Misfire on boost since Head Gasket change

Arnold

Arnold

Lifer
Hi guys

I've recently had my head gasket replaced for an Athena MLS 1.4mm one, as the old one was knackered, but ever since this has been done, my car mis fires on boost. I've been told it's probably a weak spark so changed the cap and rotor arm, but the problem remains. The plugs were changed too. Thing is, it ran spot on before the work was done.

I'm not sure what to check. The price of a new dizzy is quite expensive, especially if that doesn't need changing.

Cheers
 
Arnold

Arnold

Lifer
Not checked for faults but not had any warning lights appear.

I'm running 0.9 bar, which is the same as before the head gasket was changed.
 
5e colin

5e colin

Member +
did u check if the head was not warped , if it is water might be getting in the cylinders and coursing misfire i had this before but on a stock gasket
 
weeJohn

weeJohn

Lifer
Check the injector o rings and seals are not nipped and the map sensor and fpr vacuum hoses are in good condition, no cracks or leaks.
 
Arnold

Arnold

Lifer
5e colin said:
did u check if the head was not warped , if it is water might be getting in the cylinders and coursing misfire i had this before but on a stock gasket
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It was skimmed etc and I'm told it was fine. Obviously that may just be what I was told. It doesnt misfire when off boost though if that makes a difference.

weeJohn said:
Check the injector o rings and seals are not nipped and the map sensor and fpr vacuum hoses are in good condition, no cracks or leaks.
Click to expand...

Will do, cheers

Murray said:
What head gasket did you have before?
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Standard one mate from new. engine has done around 60-80k miles. It was converted from KMH/MPH at some point so not exactly sure.
 
Arnold

Arnold

Lifer
I've got Magnecor KV85's, had them a couple of years and they appear fine. No corrosion or anything on the dizzy cap side, not sure about plug side. I've got a set of spitfire ones which I can swap out just to test.
 
dac69er

dac69er

Super Moderator
try another set. i had a set of those magnecors and they came apart once and caused a misfire. i disassembled the plug end, re-crimped it myself and they were fine until another one did the same. may be worth a check with another set of leads.
 
Arnold

Arnold

Lifer
Tim@TBDevelopments said:
did you remove the dizzy when doing this? i assumed you did.

Have you double checked your cam timing and also your ignition timing?

Tim
Click to expand...

Hey Tim

That probably was removed (I didn't do the job). I was going to fiddle with this at the weekend to see if that makes a difference, but annoyingly after about half a mile, I lost all my gears apart from 1st, so now the bloody thing is back in my garage with that issue to sort as well.
 
4efteboost

4efteboost

Member +
i would also check that they put a service bolt in the cam when removing, my mate didnt and the teeth were well out and caused me to misfire really bad on boost. i took it to an engineering shop and got it sorted then when i put it all back together i had no misfire
 
Arnold

Arnold

Lifer
4efteboost said:
i would also check that they put a service bolt in the cam when removing, my mate didnt and the teeth were well out and caused me to misfire really bad on boost. i took it to an engineering shop and got it sorted then when i put it all back together i had no misfire
Click to expand...

Cheers mate, I'll ask. Wouldn't that effect the car off boost as well as on boost if the timing was completely out?
 
Arnold

Arnold

Lifer
Just a quick update, I've now changed the leads, plugs, rotor arm and cap and it still misfires as before. One thing I noticed this morning though is I have a rather large oil leak down the drivers side of the engine, where the head gasket would be. Could a leaking gasket cause my misfire?
 
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