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Discussion Starter #1 (Edited)
My kids were driving this '91 164L car for many weeks, then it sat idle for a couple of months in the driveway. When I tried to get it ready for the fall commute, the #1 cylinder showed no power. Wouldn't drive well at all. Pull a plug wire from any other cylinder and there's a readily apparent power reduction, but not #1. Okay. Continue.

I eventually learned that the plug was wet, swapped it out in case of an internal fault, but no improvement. The plug wire was delivering spark, as I could hear the snap-snap from pulling the socket partially back from the head. Even put another plug into the socket and could see good spark. There is a burbling, back-fire kind of noise from the exhaust system after the car idles a few minutes to warm up, with only a couple of seconds long smoothing of idle through the transition. No real sounds-functional interval. When I pull the injector power socket, the burble/back-fire quits, so it appears that _some_ fuel is getting into the cylinder. Maybe not enough for firing, though.

I swapped out the rear injector rail without success{!}. Unfortunately the injector for #1 as replaced was leaky at the rail junction, and I ultimately put the old one back without learning anything. Oh, the car still missed with the other rail, still on #1. I was getting frustrated with all of the time passing. I measured compression on #1 and got 195 psi on this old engine. Seemed ok to me. All signals appear to point toward an injector failure. I swapped the dist cap in case the #1 plug port was shorted internally or similar event. Swapped plug wire from a set on a broken engine, and it seemed still OK.

Did I just get a bit of trash into the injector? I've had an injector set from a Spider serviced via mail. I could purchase a single injector easily to install there. Or I could do something different. Any suggestions? How do I reasonably check an injector. I did touch a 12V supply to the injector terminals and verified that each one would at least respond.

Is there anything I overlooked here? Is the injector the likely problem child?
 

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Compression and spark OK with no fire would seem no fuel. You can hear the injector clicking? Is fuel pressure OK? If so it seems a clogged injector to me.
 

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I might suggest you start using some Techron or similar about every 2nd tank filling or so, as that does keep injectors clean, at least to the point where they don't seem to give problems worth talking about. Have used it for years, with no injector problems, or maybe
I'm just lucky, lol.
 

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If plug is getting wet then injector must be working. Did you meg out #1 wire for 2.5 ohms resistance?

If you change out a bad plug for a good one and still no go I suspect bad wire.
 

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Dizzy checked?
Charles
 

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Discussion Starter #6 (Edited)
Thanks all... I thought I'd put some sentences into post 1 that I lost in edits somehow. There is a click from the injectors during the ECU test for them, and it goes away from #1 when its socket is removed so it's not just sound conduction from the rail from the synchronously firing group of injectors. While the original group of 3 (rear bank) was out I brushed a 12V supply to each and got the standard clickety-clickety with gasoline droplets ejected from pintle cap. I have kits consisting of seals and replacment pintle caps which I will install soon (if they are indeed the correct part).

I went so far as to swap #1/#4 plugs in the engine, to avoid the outlandish possibility of getting a bad new plug to swap in for a bad old plug. I'd already swapped in a new plug for #1, but stranger things have happened. Dist cap swapped out. I applied another #1 wire from another wire set with no change in behavior, and when I inserted another plug into the old #1 plug well fitting, it fired admirably. Wire passes all tests I have made but I have never ohmed out a plug wire. I'd have thought poor, rather than no, ignition would result from resistance change in the wire. I probably don't understand well enough the practical reasons for resistance in the wires. I thought it was to extend the spark duration rather than allow a brief, intense spark with reduced quality of ignition of gas/air mix.

The car backfires when warmed up and #1 injector is powered, but no backfires are apparent when #1 injector power socket is disconnected. I'd wondered whether the injector might simply be leaky, flooding the cylinder. I don't know what the typical engine response is to pulling a plug wire for minutes. I don't do that for fear of pushing too much raw fuel through the cat and overheating it, so I don't know whether the cars operating otherwise normally make backfire noises in such conditions.

I'd thought to purchase a new single injector, but I recognize that uniformity is important for mixture reasons. The ECU only controls the average fuel per cylinder and a lean injector can result in overheating one cylinder and damaging rings/piston through detonation. That may be only a remote possibility, but it is one of the bad outcomes I'm trying to avoid. However, swapping in an old injector from another engine is probably no different, and possibly worse. The cost scale as known to me for sending the whole set out for cleaning, inspection, and patterning is ~$120. It's getting to be a nuisance having the car resist me this long.

Thanks for all of your input. I'll post the outcome and logical path so folks can benefit most from whatever debugging info shows up.

Michael T
 

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Discussion Starter #7 (Edited)
Still no joy after replacing #1 injector with new Beck-Arnley from RockAuto (yes, clearance item, $40 to my mailbox).

1) 195 psig cold compression.

2) All plugs other than #1 cause further loss of power for engine when pulled.

3) Engine backfires when #1 injector socket is connected but not when pulled to deny fuel.

4) When #1/#4 injector sockets were swapped (synchronous injector firing, not timed cylinder-by-cylinder) problem cylinder remained #1

5) #1 plug connector can be heard sparking when partially pulled from plug well

6) #1 plug connector sparks a plug placed into it while the engine is running and throws spark to valve cover w/o plug inserted

7) swapped #1/#4 plugs also and found problem remains with #1 cylinder

8) checked valve clearances (part of first go-round on debugging) and found OK. I don't remember any more precisely than ~18 mils for exhaust, 11-12 mils for intake.

9) car is now giving me 1223 CheckEngineLight code, which is that the lambda probe correction has reached the correction limit, unspecified whether rich or lean.

The car's backfiring would indicate to me that unburned #1 fuel is passing into the exhaust. There is the possibility of a gross air leak, but I do not understand why it would affect #1 cylinder preferentially. I found splits on bottom side of both the oil separator and idle air controller hoses by spraying hydrocarbon brake cleaner around the areas and hearing the engine speed change. [Addendum: I repaired these leaks.] I believe there are no other gross leaks but may be wrong.

This is getting frustrating. And when reinstalling the #1 intake runner this afternoon, I was having trouble getting the screw started. When I pulled the Allen wrench out the screw came with it for a few inches, then fell into the timing belt area. This occasioned pulling some covers and fishing it out with a magnet. I couldn't be certain where it had lodged, couldn't see it, and couldn't take the chance that it was stuck somewhere harmless. It turned out it was in the second worst place, at the crank timing gear but forward. The absolute worst place would be at the rear of the timing gear where it would be guaranteed to pass through between gear and belt and either simply spoil the valve timing or possibly break the belt and not so simply spoil the timing. Major disaster averted. Continuing nuisance continuing.

Any help you can offer is welcome. I'm not used to having to fight the car this vigorously. I've been thinking of putting a spare Bosch 2-connector socket on the #1 injector, turning on the engine, and hooking it up a 12V supply to check whether nominally too much fuel actually makes it fire. I don't know whether #1 is too lean to burn or too rich, but I don't really hear a fires-in-transition when I pull injector power. If too rich, I'd expect that transient run condition.

Michael T.
 

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You have a real puzzler. I wonder what the click and clack tappet brothers would have to say on this one.

Are you sure you don't have an issue with #1 terminal in your dizzy cap such as a cross talk crack.
 

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Discussion Starter #9
I mentioned above that "Dist cap swapped out. I applied another #1 wire from another wire set with no change in behavior, and when I inserted another plug into the old #1 plug well fitting, it fired admirably." It's a real head-scratcher for me, too. Frustrating.
 

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I'm sure that this is not the same, but I remember years ago, a friend of mine had a 62 Ferrari, and it would run on 11 cyls. Could not figure out what the problem was. finally discovered that one spark plug hole was drilled just a tiny bit deeper than the rest, and one of the plugs he was using would stick into the combustion chamber just a little bit more, and piston coming up would tap the electrode and close the gap to nothing, thus no spark in that cylinder. Had to go to double washers in that cylinder.

We will continue to think about this one. I suspect that something is not as described in the above diagnoses. Trick is to figure out just what it is.

One thought, is the no. 1 intake runner fully sealed at the head and air plenum when installed, or does the runner have a hole or crack in it?
 

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Discussion Starter #11
runner cracks, leaks, etc, were the reasons for my spraying brake cleaner around everything as a leak detector. Found some unexpected ones, but none of the hoped-for leaks around the intake runner. I agree that something must not be as I have perceived it. But what? I'll keep looking.

Michael T
 

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have you checked cam belt timing
 

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"I eventually learned that the plug was wet"

Wet with what? Gasoline, coolant, or oil? Do you think it might be possible that there is a coolant or oil leak of some kind into that cylinder, wetting the plug, and shorting it out when it is installed in the head, but not when it is out of the head in open air? This quite possibly might not affect the adequate compression you have measured to an appreciable extent. Is there something in the plug chamber in the head which is shorting out the lead ie, coolant there? Is the ignition lead cap staying on the plug top when it is pushed on the plug, is something preventing the plug from reaching all the way down onto the plug and making proper contact?

My impression is that something is preventing the plug from sparking ONLY when it is installed in the head. You've changed the cap, the rotor, the lead, the plug, the injector, the compression seems to be near normal, you say you found no air leaks at the runner ends, so what is left?

I don't know whether or not a jumped timing belt would cause this problem. Maybe the rough running of the engine is mistimed valves, and it is only an assumption that cyl 1 is not firing, but is not at the proper cam settings? Have you actually checked the valve timing using the template?
 

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I had the same problem with cylinder no2. I tried every possibility you tried. No luck. I removed the head and I found out there was a hole in the water passage. Irreparable. Bought a second hand head, reconditioned it and now the 2nd cylinder works properly. Check my post with photos - injectors removal - and good luck.
 

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Had this happen with an Alfetta head, small casting flaw opened up and leaked coolant into an exhaust passage behind the valve. Luckily, was able to get it welded up.
 

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His compression would not support a hole into a water passage I don't think. That backfire I think will be key in the solution. ciao, chris
 

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It doesn't take much of a leak to cause problems, but not appreciatively reduce the compression I would suspect.
 

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I'm sticking to my dizzy cap story new or not cracked or not something not firing at right time if he has wet fuel in the #1 hole.

Recheck wiring firing order in cap, too.

Take the black cover off and inspect orange cap for cracks/defects.
 

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Possible, but he says he gets sparking at plug when stuck into the ignition wire socket and grounded.
 

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