If the head goes again I’d be banging on CTMs door demanding they 100% foot the bill…but hopefully its not that!
Absolutely Dave, all hell will well and truly break loose. It’s all feeling very familiar at the moment, that’s my concern.
Can anyone school me on symptoms with valve issues if a valve is failing or not doing it’s job properly? Would it not be more obvious than a simple miss ? Are there other obvious tell tale signs?
Damn, you would be experiencing what i am going through, of sorts.
Sticky valves (sometimes dont close fully) cause erratic idle and running like when on steady speeds you quickly pressed and released the brakes but no audible engine misfire, also my valve noise changes from cold to fully warm (sound increases) and finally the vacuum readings are very distinct, gauge needle vibrating like theres no tomorrow. Worn valve guides / sticky valves would cause all sorts of havoc in your afr readings, as happens in mine, lean afr but almost fouled plugs with excess fuel…
Loose valve guide, well that one you know already!
If your vacuum at idle is stable with an analogue gauge, digital may stabilize readings, you can pretty sure rule them out.
Valve seats, perhaps a leakdown test may tell something…
To be honest the engine is absolutely spot on during normal off boost driving conditions. AFR’s are perfect on cruise, the absolute only time that I get a miss is during boost. When idling I get a tiny tiny tiny little miss but to be honest it’s barely noticeable. Probably not even a miss and just a lumpy cammy idle.
Will investigate further over the next 48hrs and report back.
One thing to add is during mapping the car was absolutely beasted for hours and ran fine with consistent numbers. The road test was exactly the same and that was 30 minutes of 3rd and 4th gear pulls to the limiter. It’s mapped to high 10s/low 11s and no where near det according to mapper.
The data log is showing no ignition cut due to rev limiter (7500) or hitting over boost (set to 32psi)
The more I think about it the more I’m convinced its something as simple as plugs, it’s just my paranoia about the head as it happened before producing such a catastrophic failure, I’d have to be seriously unlucky for CTM to fuck up again considering the amount of attention the issue was getting at the time.
Yeah, you said it beasted for hours, 3rd and 4th pulls to the limit…heat and more heat on those plugs…
If there was no indication of detonation, why did you mention removing squish pads on hypothetical future head work? Arent those designed to avoid detonation?
I hear alot about flattening piston tops to decrease hot spots, but dont know…
I have planned some coating on pistons, piston skirts, manifolds, turbo and downpipe when the decision to remove engine arrives, a friend of mine brought here CamCoats products.
Wossner Piston half coated and half original, hit with acetylene blow torch.
Well as it stands I’m at around 32 psi and mapper says it loves boost and will do more safely (no det yet). My turbo is rated to 45psi so theoretically I’ve got plenty left so play with so perhaps removed squish pads would help ?
Also been considering methanol kits.
The first step though was always to prove the car is reliable at this power level, so far it’s failed at the first hurdle.
Reliability claims may come in future times, you have just now entered the “bug” hunting phase.
If plugs is what you have wrong for now, come on, almost every 5 GTT owner I have talked to have mentioned plug issues/doubts in one time or another…these iridium plugs are so prone to fouling its insane!
Yes plugs are the most likely issue in this case
Yeah and that 3rd cylinder (apparently) leaner, if all else is OK I would re-tighten the intake manifold as well, or better still, spray the gasket area beforehand with some brake/carb cleaner or wd40 and check for leaks…sorry this is my paranoia thought…
That or check you exhaust muffler bearings, brake disk oil or side repeater fluid.. LOL
Car would just cut out…
could sit there on idle perfect, then off
No warning,
The worrying thing for me it happened during races when flat out too.
Scoff told me they wasn’t the right plugs for EFI but because the car didn’t miss a beat when he mapped it I left them in.
Yeah I bet that was worrying going flat out and then just cutting out. Plugs will be with me tomorrow so will hopefully solve my issues.
Well I’ve had a busy afternoon.
Long story short head is spot on and so is engine. No problems with valves or valve guides which is good news. Head gasket is perfect so at least that’s put my mind to rest. Pistons and liners looks mint.
However is there a way to check cylinder head function with it off ?
My compression tester from Clarke was a load of wank, tried another one and all cylinders around 140psi.
Going to upgrade to MLS gasket just because I can as will run more boost sooner or later.
Ran checks on all leads, coil pack and injectors all fine. Still doesn’t explain why number 3 is missing however. Scratching head a little.
So will put it all back together and try new plugs. Going to order HG, bolts and type d now.
Put a spark strength tester on it [emoji106] I should think there’s a output test to run in adaptronic for coils
We tested the spark strength, it’s strong as fuck. Jumps almost 2 inch when earthed.
Gone through every check under the sun today. It’s very odd.
Not something strange like fuel rail flow to cylinder 3 or something random like that
Some marks on the pushrods there @Mark Davis
Any signs of rubbing ?
There are marks yes but no sign of rubbing. Absolutely no identation on head or rods.
I’ve read a lot about cylinder heads having minimal gap between rods as to act as a guide helping to reduce flex etc.
Will investigate further.
Move the injectors around, see if the fault follows the injector.
Move the plugs, see if the fault follows a plug.
Even if it doesnt follow the plug or injector you can rule them out at least.
Yes we did that Dave, always stayed with 3 regardless.