Author Topic: ABF lumpy, VW mechanic stumped!  (Read 23052 times)

Offline clipperjay

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Re: ABF lumpy, VW mechanic stumped!
« Reply #20 on: 06 March 2013, 22:12 »
I think the over fueling is a good indicator, look from start to finish the fuel delivery system.
I have known old fuel rail looms to get brittle from heat and sometimes intermittenly leave injectors to jam open or the Ecu is not sending the right signal to the injectors?
Where the injector test done flooding on all chambers?

Offline tshirt2k

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Re: ABF lumpy, VW mechanic stumped!
« Reply #21 on: 06 March 2013, 22:20 »
Another thing to check is fpr. I had a dodgy one and have heard people squirting wd40 in them. Beware though mine stuck in a using grips to get it out f@&ked it.


Mk3 ABF 16VT Megasquirt V3

Tshirt knows........ How to diagnose

Offline Classic16v

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Re: ABF lumpy, VW mechanic stumped!
« Reply #22 on: 07 March 2013, 12:05 »
Wires down the back of the inlet manifold?
Wires all look good as far as I can see. No areas of wear/melting on the black cloth tape surrounding the wire near the idle switch or TPS, I can't feel any breaks in this area, and the rest running along the manifold is encased in ridged plastic tubing.  However, yesterday I tried depressing the idle switch with the throttle open and it didn't do anything.  I also removed the plug on the throttle position sensor and the revs increased at idle, with a little bit of creeping up then dropping back down to around 1000.  Things seemed a little more stable so I tried driving it like this (!) but still had the lack of power and jerkiness.  Even if the idle switch is broken, would I still get the misfiring/lack of power and the engine flooding? My dad fired it up this morning just to move it on the drive (engine running for about 30s) and when I just went out to check the idle switch again it won't start (flooded?!).

I was going to check the fuel lift pump but it's raining at the moment - still, I would have thought if the lift pump was dodgy it wouldn't flood.  It could explain a lack of power I guess, but not over-fueling, surely?

Another thing to check is fpr. I had a dodgy one and have heard people squirting wd40 in them. Beware though mine stuck in a using grips to get it out f@&ked it.
Forgive me, but what's 'fpr'?

Cheers

Offline Diamond Hell

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Re: ABF lumpy, VW mechanic stumped!
« Reply #23 on: 07 March 2013, 13:40 »
Fuel Pressure Regulator.

I would suggest throwing a new lambda at it, or at least see whether disconnecting it makes any difference, but it says above it's got a recent one and TBH the symptoms sound more serious, although the cycling revs runs with the lambda suggestion.  Disconnect it, see what the motor does.
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Offline tshirt2k

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Re: ABF lumpy, VW mechanic stumped!
« Reply #24 on: 07 March 2013, 14:47 »
Lambda doesn't really affect power or how it drives. Will affect efficiency though. It's not a wideband so doesn't control fuelling that much. On high loads above 4k fuelling goes open loop and runs rich for component protection.

Misfires under load are ignition related. Check resistance of plug and king leads.


Mk3 ABF 16VT Megasquirt V3

Tshirt knows........ How to diagnose

Offline Classic16v

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Re: ABF lumpy, VW mechanic stumped!
« Reply #25 on: 07 March 2013, 14:49 »
Need to get it started again before I try anything else! The mechanic was saying that when it wouldn't start for him he had to remove the spark plugs, and heat them up to dry them out and get things going again. Does that seem reasonable? And is it literally as easy as sticking a flame on the end??

Offline Classic16v

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Re: ABF lumpy, VW mechanic stumped!
« Reply #26 on: 07 March 2013, 15:22 »
Misfires under load are ignition related. Check resistance of plug and king leads.

Haven't checked the king lead, but the plug leads were all replaced with no effect.  How do I check resistance of the king lead?  I haven't really got much kit...my dad might have it's it's straight forward.

Offline tshirt2k

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Re: ABF lumpy, VW mechanic stumped!
« Reply #27 on: 07 March 2013, 15:30 »
Check the resistance of all leads with a multimeter. Should be less than 12kohms.


Mk3 ABF 16VT Megasquirt V3

Tshirt knows........ How to diagnose

Offline Classic16v

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Re: ABF lumpy, VW mechanic stumped!
« Reply #28 on: 07 March 2013, 17:09 »
Got the multimeter out, and it's dead! Tried a new battery, but no luck. The saga continues...

Offline DanChave

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Re: ABF lumpy, VW mechanic stumped!
« Reply #29 on: 07 March 2013, 18:02 »
As I have continuing issues with my Mk3 abf that sound quite similar to this, I will be keeping tabs on this thread!