the engine off...the 2bars start at 2.5volts on the output and the 1bars start at 0 volts on the output. If this is not the case ...check everthing else. Quote Link to comment Share on other sites More sharing options...
Guest fatguy Posted August 20, 2003 Report Share Posted August 20, 2003 Since it was running poorly.... Is there a cat. conv. and if so, is it plugged. Take it to an exhaust shop and they should be able to help you with this. Quote Link to comment Share on other sites More sharing options...
TGPilot Posted August 20, 2003 Report Share Posted August 20, 2003 I agree with idbeast. :shock: Check the MAP sensor for correct 2 bar. Then check your plugs and wires and if that doesn't help you may have a fuel delivery issue...filter, pump, pressure regulator, or injectors. Do you have access to a gauge to plug into the fuel rail? 8) Quote Link to comment Share on other sites More sharing options...
god910 Posted August 20, 2003 Report Share Posted August 20, 2003 [mumbles] Damn injectors, stupid car can't make up it's mind what's broken[/mumbles] Injectors fixed my car, it would only idle for 5 sec. at a time. Quote Link to comment Share on other sites More sharing options...
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