Join Date: Oct 2001
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1990 EFI Zuk Problem - 911 need help!
Long time no post, but I told you guys I would eventually be back!!...Just cant leave the Zuks alone.
My buddy and I have ran into sort of an issue with a 1990 EFI ZUK. The thing seems to start and Idle perfect, but no power when you go to take off or stomp the accelerator hard. If you bring the throttle up slowly, it does fine and rpms rise fine.
We troubleshot just about all day yesterday and I have come to a fairly simple conclusion...Using a timing light, I noticed that the engine isnt advancing when there is a drastic change in throttle position (Like stomping on the gas quickly)...When the rpms are brought up slower, the engine will start to advance later in the rpm range. I even went as far as to manually advance the timing WAY ahead in an attempt to simulate the need for high advance under load, and was able to get the mototr to run close to good when WOT (Wide Open Throttle) was attempted.
On a carburated engine, this is usually the job of the Vacuum advance...But not on an EFI rig.
I had a similar problem with a rig I got from Max (MAXNHID) when I was in NE...In that scenario, I swapped in my computer from my 1994 rig and it ran fine, so I bought a used computer for it and I was on my way.
We have chased the entire wiring harness looking for shorts, and re-taped a lot of it.
We have done Plugs, wires, oul, air filter, checked fuel flow (Shot gas all over the place)
We have checked to see if the timing belt was off by a tooth, and I do not believe it is.
We have bought a completely rebuilt computer for it from AVPROECM out of Florida, so it should be better than new.
We also got a brand New Throttle Postition Sensor (TPS) from NAPA.
Still the same issue...I do honestly believe the computer may have been bad, and now know for a fact that the TPS was as it was actually cracked...
Problem is, we are $400 into troubleshooting and have run out of money to keep throwing at it without knowing for sure exactly what the issue is...I have exhausted my knowledge base on what the actuall issue could be...Basically I am just guessing at this point and its too expensive to guess on these EFI rigs.
SO here is what I was wondering:
Im near certain the problem either exists in the Distributer, coil, igniter, or even possibly the Throttle body Injector.
The reason I say this is because these are the parts that we havent touched or been able to swap out yet...
Any idea what I could look at next??
Do you guys have any spares of these hanging around for us to test with or possibly even buy as spare parts for the rig??
We deperately need to get this issue worked out, and due to my lack of any EFI parts, its near impossible.
This is what I would need:
Injector with attached TPS
Entire Distributer (With all the electronic goodies inside of it)
If you dont have the parts, do you know anyone that might, Know what the issue could possibly be, or point me in the correct direction to find out?
Also, I used to have a coputerized version of the Factory Service Manual back in my days in New England (I even donated a bunch of copies of it for raffel prizes at the last GoneZukin that WildWeasel hosted)...Do any of youstill have a copy of it I couldd get my hands on again.
Thanks guys and I look forward to hearing back from you as Me and my buddy are both running out of ambition now.