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Discussion Starter · #1 ·
Right then gents.

Heres the problem, when i am under boost i get to about ~6,500 rpm and the car hesitates, i can drive through it but im losing power like there is a misfire?

This only happens under boost, if i zip tie the the bypass actuator then i can see the red line with no problems, the same if i am in neatural i can hit the limiter easily without hesitation.

Heres my set up (key points)

MS2 ECU
Dual Feed fual rail
440cc Yellow top injectors (flow tested before fitting)
JRSC M45 with a 53mm pulley
Intercooler and IAT
Decat with wideband

I think that covers the main things ive done to help narrow things down.

Heres the background information:

Ive fallen for the trap where i had a few things fitted at one time so im strugging to narrow down the problem = ECU, fuel rail injectors and small pulley went on at the same time.

I used to have a standard ECU and 67mm pullyey fitted with standard fuel rail and injectors. when running this set up i had no issues at all, hitting the redline wasnt an issue at all.

I have tried the following so far:
  • Re gapped the spark plugs to 0.9mm, then 0.7mm then 0.5mm - no cure
  • New HT leads - no cure
  • Raised the rev limit on the MS to 8,000rpm, so is definatly not the limiter
  • I had a new coil pack 2 years ago - new from mx5 parts
  • Done a compresion test, all good with 1-2 of each other

The only thing i have yet to fit and try is my COPs kit, this will hopfullly rule out the coilpack and it being an ignition issue completly.

Failing that im pretty much stupped, i have the below theories but a more experiance mind/better person may be able to help me narrow down the problem

Theroy Problems:
  • ECU poor ground?
  • Fuel starvation issue, maybe a dodgy pump or poor pressure at the rail
  • Possible valve float from HLAs?
  • Weak or worn valve springs?

I have a data log from a few drives, it may show some information in thoses areas to help?

Can anyone tell me how to upload it here or i can email it to someone.

Cheers Ryan
 

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Discussion Starter · #3 ·
would it hesitate under knock? I was lead to believe it would. That said i havent, it was only at 190bhp when dynoed so i would have thought it would be knock... still im happy to try it.

i have the Data log file, how can i upload it Richy... may help to view it.... They fluctuate in that area but in the low 11s

it doesnt always happen, just 90% of the time which is why its so frustrating
 

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Discussion Starter · #4 ·
actually looking at that in more detail on another data log i have i flutuates to 12.5 then back to 11.3 then up to 13.0... this maybe the hesitation though making this happen...

i need to time a data log with a incar video to know if and when it occurs.
 

· Dimitris
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1,575 Posts
The COPs will more likely than not, cure this problem.

In my latest revision of ECUs I have also revised the ignition circuit, which helps a lot. Apparently this only happens on the Mk1, not at all on the Mk2/2.5.
 

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would it hesitate under knock? I was lead to believe it would. That said i havent, it was only at 190bhp when dynoed so i would have thought it would be knock... still im happy to try it.
You can have knock at 50hp, you making 'only' 190 doesn't make you immune.

Yes if knock is sever enough it'll hesitate, I really wouldn't be driving it WOT again until you've listened with some det cans to be 100% sure it's not knock

That AFR swing isn't really enough to cause it to hesitate suddenly, but it could be indicative of a knock event.
 

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Discussion Starter · #7 ·
ill try the COPs then, if that doesnt work ill report back, ignition problem is still th most likely cause then i suppose.

Been on two dynos one with det cans, hopefully it should be that but ill make a home brew set to check soon as i want to tune in myself once this issue is sorted. No point masking the issue and tuning around it.

Dimitris ill find out how to swap the resitors around from you if thats ok, perhaps this will boost the spark as well
 
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