I have an '88 GSL with mild porting, air box removed, all smog stuff removed and S5 VDI intake installed. I have 50,000 miles on this engine since I rebuilt it 10 years ago. I have done all my own work on this car over the years but this time I am stumed.

Several months ago, the engine started faltering at approx. 3800 RPM. Several tests proved the secondary injectors are not coming on. I can unplug them and the car runs exactly the same. That is the first problem and I have not found the source.

Now a couple days ago, the EGI main fuse blew while I was driving on the hyway. Swapped the fuse and of course it goes again. A 40A fuse instead of the stock 30A will last about 5 seconds before going.

I am at a loss for how to trouble shoot this one. I assume I have a short somewhere but don't know where to start.

Any help or suggestions would be great.

 

Egi fuse runs a couple of things.
The "bottleneck" of the wiring is usually behind the alternator/Waterpump housing area where the harness can rub and start to short out wires.Check there.
Oh also the ACV valve on the lower manifold can short out it's sensor and blow that fuse.
It's a start anyways.

 

You should never place a higher rated fuse in place of another. Secondly, there are two EGI fuses so which one is blowing? Is it the Comp or Inj fuse (the Comp fuse is supposed to be 30 amps and the Inj fuse is 40 amps). A grounding problem could cause a problem w/the secondary injectors as well as the injector plugs being loose or poorly wired.

 

Thanks for ideas guys.

It is the EGI Comp fuse that is blowing. Yup, understand it needs to be a 30A but the parts store ran out so I had to buy 40A fuses. I'll get more 30A fuses and get the right one in there.

You mention a grounding problem and now that is making me think. Last year I had the VDI intake completely off and removed injectors for cleaning. I wonder if it could be the engine ground wire on the top of the block and under the intake plenum??

I am not looking forward to taking that apart again to check it but guess I will have to.

Thanks

 

The Comp fuse powers the ECU via a Black/White wire but it also powers all of the emission solenoids (such as the relief, switching, BAC, EGR, port air,pressure regulator control valve, split air, air bypass and air bypass relay) so chances are one the B/W wires feeding a solenoid is accidentally grounded out.

 

OK, I found the shorted wire behind the alternator in fixed it. Re-wrapped the entire harness in that area and we are up and running again.

But, I am still having the problem with loosing power at 5000 RPM. Under light load, it might make it to 5500. It seems to be temperature dependent, so I keep thinking it is fuel delivery dropping off. But I can't find anything wrong with fuel injection.

I have checked all plugs and swapped the trailing coil.....ignition seems to be fine.

Anyone have any ideas of what I am missing?

 

Clogged air filter, clogged cat, poor grounding, ineffective VDI/secondary ports, weak fuel pump.