Surging

Anything and everything to do with mechanical issues with your Mk2

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LimeyMk1
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Surging

Post by LimeyMk1 »

Not a serious problem but it's a niggle just the same! As I come off the throttle I occasionally get a bit of a kick from the engine like I've blipped the throttle which can be somewhat disconcerting :shock: .

I've checked the TPS and it's within spec. I think it may be due to my timing/fueling setup; the timing is set at 8 degrees BTDC with the diagnostics bridged (E1/T?), if I set it at 10 degrees I get serious detonation unless I run super unleaded with the MAP fueling mix turned up. The engine is higher compression than standard (skimmed head and TRD head gasket), the compression test after I rebuilt the engine was 200psi on each cylinder.

Any thoughts guys and gals?

(MK1 1987)
crazylegs
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Re: Surging

Post by crazylegs »

have you tried it with optimax or ultimate?seems a shame to go to the trouble of increasing performance with the higher compression and then not use it .my first thought would be invest in a rolling road session.you will never set it up right without. all your starting points for timing, fueling etc have been changed with the compression increase.i`d be Very interested in the results cos i had the compression mod niggling at the back of my mind.spend that extra £60 on the RR the extra power can be your Christmas pressy to yourself.
crazylegs
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Re: Surging

Post by crazylegs »

have a trip to millway. they are really helpfull and have a great reputation.i`ve only been there a couple of times once for a unichip and once for free advise.they have been superb both times.
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LimeyMk1
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Re: Surging

Post by LimeyMk1 »

Already spent £990 on body work for a 'christmas pressie'! :lol: I guess I have 'detuned' her to get reasonable milage as she's my everyday car.

Session at Millway seems in order, anyone got any contact details? (IMOC discount :lol: )
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tonigmr2
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Re: Surging

Post by tonigmr2 »

Don't want to suggest something stupid...but I had this problem previously on an SC which it came to light had the following

1) sticky accelerator due to a stiff cable!
2) Can't quite remember but something about the butterfly valve in the throttle being a problem.

T
crazylegs
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millway

Post by crazylegs »

spudgun
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Re: Surging

Post by spudgun »

Hi Limey, you have raised the compression fairly significantly there, sir, make no mistake. The only way your gonna keep detenation at bay is to use super unleaded or an octane booster.
As toni has stated it could be crud all around the throttle body butterfly. This is caused by the crankcase ventilation system, and can be cleaned up with carb cleaner. hth.
crazylegs
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Re: Surging

Post by crazylegs »

Hey spudgun good to see you back here .have a good Christmas.
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LimeyMk1
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Re: Surging

Post by LimeyMk1 »

Cheers for the responses guys, don't think the throttle body and cable are a problem as I only finished rebuilding the engine in April/May and the whole enigine was pretty clean. However I have noticed a reasonable quantity of oil coming from the crank case vent so I'll double check that. I've fitted a catch can to reduce this and it helped a hell of a lot in reducing the detonation
crazylegs
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Re: Surging

Post by crazylegs »

did the catch can really make that much difference? it might be worth looking at on a standard car you could maybe run a bit more advance.maybe get an extra horse or two?
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LimeyMk1
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Re: Surging

Post by LimeyMk1 »

Seemed to, the theory is that the oil mist which is dumped into the throttle body reduces the octane rating of the fuel when they mix. Plus you reduce the temperature of the air going in to the manifold, can't be bad can it? Only problem is that most catch cans are too big to mount on the right of the engine, mine ended up bolted to the battery bracket! :lol:
spudgun
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Re: Surging

Post by spudgun »

How do Kev, Merry christmas to you to sir.
I still reckon 200psi is a lot for your car limey. I'm pretty sure they should be around 140psi stock so you have increased it by about 25% or so. As for the catch can, doesn't the mk1 have baffles in to rear cam cover to stop all the oil getting chucked out?

Anyway best of luck getting on top of it.
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