the theory is that there is no power delivery?

anyone had trouble like this before?

currently im running 3 cylinders and i dont want to drive the car since i might brake it


guys what do you think is the issue?

i just replaced the spark plugs too so it's not it and injectors are fine

what would make the injector stop from supplying fuel

help please

 

How do you know it's a fuel delivery problem? Without fuel the cyl will just pump air and car will be at 75% power

 

I'm having a similar issue. I drive an Evo IX with slight modifications (3" exhaust and a moderate flash). I was having no issues whatsoever with the car until about 2 weeks ago. All of the sudden it goes back and forth between running perfectly and missing cylinders. That is, it will run great for a while and then all of the sudden start shuddering, not running on all cylinders. After a short while it will go back to running normal again. My ODBII reader said cylinder 2 was misfiring.

I thought it might be the spark plugs, as they were pretty corroded and gunked up, but after changing all 4 of them with brand new ones the problem persists. Some testing with a test light confirms that while the car is running rough, the spark plugs are not firing like they should be, so it has do have something to do with the electrical system. Does anybody have any ideas?

The car is still under warranty, but the dealership won't do anything because they're blaming it on the tune. However, my car has had that tune for over a year and a half and never has had any problems until now. I'm starting to suspect the computer may be on the fritz.

If anybody has any suggestions or advice it would be most appreciated! Thanks!

 

Can it be the stock ignition setup?

 

injectors would fall under fuel management. if you checked all the physical aspects of the misfire,(spark good, coils good, compression good, wiring good), noid light the injector. if that is good, then you can blame the computer. check the wiring harness for rubs. good luck.

 

If you suspect the injector the first test is a noise test. Stethoscope or long skinny screwdriver, handle in a fist and jammed against your ear. Touch the end on the middle of the injector, should hear a distinct click on same frequency as ignition (unless your batch firing). This tests the end result, no noise then narrow it down with the noid light.

If you have signal but no noise then swap injectors with another cylinder and see if the problem follows to that cylinder. Confirms bad injector before throwing parts at it. Watch out for spraying fuel when removing fuel rail and lube injector sealing O-rings with Sil-glide or WD-40, they pinch easy.

If it's ignition then you can do a similar swap with coils/ plugs to see if it follows.

If you suspect ECU, first visual check all wiring connectors in the MFI system, look for corrosion or backed out/bent pins. At ECU, dist, injectors, coils, etc.

ECU's rarely fail, more often an intermittent problem is loose connector terminal pin fit. At the ECU these are very small pins with small contact surface area. With a couple disconnect/connects the spring loading of the pins can get loose.

You can get really technical and check pin fit in the spring loaded female half of each terminal. You need a tool the same size as the male terminal (no this is not ****) and check how tight each terminal is.

You can avoid all this and just put some die-electric grease in the ECU terminals, and all other MFI terminals if you want to be thorough. Die-electric grease is sort of majic. It insulates between different terminals in a connector and increases conductivity between same terminals. It also is an effective moisture barrier, good in the case of an AM or occasional OEM connector that's not sealed from the elements.

I generally use it as a matter of course when disconnecting/reconnecting any critical connector. Especially on an engine job where coolant is getting splashed around. Coolant is very non-conductive. With a "race car on the street" like the EVO die-electric is an extra margin against problems.

When diagnosing, try one thing at a time then retest for the problem. That way you know what fixed it and can post the result here.

Don't know about tune maps. Can you reflash the stock program or is that too problematic? Probably so if you got stuff bolted on. You might need to search a dealer that's more sympathetic to tuners, like the benefit of the doubt. If it's a stock part failure and AM parts didn't cause it to fail, then it should still be warranty if within miles/time. You have to go in with reasonable expectations, if it's really an AM problem it won't be warranty.

sorry to ramble on but there's a lot of stuff in this thread.

 

Thanks for the advice everyone. What's the likelihood of it being simply a bad coil? The ODB-II reader kept showing cylinder 2 as the one that was misfiring, and using a light gun showed that the spark plug wasn't firing as it should have been while the car was having issues (slow, irregular pulses as opposed to fast, constant pulsing). I don't think it's computer, or else the problem should be jumping between different cylinders, not constantly showing up on the same one. If I read the layout correctly, cylinder 2's spark plug sits directly under one of the two coils, so there is no wire but merely a boot (which could also be the culprit). In my case, the car is bone stock except for a 3" Megan exhaust system. I could be wrong, but I'm almost certain the problem is somewhere in the ignition setup, so that would narrow it down to wires, coils or ECU as far as I know. I've already replaced the plugs themselves so I know it's not that.

I'm no mechanic so I could be way off here lol. I'm just going on what limited knowledge I have of the car. Is there any reason to think it can't be the coil, or should I replace it first and see what happens?

 

Thanks for the advice everyone. What's the likelihood of it being simply a bad coil? The ODB-II reader kept showing cylinder 2 as the one that was misfiring, and using a light gun showed that the spark plug wasn't firing as it should have been while the car was having issues (slow, irregular pulses as opposed to fast, constant pulsing). I don't think it's computer, or else the problem should be jumping between different cylinders, not constantly showing up on the same one. If I read the layout correctly, cylinder 2's spark plug sits directly under one of the two coils, so there is no wire but merely a boot (which could also be the culprit). In my case, the car is bone stock except for a 3" Megan exhaust system. I could be wrong, but I'm almost certain the problem is somewhere in the ignition setup, so that would narrow it down to wires, coils or ECU as far as I know. I've already replaced the plugs themselves so I know it's not that.

I'm no mechanic so I could be way off here lol. I'm just going on what limited knowledge I have of the car. Is there any reason to think it can't be the coil, or should I replace it first and see what happens?

 

Whoa, double post? How did that happen?

 

I had the same exact issue, diagnosed it tonight, turns out there's no 12V ignition supplied to injector #2

 

If it's physically possible try swapping one of the other coils with number 2. Then see if the miss shows up to where you swapped it to.

Diagnosis without buying any parts.

 

LOL I actually thought of that same thing about a day after I posted that. I did the swap test, and found that cylinder 2 was still the one having issues, therefore ruling out the coil. My best guess at this point is injectors, since that seems to be a recurring theme among other evo's with this problem. The only thing that seems odd to me about that is the fact that the problem seems to come and go with almost predictable consistency. It seems to run fine for about 10 minutes, then have issues for 10 minutes, then run fine again for 10 minutes, etc. I just hope that doesn't point to a problem with the ECU.

 

Just like coils, swap injectors with another cylinder and see if the problem follows to that cylinder. Watch out for spraying fuel (50psi) when removing fuel rail and lube injector sealing O-rings with Syl-glide or WD-40, they pinch easy.

sure could, distributorless sequential firing coils each have their own separate electrical firing circuit in the ECU. Electrical components can heat up and shut down, then cool off and start working again.

not positive that the ignition is sequential though?