Misfires at idle

DClipse · Apr 6, 2008, 07:27 PM

I've been having misfires at idle for a few weeks now. We checked the spark plugs, which looked good. Tested for boost leaks and couldn't find any. My afr's are not perfect, but it wasn't an issue before. Any ideas as what to look for?

OttRalliart05 · Apr 6, 2008, 11:05 PM

If I remember correctly you have the 2.4 4G69 turbo Eclipse. I am pretty sure your system is very close to the Lancer, if you have a scanner look at your LTFT. This ecu is a bugger and even thought the AEM unit you have has a O2 sim it does not work exactly the way we need it to. I have a turbo Lancer 05 RA and we are having the same issue, I think we have a fix I will keep you posted....

DClipse · Apr 7, 2008, 05:28 AM

We tried tuning with the scanner, but it's still missfiring. It seems real ****ty now driving in general. It's got to be the spark plugs. I'm gonna get new ones and see.

Ralliart_on_LSD · Apr 7, 2008, 09:13 AM

I have this problem on cold starts, and in really cold weather. And also in the rain. but when its warm outside, not wet out, and the motor is warmed up, it has a smooth sounding idle. turbo's hate rain and cold weather. They like cold air cuz its more dense, but they just react better when its warmer outside. Thats my experience w/ my turbo'd ralliart. close to the same setup.

DClipse · Apr 9, 2008, 07:38 AM

I never asked, but what spark plugs are you guys using for turbo?

Ralliart_on_LSD · Apr 9, 2008, 12:56 PM

nissan 350z stock plugs from the dealership.... good temperature range

o2thag · Apr 9, 2008, 02:10 PM

Have you changed to different fuel or anything like that. My Evo was perfect on Husky's 94 then one time I put in Shell's 91 and I kept getting random misfires until I filled up with Husky's 94 again. Try different fuel?!? Good luck.

DClipse · Apr 9, 2008, 08:38 PM

Looks like there's a big problem with my car. I went to my buddy's house and we changed the spark plugs. The old ones were black. When I looked at them on Saturday they looked fine. They got soaked in the last few days. We checked the coils and they were fine. AFR's are good. All 4 plugs were evenly burned. This leaves only the timing as the problem. The strange thing is we never touched timing except in boost. So, if that's the problem means the FIC is ****ed or my ECU is. What else could it be?

DangerousDan · Apr 10, 2008, 06:02 AM

you said in the OP that your AFR's arent' perfect, do you have any logs you would care to share?

if you tuned for your knock and didn't touch timing in vacuum... I agree with you on this one, it would be hard to be timing. are you exhibiting any knock? you did mention misfires but are you running logs to see what else is going on?

o2thag has a point, it does sound a little like bad fuel considering some of the facts. I doubt it would cause misfiring at idle for weeks then all of a sudden destroy your plugs though

which one is closest to your plug

I love these little manuals, and they always have the spark plug insert

DangerousDan · Apr 10, 2008, 06:08 AM

one more thing, I believe your ECU is CAN bus. that means you can't use the tactrix cable, right? can you log knock from your obdii scanner then? I don't own a scanner (bought the tactrix cable before I ever thought about obdii scanners) but I know they all have different levels of functionality

DClipse · Apr 10, 2008, 07:42 AM

No my scanner can't read knock. But the plug looks the most like the Carbon deposit one. The codes I got are random misfire and bank 1 too rich. It could be something with the piggy. Looking at the AFR's yesterday, they were close to perfect. But it's just not sparking properly. The timing we altered was only in open loop with boost.

DangerousDan · Apr 10, 2008, 09:00 AM

yeah, you are probably on the correct track then. probably beat the crap out of your stock plugs so far

since it's "cheap" I'd start there too, you already said you were though, so I guess what I mean to say is

how did you tune your timing then? I assume with an aftermarket knock sensor...

Bank one too rich is most likely due to improper burn, I would "ignore" that code since it's likely to be secondary to your misfire. timing probably isn't your root issue either, since your misfire happens at idle and has been happening for weeks and your plugs looked good until recently. since they are all equally worn I would assume you can rule out your coil packs as well. I also don't think it's the piggy or your secondary issue would be your AFR's. it "could" be a cumulative effect of poor timing, but it's very unlikely.

I'm thinking through my fingers, hopefully I've offered something useful

DClipse · Apr 10, 2008, 10:19 AM

Thanks for your input Dan. We checked the coils and they were fine. All 4 spark plugs were evenly burned. The car drove ok under boost. It was just idle that was rough. But now I can't drive at all. They get soaked right away and the car boggs down.

DangerousDan · Apr 10, 2008, 10:49 AM

so it's dumping fuel? the fic controls the injectors directly right? does it supersede the ECU's instruction or does it "piggyback" the signal and add or subtract duty cycle? if it supersedes the ECU or bypasses the factory wiring all together I'd lean toward the FIC, if it adds and subtracts then you could still have another issue.

I am having trouble understanding what you are saying about your AFR's. are you saying they are STILL good, or that they were but now they aren't

it seems unlikely your AFR's are still good, but I'm not there so I

DClipse · Apr 10, 2008, 12:25 PM

Well I'm picky with the AFR's. They were always between 12-14. Driving they're in the 14's, but when I stop they go down to 11's or 12's which is way to rich for idle. We couldn't fix it as the FIC is not listening anymore as good as it used to. It wasn't a problem before, but now for some reason it's not burning properly. There is definitely problem with the ignition. I'm not sure if that is running thru the FIC. And yes it is piggybacking the injectors. Btw, how is the ignition controlled?