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Discussion Starter · #1 ·
Here's my background:

AC3, Lidio's chip, 42lb injectors, txs type s BOV, FC TB, No EGR, Fidanza cam gears at (I -4, E -4), FS shorty header, Random tech cat, Borla 2.5" catback, AFX UDP, Motorcraft AZFS22c plugs, brand new o2 sensor, 94 octane all the time,


Here's my problem:

Every time I get to about 8 psi in all gears at all rpm's I get a very noticeable missfire. I've decreased the plug gap three twice since the turbo install.

When I was at Lidio's, we noticed a slight missfire at the same place (8 psi). I changed the gap then from 0.035 to 0.028. This solved the problem immediately and i retained decent idle and the car drove flawlessly.

After driving home from detroit, (about 6 hours), It took about two or three days to come back. Then it was the same thing, missfire. I shrank the gap to 0.026 and it went away. I noticed it again in a few days.

Today I pulled the plugs and decided to cut the ground straps a little because they were sticking out slightly, at the same time I used a wire brush dremel attachment to clean the small ammount of carbon buildup from the plugs. Once again the car ran flawlessly, until tonight. It started doing it again.

I replaced the o2 sensor due to a misshap while installing a new gasket. Lidio recommended a MSD DIS2 while I was at his shop. I think this may be unneccessary because it seems to me I might be the only one having this issue. Others are running much more boost and horsepower with larger gaps and stock coils...

My autometer A/F gauge, allthough I know it isn't accurate, has always been pretty good with boost and telling me i'm running rich. If I am in boost it goes rich until I let off the throttle then it does it's bouncy thing. When it missfires it bounces very erratically and almost every led on it comes on at the same time. Also, during the missfire it is very jerky and power loss is very evident.

Could the carbon buildup be the reason for the miss? There's not a whole lot, just a thin layer of dark gray. Is changing the gap just cleaning the electrode when I check it? Could my coil be getting progressively worse, hence the ever-decreasing gap size? Any help would be greatly appreciated, this problem sucks.

thanks,
nick
 

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i dunno much about your setup, but how is the car getting more fuel at boost? are you running a FMU? or does the car use a map sensor to control this with the 42lb injectors? if its the fmu maybe your fuel pump is maxing out its psi rating, and if your not using fmu and its just adding more duty cycle at boost then maybe your having fuel delivery issues, either clogged filter, or pump cant handle the flow needed, sounds like fuel problem to me, spark gap isnt usually a problem at such low boost levels...
 

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Change your coil i have run into this many times and if your running anything like a dinso,NGK or any crap like that get rid of them there junk

You should be able to run a .035 to .038 gap with 20PSI if you cannot you have the wrong plugs or a weak fire

Tom
 

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Discussion Starter · #5 ·
Thanks again tom. Do you, or does anyone else have any experience with the screamin demon coil pack and the live wires? The stock coil is about $100+ at the dealership, and these aftermarket ones are about $150 for coil and wires. I'd rather get the aftermarket if they're of decent quality.
 

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1. I have a low milage stock coil laying around, PM me.

2. I had a similar problem, turned out to be a plug wire. The car ran great out of boost, but each time I'd hit 3+ psi, it would miss. Tried new plugs, gap, no dice. Took off my nice blue JBA wires...fixed


L8r

Brad
 

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I have a very similar setup, including plugs, and I think I am currently running them at .045. No missing problems even at 10 or 11 PSI.

BTW, is it possible the gap could be too small for good ignition??? Don't know if that is possible?

Actually I was kind of thinking the same as Crankor's first post. I would want to elimate the easy stuff first (plugs, wires, coil) but then I would also be thinking possible fuel starvation. I am sure you know the history of the clogging fuel pump pickup screens and fuel filters....
 

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Discussion Starter · #8 ·
I regapped the plugs to 0.030 today to see if that was it, nope, still there. I also removed the sock filter and cleaned the pickup cup and disc filters about four days ago, so that's not it either. About fifteen minutes ago, I changed the coil with another that is known to be good from another focus and checked the plug wires for proper impedence. The problem is still there. This is driving me crazy.

Oh yeah, I had the common oil spraying out of the valve cover issue too. So I put an svo mustang pcv valve in today and it's boosting about 500 rpm earlier. It's causing my autometer a/f ratio gauge to show leaning out a little when boosting below 3000 rpm. Does this mean i need to retune my chip for this?

This car is such a PITA.....
 

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Discussion Starter · #9 ·
If for some reason i'm over 200 fwhp could the coil just not be able to keep up? Just another idea, I haven't been dyno'd yet...
 

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I'vr got a spare coil if u need one. PM me. I'll let it go cheap.
 

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Discussion Starter · #11 ·
thanks, but I already tried a new coil, I got no love. I think I might have to go MSD DIS 2...
$370.00 down the tubes if it doesn't work..

this car is a all about being a
leach for my $$$
 

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ok let me ask again, how is your car adding more fuel, cuz now your saying its leaning out because its spooling earlier...wtf...your car should sense boost and add fuel, if its not doing this then i would again think this problem is fuel related, i know people running recalibrated mafs, and different chips, but your setup puzzles me...sorry if i sound confused...
 

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I'd guess the problem could be bad wires, or Lidio got the fueling wrong. When it's misfiring, is there black soot visible out of the tailpipe? You can only see it at low speeds, like 2nd gear. When it's misfiring, can you see black smoke out the back?

That's a rich misfire. The flickering A/F gauges is normal even if it's super rich. Everytime a cylinder doesn't fire, it sends a pocket of raw oxygen down the pipes that the O2 sensor will pick up. That makes it go wonky, even though you're super rich.

If the car is leaner with the addition of that PCV valve, that's a problem with Lidios tuning. If he was doing it right, that wouldn't happen. Again, he is using the stock MAF, and the load is PEGGED. He's tuning the upper fuel line for the load the engine is seeing on the day you were in his shop. Now that airflow has changed, the A/F changes.
 

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Discussion Starter · #15 ·
Poster: lourenco
Subject: Re: Help!!! Boost related missfire...

What about a set of 2 step colder spark plugs.
AZFS22C is the colder motorcraft plug.
Poster: crank0r
Subject: Re: Help!!! Boost related missfire...

ok let me ask again, how is your car adding more fuel, cuz now your saying its leaning out because its spooling earlier...wtf...your car should sense boost and add fuel, if its not doing this then i would again think this problem is fuel related, i know people running recalibrated mafs, and different chips, but your setup puzzles me...sorry if i sound confused...
Lidio tuned my car with an autologic chip using my 42 lb injectors and stock mafs. It ran perfectly the day he tuned it, just doesn't now.
 

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did you try a used coil off another boosted car or an na one? If it was na it's possible the coil has the same problem yours has and isn't noticeable when not under boost.
 

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Discussion Starter · #17 ·
It was a na car and it had about 12,000 miles on it. It was not modded to my knowledge.

I put another set of plugs in today gapped at 0.030 and the problem mostly went away. They were AZFS22C's.

Now I'm still having an issue with the a/f gauge showing lean during boost... i think it's the pcv valve. I can't hear deto, but it might be there. Gotta call lidio tomorrow. i really don't want to go back to detroit again.

Thanks, everyone, for all your input and helpful comments. It's running okay now, but the problem will be back, it always comes back. This car was never destined to run well for me.
 

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Check your pulgs and see if what your A/F meter is telling you is true, your O2 sensor just could of taken a dump.
I had the same problem, I brought the plug gap down to 25, seemed to help for a while, I was thinking of a stronger (higher voltage) coil would fix the problem, but I ended up playing with the fuel managment and turnes out I was running too rich @ WOT.
I'm still a little too rich, but I want to keep it that way, It doesnt stumple like it used to, but I can tell it makes a little more power when the throttle is held just before WOT, before the injector pulse width goes longer.

Crankor, the Focus cant use a normal fuel psi rising FMU like we can, all of the foci's have no return line.
 

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JeffescortLX is correct. With Ford's returnless system you have to throttle the pump to raise fuel pressure. Gone are the days of using a boost sensitive fuel pressure regulator
This can be done through a chip or with a performance reflash of the factory computer.

If shrinking the plug gap fixes the problem for a short while I would have to guess it would be fuel related. When you pull the plugs do they look like Kingsford? With the relatively low boost levels and low cylinder pressure on these cars I really don't see any reason to go below .030 on gap. A big boost Turbo maybe but not a blower with less than 10 lbs.

Curtis
O&C Racing
 

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I am running .035 to .038 on my car with 25+PSI on one car and 14 PSI on another and no misfire

You have other problems with coil,wires,or tuning

Get that piece of crap stock air meter off there and make lideo do it right thats what you paid for

Tom
 
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