How do you adjust the throttle pots?

[Jabbah]

Been reading up on how to set up the throttle in this thread and just have a couple of questions...

1) As per the last two posts, how do you adjust the actual throttle pot readings once the throttle position is set for idle and adpatives?

2) To reset the adaptives do I need the cable with the resistors in or can I do that with just the wires connected?

[Rawhide]

The pots adjust by slacking off the screws a little and then the whole unit will move slightly left or right. They are very sensative and small movements result in big changes in the readings.

To reset the adaptives you need the serial cable and ECU software. If you can connect properly you will be able to reset.

[Tanguero]

The entire procedure for setting up the throttle pots is in the workshop manual. You need to follow it exactly. As well as a computer with the ECU diagnostic software and the cable you will need an airflow synchrometer.

[Rawhide]

Please let me know how you get on if you tackle this. I've been trying in my limited time to get my car setup correctly and it's not easy. I seem to end up with high adaptives and bad AFR faults on both banks.

The thread you linked it pretty helpful.

[aide]

I spent some time doing this a coulpe of weeks ago as I got an AFR fault.

I found that the ball joints on my throttle linkage had a bit of play in them so I swapped them for some studded rod ends.

Also got an airflow meter and followed the workshop manual but I couldn't get it perfect.

I'd like to try again the weekend of March 24th and 25th.

If you would like to use my tools that weekend as well you're more than welcome.

My underground carpark has loads of space and it's dry and well lit so we could work away all weekend.

Perhaps someone who knows how to do this could help out as well ?

[pmessling]

It's a time consuming job. Check how tight the bolts holding the inlet manifold are. Some of mine were hand tight and should be sealed tight to stop are by passing the throttle bodies.

Follow the manual and you'll get it. I also used feeler gauges on the butterfly's to get the same gap on all 8. They can then be adjusted if needed. Rose joints are a great upgrade on the ball joints. I also made a better rod to aid easy and finer adjustment. I also had excess material on one of the can overs stopping the rod end sitting correctly. You want a stinking hot engine. Remove all the induction hoses and check them individual with the air flow meter and get them to a close average.

Do the job slowly and you'll get it right. Whilst getting the figures and adaptives to spec I used them as a guide line and got the car running perfect. Although my throttle pots at idle where about 14% with a healthy warm idle with a bit of throttle at start.

Peter

[Tanguero]

Agreed! In my experience it is a job that needs to be done slowly and methodically to get a good result and as always it is a balancing act getting everything as close as possible as well as the car running at its best.

If you are still getting AFR faults once you have worked through the procedure and got everything else set up then you should probably be looking for other faults, Lambda sensor connectors being a prime suspect.

[aide]

pmessling said:

It's a time consuming job. Check how tight the bolts holding the inlet manifold are. Some of mine were hand tight and should be sealed tight to stop are by passing the throttle bodies.

Follow the manual and you'll get it. I also used feeler gauges on the butterfly's to get the same gap on all 8. They can then be adjusted if needed. Rose joints are a great upgrade on the ball joints. I also made a better rod to aid easy and finer adjustment. I also had excess material on one of the can overs stopping the rod end sitting correctly. You want a stinking hot engine. Remove all the induction hoses and check them individual with the air flow meter and get them to a close average.

Do the job slowly and you'll get it right. Whilst getting the figures and adaptives to spec I used them as a guide line and got the car running perfect. Although my throttle pots at idle where about 14% with a healthy warm idle with a bit of throttle at start.

Peter

Thanks Peter, I didn't check the manifold bolts so will keep that in mind. The airflow for each intake was more or less the same at 4.5-5.0 on the meter so I'm unsure if I'd need to adjust each butterfly, so I might check the mainfold bots first and if they're ok I might leave it as it is and carefully go through the process in the manual from scratch again. I'll get some allen bolts to replace the throttle pot screws to make it easier to adjust them as well.
Adrian

[aide]

Tanguero said:

Agreed! In my experience it is a job that needs to be done slowly and methodically to get a good result and as always it is a balancing act getting everything as close as possible as well as the car running at its best.

If you are still getting AFR faults once you have worked through the procedure and got everything else set up then you should probably be looking for other faults, Lambda sensor connectors being a prime suspect.

Thanks for the lambda sensor info - I did keep a close eye on them and they seem to be switching ok. But the one on the bank that was throwing the fault was switching more often and more extremely that the other.

[Tanguero]

If you can see them both switching then they (and the connectors) are almost certainly OK. If the adaptives are maxed out trying to lean the mixture then I would maybe suspect a stuck/leaking injector, if they are trying to enrich it then I would be thinking about air leaks. (you did block the purge line didn't you?) You should be able to hear each injector clicking clearly with a stethoscope or a screwdriver pressed to your ear.

[aide]

Tanguero said:

If you can see them both switching then they (and the connectors) are almost certainly OK. If the adaptives are maxed out trying to lean the mixture then I would maybe suspect a stuck/leaking injector, if they are trying to enrich it then I would be thinking about air leaks. (you did block the purge line didn't you?) You should be able to hear each injector clicking clearly with a stethoscope or a screwdriver pressed to your ear.

I can't remember if the adaptives were adding or subtracting fuel but will look at the saved results this evening.
Hopefully they were adding fuel as I actually didn't block the purge line

[greenracing]

Also worth checking the value the air temp sensor value when you plug in the computer. Mine was knackered and showing a constant minus figure so the afr was way to rich. Also worth turning the main buttefly shaft by hand to check that it moves freely. If it binds, slacken all of the butterfly screws, rotate the shaft a few times then re-tighten the butterflies.

I would also recommend checking each spark plug before you dismantle anything as they may indicate a faulty injector or lead. If a plug seems cleaner/whiter than the rest it could indicate an air leak or blocked injector, black and sooty may be a dodgy lead or coil pack.

One last thing, slowly rotate the shaft and watch the values, they should go up and down smoothly, large jumps may mean the throttle pot is worn.

[aide]

Some sound advice there greenracing, much appreciated. I did a few checks today and the air temp sensor is ok and from what I recall the butterfly shafts were moving freely the last time I had it stripped down.

I will certainly check the spark plugs first before I begin the rebalance in a couple of weeks to see if there is any indication of faulty injectors or leads, coil packs or air leaks.

I also checked to make sure that the throttle pots are increasing and decreasing smoothly.

But the main thing I noticed when I downloaded the adaptive maps was that they were positive, which is probably a good thing as I didn't block the purge line the last time.

So hopefully, if the sparkplugs are all clean, then I might be just looking at an air leak somewhere as the cause of the original afr fault..

If I find a cleaner spark plug, as you mentioned above, indicating which intake might have an air leak, how do I actually track it down and fix it?

[greenracing]

Hi aide,

The air leak can only be from a few of places:-

The purge line (s)
The seal between the throttle body and the head
The connection between the purge line and the throttle bodies

if everything goes well with the purge line blocked off but once its reconnected the adaptives star to move, suspect the carbon canister purge valve.



I think thats it. Hope it all goes to plan!