Hi all first post here. Friday mixed day driving car ran great very hot in U.K. this week temp gauge hall way no problems there. After about 100 miles stopped at junction for quite some time tick over at showing just bellow the 1,000 mark pulled away 300 Y.R.D. later car went sick miss fire felt like it went on 4 cyl slipped in to neutral and gave it some hard right foot took some time to clear then sort of ok but not running as smooth as before miss fire .Sat out in car this morning tick over very low needle on rev counter just about at first white mark .Car stalling when turning at low speed engine still a little lumpy no way as smooth as be for problems. Had head gaskets replaced plus plugs plug leads distributor caps and arms knock sensors idle control valve . Help please cheers.

 

Has the computer ever been rebuilt?
John Speak is in your neck of the woods.

That said its usually a failed or grounded ignition coil wire,
NOTE your car should not have the thermal sensors in the ex manifold or the ignition cutoff relay.

That said if you have cats look at them,
if the engine isnt running on all 8 and if they are glowing red then shut the engine off,
dont park near any buildings ,
till you figure this out.

 

Are you sure both coils are working?

 

So 87 means no ignition monitoring system to worry about, and UK 87 means no cats or O2 sensor to worry about. That narrows it down a little.

First step is to test for spark on both ignition banks (i.e. one spark plug lead off each distributor). If both show spark, test the other remaining plug wires too (may as well make sure the problem isn't a specific cylinder's lead or spark plug).

If one bank has no spark, then you can trace it back to a failed ignition amp, coil, or loose lead.

If spark everywhere, then its time to look at:

• MAF (check connector, measure pins at the LH ECU plug to make sure they match WSM specs, and check for shorts etc.)
• Check there's a pulse on each bank of injectors (a small 12V bulb with a couple of filed-down spades soldered to it - plug it into each injector plug). A short in the injector harness can take out four injectors.
• Idle control valve - check it operates (plug in a Bosch Hammer/JDS Spanner etc. is easiest way)
• If both injector banks are working, and there's spark
• Temp II - check each pin in the sensor matches WSM spec for temperature and isn't open

 

You can go through all of the standard troubleshooting if you want, but if you have not had the LH computer rebuilt, you are wasting your time. The exact symptoms as described point to the LH computer, especially in hot weather, after checking the connectors for the crank position sensor and coils primary and secondary wiring.
Sooner or later the LH will have to have the hybrid circuit board replaced, so put yours into a running car to test, or just swap it out to eliminate this primary issue.
John Speake in the UK can arrange this.
Just my experience with my 87 S4.
Dave

 

Go through the check list that Hilton has outlined. Do drive the car any more than necessary as the vibrations can damage transimission components.

The symptoms are not typical of LH failure but I can certainly test your LH ECU to save you replacing parts at random. Maybe a good idea to send the EZK igntion ECU at the same time.

 

Inspect the coil leads. Corrosion at the connection can cause these symptoms.