I have searched for an answer but have not had any luck. Someone PLEASE help me I am about to pull my hair out. I have an Engine and trans out of a wrecked 92 Camaro. 350TPI with 700R4. It has large tube runners, BBK large bore throttle body. Painless wiring harness.

This is a project 10 yrs in the making and finally got it running last year but the idle was high... Got some exhaust and stuff fabbed up, misc wiring tidied up, tried to sort out the idle... So far we have been unable to find a vacuum leak. TPS is .57 VDC. car revs great. Timing is 6BTDC.. We are getting a Code 42 but I think it’s due to fast idle. I have sprayed the engine down trying to find a vacuum leak but have not been able to find one.

I clamped off every vacuum line no change. Unplugged the IAC plugged the IAC holes no change. I even bought a new IAC because the plunger did not seem like it was working. I tried the reset procedure for the IAC but I can not get the idle to go down low enough to set it correctly but I don’t think that is the problem. I then tried clamping all my vacuum lines to I could try to track down a vacuum leak but this did not make a difference until I clamped off the MAP sensor vacuum line and the idle dropped to 450rpm... unclamped the line back to 3000... Unplugged the MAP wiring the RPM drops to 450.... I tried a new MAP sensor but no change.

I have replaced the coolant sensor because someone said that could be the problem (also had a problem with my fans not kicking on). I also installed a new O2 sensor when I put the engine in the car.

I am tied of just throwing money at sensors and don’t know what else to do. A buddy of mine mentioned that if the spring on the fuel regulator is bad it would cause it to Idle high because it is getting to much fuel. Could this be the problem?

 

Code 42 EST circuit grounded (HEI module failure)
per: http://www.metzcon.com/racing/gm-ecm-codes.htm


42 Bypass or EST problem (All) - # If vehicle will not start, check wire leading to ECM terminal 12.
# An improper HEI module can cause this code.

"The most common is code 42, which is the EST or bypass circuit. If the ECM detects loss of signal with the EST (when performing base timing adjustment for example) then regains connectivity, the “Check Engine” light will extinguish, however, a code 42 will be stored until erased from the ECM’s memory.

Once the problem area has been determined, locate where the problem
area resides. Once a repair action has been taken, reset the ECM and see if the code re-appears during normal driving conditions."

per: http://www.iroczone.com/2009/10/1982...maro-firebird/

 

have you tried backing the minimum air adjustment screw out so it doesn't contact the throttle stop?
if you have, try plugging off the throttle body.
pull the air boot off and place something over the inlet.
a piece of plywood large enough to completly cover the inlet should work.
to get a good seal you may need to cut an old truck inner tube up and lay it on the wood, then staple in on the back side of the wood so it doesn't suck the rubber into the motor.
if the idle comes way down or the motor stalls, take a good look at the throttle body. the blades may not be properly installed and sticking or the housing could be damaged in some way.