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snicko1

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hiya all having problems with a 4.6 v8 its hunting and cutting out when hot we have changed

ecu

temp switch

air flow meter

lambda probes

throttle potentiometer

checked for vacunm leaks

idle valve

now checking wireing loom

anything else anyone think we could do cheers

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lloydox

Sounds like an air leak on the inlet manifold. guess this is what you mean by vacuum leak ?

How did you check for a vac leak ?

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Nicks100

Sounds exactly the same problem I have had for the last 2 years. Had a smoke test done 1 year ago to see if a leak.  Don't do it...it wil only give you a coronary! And sealing the "leaks" did not solve the problem.

All the same check hose between AFM and plenum. I am not sure how bad a leak has to be to have any effect but you could look at the throttle linkage where it enters the plenum. I have changed EXACTLY the same parts as you have. Also the coil and distributor !

My problem was partially resolved by ensuring timing was spot on (J Eales 4.6 stage 3 At 12 degrees btdc at idle - equating to approx 28 btdc at 4000rpm) and screwing the plenum air idle screw out until the engine rpm rose to about 1000rpm. Then reset the base idle!  Do your spark plugs always appear black? If so see next paragraph!

I have every sympathy! You may be interested to know that  this year I have also had the problem of massive overfuelling - despite trying 3 different ECUs with different fuel maps. Timing was spot on but made no difference- diagnosis... After sorn during the winter the injectors have stuck semi open - so check them as well. May be worth getting them sent off for cleaning and flow checking.

I hope that my problem is about to be resolved... but only by a radical change to a Weber 500. in other words I have had it with EFI !!!

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JohnBlenk

That is pretty radical going from EFI to Weber 500 ! I have the latter and when it was hunting it was down to a weak mixture. I changed the rods in the carb and hunting disappeared. Simple !

Have installed Innovate AFR gauge as only way to know for sure whether the mixture is right.

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Nicks100

Sounds radical but I am assured that it is simpler than it sounds ! I hope so !

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Nicks100

Snicko. Any progress ? let me know.

I have had to change my mind about Carbs as I cannot isolate the EFI loom. It is part of the modified harness in the Westy. So am going to replace faulty injectors and see what happens !

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luxseven

The only other thing I could think about is bubbling fuel due to heat or something alike.

EFI in itself is no witch thing and after I converted my engine from carb, I can say it's no rocket science either.

It should be possible to find the fault with all you did, except if you "transported" the fault i.e. a wiring that damaged the ECU or something else.

Cheers.

 

Jos

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took it for a spin better but still not right ,when I take the foot off the peddle the revs drop to bout 1200 then slowly drop off to 7000 and when going a steady 40ish its still hunting a bit and when I get to 5000 revs its just spluttering then took it out about a hour later and it went up to 6000 revs ok ,

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  • 2 weeks later...

the car is running loads better took it to rpi and they adjusted the tps from 0.25 to 0,35

reset air mass meter from 3.22v to 1.8

plugs from bp7 to bp6

removed westfield air filter and system refit with k&n

 they also  said it would run better with a fuel pressure regulater  and also a rpi plenum ..I have had problems starting it when warm they suggest to put a heavy duty starter on it .. now is  anyone running a rpi plenum and does it make a lot of differance as they don't come cheap... cheers

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