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I’ve posted about this car before, years ago and thank you to those who replied.
This is a 1988 4ZD1 2.3L 5spd MT EFI non turbo with about 128k.
A few weeks ago it was running great and just switched off. The tach zeroed instantly
then the engine spooled down and stopped. It turned out the sensor pack in the distributor had kind of rotted
apparently due to a small oil leak into the dist. I bought a new, not reman dist, installed it observing timing as we all know to do. It started and ran good for about three seconds, started missing on several cyl., slowed down and died. I could repeat this at will. So I tried another one from a different brand with the same result. I checked for consistent spark, even installed a set of plugs I already had and subbed the cap and rotor from the old dist. It appears cyl 1 and 2
at the down stream end of the rail are contributing the least. When I looked at the plugs 1 and 2 were dark compared to 3 and 4.Then I looked to fuel. I checked fuel pressure and it looked reasonable considering I had looked at it before when the car was running well then turned the key off. The pressure zeroed instantly. I squeezed off the return line, recycled the key and it held. I removed the FPR and I could blow through it while holding it in my hand and applying vacuum with a hand pump made no difference in the apparent opening. Most recently I replaced the FPR and now the fuel pressure holds when I turn the key off but it is still loading up and dying at idle. I have not looked at the output of the O2 sensor but my nose tells me it’s just flooding out. At higher RPMs I can run it indefinitely on all cyl as long as I hold it there.
This is a simple non electrical FPR and I don’t know what the proper characteristics should be on an out of car manual test. Should it be closed with no vacuum applied or have some opening? Should you be able to see an effect by applying vacuum and how much vacuum? Even the new FPR did not change in any way I could tell with vacuum applied in an out of car test.At this point I don’t know how to make this beast run right.
Thanks for any thoughts.
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After going through two distributors I gutted the second one and built up the old one with the parts from the new one. Ran perfectly in all respects, so since It had a leaky shaft seal which I did not switch over I went back and carefully duplicated what I did using the new dist case. What I discovered is that the height of the sensor tone wheel is critical where it slices through the horseshoe sensor block. Get it too far from the sensor side of the block (too close to the LEDs) and all hell breaks loose. Put it as close to the sensors as possible without scraping the block and it runs perfectly. The problem was that they never included the little flat washer that raises up the tone wheel in the new distributors. When I looked at the sensor output on the scope I could not tell the difference between the good and bad config. That mystery remains but the car is back on the road. My only concern is did I ratf%$#k the cat during all these shenanigans? We will see in December on the state inspection.
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