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One injector randomly stops firing

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jdxnc

DSM Wiseman
1,455
2,943
Sep 15, 2009
Stanstead, QC, Canada
I put a 1g 7bolt in my car a few weeks back after blowing a rod through the side of the block on my stock 2g 7bolt. I put my 2g head on it, wired up a 1g green top cas. Everything has been pretty decent, but I have a pesky issue with my injector on #4 randomly stopping. These are the same injectors I used before the engine blow with 0 issues.

Car runs and drives perfectly, for say 10 minutes or so till it warms up good, then out of the blue while cruising the injector on #4 will just stop firing. I found that quickly turning the key to acc then back to on, more or less resetting the ECU I guess, makes it go away for a bit and returns to running like normal. Now the strange part is that it does not do this if I basically drive in pulses, give it gas for 30 seconds, let off for 5, then another 30 sec, etc, the car will drive fine for hours like this(I know, it happened to me in Montreal I had to drive it back 1.5 hours like that). But if I stay on the throttle for more than 30 seconds or so if will stop firing on me until I flick the key switch again. It also seems to handle WOT no problem, it really only happens during a gentle cruise, but occasionally does under high load.

I checked the connector, it looks good. I swapped the resistor/ballast or whatever it's actually called on the firewall for the one from my parts car and the problem remains exactly the same. Tonight I took the ECU out to check for any leaking caps and couldn't see anything wrong with it.

The ECU throws a 0300 random misfire code when this happens as well as a 1500 generator fr terminal circuit malfunction at the same time.

Could this all be related to a problem with the alternator? I'm thinking I may switch my injectors around to see if the problem follows, but to me it really seems like an electrical issue. Any ideas?

Details of the car:

1997 Eclipse AWD swapped GST - 1G 7bolt with 2G head - PTE 5031 - FIC 850cc - DSMLink V2 - PR FMIC - 3" TBE - Walbro 255 - Fuelab AFPR -LC-1 WB
 
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