Runner4Luke

PROBLEM SOLVED
See page 10.

Hello to the yotatech community! This place has been a gold mine for me over the last couple years in trouble shooting and building up my own 22re for my 87 4runner.
Now I am trying to diagnose a missfire condition in a 22re, 88 runner.
I aware there are tons of threads on this, but I haven't found any that match these symptoms. Hoping for some fresh ideas.

Symptoms (very basic)
-Cylinder 1 does not fire at idle at all.
-Fires for all other driving conditions (smooth and strong while driving).
-Positive Spark (nice and blue)
-Audible injector firing via the screw driver stethoscope
-Good compression.

What I've Done
-New head (engbldr), it all started after this (ran beautifully before the head went)
-Exhaustive Vacuum check, no leaks.
-Cold/dry compression 150 lbs, Hot/dry compression 165 (good enough to not inhibit combustion. Slightly higher PSI than cyl. #2 @ 147 & 160 respectively)
-Pulled all the injectors, cleaned them, tested them, and ohm'd em all out. New seals. All good.
-Swapped injectors 1 & 2, problem remained with cyl. #1
-Attached the clip for injector 2, to injector 1. No change.
-Measured resistance from #1 clip to ECU(ground), zero ohms. Good.
-Measured resistance from #1 clip to(not across) Resistor box, zero ohms. Good.
-(I can hear the injector start and stop firing when I dis/re-connect it's clip)
-Swapped distributer cap and leads from my truck to the 88. No change.
-Timing set to 5 BTDC with jumper.
-Fresh plugs, and swapped them around.

It would seem I've got spark, air and fuel. No idea why it's not running.
Soon as the engine gets loaded, it starts hitting. (checked manifold temps after driving the car, definitely firing. Also just drove it with the #1 plug off to be sure, and I am)

The only possible clue I have, is when I last swapped the injectors around, I saw a small pool of oil in the intake leading to cylinder 1. Thought blow by might have forced oil through the forward breather tube (near cylinder 1), but no oil blows out while running.

I must have made a mistake or overlooked something in my diagnostics somewhere, any ideas?


Other symptoms.
-Hardstarting when cold as well (to be expected with only 3 cyl. right?)
-Coldstart injector doesn't work most of the time (timing switch checkout via FSM procedure), The injector itself checks out. Obviously contributing the hard starting.

Runner4Luke

I also just enriched the mixture by changing the spring tension on the AFM, it improved the idle slightly, but still completely missing on number 1.
So brought it back to one tooth richer.
Tried out another igniter coil on the 88, no change.
It strange, because the idle has good little shake, but not nearly as bad I would have expected for missing completely on a cylinder..

Shady Cadence

Use a noid light and verify your injector pulse at idle, you might be losing it.

Runner4Luke

Good idea, I was looking for an oscilloscope.

So I made a noid light out of a 12v incandescent (~2.4ohm) in parallel with a 12v led (~600ohm) to simulate the resistance of the injector (~1.9ohm), and because the incandescent wouldn't light up on its own.
The LED lit up dimly at idle and increased in brightness with RPM.
Same results when I tried it on #4 cylinder.
So the signal appears good.
Any other ideas guys?

abecedarian

Maybe physically swap IJ1 and IJ2 to see if the problem is the injector spray pattern.

Check valve lash; check compression. If both are okay, do leak down test.

Runner4Luke

Valves are definitely in spec, just did them.
As stated, I swapped IJ1 and IJ2, and their respective leads. The compression produced decent numbers as well.
If compression is ~150 cold/dry and 165 hot/dry, is a leak down still necessary? Cylinder 2 has slightly less compression and its running fine.
I thought leak-downs where more to diagnose poor compression..

Shady Cadence

At this point, i have to suspect something with the cylinder head. Try doing a running compression test. Put your tester in cyl 1, start it, then release the compression on the gauge and see how it builds at idle. There's only three things needed to fire: fuel mixture, compression, ignition. One of them has to be going away.

abecedarian

Don't know if you caught my edit of my post but maybe try moving #1 injector itself to another cylinder.

Fuel pressure should be ~38 at idle but increase to > 40 off idle- somewhat based around manifold vacuum. That doesn't sound like a lot, but that could be the difference between a dribbling injector and one with acceptable fuel atomization.

You've already hinted at that when you mentioned "I saw a small pool of oil in the intake leading to cylinder 1." That might not have been oil, but rather a puddled accumulation of crap dissolved in fuel, if that injector weren't spraying properly.

Runner4Luke

Sorry my original post isn't that clear.
I did physically swap injector 1 to cylinder 2, and injector 2 to cylinder 1.
No change.
After that happened I put the injector 2 lead onto the cylinder 1 injector to test the lead. No change either.

I guess I'll try that running compression check, strange that it would change when running.. sticking valve? Its a brand new head from engbldr..

abecedarian

If the problem didn't follow the injector when that was moved, it's apparently some issue mechanical. I wouldn't rule anything out, regardless who did the head work.

You might have a slightly warped intake manifold or head preventing the gasket from fully sealing, sticking valve or even imperfect valve seat / valve face matching. And it's possible none of these would show up during the typical compression test. But an issue with the valve / seat would reveal itself with a leak down.

Runner4Luke

Are you talking about the intake gasket? I did a smoke test, starter fluid and propane. Found no leaks..
Better find somebody with a leak down kit.

Punchy

Never mind, Missed a reply.

abecedarian

Leak down is easy: if you have the tools to do a compression test, you're almost all the way there. Only need a source of compressed air, a pressure gauge and the fitting to mate with the spark plug hole.

Put the cylinder being tested at BDC between power and exhaust strokes, intake and exhaust valve rockers should be totally slack- if you can't wiggle them around, that might be a problem...
... put the gauge and adapter in, then fill it up with compressed air- as much as you can.

bubbles in the radiator = leaking head gasket or cracked cylinder / head
hiss in the intake = poor valve / seat surface seal
hiss in the exhaust = poor valve / seat surface seal
hiss in the oil fill = excessive cylinder taper / out of specification, worn / relaxed oil scrape / compression rings or possible head or cylinder cracked / gasket issue, possible issue with ring "clocking"- gaps are aligned instead of offset.

Shady Cadence

Ah, I'm going to amend his procedure for a leakdown test.

perform the test at TOP DEAD CENTER of the COMPRESSION stroke, any other position in the cycle will result in a false reading. In the BOTTOM dead center, either the exhaust valve or intake valve will be slightly open. At TDC on the exhaust/intake stroke, BOTH will be open.
If your rocker arms are both slack in bdc, your valve lash is out of adjustment.

abecedarian

I was wondering if someone was going to catch that or not. Murphy is an optimist.

Reality is, you should do it at BDC but also release any tension on the valves too. TDC is a pain since compressed air will make the piston want to move and at TDC, cylinder taper isn't accounted for.

Runner4Luke

I pulled the valve cover again to check valve lash, bought 1 thousandths tighter than specified by engbldr, but I always do them with the engine hot, and the engine was cold when I checked them. There is definitely lash.
I unfortunately have none of the equipment for the leak down test, gotta track down a rental in town... plenty of compression testers about, not so much leak down w/compressor.
Interesting note while I was rotating the engine manually, could hear small leaks on a on all the cylinders (little hissing), but noticeable more on number 1. BUT, I could physically feel significantly more compression on number 1. Pushed through compression easily with 2-4, more resistance on number 1 and more hissing. I don't think it's conclusive. Leak down would tell. It produced higher compression numbers than 2&3 (tester broke before I got to 4, crappy rentals).

Runner4Luke

Also, concerning fuel rail pressure.
I had ruled it out, as I figured it would become much more of an issue when the engine was loaded down and fuel demand was increased. Not an issue at idle due to minimal demand.
Bad assumption?

Shady Cadence

Uh, that would be a big no, no, and finally, no.

The top of the cylinder is what concerns us, that's where the combustion pressure is highest. Most of the generated energy is expended toward the bottom of the cylinder, and the exhaust valve will already be open.

You don't go changing adjustments on an engine you're trying to diagnose, you just work against yourself when you do.

Pain or not, you CAN and SHOULD line up the crank throw and rod to hold the piston at tdc.

Could you link me to some literature somewhere that instructed you to perform this operation in this way? I'd love to see it.

Edit: not a bad assumption at all. So no running comp. test yet?

Runner4Luke

I'm aware that TDC is the proper position for a leak down test. It's replicates the engine condition under maximum pressure. Its the position where leaks would be most detrimental, and show up the most (at least under 'natural' compression). I did study and work as an Aircraft Mechanic for short period before going back to school, I'm not completely green. We only did leak downs, and had to physically hold the prop haha, don't let that ˟˟˟˟˟er go.
Anywho..
BDC, TDC ....what ever. Leak down test for sure.
Through it in 5th to keep the car from moving while pressurizing.
Any thoughts on the fuel rail?

Shady Cadence

Doubt the fuel rail. Really would like to see a measured pulse width, at the injector, at idle. Oscilloscope would be ideal here.
I also doubt a leakdown test will show us anything, but at this point any test is worth a shot.

well, except for one done blatantly wrong.

Your issue occurs only at idle rpm, that's likely the only place we're going to see it.
Work on that running compression test first, then post back here.

And hey, just for giggles, replace the ground connection for the two brown wires above the driver's side kickplate, between the fuse box and the door. Cheap and easy, then try it out.