Very lumpy idling and hesitant acceleration when warm

[Quaser]

Hi Guys

Been getting the touring ready for MOT - went to go for a drive after fitting my 6 branch and Remus exhaust but the car is not behaving!

Its idling at around 500k and is very lumpy.

When im driving, im kangarooing down the road! - Only when its over 4k revs, its better and accelerates but when it goes back down it kangarooing again!

I have changed dizzy, rotor arm, plugs, leads, fuel filter, and maf (unichip maf conversion)

What else could it be?

Q

[uzdubmwe30]

idle control valve?

[chief]

did it play up before fitting the manifold & exhaust

[Quaser]

i had a standard manifold and exhaust on it before with no lambda and without changing any of the above - it was lumpy but not as bad as it is now.

Dont think its the ICV as it would not cause the hesitation in acceleration would it?

[abelai]

Have you checked that the TPS is working properly? The TPS tells the DME which map to use, idle, normal or WOT.

[abelai]

Oh and the obvious one air leaks around the inlet manifold

[Quaser]

How can i tell if the tps is working? it was apparently brand new 3000 miles/18 months ago

[abelai]

The first check is can you here it click when you open the throttle with your ear by the throttle body and engine off. Also does it make any difference to the idle with the TPS disconnected it should.

[Quaser]

OK - just tried it - i can hear clicking with the engine off

started car - lumpy idling, unplugged it - revs instantly rose and it seemed to idle better - still slightly lumpy but that could be cause its cold

Will have to try it out tomorrow and take it for a drive

So is it faulty or doing what it should do?

[Quaser]

OK - this thing has me stumped so i took it out for a quick spin with the tps off - hesitation i still there but it is a bit more driveable.

Do you think its a case of it needing a remap or could it be something else?

[abelai]

Well that at least means your TPS is acually doing something. Does it smell rich on idle whats the cold idle and hot idle speed?

You might want to try reading through all of this:
http://www.e30zone.net/modules.php?name ... ic&t=78455
It has lots of info on testing the TPS, CPS, CTS and ICV.

What difference does disconnecting the vacuum hose to the FPR make(creating an air leak) do the revs increase?

[siddiqi1]

i think it is either ur icv or your crank pos. sensor!

Sabs

[Quaser]

ok - tried icv and no difference - tried different ecu - no effect!

tried spraying brake cleaner on the rubber elbow - no effect, tried it on cps (dont know why - suppose i just had the can in my hand!!!!) and the revs went up!

Tried the vacuum hose - revs went up slightly

Checked the rubber connectionsunder the inlet manifold as advised by the other thread - and everything seems fine there.

[M5pilot]

Crank sensor is the likely culprit here dude.

Are you sure there are no really big airleaks?

Is there something else you could have missed?

[Quaser]

Just a quick question - whats the order of the leads at the dizzy cap starting from the top?

Just wanna make sure i put them on right

[Quaser]

Anyone?

[abelai]

The cap is numbered and so are the leads. Firing order is 1,5,3,6,2,4 and number one is at the front of the car

[Quaser]

my cap isnt numbered and neither was the previous one - thats why i want to make sure - i take it 1 is at the top of the cap -

1 5, 3, coil, 6, 2, 4

right?