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As some may know my 1990 Corvette ZR-1 had engine management problems.
It sometimes idled too high, until recently when one day I went to start it and the engine backfired.
After the backfire it would only idle at 3,000 RPM, would not stay running, when running would run very rough and blew black smoke.
A few weeks later it was time to find out why, we pin pointed it down to the idle solenoid and a two vacuum hoses were blown off. We put the Corvette back together and managed to get the idle back to where it should be only to find that when you touch the accelerator the engine would stop running.
It was decided to wait until the idle solenoid to arrive before we retested the system again as the faulty solenoid was making other components compensate and making any further diagnosis impossible.
The new idle solenoid arrived and we fitted it, we then were able to test/diagnose the system again. We were able to locate the other problem using our scanner, which is now compatible with the corvettes. The throttle position sensor was not responding, in other words when you opened the throttle the computer was still being told it was only idling because no extra fuel was being delivered the engine would stop. It was not a faulty throttle position sensor, but the fault was that it was not getting a 5 volt base current from the computer. The computer was sending the signal, the idle solenoid was receiving it and so was the map sensor but not the throttle position sensor. We removed the upper half of the inlet manifold to get access to the wiring loom coming from the throttle position sensor to the back of the engine; naturally it tested ok (no breaks in the wire).
We then removed the wiper motor to gain better access to the wiring loom at the firewall and finally found the fault. It was where the factory spliced a single wire into three wires, the solder joint had failed.
We put the Corvette back together and tested everything as we went; we reset up the throttle position sensor to factory specs and then started up the engine. The engine functioned as per factory, idles correctly and performed on the street as the factory intended.
Because of my ZR-1 having engine management problems I am now set up to diagnose/repair engine management issues as well as ABS, Air bags, Electronic adjustable suspensions and anything else the computer controls.
But remember this is not an overnight repair as in most cases once you have found the fault (and there maybe more than one fault) the Corvette is usually in a dismantled state and will have to wait for the new part to arrive and then be retested/diagnosed/adjusted to make sure there is no other faults. Parts usually take less than ten days to arrive.
For more information please do not hesitate to contact Scott at Corvette Alterations on 02 9971 8218
