ExViTermini

iTrader: (25)

The past few weeks I've been dealing with a sever misfire issue on my evo. On low boost(23psi) I will SOMETIMES get a misfire above 5k rpm, however its rather infrequent. On high boost(30+) I am usually guarenteed to get a misfire, which has caused the freeze plug in the water pump to shoot out.

I have changed plugs multiple times, at multiple different gaps down to .020. I changed out the stock ignition + amp system to a better set of coils and driver box. Nothing will resolve the issue. I'm including two logs on two different pulls, to see if someone has any input.

Something wierd that I notice is when it does misfre the RPM's read higher than what they were for a short bit. Do I have a camshaft or crankshaft sensor failing and/or faulty wiring?

Thank you for all of your input! BTW, these runs were on low boost.

MZP@TeamD

T2per (the time between each cam sensor pulse) should be inversely proportional to the engine rpm at all times if not you have cam/ crank sensor problem not the ignition.
Your misfire comes at 6500 rpm and you cam/crank signal goes away,it would be good if you log the crank tooth period and stat sync at the same time so you we can look at all signals at the same time.
Check your cam and specially crank angle sensors, wiring,trigger plates.
goodluk and keep us posted.

ExViTermini

iTrader: (25)

Thanks again for you input.

I did a few more logs tonite with the crank and stat sync, they are fine. I did notice after zooming in bit on a few more misfires that I had tonite, that the t2per gets a tiny bit erratic and kind of "flat" instead of the sharp consistent waves I had up until that rpm.

I'm going to check once again the camshaft trigger wheel as I remember setting it properly when I built the engine, but I had to change cylinder heads, so its a possibility, though I don't think it great, I take great care in being precise, that its in 180 out.

As well I have another CAS that I might swap in and see how it reacts.

Aby@MIL.SPEC

iTrader: (161)

is there a channel that can be logged to see if any type of cut is being applied?

are both misfire log's happening @ the same car speed too?

since both misfire logs are both @ 6,500 revs.....

not sure if something is being activated by car speed....

ctracer911

I am having the same damn problem but cant find it out. ANYBODY have an idea??

ExViTermini

iTrader: (25)

Well, my car ended up having a blown headgasket, that I thought was causing the issue. Tore the motor down and replaced the o-rings, new headstuds, and a new gasket.

All was well till I pulled it out of the garage and got a half a block down the street when the car bucked jerked and shutoff. Started right back up. Made it another 50 yds, same thing.

One of the leads going into the plug for the AEM map sensor, the wire had broken inside the insulation. I fortunately had another pigtail, wired it in, and its perfect now.

Weird though it never showed up on the logs....Very odd. BTW it was the older pigtail that had the shielded insulation, they seem to have used cheaper wire back then that is more fragile. The new ones come with no insulation.

joeracer321

iTrader: (9)

I am having this same misfire problem, I am beginning to think that this is a common problem and that the only way to fix it is a complete ignition upgrade. I have a DLI-II and I can not run more than 25 PSI before I get complete ignition break up at 6500 RPM. I have tried to swap out the DLI thinking it may be bad, but it still does the same thing. If I take it off it only gets worse, so I am thinking it might be AEM related. I have seen quite a few posts with this issue with the Evo's but also the Supra crowd seems to have the same problem.

joedr

iTrader: (27)

Did you guys tried 0.018 gap on the sparks. Also.... What type of sparks you guys are using? OEM? One step colder?

My recommendation will be to run one step colder for every 100 HP above stock.... gap at .018 if above 24 PSI. Good luck!

BBrooks

The first batch of 1313 boxes released from AEM had an issue that caused the coils not to charge completly. It required the box be sent back for repair. I believe it was box numbers 1-25

You can try upping the Coil dwell factor slightly to charge the coils more. This combined with a smaller plug gap will get most evos by at higher boost on the stock coils.

GTVEVO

iTrader: (22)

I had similar issues, it didn't break up as bad as decribed but you could see it dump rpms in the logs. I tested two types of ignition amps and they both tested out with the same results (some improvement but not ideal) so I just built my own ignition upgrade using a 1g DSM coil and ignitor and the problem was solved. You can dwell the stock coils longer but their life will usually be shorter if you set them too high. Also noticed anytime I run race gas I have to use fresh plugs otherwise it seams to foul at least a couple of them badly causing a very bad misfires.

ExViTermini

iTrader: (25)

Ditto. Up the dwell with the EMS and 1g set and you can pick up a few ponies

EVO Tweeker

iTrader: (7)

I had a similar issue and it ended up being the plugs. Meth corrodes them quickly. I installed new NGK plugs and gapped them to 0.022 ....voila!

BTW - I have a 1G coil on plug setup, hardly used, that I will let go for $500 plus shipping.......if you are interested. (PM me)