I've been looking after this Corvette C4 for some time now and today made quite a step forward in the understanding and solution of a problem that has plagued the car, one way or another, since it came into its current ownership. Basically the engine never felt like it was runnning quite right and, at the same time, with the ignition off there was a 1A drain on the battery. I suspected the ECM but as they are not so easy to source over here, particularly for a Euro spec car, I ruled out any other possible source until there was no option but to replace the computer. A US spec ECM was found & the PROM changed over (as it is that which defines the car), when it was fitted the engine started and ran but not well and I was presented with an error code that indicated a PROM fault, something the old ECM would never do. The 1A drain had also gone so I was certainly heading in the right direction. I had no option but to fit the US spec PROM, the car would now start and run a lot better but after 15 minutes or so of driving I would get a fault code that pointed to the oxygen sensor, unfortunate as the Euro spec cars didn't have one fitted and there is no allowance for one in the loom. There was, though, a blanking plug in the exhaust downpipe that filled the hole for the sensor so one was purchased and installed. That just left the small problem of not having the wiring, it turns out the contacts in the plugs that connect to the ECM are made out of rocking horse sh*t and I would need to find a plug that had been cut from the loom to strip for the required contacts. As luck would have it there was a pair of plugs in the US, I had a friend in Florida buy them (the seller wouldn't ship to the UK) and post them on. Today they arrived and I was able to rig the system with a wire from under the bonnet, through the window and to the ECM as a test - no more fault codes and a marked improvement in way it drives. Now all I have to do is find a way to get the wire from the engine bay to the ECM.
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