Misfire after Fuel Injector servicing (1 Viewer)

[LifeOverland]

I pulled my fuel injectors in my '97 LX with 253k miles and brought them to a local injector shop for cleaning/servicing. I've used them many times before for diesel injector cleaning/servicing.
While the upper plenum was off I decide to clean the oily crap out of it, and wiped out the lower plenum.
Also changed to new OEM plugs while everything was apart, wires are fairly new. Everything was running perfectly fine before pulling the injectors.

After reinstalling as per the FSM, the LX was really hard to start. I kind of expected this due to the fuel rail being empty. Ok, no prob. Once it started up it had a bad shake to it and tons of smoke. P0305 misfire in #5.
Damn, should've inspected the wire harness at the EGR better like everyone suggests. I proceeded to pull the EGR valve, and inspect all wires at the location, all good. Sealed it up with some heat wrap. I then checked the main harness behind the glove box, all good. Checked the continuity and 12V at the ECM, all good.
On to the spark and compression test. Spark is good at cylinder 5. While doing the compression test there was excess fuel spraying out of the spark plug hole. I had run it a bit, so I think that's just from no ignition what so ever. But it's getting fuel.
Compression test 145-150 on all cylinders but #5, 110. This was done cold, with the harbor freight tester and mediocre battery charge.

Not sure how or why, but could that injector be failing and just constant fuel coming out?
I've never used this shop for gas injectors, they specialize in diesel injectors and turbos.

Next step, I'm going to pull the lower intake plenum off to take a better look. Maybe there's a tiny bit of crud that I dropped in there that is keeping the intake valve from seating?
Swap the injector to a different cylinder, button everything up and see if it moves?

 

[Michael Hanson]

Hi, Check wiring to sensors on thermostat housing and the sensors.Then check ALL vacuum hoses. Mike

 

[baldilocks]

Have you checked resistance through the injector itself. Should be like 13 ohms. If the injector is constantly grounded it will stay open. I Know that you inspected the harness but it is old and you did disturb it which may warrant a second inspection. Sounds like cylinder 5 is suspect. I don't think a tiny piece of crud on the valve is your problem as this theory seems very unlikely in my experience. Had you done a compression test ,as a reference point, in the past?

 

[LifeOverland]

All vacuum hoses are new.

I did check the resistance on the injectors as well, all within spec of the FSM. I checked through every wire on the harness at the EGR and towards the injectors. My wiring all looks to be in good condition.

Unfortunately I did not do a compression test in the past. Everything was running very well, with only the normal (okay maybe slightly higher than normal) oil consumption. I've used only OEM parts for everything and have been maintaining/rebuilding everything before it becomes a problem.

 

[baldilocks]

How's your head gasket?

 

[LifeOverland]

Well, no signs of anything head gasket related before pulling the fuel injectors. It was replaced by the previous owner.

 

[mod5csi]

Make sure the injector o-ring sealed properly in that #5.

 

[LifeOverland]

I'm fairly certain there is something up with the injector at #5. I just did another compression test. This time only 90 PSI on #5, dry test. BUT there is still fuel pouring into the cylinder while testing. I pulled the EFI relay and still get fuel into the cylinder. Pulling the harness on #5 injector seems to kill the fuel flow into the cylinder.
Dropped a little oil into the spark plug hole and now getting up to 120 psi. I feel like there has been so much fuel dumped into the cylinder from that injector that it diluted the oil and crept down to the rings lowering the compression. Plausible?

Everything checks out with it though, could it be stuck open when grounded? Resistance on the injector was in line with the others.

mod5csi, I'm pretty certain all injectors are sealed, I can't find any traces of fuel around the base of any. I will pull them all and swap #5 to another cylinder and see what happens.

I feel like I'm chasing my tail on this one. Should've just sent them to RC Engineering instead of using the local guys. They claim they all tested good after cleaning.

Thanks for all the input.

 

[mod5csi]

I just went thru a similar episode. I think your head's in the right place. Swap it to another location. Or take it back and have it checked, that's the advantage of using the local guys.

 

[BILT4ME]

I have read many issues with the injector plugs themselves and the plugs breaking or not connecting properly.

Check 5 wire plug.

 

[ajax1]

I've seen it couple times after sending injectors out come back good from the report then leak, operator error on part of the cleaner people. Make sure when installing the injector once in both rails it can rotate easily if it won't or is real stiff then it is not seated properly or oring has torn. I use spit as lube when seating them.

 

[mod5csi]

Make sure when installing the injector once in both rails it can rotate easily if it won't or is real stiff then it is not seated properly or oring has torn. I use spit as lube when seating them.

Yes they should rotate real easy. I used motor oil.

 

[flintknapper]

You clearly have a lot of fuel going into that #5 cylinder (not good for it). DON'T waste your time 'swapping' that injector, just go get a new/refurbished one and replace it. Chances are....that will solve your problem. If it doesn't you need to have a spare injector on hand anyway.

Do you have a puff of white smoke out the exhaust upon start up? If so...its probably unburned gas/fuel...which means you don't have spark on that cylinder or the injector is dribbling (instead of spraying) or worse...is sticking open.

Of course.... check your wiring and connection first, but I'd put a new (known to be good) injector in that spot and see what that gives you. Its too much trouble pulling the fuel rail up each time to 'swap' one.


Check your oil level too. IF the level is high on the dipstick you've got fuel getting into the crankcase (past the piston rings).

 

[GeoRoss]

I had a similar problem. It ended up being the wiring harness injector connector broke during installation. I was getting some sort of funky combustion but the injector was not clicking when using a stethoscope. I would confirm the injector is not firing with a stethoscope. Then just pull the throttle body and make sure the connector is on there good and also ohm out the injector while it is installed.

After that I would go through checking the wiring harness. The FSM EWD has a detailed check list.

 

[blkprj80]

At each injector plug, there is a black wire with a red stripe that is +12V ignition. The other wire is "pulled" to ground via a FET inside the ECU. If you ohm from the "other" wire to ground, it should show high resistance if it's not plugged in. If it's shorted to ground, you will constantly dump fuel and you should locate the short. It might be that wire is shorted to something else in the harness. If you wiggled the harness where it goes through the firewall, check inside for a short to a sharp piece of metal, it's common. Otherwise, your harness might be melted up behind the EGR valve.

 

[LifeOverland]

Do you have a puff of white smoke out the exhaust upon start up? If so...its probably unburned gas/fuel...which means you don't have spark on that cylinder or the injector is dribbling (instead of spraying) or worse...is sticking open.

Ok, just swapped the injector to #4 and buttoned it all up. Still runs like garbage. I did a quick check and pulled the #5 plug wire, RPMs went down. Pulled the #4 plug wire, no change.

The puff of white smoke out of the exhaust is more like a constant stream filling the neighborhood!

Ordering a new injector, just need to decide if I should ship them all off to RC Eng to have them retested/calibrated.

 

[baldilocks]

I would send all six to RC engineering. They are fast and reasonably priced. Chances are, they will repair the bad injector and then you will have a eventually spare.
Hand your local service shop the bill.

 

[LifeOverland]

Got it down to 50 minutes to pull the injectors from getting the tools out to clean up.
Overnighting them all to RC tomorrow.

Thanks for all the ideas!

 

[LifeOverland]

Just wanted to update this, I hate when people solve the problem and don't post!

Went ahead and sent all injectors to RC Eng. The one suspect injector was stuck open with a terrible spray pattern. There was another one that was dripping. None of them had adequate flow. Cleaned balanced new screens. They said the one bad one had pieces of old screen in it.

I put them all in with really high hopes. Got it buttoned up and still had a misfire, this time cylinder 3. Pulled the spark plug and of course, full of fuel/oil. Luckily my wife talked me into buying a new OEM spare injector with the gaskets. Popped that one in and it cranked right up. Well, minus the massive amount of smoke that filled the neighborhood. Burning all of the fuel/oil out of the exhaust.

I'm wondering if 02 sensors need to be replaced?

I learned a few things out of this. Always do as your told on 'mud. Should've just sent them to RC to begin with. Be super clean when installing those injectors. I have no idea what happened on that last install, I had everything amazingly clean.
Going to need a new exhaust at some point, smoke was coming out of all sorts of cracks!

Injectors original 'cleaned' at Test Calibrations in Mobile, AL.

Thanks all for the help.

 

[mod5csi]

Thank you for the update, glad you got it resolved.

Were you able to track which injector went where? Seems like RC Eng failed you just as much as the local shop. Or am I missing something?