electrical gremlins??

[pizzapete]

Hoping someone may have had a similar problem or know the solution to this. A few days ago the engine (3.9 serpentine v8) started missing and losing rpm after getting to operating temp. Over the last couple of days it seems to be a little worse with the odd backfire thrown in for good measure. I have checked the ign leads ign module temp sensors dizzy cap for moisture and cracks and all good. It seems like it may be over fueling though as the plugs are dry and black in colour. Replaced the plugs and now the new ones look like the old ones. Am now stumped and leaning towards either the ign coil or the ECU being the culprit. Any ideas from any one?

[sparky34]

Pizza

My V8 developed a bad miss when hot several months ago, the hotter the engine got the worse the miss, replaced the Lucas ignition module as per beeuty"s excellent tutorial and problem gone.
Search for " Lucas ignition amplifier replacement by Bosch 024"

Sparky

[bee utey]

1. Ignition amp as mentioned by sparky. Lucas ones and their aftermarket clones are crud. Thread here:

http://www.aulro.com/afvb/technical-chatter/96950-lucas-ignition-amplifier-replacement-bosch-024-a.html

2. ECU temperature sender, it has a plug that looks the same as an injector plug, just behind the thermostat. It should read approx. 300 ohms across the two connections with the engine hot. Open circuit means the engine gets full rich cold mixture all the time.

[pizzapete]

Ignition module is a bosch unit. Doesnt look very old. Will check that sensor again in the next couple of days when I may get a chance to play with it again. Thanks

[pizzapete]

Ok not the ecu temp sensor. Its got me stumped. Dont think it is an ignition issue??? Obviously its not a common problem.

[bee utey]

Have you checked the terminals around the coil to see that they are really tight on their connectors? I usually squeeze all terminals with a pair of pliers, put them on and off a few times to get clean metal to metal contact.

Another good lurk is a failed fuel pressure regulator, remove its vacuum hose off the back of the manifold and see if petrol dribbles out. I replaced one on a '92 RRC a couple of days ago. The vacuum hose had been feeding a small amount of petrol into the manifold until it perished and fell off.

[pizzapete]

Bloody Coil. A huge thank you to bee utey who took the ecu out of the equation. Even though I tested the coil in the usual manner it appears it was faulty only at operating temp..