Throttle Pots and Adaptive readings

[JensenA]

I'm stuck!

I can get bank 2468 running with adaptives of about 7.0, with the TP set at 17.3.
However bank 1357 (The driver side) is consistently reading about -23, and I just can't for the life of me get the reading down, unless I move the TP to a reading of about 40, but obviously I cant leave the TP at 40.
I have screwed in the idle screw so it is having no effect, and the 2468 TP is at the limit of its anti-clockwise adustment arc. ie I can't get it any lower than 14.0

Does any one have any suggestions as to what I should be doing, or doing wrong?

[mooey]

Following advice on this forum and before I set about adjusting the throttle potentiometers I used a flowmeter to check / adjust the mechanical linkage between both banks. Once set so both banks were as close to each other I then went about adjusting the throttle position pots and the adaptives just settled down on about -2

[jbvipercerb]

Is there play in the throttle cross shaft? Maybe the aluminium cross shaft has got bent, very easy to do when leaning over the engine.
Start at the begining disconnect everything and make sure both bank butterflies are shut, put the cross shaft on, making sure the butterflies stay shut, then set up the throttle pots as normal. Hope this helps.

[trackcar]

I would suggest that if you can't get the reading down then you possibly have water in the pin connector down to the lambda .. this generates a voltage across the terminals so the ecu thinks the mixture is richer than it really is .. if this is the case then with the engine not running but teh ecu powered up you would see the good lambda down at 0.00 or 0.01 or something close and the faulty lambda up at say 0.3-0.7v .. is anything like that happening?

What prompted you to delve in there anyway? was the engine running bad already or have you had a bit of a play and now can't get the readings correct? Do teh readoings come better at higher revs or are they always a long way out?
Posting several screenshots of your engine running screens and the adaptive tables would give us more of a clue aswell.

[JensenA]

Cheers for the tips/advice Joo.
I replaced the 2 rose joints because they were worn, so had to 'delve' in. It's one of those jobs that I normally leave to the experts, but one I'd like to learn, or at least understand.
I'll get some adaptive maps done tomorrow, and post them on here.
In the meantime (from what I remember) at 1000rpm, TP1 is reading +/- 18 with adaptives of -7.
TP2 is on 28.7 with adaptives at -31. And TP2 has reached the limit of its adjustment arc, so I can't move it to get them any lower.
I'm beginning to suspect a faulty Lambda1, as the log reading showed Lambda 2 was reading 1.2 only. Based on on the limited info I've given, Is this a possibility?

[trackcar]

right don't do anything until you get that tpot2 reading down. if you cant get it lower then it must be that the link rod is too long, throttle bank 1 will be at fully closed and the long link rod is now holding the even bank open. Shorten the link rod by whatever means is at your disposal if you've run out of adjustment on the threads to the ball joints you'll have to chop the end of the alloy rod or find some other fiendish way of getting some length out of it.

[mikesr]

When I replaced the ball joints with mini rod ends I had to cut the rod down by 4 or 5 mm to get the mechanical adjustment in the range needed.

Did you replace like for like or put something different on?

If they are different check if they are longer than the old ones

[JensenA]

Thanks to all those offering advice.

1. I'm relacing like for like, the new rose joints are identical to the old ones.
2. With the ECU on, engine not running, Link Rod disconnected, and the Idle screw wound fully out, TP2 (2468) has reached the limit of its adjustment, and I can not get the TP readings any lower.

The logs show no fault on both Lambda's.

[trackcar]

if youve got that tpot reading with the throttle closed something is defo amiss .. have you taken the induction pipes off and looked at the butterflies to see if they're actually closed? there must surely be something holding the even bank open?

[mikesr]

First thing I would try is swapping the tpots over.
If the high reading moves its a duff tpot.

If it doesn't move its mechanical or maybe something in the harness.
So second thing - if the tpot wires will reach try plugging them onto the wrong tpot. If the high reading is still on bank 2 then there is an issue with the harness/ecu connector.

If it moves to bank1 then its mechanical re the tpot position.

The car is a 4.5 isn't it? Have you checked that the butterflies on bank 2 are closing properly? Do you have a synchometer to check the flows? - duh! just reread your post - you have already checked this.

If the butterflies are OK then it may be the casting that the tpot fastens to. I remember an issue with a 4.5 that Joo and I were doing some of the early mapping work on. It was something to do with the casting that the tpot bolts to. IIRC it can move a bit.

Can't remember what he did to resolve it but it was the same symptoms - high tpot reading but no adjustment left.

I've got a 4.2 so can't help with the detail of exactly what to look for I'm afraid

Edited by mikesr on Saturday 28th June 12:14

[marcus1970]

I suspect a dodgy TP. Swap e'm over like mike said and at least you'll then know whether its the TP or something else.

MB

[JensenA]

I think I've finally got it sorted, faulty Throttle Pot (well done all the Sherlock's )

I removed TP2 and elongated the 2 screw holes to allow a bit more adjustment, and when I refitted it I could get the readings down to 13, but it kept creeping back up to about 29 on tickover, so I removed it again and cleaned it with electrical contact cleaner, and refitted it, and it all seems OK now - At 1000Rpm I have TP Readings of 17.3 on both TP's with the adaptives on Bank 1 fluctuating between -6 and +4, and Bank 2 -3 and +8.
Does that make sense - a 'dirty' TP? Or was it just a fluke and I really should be ordering myself a new one?

2 observations on this procedure...
Firstly it gets bl00dy hot leaning over that engine, after a while the link bar between the throttles is literally to hot to touch, and secondly it doesn't half use a lot of petrol! Yesterday the engine stuttered to a halt after 30 mins of running, so I trudged to the garage and filled up my emergency 5L fuel can - £7.30 for just over 5 litres somehow, that seemed to ram home how expensive petrol now is, a lot more so than putting in £50 worth does.
And it ran out of petrol again, just as I'd finished, so its used a gallon of petrol just sitting there on tick over for about an hour !!

ETA - Thanks Joo, Marcus and Mike for your help.

Edited by JensenA on Saturday 28th June 18:56

[trackcar]

good deductions all pleased you got it sorted