matmidgley

Running Problems

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Hi,

Having a few problems with my scoob recently.

under about 2.5k rpm it feels jerky, occasionally when coming to a stop the revs drop really low sounds like its about to cut out but never has so far.

over 2.5k rpm or at wot its fine, not jerky it boosts properly and pulls like a train it only seems to be at low revs.

but weirdly my MPG has gone up, i was getting 21-22 constantly for last 3-4 years, its now gone up to 24.9 over last couple months??

it was worse once warm but now its doing it from cold also.

There is no CEL, no codes when read with obd2 scanner.

I have tried changing some of the vacuum pipes the smaller 4-6mm ones and the brake booster which made no difference, I have ordered some new spark plugs (only done 13k since last change) and a new gasket for dump valve.

20180324_150449.jpg

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Hi,
Having a few problems with my scoob recently.
under about 2.5k rpm it feels jerky, occasionally when coming to a stop the revs drop really low sounds like its about to cut out but never has so far.
over 2.5k rpm or at wot its fine, not jerky it boosts properly and pulls like a train it only seems to be at low revs.
but weirdly my MPG has gone up, i was getting 21-22 constantly for last 3-4 years, its now gone up to 24.9 over last couple months??
it was worse once warm but now its doing it from cold also.
There is no CEL, no codes when read with obd2 scanner.
I have tried changing some of the vacuum pipes the smaller 4-6mm ones and the brake booster which made no difference, I have ordered some new spark plugs (only done 13k since last change) and a new gasket for dump valve.
20180324_150449.thumb.jpg.37b0b4bb8c7b8bf5b855213e487a0376.jpg


Could be the clutch or flywheel near the end of its life


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Pcv valve blocked?

You'd probably see oil in the tmic or y pipe if so , might be worth checking .

Or idle control valve might need a clean , for the cost of a icv gasket it might be worth a go

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u reckon?
its only got 50k on the clock and no slips or smells. revs will also dip when in neutral


Probably not now after reading the symptoms again I think savage could be onto something with the idol control valve could also be a throttle position sensor or crank position sensor but as it’s not throwing any code. it’s obv very difficult to diagnose unless you want to start paying out for sensors I could be something as simple as a maf needs cleaning. have you got any mods like induction kit etc ?


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no induction mods, i do have others and they were mapped in and it has been running fine until recently.

i have cleaned the maf and then swapped for another but no difference. i have found a very small amount of oil in the y pipe if I run my finger around the pipe but thought that was normal.

I have cleaned the throttle body, was not that dirty, does the hawkeye have a iacv?

I was leaning towards a vacuum leak but its hard to find it, if it is. its just weird how the mpg has increased since the problems have started lol. thought about fuel filter but expensive ti change on a whim.

I will look into the pcv valve thanks.

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If it's only a little bit of oil in the y pipe, yes thats normal. Couldn't tell you if a hawk has a icv and tbh i haven't even checked if the bug I've got in bits has 1 either

Doubt its a sparking issue , as it's fine at wot /full boost but maf or 02 sensor and anything airflow wise . Ie vac or intake pipework leak , clogged airfilter .

How long has it been mapped ? As a recent change in air temp might affect the cold start enrichment /idle / map in general , if it was recently mapped in cold weather

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been mapped for over 3 years now. air filter is a month old 

so could be a sensor/maf/or leak.

guess i start with cheapest and work from there

 

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I reckon it will be the speed sensor switch on gearbox. They have like a nylon tip on and wear down. But iv just chucked another “could be this” into your troubles, so id start with simple things. Speed sensor wasn’t that expensive for my bug anyhow from ICP.

Savage, bugs do have idle control valve. Located down from throttle body. 

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Its sorted and it was something stupid...

The Dump valve bung had worked one side slightly out but enough to be effecting the air and causing problems. going to be putting a better clamp on :)

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