out of tune

[V8CER]

Have been trying to get rid of a misfire for a few of weeks now. i am waiting for a new set of ht leads to arrive and am thinking is it a basic set up problem?
So the question is
what are the symptoms of poorly set up throttle pots?

thanks in advance. Peter

[JensenA]

Peter - your best bet is to get it hooked up to your Laptop, that will tell you exactly what is wrong. Byker28i has the s'ware on his site, or I can email it to you if you want.

[marcus1970]

V8CER said:

Have been trying to get rid of a misfire for a few of weeks now. i am waiting for a new set of ht leads to arrive and am thinking is it a basic set up problem?
So the question is
what are the symptoms of poorly set up throttle pots?

thanks in advance. Peter

Bad adaptive readings, poor running, smelling of petrol, popping on idle, stalling, etc etc.

Need the laptop as above.

MB

[Byker28i]

Well worth having the software and getting a map saved of when it's running good to compare with when its poorly

Check out: http://homepage.ntlworld.com/dave.hinns/software.h... for the software, curtousy of all the other helpful people on here. I just provide the storage space.

[WIL35]

Have the same problem with mine since a top end rebuild after the timing chain broke. Have tried adjusting things using the manual and the laptop and it isn't getting much better.

I spoke to someone who mentioned the 'O' rings. I take it these are between the cylinder head and the throttle body assembly.

Would a poorly sealing 'O' ring cause pooping and banging? Also, one of my Throttle Pots kept flickering between two different values, does this suggestt it has had it? Strangely it wasn't on the side that was causing the problem!

[V8CER]

perhaps I should explain further
I took it to my Indie for the MOT telling him it wasnt 'tip top' and could he change the noisey throttle pot he had cleaned last service,
he fitted the cats changed the plugs and adjusted the pots.
it sailed through the MOT and removed the cats
i went to pick it up and the misfire had appeared on the way home.
I went back to him asked him to change the plugs again (thinking this was the cause) made no difference he adjusted the pots with me there (balanced at 18 he didnt consider the adaptives)
I took it home still no good. 1 pot was dirty so I changed both, the airflow temp was reading high so I changed that, the coils are only 5 weeks old (changed when I changed the oil pressure transmitter)which leaves me with the leads (18 month old magnecors) I have ordered new 10 mm ones from TCS but the delivery is F&*^ked up and I havent got them 2 weeks later so other than the dirty filter I am looking at basic tune??? until the leads arrive
I even took the exhaust off to prove there wasnt any rag up the pipe ?

it starts and runs OK on light throttle. misfire is on accelleration (its awfull)
my laptop hasnt a serial port but when connected to my PC (so obviously I cant drive with it) its showing massive adaptive values -30 and -37 at 3k rpm load site 8 . I couldnt get the pots low enough value (14ish)to reduce the idle adaptives below -6

I have just found the air filter to be blocked cleaned it and it is better but not right.
Peter

[Codfather]

i had misfire on mine recently, was a faulty lambada. put 2 new ones in and its as good as gold

[marcus1970]

V8CER said:

perhaps I should explain further
I took it to my Indie for the MOT telling him it wasnt 'tip top' and could he change the noisey throttle pot he had cleaned last service,
he fitted the cats changed the plugs and adjusted the pots.
it sailed through the MOT and removed the cats
i went to pick it up and the misfire had appeared on the way home.
I went back to him asked him to change the plugs again (thinking this was the cause) made no difference he adjusted the pots with me there (balanced at 18 he didnt consider the adaptives)
I took it home still no good. 1 pot was dirty so I changed both, the airflow temp was reading high so I changed that, the coils are only 5 weeks old (changed when I changed the oil pressure transmitter)which leaves me with the leads (18 month old magnecors) I have ordered new 10 mm ones from TCS but the delivery is F&*^ked up and I havent got them 2 weeks later so other than the dirty filter I am looking at basic tune??? until the leads arrive
I even took the exhaust off to prove there wasnt any rag up the pipe ?

it starts and runs OK on light throttle. misfire is on accelleration (its awfull)
my laptop hasnt a serial port but when connected to my PC (so obviously I cant drive with it) its showing massive adaptive values -30 and -37 at 3k rpm load site 8 . I couldnt get the pots low enough value (14ish)to reduce the idle adaptives below -6

I have just found the air filter to be blocked cleaned it and it is better but not right.
Peter

Balancing them both at 18 is the text book answer, but due to engine wear and loads of other variables, it's probably not the best thing to have done. The adaptives show you how much/how little fuel is being chucked in and very minus as you describe has, in my experience, led to loads of popping and banging and a hefty ploom of smoke out of the back under acceleration.

I'm no expert, but have found that in between services your best bet is to warm the engine through and then undo your idle screw so its right down out of the way. Adjust your pots until the adaptives are somewhere acceptable say +/- 15'ish. It may be that the pots read totally different on the screen ie one at 17.5% and the other at 16.4% say.

This is ok as its the fuelling that you should be concentrating on, not the pot reading itself. Now pop the idle screw up slowly until a reasonable idle is obtained say 1000rpm. Then check the adaptives again. If they are ok'ish then leave it for a while and see how it goes. If they are well out again then adjust the pots again slightly. It is quite hassly, but worth it when the car starts to behave itself a bit better. What you dont want is a constant +/- 37 'ish as this is the outer limits of the ECU capability.

Let us know how you get on.

MB

[BCA]

I know this will sound odd, but has it been like this for a while, or has the battery been flattened/disconnected for a small period of time?

If so, I suggest you find a private test track and do a few runs to the top of third gear. Our car ran like a dog after it was broken into and the alarm flattened the battery - the solution was to give the thing a damn good run through the gears repeatedly and all has been fine since... (this was about 40k miles ago!)

Edit: re-read and it seems im out of my depth on this issue, though the above information may still be of use to someone?

Good luck with it.

Edited by BCA on Sunday 1st July 18:41

[BCA]

I know this will sound odd, but has it been like this for a while, or has the battery been flattened/disconnected for a small period of time?

If so, I suggest you find a private test track and do a few runs to the top of third gear. Our car ran like a dog after it was broken into and the alarm flattened the battery - the solution was to give the thing a damn good run through the gears repeatedly and all has been fine since... (this was about 40k miles ago!)

Edit: re-read and it seems im out of my depth on this issue, though the above information may still be of use to someone?

Good luck with it.

Edited by BCA on Sunday 1st July 18:41

[V8CER]

ITS FIXED!!!!!!!!!!
HT Leads finally turned up today fitted them and the mis-fire is gone
PHEW! I had almost forgotten how good it is to drive (had misfire for over 4 weeks)
Thanks for all the input.

RGDas peter