In reply to AngryCorvair (Forum Supporter) :
It is the farthest from the feed line, so it's possible. Guessing we'd have to pull the rail and flush it if that is the problem. Or buy some chintzy anodized aluminum fuel rail on eBay.
Hope it's just a very tight exhaust valve on cylinder #1.
If the injector wiring has some covering or wrap, remove the covering. I had a somewhat similar problem, car had a little oil leak, the oil got into the injector wiring. The wire covering, kept the oil on the wire, it was a mess. On that car, one wire to each injector was a ground, so part of the rewiring was fairly simple.
Some systems the ECU provides power pulse to the injectors, some the ECU provides a ground pulse. Either way, one wire to each injector will go to a common group connection, that side is simple to redo.
There is a small valve opposite the #1 injector we can pull off to get a better look as well. Will try running the injector into a jar and see what thatbshows as well.
Back at it again this morning with Dave while Tim is off on an adventure
First things we pulled the FPR and flushed the rail. Flow looked good and no debris knocked loose
We pulled up a YouTube video, said a small prayer and dug into the valves. This is our first shot at it
Rotated a few times and dug in.
our feeler gauges were .004 at the smallest, and we went off the google advice of the acceptable ranges being
intake .003-.005
exhaust .006-.008
we measured all, found a few that were borderline and cyl 1 intake were .006 and .005. We adjusted down to a slight drag on .004 feeler and buttoned it back up with the new VC gasket after de-scuzzing the vc.
(Ground cable was reattached after this pic)
Fired it up, and it idled happy for about 3x longer than before then the misfire started again.
Checked exhaust temps again and cyl1 is now much closer to the others.
Before the temp delta between 1 and 4 were ~ 100F. It's now down to ~50F. So it seems to be generating more heat.
Not sure where this leaves us, but it seems a little happier with the adjustment. I think next plan is to get a .003 set of gauges and reset all the valves and see where it leads. It seems for whatever reason (maybe coincidence?) cyl 1 is doing a little better after the tweak. Maybe a better adjustment will set it right
I'll do some research to see what is happening system wise in the warm up cycle.
It was happier 3x longer than before but then progressively gets crappier as it heats up.
Seems so odd to me that a minor adjustment to two valves on #1 cyl made a 50deg improvement (towards balance with the others). Still off by 40deg low vs others but much improved.
My experience is that I rather have valves loose than tight. So I would leave them as is. I doubt that tiny adjustment made any difference, most likely a coincidence.
Too tight a valve and it might not seat properly once warm and then you burn it as it cant dissipate heat through the seat.
I would now concentrate on the injector, wiring to the injector and spark.
I wish you guys were closer as I have an injector cleaning machine that I could run them through and test them. But you can do the same just running them off the rail with some plastic cups as I did on the previous picture.
Any chance you guys can check compression on that cylinder?
Eastside Tim ultrasonically cleaned the injectors (that looked like diesels, we tried swapping them around cyl to cyl, noid light tested each, and tested power/ground to each. They are flowing and firing. No obstructions in fuel rail following testing this am.
The big change in egt temp deltas following valve change can't be coincidental as we didn't touch anything else.
Setting all valves to a baseline can't hurt and won't take much time. Researching the magic number but it seems like you set intake at the bottom 0.003 and exhaust at the top 0.007?
Going to test the ECT sensor as that drives the ecm signal for cold/warm.
Going to clean the idle air control valve as that is apparently an issue on these cars.
In reply to Slippery :
We checked comp on all cylinders when we first dug in. It was cold but they were all similar, 140-155, with the 155 being cyl 1
we are getting pulse on the injectors confirmed with the noid light
We swapped 2 injectors and the issue didn't follow the injector.
Ignition- confirmed getting spark
plug is new, distributor is new. Plug wire resistance checked good
fuel-
new filter, cleaned injectors, confirmed voltage, confirmed pulse, confirmed issue didn't follow the initial problem injector.
Other:
Cyl 1 exhaust temp lower, was 100F lower than cyl4, now 50F after cyl 1 intake valve adjustment.
have not re-checked timing but would assume it would impact all cyl
Have some sensors to clean and check but still puzzled a bit.
Possible there's something in the ECU that when failing would just impact cyl1? Suggestions on where to find a known hood ecu? This car has a P75-A51 ecu.
In reply to Cooper_Tired :
I had forgotten about the initial comp test. Scratch that.
In reply to 84FSP :
I agree that adjusting the valves cant hurt, but a .001" will not cause an intermittent problem like this.
To me this points to an electrical problem more than a mechanical given how the injector was swapped and the problem stayed in the same cylinder.
You guys are on the right track covering all bases.
Where is the ecu in these cars? Any chance it got wet?
In reply to Slippery :
Passenger floor board.
doesn't look wet but no clue
Have a lead on a cheap ecu from FB I may buy to swap and test
also apparently the ECT on this can also cause weird electrical issues so going to dig into it as well. Aftermarket ones are $15 so cheap theory
Man this is just a weird issue. If you want me to look over anything, I should be free tomorrow, as long as the rain stops. Although it sounds like you've covered everything I would have thought of.
Had another thought. Have we figured out how to pull the codes from the OBD1 port yet? Should just involve a paper clip or a jumper wire if we are lucky. Maybe that'll clue us in to a bad sensor or other issue.
Yeah - it's as if the engine doesn't want to run right to avoid it's dose of nitrous? Or maybe is playing sick and enjoying all the attention, cleaning, and new parts? It keeps improving and everything we have touched is better for it but...
Might try doing a compression test, cold and then do again with it warm. Would only have to do 2 cylinders, the one with the miss and one other.
Running it some with fresh clean oil, might actually make it a little better.
Try running it at night and watch the plug wires for any arching.
In reply to TED_fiestaHP :
Was just thinking about a warm compression test to see if it improves. We checked the ground wires for the injectors back to the ECU, and #1 and #2 were the same resistance, so it is looking less like damaged wiring. I think Cooper_Tired is going to order some plug wires, because even though we had also checked their resistance, they are about the last thing we can think of that would affect performance in an individual cylinder. 84FSP managed to straighten out the driver's fender some, today, too.
Update.
Tim and Dave stopped by to dig around some more
Pulled codes and had code 4 and code 16 which are CKP sensor (in disty) and fuel injectors. Had not previous cleared so it's possible it's from pre-disty change.
pulled the plugs and re-confirmed .044 gap and swapped plugs between cyl 1-2 to ensure nothing weird with the plug. No change.
Tested the ECT by running plugged and unplugged. No change in misfire.
We hooked up a timing light and reset the base timing. Timing was a little off, but it didn't resolve the misfire.
Tested injector wiring resistance.
Engine side confirmed continuity and 0.4 ohm resistance.
Tested continuity back to the ECU, confirmed and 0.4 ohm resistance.
Dave took out his frustrations by cleaning up the headlight and popping the fender back into reasonable shape
The #1 plug wire pulled apart when we were testing spark so a new set of NGK wires are on order. The old ones checked fine on resistance before so not expecting this to fix it.
That will put us with new plugs, wires, and distributor on the ignition side.
Fuel side we have new filter, cleaned injectors, confirmed wiring, confirmed ECT seems to be operable.
trying to think through it's something that is impacting just cyl 1, or seems to be.
Spark - maybe bad wite
fuel- maybe ecu?
mechanical - maybe burned valve or stuck valve? Cold compression test was in line, but need to confirm hot
Given cyl 1 is probably the shortest wire see might not be able to swap with two, but you might be able to steal the #2 wire for a minute and use it for one, leaving two with no wire. See if it still runs in 3 cyl or 2 cyl, if it runs in 3 cyl would confirm the wire as now 1/3/4 are running instead of 2/3/4.
In reply to Slippery :
It's the longest wire unfortunately
How's fuel pressure?
In reply to solfly :
40psi
Same as manual states
How sure are you on timing?
This weird for sure. i was also wondering about fuel pressure but fuel flow shouldnt be affected by temp like that.
If a plug wire had an internal break somewhere would it act like this? Heats up slightly enough to expand and interrupt the spark? Guess we'll eagerly await the new wires...
In reply to XLR99 (Forum Supporter) :
This is kind of my hope. I'll be elated and annoyed at myself if that's the case
In reply to solfly :
Not 100% sure.
we put a light on it today and put it as close to 16 past tdc per the manual but the disty was at the end of its advance.
It smoothed it out overall a little on the 3 working cylinders but didn't resolve the cyl misfire.
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