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paulhide · Posted: Tue Dec 18, 2007 1:36 pm Post subject: Any Ideas?

Replacement engine in P4 ticks over fine – all leads doing something if I take them off, and it runs great above 3,000 revs, but runs rough and stutters badly, slowly improving, up to 3,000. If it didn’t tick over fine I might understand this, but otherwise I find this weird. Any ideas?
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bobbber · Posted: Tue Dec 18, 2007 1:55 pm Post subject:

Air leak
Throttle body balance (or whatever it's called... synchonization maybe?)

I'd go for the second one at the moment.

Bob
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john 33_16v · Posted: Tue Dec 18, 2007 5:46 pm Post subject:

Hi,

Have you tried swapping the air flow meter with another one?

Is it any better warmed up?

John
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Admin · Posted: Tue Dec 18, 2007 10:24 pm Post subject:

Hi

Is this just in neutral, or when driving? Doesn't take much throttle to get to 3k, so wondering if it could be the throttle position sensor badly adjusted (as the fuel injection kills the fueling on a closed throttle when slowing down to save fuel).

All the best

Keith
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paulhide · Posted: Tue Dec 18, 2007 10:26 pm Post subject:

No difference warmed up, but I reckon Mr. Bobbbbbber might be on it, as it was already something I'd thought possible, as I had changed one of the throttle bodies last year when I put he engine in and didn't really run it much then. Was just going to try changing leads first and then get onto this. Wanted to see what other people thought or if there was something that was more likely.
So I guess I've got to muck around with those extending linkages. Is there an accurate way of doing this? Or is it a case of try a bit and see over and over?
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Admin · Posted: Wed Dec 19, 2007 1:10 am Post subject:

Hi

Time to buy some vacuum gauges. Morgan Carbtune seem to be about the best for reasonable money.

All the best

Keith
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bobbber · Posted: Wed Dec 19, 2007 10:47 am Post subject:

I've been wondering on my rebuild just how I'm going to synchronise those things!

Bob
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paulhide · Posted: Wed Dec 19, 2007 10:55 am Post subject:

How do you adjust the throttle position sensor as I think that is also on the side I changed?
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john 33_16v · Posted: Wed Dec 19, 2007 11:56 am Post subject:

bobbber · Posted: Wed Dec 19, 2007 12:43 pm Post subject:

I don't think you undo the bolts fully.... only a little to allow you to rotate the switch?!?!?!

There are two switches on it... 1 for closed throttle (on when accelerator unpressed), 1 for full open throttle (on when accelerator fully depressed). Anywhere in between both switches are off.

Bob
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lee16v · Posted: Wed Dec 19, 2007 6:19 pm Post subject:

Paul, from your original description it's exactly the same problem i had when i changed my engine. One of the throttles was opening (fractionally) before the other. A couple of twists on the adjusters was all it needed and i did it by eye which did the job well enough.

paulhide · Posted: Wed Dec 19, 2007 11:20 pm Post subject:

Yes Lee (thanks), this is what I was going to try first (at some time when I get 5 min!) as it slowly improves with more revs, a distant part of my mind seems to think it might be a balance problem Question

Useful to know the throttle position stuff if it isn't that - thanks everyone.
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paulhide · Posted: Sat Dec 22, 2007 9:12 pm Post subject:

Sorted!!! In fact, to such a degree that, with a bit of tinkering, there isn’t even a hint of a stutter at 1500 revs (stop-start-stop-start) as I’ve had on loads of 16v cars in the past! It’s actually a really nice engine and this dispels my fears that it might have been a valve problem as this engine jumped a few teeth earlier in the year when I had originally installed it. (It’s only just been run properly the past couple of weeks) So that’s the trick then. Interesting to know what happens when the throttle bodies are out of balance. I am very happy now

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bobbber · Posted: Sat Dec 22, 2007 9:26 pm Post subject:

Told ya!

Bob
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paulhide · Posted: Sun Dec 23, 2007 1:43 pm Post subject:

Maybe we could balloon your avatar head aswell as adding the Christmas hat Idea

Cheers, and have a great Christmas. Speak to you in the new year.
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