#3 not working HELP

[narfire]

Finished installing an engine that has been a bit of a work in progress. Car is an 80 FI. the engine has new Mahle pistons .4 over, balanced,lightened flywheel and big valves and a 1800 head.
Started it up this afternoon. Sort of runs, now back in school, 75% for me would be pretty good but not on a 4 cylinder engine.
There seems to be a definate miss.
I have checked spark : yeup good there.
When I pulled the fuel injector connectors there was a definate change in all cylinders except... #3.
Noids light check on all... yeup good there.
Swapped #3 injector with a known good one from the old engine... same miss. swapped out the whole rail with the old rail... same miss #3 I pulled connector and no change.
Compression check.... 145-150 on all 4
The fellow whose shop and hoist I'm using (retired eye surgeon from Dallas) suggested check valve clearance, going to do that tomorow but I thought if compresion was good then valve should be OK.
Any other suggestions?
Wing night at the pub.. going for dins now.
Thanks
Chris

[maytag]

you're correct that if compression is good, so should your valves be. (at least for the purposes of this conversation)

Double-check the simple-stuff first: Firing order! (I assume you have)
Have you pulled the spark-plug on #3? Does it LOOK like it's been firing? I mean, is it brown? compare it to #2. same color? Swap their positions, as long as they're out!

try it again: report back!

and enjoy them wings!

[So Cal Mark]

can you hear an audible click from each injector? If the injectors have been sitting for any length of time, they're probably stuck.

[narfire]

Had a guiness and wings.. good to go

I hope i've put the leads on right.Check again tomorow there is spark at the plugs.
The car moves but no power, sure sounds/feels like 3 cy. working. When I put the engine in, I had made up an injector rail with new lines,seals ect.for that engine. After finding the miss, I took it off and put the rail from the original engine back on. The original engine ran fine with no issues,so I'd hope all the injectors were good. I had also ,if this makes any sence, taken the old #2 injector and put it onto the #3 pos. of the rail with the new engine, so in effect I have tried 3 different injectors on the #3 cylinder.Weird that when I pull the injector lead there is no change in the engine note.
I'll Take my shim kit over there tomorow and have a look see.
BTW the compression in the old engine was around 130 +- 5pounds, I hope 145-150 won't be too much. I have a feld-pro head gasket on.

[So Cal Mark]

could you have a large vacuum leak at #3? If the lower injector seal is leaking it can cause a lean misfire. With the engine idling, try pulling the spark plug wire from the dist cap. Hold the end with insulated pliers close enough to the cap so that spark will jump to the wire. That increases the spark intensity and can cause the plug to fire if its' fouled. If no change, try spraying some carb cleaner around the injector. Rpms will increase if there's a vacuum leak

[narfire]

Thanks Mark. I'll try that. NOW that you mention it.... the compression tester, when on #3, after reading 150,started to bleed off,not sure if it supposed to or how fast, but from 150 to 0 took about 2 seconds. I have a handfull of seals and will take a few minutes to change now I have done this a gazillion times.
Looking forward to that insted of fiddling with the shims. Got my fingers crossed.


BTW have a fun day tomorow, sounds like a good time comming up.

[htchevyii]

my compression tester has a valve and doesn't release the pressure until you hit the button. If your is like this, it shouldn't leak down. Good luck, hope it's something simple.

[majicwrench]

Just to run down some things..... some you have checked already but...
If compression is 145, that's fine. But along with compression test, I like to crank and engine, plugs in, ignition disabled, and listen to the cadence. An engine with everything in good mechanical shape with have a nice rythmetic sound, "RRRRRRRRRRRRR" , an engine with some sort of issues will have a skip in the beat "RRRR-rRRRR-rRRRR-r"
LISTEN to injector with stephascope or long screwdriver, compare it with the others, it should go "click-click-click" as it opens/closes. If it does, that is fine. THose connectors at injectors can get poor, but if you can hear it click..is OK.
If you are getting desperate, pull entire inj rail and watch all inj spray DISABLE IGNITION FIRST
Spark, put spare plug in #3 wire, run engine with spare plug grounded on something, zap zap zap.
LIIke Mark said, pull plug and inspect, swap with diff plug.
LIke Mark said, vacuum leak. WOuld have to be a pretty good sized leak, not sure if an injector seal would make it miss, other than at idle. What vacuum hoses/fitting attach on the #3 intake runner??
Let us know,
Keith

[racydave]

All the other suggestions are dead on, esp the vac leak at that cylinder. I wonder why that cly bleeds off so fast? Could the valve be shimed a little tight???.

[narfire]

I think I've got it
Before I started mucking about with the shims I swapped plugs and put a set of wires on from another fiat.
Yeup, after a very brief hic-up she ran smooooth. Going to replace the cap and rotor and pickup just cause and a new set of wires.
Had to take the headers off to fix a leak at the coolant connection at the end of the pipe,but after that... holey sh.. there is a marked difference in get up and go.Gonna look for that orange mg next summer.
I have one more day with the insurance,bummer but the weather is going to go downhill real quick here.
A hour of driving around the immediate area to set the rings and check again for any more leaks and then I'll attempt the 40 klics home.
Thanks for the suggestions
Another question though, I was told to re-tourque the head after a few cycles of driving and cooldown, any thoughts? how many cycles?
Gotta love easy fixes

[So Cal Mark]

that's good news! You can retorque after 2-3 heating/cooling cycles

[narfire]

Put new NGK's in today,not fancy ones but good ones and a set of leads. When I removed #1 plug(used to be #3) it kinda fell apart. There must have been a serious crack in it, that was the problem with #3 not working right. I did'nt notice till the plug was in my hand,looked in the plug reccess and there was porcelin chunks real close to the hole.... kinda about to drop in. Remembering a previous post about bits falling in, I grabbed the shop vac. and was going to suck the bits up. I have a 2 inch suction so looking around... found the rubber boot covering a spare ignition switch and taped that onto the end,stuffed it down there and no more porcelin chunks. Car runs great,let a buddy who has a 300ZX try it and he was impressed besides the fact my fiat was running and his ZX was not. Perhaps a convert?