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Top 2GNT Technical Turbo/Nitrous Tech topic #107870
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Subject: "Help with stuttering/misfire" Previous topic | Next topic
bagged420aMay-16-10 01:55 PM
Member since Mar 12th 2009
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#107870, "Help with stuttering/misfire"


          

I'm tryin to tune the car using the PF, but under load it hesitates or misfires at about 7-9psi(usually around 3k rpm). Now when I log it shows AFR to be around 11.1-11.8 on anything less than 70% throttle. But anthing above 70% its in the 9's or 10's. The more throttle the richer it goes. But I have only been able to hit like 9psi before the misfire happens. So should I continue to lean it out and hope that takes care of it or should I be looking for other problems that may be causing the miss. The car idles and runs great if its not under load.

  

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Replies to this topic
RE: Help with stuttering/misfire, Babbz413, May-16-10 04:03 PM, #1
RE: Help with stuttering/misfire, bagged420a, May-16-10 09:30 PM, #2
      RE: Help with stuttering/misfire, Ebster1085, May-17-10 08:55 AM, #3
           RE: Help with stuttering/misfire, bagged420a, May-17-10 11:51 AM, #4
                RE: Help with stuttering/misfire, Ebster1085, May-17-10 06:51 PM, #5
                     RE: Help with stuttering/misfire, bagged420a, May-17-10 09:41 PM, #6
                          RE: Help with stuttering/misfire, Ebster1085, May-18-10 09:04 AM, #7
                               RE: Help with stuttering/misfire, bagged420a, May-18-10 10:51 AM, #8
                                    RE: Help with stuttering/misfire, RoninEclipse2G, May-19-10 05:57 PM, #9
                                         RE: Help with stuttering/misfire, Ebster1085, May-19-10 07:37 PM, #10

Babbz413May-16-10 04:03 PM
Member since Mar 18th 2009
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#107871, "RE: Help with stuttering/misfire"
In response to Reply # 0




          

My car was stuttering at like 4k, changed spark plugs and problem solved.

95 GS Boosted

  

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bagged420aMay-16-10 09:30 PM
Member since Mar 12th 2009
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#107872, "RE: Help with stuttering/misfire"
In response to Reply # 1


          

I'm going to pull them out tomorrow after work. I had them out a few weeks ago and they looked fine, but if the plugs look good I'll check the wires and coiles.

  

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Ebster1085May-17-10 08:55 AM
Member since Jun 11th 2009
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#107874, "RE: Help with stuttering/misfire"
In response to Reply # 2


          

Yea, sounds like you are blowing spark. If the PF is richening up the fuel mixture as you create more boost with more throttle, it is working correctly.

Throw in a set of NGK BKR7E's and then go back out and log some runs. Try to get a nice constant AFR curve of about 11.2-11.5 across the board and you will be happy with the results. You should be able to take off 10-15% from Hahns base map, but just do a little at a time to play it safe.

1999 Eclipse GS
Built motor
Hahn 16G Turbo w/ FMIC
Hahn Stage 5 Portfueler (270's & 500's)
Zeitronix Zt-2 wideband w/ 3.5bar MAP
3" SS Turbo Back
CM Stage 4 Clutch and Fidanza Flywheel
Baer Big Brake Kit

  

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bagged420aMay-17-10 11:51 AM
Member since Mar 12th 2009
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#107877, "RE: Help with stuttering/misfire"
In response to Reply # 3
May-17-10 03:10 PM by bagged420a

          

I already have the BKR7Es and already have 15% taken out of the base map. But when the car cools down I'll start figuring out what is goin on with the spark. I got my codes read and I got two for the coil, so its probably the coil, wires, or plugs. I'll update in a little while.

Okay, I checked the plugs and they seemed to be ok(Black on the base ring indicating a rich A/F.)

So I used a timing light to see if spark was goin through and it was. However, the light wasn't hitting as fast on cylinders 3&4 as it was on 1&2. So I switched the wires and that didn't change it. So I reved it and the spark cut out on 4(didn't test 3 but I'm sure its the same). So anyone have any clue about this?

  

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Ebster1085May-17-10 06:51 PM
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#107878, "RE: Help with stuttering/misfire"
In response to Reply # 4


          

Probably need a new coil. Do you have another working coil available to swap in and test?

  

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bagged420aMay-17-10 09:41 PM
Member since Mar 12th 2009
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#107881, "RE: Help with stuttering/misfire"
In response to Reply # 5


          

Man I hope not, I just got the MSD last year I believe. But thats what I was thinking at first, then I found it odd that cylinders 3&4 where being wierd and 1&2 where fine. Because the coils run 1&4 on one and 2&3 on the other, which doesn't make sense for 3&4 to be bad like that. But I'm going to pick up new plugs tomorrow and see if it changes, if not then I'll put my stock coil in(hopefully its good lol).

  

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Ebster1085May-18-10 09:04 AM
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#107882, "RE: Help with stuttering/misfire"
In response to Reply # 6


          

The MSD coil is an inferior unit to the stock one. It puts out the same amount of voltage but doesn't have close to the longevity that the stock piece has.

As long as the stocker was working when you took it off, put it back and see if you get better results.

  

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bagged420aMay-18-10 10:51 AM
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#107883, "RE: Help with stuttering/misfire"
In response to Reply # 7


          

So the MSD isn't an upgrade?
Well I changed plugs and coil and problem gone. I'm pretty sure it was faulty plugs, becuase the timing light was the same with both coils.

  

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RoninEclipse2GMay-19-10 05:57 PM
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#107888, "RE: Help with stuttering/misfire"
In response to Reply # 8




          

Originally posted by bagged420a
So the MSD isn't an upgrade?

Nope. Not at all.

IIRC the coil that's an upgrade is the Screamin Demon

Erik P.
Official 2GNT thread Hijacker
Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be...
All we know is, He's not The Stig... But he is The Stig's Spartan cousin!

  

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Ebster1085May-19-10 07:37 PM
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#107889, "RE: Help with stuttering/misfire"
In response to Reply # 9


          

Ronin is correct. The MSD is a stock replacement, meaning it puts out the same amount of voltage as a stock coil. The problem is, it does not have the longevity of the stock unit and will not last nearly as long.

If you want an aftermarket coil that is actually an upgrade, go for either the Screamin Demon which is sold by Howell Automotive, or the 034 unit which can be found at the link below:

http://www.034motorsport.com/shopping_cart.php?sort=2a

If you are handy, you could also rig up the good old dual Accel unit. Do some searching on the forum and you will be able to find some threads on it.

  

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