Misfiring at high boost+RPMs
 

Well I'm having a hell of a misfire and it's robbing the ---- out of my horsepower.

I used to run 7 psi of boost on my .48/.60 and have no problems. I upped the boost to 9-10 psi and now it pulls harder, but at about 4000-4500 RPM it starts to misfire and I just lose power. Ocassionally I can get a full pull without misfire and it just ------- rips, but most of the time I get the misfire. I am running uberdata and have tuned my map as well as I can with the misfire, when it does misfire I get erroneous lean readings so I can't really tune that. I am confident that this problem is not with my map.

I don't think it is plug wires because they look just find and don't misfire under any other conditions that high boost+high RPM.

Thought about it being the distributor cap, I actually had an almost new distributor that I was using on my old setup working perfectly. I just swapped that one over and I still have the problem.

I reused the spark plugs from my old setup, NGK BKR7E gapped at .030, I also tried .028. They did get a little black around the edges (not the electrode) from when I was running rich on the basemap but I don't think that should make a difference as long as they are gapped right... or would it? I have ordered a new set of plugs just incase, because that is the only thing I can think is wrong besides....

My base timing. I don't have a timing light and haven't set my base timing. Could this cause a bad misfire if it's too advanced or retarded? I am going to rent a timing light to check that.

Help !!

Re: Misfiring at high boost+RPMs
 

buuump

Re: Misfiring at high boost+RPMs
 

Check your grounds and your plug gap...ignitor might be on its way out too.

Re: Misfiring at high boost+RPMs
 

I have a similar problem with my new setup but its mainly cause once I hit 10lbs it gets insanels rich, goes from 12 to 1 to nearly 9 to 1 in 2000rpm :-X I would just run some cheap ass copper plugs, thats what I'm running and they work great. I would think if your base timing is off than it would have issues at lower rpms as well as lower boost levels. I would look at the map sensor you may be overloading it.

Re: Misfiring at high boost+RPMs
 

put some fresh plugs in and slam the gap down to like .025 or something rediculous. If I fixes it, keep working your gap back up. For 9-10psi though, stock gap sould give you no problems. Do you have a spare set of plug wires your can toss on? Old old ass plug wires can easily do what you describe when in boost (the more boost, the harder it is to jump the gap, and if there is any weak spot in the ingnition path, it will jump there)

Re: Misfiring at high boost+RPMs
 

whats your timing map look like in that area? i bet there isnt enough timing....

Re: Misfiring at high boost+RPMs
 

Holy crap maxing out the map sensor... I never thought of that. When I datalog in uberdata I get values up to the 10.41 column, maybe I am maxing it out and that's why it's shitty. But wouldn't I get a CEL if I was maxing out the map sensor? Anyways, here's a screenshot of my timing map:

http://img377.imageshack.us/img377/111/timing9or.jpg

Re: Misfiring at high boost+RPMs
 

sounds like ignition.

i had a t3/t4 setup with a z6 in a crx that i tuned a while back. at 10psi it started cracklinup on me.

gapped to 028 and all was happy.

try some new plugs, inspect your cap/rotor.

Re: Misfiring at high boost+RPMs
 

Well new plugs seems to be the concensus here, they will arrive on Monday and I'll let you know if that fixes things.

Can anybody answer the question about the MAP sensor throwing a code if I maxed it out?

Re: Misfiring at high boost+RPMs
 

it's not your map sensor, i've boosted well over 11.xx psi on stock map sensor many times. timing in your maps looks fine, don't see any sudden changes or anything that should cause a sudden loss of power. my guess would have to be plugs/wires, i too have had some problems with shitty/old wires causing misfires at certain times.

Re: Misfiring at high boost+RPMs
 

mm detonation?

Re: Misfiring at high boost+RPMs
 

map sensor will not CEL if its maxed.

I've pushed 15psi on mine, it jsut reads from the top column at that point, which means you're stuck with the same fuel timing curves from 11psi to 15psi (or however high you go)

Re: Misfiring at high boost+RPMs
 

Back up top.

I just put new plugs in today and it's still doing the exact same thing.

Starts misfiring and kind of acting like a rev limit at 4500-5000 rpm, sometimes it will go a bit higher.

Re: Misfiring at high boost+RPMs
 

One of My Friends is having the exact same problem in his eclipse, Its almost scary when it misses cause of the boost loss, Cant figure the damb thing out.

Re: Misfiring at high boost+RPMs
 

i would take it off and see if its all jacked up. having a bad cap/rotor will make it misfire

Re: Misfiring at high boost+RPMs
 

hmmm, maybe your loosing fuel pressure? i know if my car runs low on gas and i get on it hard itll loose fuel pressure and act like that.....

Re: Misfiring at high boost+RPMs
 

Well my gastank is full... Maybe I should get a fuel pressure gauge. But the stock pump worked fine on my old setup.

I replaced the distributor with the one that was on my d15b7, only has a few thousand on it and worked great on that motor when it had the turbo setup.

Any other ideas?

Re: Misfiring at high boost+RPMs
 

mine did this.. it only did it when i was low on fuel tho...

Re: Misfiring at high boost+RPMs
 

Someone on H-T said it could be my map... but I don't think it would be bad because the AFR is around 11.7 when it happens. Maybe I should start over from a fresh basemap... I'm getting frustrated.

Re: Misfiring at high boost+RPMs
 

yea mines doing this too, running TE at 8psi, it was working just fine all summer, and raced it constantly, never any problems with the tune, but recently had some ignition issues, ign control module and wires went out, replaced wires, plugs, ignition control module, cap and rotor, im using ngk platinum at like .28 gap.. so its kinda like wtf...?

Re: Misfiring at high boost+RPMs
 

Jago lets go back to the basis, how do u know it is misfiring ?

Re: Misfiring at high boost+RPMs
 

Well I'm not sure it's misfiring, that's kinda what it feels like tho. Basically an extreme loss of power for a bit then sometimes after it gets past that rough spot it will regain power.

I'm thinking it was my map, I took beerbongs map and modified it a little bit and it helped. Still ------- does it tho! I never had this problem with my last turbo setup when I tuned it with uberdata. I'll post a screenshot of my fuel map when I get some and maybe someone will have some more info for me.

Re: Misfiring at high boost+RPMs
 

Since my internal wastegate sucks ass (it opens at about 6-7 psi no matter what the boost controller is set at, even full closed) I attached a spring to the wastegate to raise the boost. I probably should have mentioned that before.

I had the spring pretty tight to up the boost to around 9 psi, and that is when the problem would happen. I am pretty sure the spring was causing it, because no matter how I tuned it would always hesitate and lose power at around 4500-5000 rpm.

I loosened the spring a little today by not having it stretch so much and the problem seems to have gotten better. But I'm only running about 7 psi. Any time I up the boost the damn loss of power happens. What the ----?

Re: Misfiring at high boost+RPMs
 

I don't see how it could be a misfire if the A/F is still normal when it happens. I was going to guess the fuel filter, but that doesn't sound right either if it's still getting good A/F.
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Re: Misfiring at high boost+RPMs
 

dude my car has the same problem 4-4500 act likes a rev limter i need help

Re: Misfiring at high boost+RPMs
 

well i kinda fixed my problem.. i had ngk platinums in there, i took those out and they looked fine, but i replaced them with ngk vpower(the standard ones), but really cold heat range, i think it was 4, and put the gap at .030, runs like a champ now. kinda.

Re: Misfiring at high boost+RPMs
 

I'm just keeping it at 7 psi and saying ---- it for now.

Re: Misfiring at high boost+RPMs
 

swap out the coil and ignitor
i was having the same problem at high boost; swapped coils and BAM more power and i can rev to the redline in every gear.

You say you swapped distributors but there is still a chance both could be bad; This is like the 30th case i've seen of mysterious misfires; i'm starting to think that honda ignitions aren't as bulletproof as i once thought.

In the very near future i'll be converting to a MSD box w/ external coil and cap so i can bypass the factory ignitor and coil all together; too many problems can come from those guys and its hard to diagnose them.

good luck; also make sure your engine is grounded well; we regrounded my engine before i swapped coils and it helped a lot but i still had stutters and ---- under load.

Re: Misfiring at high boost+RPMs
 

Mine did the same thing, bounced like a rev limiter at 4500 rpm. Never figured out the problem so I pulled the damn motor out and gave up.

Re: Misfiring at high boost+RPMs
 

That happend to me with uberdata when i downloaded some ones map and used it. I started over with a new basemap and the problem was gone.

Re: Misfiring at high boost+RPMs
 

did you ever figure out your problem?

Re: Misfiring at high boost+RPMs
 

Mine does the same problem and at the same rpm. I upped the psi to 9 the other day (was running 7 before with no problems) and it started misfiring all over that rpm range. Unfortunately it's still on a vafc2, but according to my wideband i'm still in the 11:1 range. I just figured i was detonating from the timing advance on the vafc even though my static timing is crazy retarded. If i ease the throttle in slowly, it revved through those rpm's just fine...until i pop a cel for the map sensor ::) I'm gonna try changing my plugs as well and see if that helps...the electrodes are getting pretty worn down. I think an msd box with the external coil is also on my x-mas wish list.

Re: Misfiring at high boost+RPMs
 

From all my readings, I'd stay stick with the stock ignition stuff for the most part.

I read alot of people going with MSD, gettting all kinds of effed up results. End up swapping in the OEM ---- and not having any problems.

Go ahead and change out the ignitor and coil, I bet that'd solve alot of your problems.