Wacky idle advance and misfire. - Tuning Forum

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Wacky idle advance and misfire.
Friday, August 26, 2011 5:49 PM
Ok so misfires only at idle/no load. Log shows only cylinder 1 but its been up to 50 some od counts though normally middle 20's. The idle advance is all over the place between 0 and 30*. Replaced the coilpacks and the icm, no change, plugs are light brown on the electrodes but black inside the shroud. All the plugs (ngk platniums 2 steps colder gapped at .032) look the same. Checked for vac leaks with throttle body cleaner, found none, though I fixed one earlier with minimal change. Its not a clogged cat, I just did the whole exhaust with no change, tune is as good as I can get, I stick with -6 fuel trims at idle, because if I bring it down to having no fuel trim the car will not start(no idea why, it pisses me off). I havent checked compression yet, but the car doesnt feel weak, not that I'd know running down a cylinder would still feel fast on this thing. I dont get any spark blow out in boost and the computer doesnt pick up any misfires at anything thats not idle.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Re: Wacky idle advance and misfire.
Saturday, August 27, 2011 2:46 AM
At what RPM is the idle set? I can't speak for why it's getting worse, but i know the damn 60 pounders cause an idle miss at a normal idle. If you want to experiment, try raising the idle significantly, say 1200+, and see what happens. If the misfires diminish or go away completely, i'd blame low pulsewidth on those relatively behemoth injectors lol.



Re: Wacky idle advance and misfire.
Saturday, August 27, 2011 5:59 AM
I had the same problem with the fuel trims when my idle was at 700 RPM. Turned it up to 1150 and am at +/- 1.5. I have 55 pounders, and they definitely don't like low idle. It also starts up after a max of 1 second of cranking every time, hot or cold.
Re: Wacky idle advance and misfire.
Saturday, August 27, 2011 7:57 AM
The idle was at 925 and I uped it to 1k I'll try 1200.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Saturday, August 27, 2011 1:22 PM
Well, misfire issue resolved for now. I put the boots on the spark plugs and then put the coil packs on the boots. I havent logged yet to see if the idle advance is wacked to hell still yet.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Monday, August 29, 2011 8:45 AM
So did you up the idle? Why dont you try the spark plug wire swap mod?


GMR has got nothing on this
Re: Wacky idle advance and misfire.
Monday, August 29, 2011 8:45 AM
Nope didnt up the idle. Just put the boots on the plugs then put the coils onto them.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Monday, August 29, 2011 9:35 AM
My idle advance is also wacky (LD9 though @ 800RPM with 60lb injectors). But otherwise spark is smooth and fine. Never could figure out why the advance jumps around so drastically at idle, but then again, never seriously looked into it because the car runs great otherwise.



Re: Wacky idle advance and misfire.
Sunday, September 04, 2011 5:38 PM
Leafy (Club Jeffie FEA man) wrote:

Nope didnt up the idle. Just put the boots on the plugs then put the coils onto them.


Just that and you solved your problem


Boost Lover
Re: Wacky idle advance and misfire.
Sunday, September 04, 2011 5:40 PM
Well coming back to this. It was logging cylinder 1 misfires, the boot from cylinder 1 was a bit bent and I purposefully put it onto cylinder 2 that time, my misfire came back last week and its now on cylinder 2. So, since I can get boots with springs for 3 bucks a piece I'm just going to replace all of them.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Tuesday, September 06, 2011 2:09 PM
Why dont you install spark plug wires?


GMR has got nothing on this

Re: Wacky idle advance and misfire.
Tuesday, September 06, 2011 8:23 PM
Because I dont have spark plug wires?


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Tuesday, September 13, 2011 8:47 AM
LOL Im aware of this....what Im saying is why dont you upgrade and install the MSD coils or 2.2 junkyard coils (or buy them new at a parts shop) and install some spark plugs. Real easy thing to do.


GMR has got nothing on this
Re: Wacky idle advance and misfire.
Tuesday, September 13, 2011 8:50 AM
Because I don't see high enough cylinder pressures to warrant an upgraded ignition. I don't think I'll see an issue with this blower until north of 300 wheel.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Monday, June 17, 2013 3:20 PM
Interesting... I know this thread is old but I'm having the same problem. Leafy, a few questions:

What exactly was wrong with the plug boots?
Did this fix the issue long-term?
Are you still in New England?



"In Oldskool we trust"
Re: Wacky idle advance and misfire.
Tuesday, June 18, 2013 10:47 AM
Long term might be a relative term, I have his blower now. I am having an idle p0300 though at idle sometimes. I have 60# injectors in and at idle, the pulse width is just a touch longer than the mechanical activation time so I am fairly certain that is my issue.



Re: Wacky idle advance and misfire.
Tuesday, June 18, 2013 10:49 AM
IRRC I just threw in a new coil block and plug boots. But it still wasnt great. I think EV14 injectors would be the real solutions. EV6's are so 90s.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Re: Wacky idle advance and misfire.
Tuesday, June 18, 2013 2:20 PM
Pull the fuel pressure regulator vacuum line if it smells like gas there is a problem. Also when you log try to not use the sae tps use the non sae it makes it more accurate as well as a better 4wire o2 sensor like the bosh or acdelco again the data will be more accurate and make easier to nail down the ltft I the idle part od the ve and the single fire and double fire. For me I have been there and wow what a difference in mpg. I thought about building a new engine or buying a new sonic rs but noe now my baby is back lol


see ya!

Re: Wacky idle advance and misfire.
Tuesday, June 18, 2013 2:33 PM
Thanks for the responses guys. Unfortunately these are even older EV1 style injectors.

I pulled the vac line, all seems good. I updated my other thread about this with a lot of good info. Basically it looks like the higher fuel pressure and "big" injectors are to blame; and that's with the afpr pulling the fuel pressure down 10psi at idle.

As for mpg, and i swear this is no bs, I ran a whole tank of 93 through on the highway with 6 cases of beer in the trunk and got 34.6mpg. I think the upped pressure may help with fuel atomization. At least, that's what I've read and heard other places.



"In Oldskool we trust"
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