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Help needed! Misfire or hesitation


Clarkey

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Hi guys ...

 

Hope you can help me out on this ... or at least put my mind at rest as this worrying me.

 

This just started this morning and is sometimes reproduceable. This problem wasn't apparent last week.

 

Accelerate from 2nd & 3rd (full boost @ 1.1 Bar) = Fine :)

 

Into 4th & when the car gets past 4k RPM and at about 4750 - 5k RPM it seems to hesitate. It's as if it's bouncing off a rev limiter or maybe misfiring. It's not smoothly climbing the rev's like it used to.

 

If the problem shows itself then it'll always hesitate at 4750k - 5k RPM

 

My oil pressure is peaking at 7 Bar - when on full boost and 1.75 Bar when idle @ 750rpm. My AFRs are showing 11 when on full boost & at the point of this hesitation - so not running lean.

 

Spark plugs you think ? I've Denso IK22's in there. Though pretty much impossible to diagnose over the phone, Mark @ Phoenix said possibly:

 

a) The stock exhaust manifold isn't up to the job to the amount of exhaust gas flowing through.

 

b) A boost leak around the SMIC piping.

 

c) The Waste gate spring is getting stuck

 

What about coilpacks ?

 

Would apprieciate your thoughts guys.

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Given the description and that you have a single turbo I would suspect the coil packs

 

After doing a few searches - that's what I thought too Jake.

Mark did suggest coilpacks .. but understandly - it's usually nigh impossible to diagnose a fault over the phone - just with my vague description.

 

Will have to take the car to Phoenix so Mark/Paul can have a ganders.

 

Are coil packs expensive ?

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If it is coil packs at fault some secondhand ones here or try Nic...

http://www.mkivsupra.net/vbb/showthread.php?t=54624

 

Cheers!

 

Also - to add further. Whether this is important - I dunno.

 

On Wednesday I was desperate for fuel - and I couldn't get any SUL. I didn't have enough fuel to get to the Shell / Tesco garage .. for 98 or 99.

 

So, I was forced to do a splash & dash of 95. I put £15 in there and then drove it to the Tesco garage and filled up wtih 99. Since then, it's had another tank full of 99 (I filled up Thursday)

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the fuel wont be an issue i went touring up to Scotland in summer where they havent even heard of optimax, filled up with normal unleaded for 1000 miles and just kept the boost very low, for what they cost i would defo try a new set of plugs i use NGK BKR7E-11 (I think) £16 a set

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I have a spare set of coil packs available if you want to try swapping to see if it makes any difference. I am away tonight until tomorrow evening but home the rest of the week.

 

Cheers Paul / Colin! May have to take you up on that offer. But won't be till January - as that's when I'll be taking it up to Phoenix - so they can diagnose it. And if it is Coilpacks & if you still have them ... I'll def take them off your hands for some dosh.

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Cheers Paul / Colin! May have to take you up on that offer. But won't be till January - as that's when I'll be taking it up to Phoenix - so they can diagnose it. And if it is Coilpacks & if you still have them ... I'll def take them off your hands for some dosh.

No worries but if you wanted to try that before you get to Phoenix then let me know. Its an easy job swapping them over.

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Did you read the Misfire FAQ? Check out 2a, if you can turn the boost down and it goes away, it's most likely your coil packs. Also, did it start with the occasional miss and it's been getting worse?

 

Also, what AFR gauge have you got? The AEM 4000 series can't read below 11.0:1 afrs so you could be running too rich - it's have to be 8:1's to cause it to seem like you've hit a rev limiter though.

 

-Ian

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Yeah I read the Misfire FAQ Ian.

 

I'm not running a boost controller Ian - as it's running off the WG. But at full boost 1.1 Bar in 4th, 5th & 6th ... at high RPM ... that's when it appears. I thought it was just 4th. But it's now doing it in 5th & 6th.

 

The AFR gauge is an AEM one. Last week, at full boost everything was fine and dandy. The AFR gauge would go to the 11's and sometimes go off the scale. I've not got the SAFC-2 setup yet on the rollers. The plan was to wait till the S-ITC, Aero FPR, RLTC & EBC was installed - then get it setup @ Thor. I haven't messed about with the settings of the SAFC-2 - since Terry initally set it up back in August.

 

Now - when this problem is reproduceable I did notice the AFR gauge go straight off scale .. and then the problem raised it's head & the AFR gauge was showing 11's, then off scale, then 11's, then off scale. That was during the misfire.

 

I'll do some more testing - trying to limit my right foot .. limiting the boost.

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Yup, try and lower the boost via the right foot. If it's coil packs it should work fine at say 0.8bar if the coils aren't too far gone. If it's overfuelling hugely then it will probably still misfire.

 

-Ian

 

Cheers bud! Will try that if I'm legal to drive tomorrow ! :blush:

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Merry Xmas to all ... :lala:

 

Quick update. Did some testing with the car. The car doesn't hesitate/misfire when the boost is around 0.8-0.9 Bar. The car climbs the rev-range smoothly as it did last week.

 

AFR's went off-scale. So lower than 11. I got into 6k RPM range in 4th & 5th without it misfiring .. @0.9 Bar according to the peak-hold on the DEFI.

 

So .... coilpacks then. Out of interest - is a single car more suseptable to coilpack failure than stock twins ? And if so, why ?

 

Colin - if I could drop around your house at convienence .. that'll be fab!

 

Cheers guys & have a boozy NY.

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Clarky

this may be a long shot but did you get the RLTC fitted cos mine started playing up a while ago nothing like what your car is doing but it may be worth linking it out to eliminate from enquires

 

Paul, no RLTC is still sitting in it's box in my bedroom ;) The plan is to get the EBC, RLTC, S-ITC & FPR fitted in January @ Phoenix.

 

I'm hoping it's something like coil packs or spark plugs. What I'll do, at somepoint this week when it's convienent for Colin .. I'll have a go at swapping the packs over and try that.

 

If that doesn't work - I'll go onto swapping plugs. If that doesn't work .. then I :giveup: .. It'll be a job for Phoenix.

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Paul, no RLTC is still sitting in it's box in my bedroom ;) The plan is to get the EBC, RLTC, S-ITC & FPR fitted in January @ Phoenix.

 

I'm hoping it's something like coil packs or spark plugs. What I'll do, at somepoint this week when it's convienent for Colin .. I'll have a go at swapping the packs over and try that.

 

If that doesn't work - I'll go onto swapping plugs. If that doesn't work .. then I :giveup: .. It'll be a job for Phoenix.

no worrys mate i just thought of it today as i'me refiting mine tommorow

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