On my 87 Trans Am I swaped from a 305 to a 350 TPI. Now sometimes when I start it the service engine lite comes on as long as I keep my foot on the pedal it runs as soon as I let off it dies. But it starts right back up without the service engine lite coming on and the lite has never come on while driving only when starting it up. I checked for codes today and got a 34 and a 42. I think 34 is the Mass Air Flow Sensor? but don't know what 42 is? I did change the knock sensor to the 350 but I did not change the knock module located on the firewall on the drivers side where the relays mount. Could that be the code 42? Any ideas

 

Code 42 stands for EST.. it's that brown wire with a black stripe that is right by your heater box.. check and make sure you didn't leave it disconnected when you set the timing on your engine

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'86 IROC-Z 305/auto with no cat, performance chip, shift kit, and 4.11s
'87 IROC-Z factory loaded with every option, 84,000 miles

Webmaster: www.IROC-Z.org

 

I'm having the same problem...can someone tell me where this tan wire w/ black stripe actually is? I don't know where the heater box is.
thanks

 

the heater box is on the passenger side in the engine compartment. big black box, it will probably be the only connector around that area with only one wire.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16