misfire issue- 2004 g35 coupe, greddy tt, haltech,rc750cc, basic RFS, stock engine, HFC


I read almost every single misfire thread on the FI section but i am still having issues. Haltech is partially tuned, mostly in vacuum.

1) I found all my exhaust leak pre-02 sensors but the haltech widebands still read the same. two points off between banks @ idle cruise. I already free air'd calibrated it twice.
2) I found a vacuum leak at cylinder #3 injector base. pressure tested it. ok now
3) While the engine was on, I pulled the plug of each coil and all of them made the idle worse.. so i know the coils work
4) installed new plugs, no change
5) cranked the car with the intake manifold up off the engine. i see the injectors are spraying.

One day it revs fine.. and another day it revs like crap. Both times warmed up to operating temp. occassion random misfire code p0300

i'm lost... any ideas?


If I read correctly on here, the stock ECU can idle bigger injectors ok? I want to check if it's the haltech also.

here's a video of the bad rev vs good rev. some days is good some not.
<iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/yEl3dpZiRLA" frameborder="0" allowfullscreen></iframe>

 

what other engine mods have you made. tuning the haltech may seem easy, but there is so many little details that makes everything much better. i read depending on the firmware on the ecu makes the misfires. which firmware software do you use.

 

the engine is completely stock. everything else is just basic greddy tt, RFS (pressure set at 45psi), RC750cc injectors, plenum 3/8 spacer, hks exhaust, high flow cats (i took off the HFC- they're not clogged)

I am using version 1.08 software with 1.06 firmware. that reminds me, I read on here, someone had to use the earliest version of the firmware to clean some misfire issue. correct me if i'm wrong.

 

I remember that str8dum1 had problems with the latest versions with his 03 G35 so he had to use the earliest version.

 

The 'bad rev' in your vid is a steady misfire... mine sounded exactly like that when a coil pack went out, like a sick WRX.

If it's overly rich on one side when doing this, it's probably an intermittent spark issue on that bank. If it's lean, then look towards the injectors.

Test pipes, right?

 

i dont know what the deal was with my car. missfire def went away when I went to the v1.0 firmware. At forged, Sharif loaded a different base map using 1.06 and mysteriously the miss went away.

I havent looked at my haltech for a while since the cars been down, but i'm almost 100% its on the latest firmware though.

What year is your car? Only takes a second to reflash the firmware so i'd try that

V1.0
http://www.youtube.com/watch?v=xiyRYpGIlzY

and switching to V1.06 where it starts to miss
http://www.youtube.com/watch?v=2uma8vUQ448

 

Regarding the loading a new basemap fixing it...I know that with other platforms at least, it's often necessary to redo a map from scratch if upgrading firmware. Sometimes things change in the way the maps are saved/parsed and things get wacky when using a map saved by an older firmware.

 

interesting, does this impact Z's as well or is it something only with the G?

 

i rewrote the maps for each version of firmware as well with no difference.

 

i downgraded to 1.04 and transferred all my values over. Started the car and it died. I increased the post enrich values and and it was idling at 10AFR then 18 AFR and it finally settled at 14.7. still got the misfire but it seems smoother than the video.

now another issue...
After fully warming up, I noticed a bit of white smoke coming from the valve cover driver's side hose and the coolant reservoir is completely drained! I was reading around and it might be a blown headgasket?!? say it aint so... i gotta do a leak down test

I've only been partial throttle driving and idling running 13.5afr! no WOT! or boost!

 

$hit happens my friend (I had two engine failing on me in less than 5k total), but hopefully its nothing serious.

GL.

 

Just to clear up the big firmware black magic thought that is taking place, I have run all versions of Zs and Gs (including '03 G35 coupe, which is not special) and have not experienced these problems when you properly tune a vehicle. Your video sounds most like a mechanical failure/short (such as coil packs), but I wouldn't 100% rule out ems. Do you have access to a stock Z/G that you can throw the Haltech in to test quickly? Otherwise you can send it to me for diag to ensure it is not the problem.

 

In for results. What was the problem? Im currently having a similar issue. Tiny missfire at partial throttle. No problems at WOT. Only throwing that same code p0300. Can't pinpoint it. Any idea which channels on haltech I could log to get a better idea where its coming from?

 

check all your wiring to the coils.

when i had a misfire one of the wires going into the injector connector was loose and backed out of it's plastic connector. It made just enough contact to work and occassionally misfire. Once i found it and pushed it all the way back into the connector my car worked fine.

 

thats a good idea. i'll check that out. any other thoughts guys?

 

i haven't resolved mine yet. when everything was installed, i checked the injectors are firing, spark plugs were changed, wiring to the injectors/coil all good.

So I plugged in the stock ECU back in with the stock injectors and everything seems to be running ok. I've been driving partial throttle out of boost for awhile with no codes or misfires but i still have a little smoke/steam coming out of the oil cap (when open) and the breather tube. i gotta do another compression test.

 

check the pins on your ECU. The harness haltech provides puts a lot of stress on the wires/pins. I had 2 pins pop out and cause me headache.

 

well i would figure if it were a pin on the harness, it would happen all the time. my problem is only intermittent. and usually between 2k rpms and 2800 rpms. never at WOT. im starting to suspect that im just simply running too rich in that area. i had a lean spot around there and drove around and added some fuel in that area. possibly i added too much. unfortunately i didnt notice if immediately after adding fuel in those cells if i was missfiring. i'll swap to my old map and see what happens.

 

pins can be loose and at certain rpms or situations cause a misfire due to a bad connection. Depending on the current being drawn through that wire it could be making contact at low amp draw and then loose it at high amp draw or vice versa.

 

well, today i noticed that i was hitting my boost cut limiter a lot. so i figured id go ahead and upgrade from firmware 1.04 to 1.06. i took it out for a 5 minute drive and so far there was no flashing cel indicating a missfire. and also, rock solid boost control. so weird. i might be speaking too soon. so i'll drive it some more and report back. very strange.