only one cylinder lean and injectors passed flow test? I'm confused

[jayson427]

So I have been running 24lb injectors on 10.5 comprrssion for almost 6000 miles on an afx ecu. My wideband was showing 13.2 at idle Then it broke on me before I got to see where I was at with wot. Long story short I took my car to a good tuning shop in Tucson Arizona to wire in my safc2. I was told my 2nd cylinder is running leaner Then the rest. Results were determined by spark plug visual only. They cleaned and flow tested my injectors and they passed I also had an exhaust leak which they fixed. I'm being told it's not good to wire in and tune my car until my cylinder matches the rest. I have even compression all across the board.

My concern is how bad can this be if I try to move forward with this issue?? I'm being told the ecu might be the cause but I'm lost since it's only one cylinder all the other plugs are black. I'm still waiting to see if the exhaust leak was the problem or not. Any thoughts? And does any know of where I can get my ecu worked on or reprogrmmed That's legit?

 

[Joethefallen23]

IM gasket is a possibility. I've seen a bum gasket cause lean misfires in specific cylinders before. It's not so far fetched to at least check, especially if it hasn't been replaced. Just food for thought.

 

[LeeSD1]

well black plugs mean your running rich. So cylinder #2 may not be running as rich

 

[jayson427]

Yeah I know. I'm running rich and the second cylinder is just leaner Then the rest. But they are worried if they got it true on the afr's Then that second cylinder could have major problems after that. I asked if I could just run half a point richer and be ok but it wasn't suggested so I'm curious what others have to say.

 

[silvreclips]

IM gasket is a possibility. I've seen a bum gasket cause lean misfires in specific cylinders before. It's not so far fetched to at least check, especially if it hasn't been replaced. Just food for thought.

This is where you should start looking. You can spray around each gasket with carb cleaner and see if the motor revs up or use soapy water and look for bubbles.

 

[jayson427]

This is where you should start looking. You can spray around each gasket with carb cleaner and see if the motor revs up or use soapy water and look for bubbles.

Your answer has Nothing to do with my questions or concerns. Tb IM have been pressure tested and passed 100%. I want to know about tuning in my afc with a leaner cylinder. I don't know if the exhaust leak they fixed recently helped my 2nd cylinder.

 

[dsmaz]

Since you are using your auto afx ecu try switching back to your stock 5spd ecu and see if u have same problem. If the problem goes away its your afx ecu if it doesnt go away I would start checking for other things.

 

[Colt4G63 also]

I think you should look again for a vacuum leak. The tuning shop already told you not to go forward until you solve the lean cylinder, and they are right. Don't forget to check the lower injector o-rings.

I highly doubt fixing the exhaust leak will make your single cylinder run richer. Since you are already running rich on the other cylinders, obviously running a half point richer would not be recommended.

If you're sure you don't have a vacuum leak, and you're sure all the injectors are good, then your car has a failure that's against all the odds. Check your injector wiring for punctured insulation (wires will corrode in those areas) and if it checks out, replace the ECU.

 

[silvreclips]

Your answer has Nothing to do with my questions or concerns. Tb IM have been pressure tested and passed 100%. I want to know about tuning in my afc with a leaner cylinder. I don't know if the exhaust leak they fixed recently helped my 2nd cylinder.

Maybe you should have included that bit of information in original post then.

And no fixing an exhaust leak will do nothing to solve your problem, an exhaust leak will however throw off your o2 sensors if the leak is upstream.

 

[jayson427]

Maybe you should have included that bit of information in original post then.

And no fixing an exhaust leak will do nothing to solve your problem, an exhaust leak will however throw off your o2 sensors if the leak is upstream.

Sorry your right I should of included that. Had a ruff morning.

Also the injector pulse is spot on. But I Did use the old stock o-rings on the lower part of the injectors. Just confused because a lot of thing checked out but still leaner Then the other cylinders. Guess I'll try to replace the o-rings and see what happens.

 

[jayson427]

Does anyone know if timing or valve lashing could cause a lean cylinder? Hoping I can get more information from people that have had this problem.

 

[Colt4G63 also]

I'll bow out then, because I have never had this problem, I've only fixed this problem on customers cars. If you pressure tested the manifold, I guess you would know if the injector o-rings were leaking though huh? And since you flow tested the injectors, you know it can't be that. I can't think of anything else that could impede the amount of fuel injected into one of the cylinders besides the ECU or the wires that supply power and ground to the injector in question.

Good luck, I hope you figure it out.

 

[jayson427]

Thanks colt and I wasn't doubting any of your info I really appreciate the feedback. I was just asking because the tuner shop is saying my timing is off a tooth or more but I have been driving it like that for 6k miles. so again I couldn't understand how my car even ran as good as it does. That's why I asked about timing not putting your knowledge down at all.

 

[boost97gst]

If everything checks out, then its got to be either the wiring or the ecu. The injector driver in the ecu to be specific. I have actually had this problem, partially stuck injector for me though. But youve had them cleaned and flowed so thats not it....
Regardless, if you find the problem def post it and mark as resolved. Could help others like yourself in the future. Good luck to you

Wait, are 24lb injectors stock on 420a's? If not, go back to stock injectors, stock ecu and run it. THEN let us know what happens. Gotta go back to the last thing you changed to rule it out

 

[jayson427]

Resolved! Finally got it figured out after a $900 shop visit. But my afx ecu went bad with the injector side of it. I'm pissed because they don't warranty them at all and it's another 250 to get it reprogrammed on top of what I originally paid. I Hope you 420a guys read this because my ecu only had 6000 miles on it. I learned my lesson plug and play or not megasquirt would of been bought and installed for what I paid and less headaches