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Noob needs hella help - 4k rpm wall

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Old 09 March 2018, 12:40 PM   #1  
Tung
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Exclamation Noob needs hella help - 4k rpm wall

I needed help before ( thank you ) and this worked so well i thought i would chance my arm, I have trawled a few things forum related and seen a few responses so i will try to be accurate with my descriptions.

I have a 1995 Subaru Impreza WRX with the normal modifications to get to 330BHP (440s - decat - fmic - fuel pump bla bla bla, im sure you all know the rules ) - New ECU fitted and mapped by Duncan @ RaceDynamics.

Sooooooo why do i need you guys.............there was a slight misfire when being mapped that we all thought a coil was folding and on the drive home I had a stuttering / misfire / juddering at 4k, assumed that this was related to the possible dicky coil so was very nice to my car and kept it under the aforementioned revs. The car drives perfect untill 4k revs and on boost, its not that venomous but its like a little misfire to the relatively untrained and I am not of the nature to try to push through this missfire / judder / stutter.

My tech has contacted me this morning, hands in the air saying help............New coils, plugs and a cam sensor have been fitted to no avail, he has asked me to contact Duncan for help ( have left a message ) but i thought that as many heads ( if you lot can help and are prepared to as i may have put this request in the wrong place ) on this would help me try to keep my sanity.

Can anyone help me!!!!!!!!!!Please!!!!!!!!!!!!Maybe!!!!!!!!!!!
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Old 09 March 2018, 01:08 PM   #2  
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So he mapped it with a misfire?

take it to someone who knows what they are doing.
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Old 09 March 2018, 01:34 PM   #3  
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Hmm bit risky of mapper to assume misfire was a coil and do the map regardless.

Could be a dodgy injector meaning one cylinder leaner than others, or poor compression / valve seats not quite sealing although the latter likely to be worse at idle, better at higher revs.

Did you gap plus to 0.65mm ?? And they are good quality ones? Some plugs might come with +1mm gap
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Old 09 March 2018, 01:45 PM   #4  
Tung
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It was the 2nd visit ( 283bhp 1st time ) and wasn't misfiring when we started, I got a bit power crazy so i am kinda blaming me.

Dodgy injector..............would that put fuel in the oil? I would assume so but as initial post stated.....relatively untrained.
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Old 09 March 2018, 01:49 PM   #5  
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.........................and i didn't answer the bit about plug. good quality - have just asked about the gapping of 0.65mm
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Old 09 March 2018, 07:31 PM   #6  
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once parts have been swapped id be on the phone to Duncan,
I would ask if the coil packs were new that you replaced ?
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Old 12 March 2018, 11:29 AM   #7  
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Ah I read your first post as it already had a very slight misfire, rather than the misfire start during mapping.

You could always try running wastegate actuator pressure to see if the problem goes away. Simply loop the turbo output nipple straight to the waste gate. Then you should be limited to about 0.5-0.6 bar of boost. Block the dangling pipe to prevent a vaccum leak. Then you can be sure you're not overboosting and see if the misfire persists.

However since the issue started during mapping I'd see what Duncan says about it. In theory if nothing mechanical has gone wrong simply reverting the map should make the problem go away!
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Old 12 March 2018, 02:21 PM   #8  
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Couldn’t possibly be the mapper they are faultless gods amoungst men
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Old 12 March 2018, 05:47 PM   #9  
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Quote:
Originally Posted by RAGGY DOO View Post
Couldn’t possibly be the mapper they are faultless gods amoungst men
some are good, some are just downright cowboys and are more interested in taking your money and running
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Old 13 March 2018, 11:19 AM   #10  
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Just a quick update.
Spark plug gap was 0.8mm, not been regapped yet - coil pack was new.
Duncan will have the car back for me but its a fair old drive for me so will see how we get on @ 0.65mm plug gappage.
0.8mm > 0.65mm - Fingers Crossed
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Old 14 March 2018, 03:34 PM   #11  
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What ECU are you running ?

Have you gone passed 4k to see if its missing at 5k and 6k ?

At what point does it misfire boost wise, as soon as any boost is used ( straight out of vaccum ) or say after 0.5 or 1 bar etc ?
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Old 15 March 2018, 10:17 AM   #12  
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Gaps have been checked. Sad to say this has made no difference.
The boost thing is apparently a red herring - my tech has said this morning that even when not on boost still hits the 4k wall.
I need to get this back to my faultless god don't I?
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Old 15 March 2018, 10:20 AM   #13  
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Alkatec ECU was fitted
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Old 15 March 2018, 10:31 AM   #14  
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Ok, a misfire and hitting a wall are a bit different.

Hitting a wall might mean its in a limp home mode perhaps due to a sensor gone bad.

I don't know anything about alcatek, presumably you can't do the normal fault code reading that you can do on OE ECUs - http://www.scoobypedia.co.uk/index.p...eadingECUCodes. Guess not - https://8378simtek.wordpress.com/faq/

Was it mapped with launch control? Could be clutch switch, thinking you always have the clutch dipped?
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Old 15 March 2018, 04:23 PM   #15  
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Yes. Anti Lag + Launch. Ironically this was done after the mapping.

I have a spare ECU so i was going to get my tech to put on just to see if the fault is still present. Is this a good idea? ( will literally be 1 run and then swap back )
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Old 15 March 2018, 04:30 PM   #16  
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Is your speedo working ?
95 impreaza`s dont go passed 4k if the speedo isnt running/connected
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Old 15 March 2018, 04:54 PM   #17  
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speedo is working. How accurately i couldn't say but the old needle moves
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Old 20 March 2018, 09:49 PM   #18  
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i heard from a friend that the insulation around the connector to the coilpacks can go bad.

Also, everyone i know that has the single coilpack connector thingies have gone to newage because they simply aint that good when pushing the power.
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Old 21 March 2018, 10:30 AM   #19  
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get it to a specialist who knows what they are doing and get them to sort it.
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Old 22 March 2018, 10:30 PM   #20  
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Have you cleaned the boost solenoid? Pipe work on fmic all air tight?
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Old 23 March 2018, 02:18 PM   #21  
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Thanks for everyone's input. I can now get past 4000 rpm.

Speedo related apparently..............................Good shout Mr or Mrs The Rig.

I hope not to have to annoy with my ignorance again.

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Old 23 March 2018, 03:54 PM   #22  
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Quote:
Originally Posted by Tung View Post
Thanks for everyone's input. I can now get past 4000 rpm.

Speedo related apparently..............................Good shout Mr or Mrs The Rig.

I hope not to have to annoy with my ignorance again.

Glad its sorted

"Mr" Rig
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