Missing/ drop of timing?

[GSX JOE]

Hey guys i have posted in other threads about this problem awhile ago and im still having problems.

Heres my parts: 2g gsx, 16g, fmic, afc, 660's, 190lph, 18psi

Heres my problem: When boost hits I get this big miss/bog/ backfire then the car picks up and on ocassion will miss again but once i get to about 5k to 7k the car runs fine.

Here is some data from my logger:

RPM TIMING 02

4309 12 .90
4527 9 .90
5125 10 .94
5449 14 .94
5859 15 .94
6203 16 .94
6555 17 .94

You can see where the miss is because my timing drops, but otherwise I dont think my timing, o2's are that bad. Also my egts are at about 860*. I hope someone can help me this is getting really frustrating

 

[candela]

Dang man, you must ahve your fuel trim up there to be getting .94 with our 91 octane crap!! You know whats weird is I had the same thing with my car. I thought it was fule cut, but maybe it wasnt...I had a 16g@18psi with similar logs 255lph, 550's and a FMIC also and mine did the exact same thing. Fuel cut sucks arse...I now have a 2g maf and it hasnt ever happened since. It just makes me wonder cause I doubt you have fuel cut with that 2g and 660's...

 

[jw]

Fuel trims has nothing to do with the .94v or octane level. When you go open loop, the trims are useless to the ECU. Besides, 2G run rich to begin with compared to a 1G.

 

[GSX JOE]

yea it feels like fuel cut but i highly doubt it. Im supposed to race a new 35th aniversary ws6 tonight too. looks like im in trouble Thanks guys for the help any other ideas?

 

[jw]

If you are sure not boost leak that is causing the problem, try rich thing up a little at the rpms where it miss. Also, run some race gas, you should be able to kick his ass

 

[GSX JOE]

jw: thanks man for the help, I doubt its a boost leak but I will test that soon. I have my leak tester I just havent gotten around to doing it yet.

O yea I tryed to richen it up and that had no effect, actually it made it worse. Its frustrating because my logs dont look that bad. I also checked my plugs and they looked good, although Im still on my stock plug wires..maybe thats a problem...who knows?

O yea the new ws6 has 335hp, plus he just got some kind of exhaust system put on. And im out of race gas Im gonna film it tonight though should be fun.

 

[GSX JOE]

ok tonight My car pulled a check engine light! Its code P0304: cylinder 4 misfire detected.

Its really late so I havent had anytime to check the car out but Im gonna check the #4 sparkplug and injector. Anyone else had this problem before?? O yea this happened has a 3g was trying to race me, God i hope he doesnt think he can really beat me

 

[sophat34]

I have the same problem, its not fuel cut. I have replaced every thing except the ignition system and I still have the problem I have a 2g with a vpc/gcc hrc s20g fmic 550's 255.....ect what spark plug wires are you running? I run the magnacores and I think that I may have a bad set. I only get the missing and back firing once the turbo is spooled and only when I run above 10lbs of boost if I stay uner 10 I am ok. what do your egt's do? if I let it go my egts drop to around 2-400 degrees F its odd though if I happen to hit the right bump on the road its fine then the wrong bump comes along and back to running like poo!

 

[TSi92]

How old are those factory wires? Stock 7mm wires are not too bad (had a friend dyno 417 on stock wires) Check the plugs, who knows maybe the gap on that cylinder is a bit too big. Try new wires with fresh 7ES's plugs.

 

[~97TalonTSi~]

I had this problem too...it was missing really bad like yours and it turned out the spark plugs were arching before reaching the electrode. I looked realy close at them and I could see tiny little brown colored streaks in the white of the plug. The gap was also way too wide. I replaced the plugs and put some dielectric grease in the wire and haven't had a problem since. Maybe check that out.

 

[GSX JOE]

alright guys you were correct it was my sparkplug wires, stopped by rre today put some magnacor wires in and it runs like new!!

Im so excited :laugh: so now im gonna make a trip out to pomona this weekend for the nhra finals and see if i can finally get into the 12's. Hopefully my stock clutch will hold up to one more weekend of abuse, thanks a lot guys!!

 

[Kevin Jewer]

Just to add more info... I had a similar issue just a few weeks ago. In my case the ECU would actually cut fuel, and this is with cylinder misfire detection disabled through DSMlink. Started when I put the HKS 264s in. After all kinds of debate on the DSMlink list, I regapped my plugs to .026 and havent see the stutter once. ECU doesnt cut fuel anymore. It seems that even with DSMlink the ECU will still cut fuel when it detects a misfire. I suppose with all the air I was flowing with the cams (up to 40 lbs/min on the street for 500+ miles per week ) the gap, which was already a couple months old, got blown open. Live and learn