Engine doesnt want to idle properly!

[JBliss]

Hi all

Just put my engine back in after doing the 6 speed conversion

I primed the engine etc and ran the car up to temp. there was no intercooler/intake pipes on at this time and the exhaust for the front turbo was disconnected

it was running fine, and idling fine. i went to start it again today after connecting everything and it started but died soon after. I only put a little bit of fuel in so thought it had run out. Filled up and it ran longer but still died. Picked up the idle manually and it ran fine up to temp. Took it for a little drive (1st gear only) around the yard and it was fine but its still hunting around 1k.

Could it be a lambda sensor? how do i check these things?

[D_G]

The lamba won't cause stalling, air leak or vacuum hose elbow pushed on too far would be my first guess. Also check throttle sensor is plugged in properly.

[JBliss]

i took off all the intake pipes and intercooler pipes to see if it changes but it didnt.

Stuck for ideas without plugging it in to a laptop

Edited by JBliss on Wednesday 8th August 21:59

[D_G]

If you want to check the lambdas, do a voltage check between the blue and grey (the other two should be both black or white) and it should fluctuate between 0-1v. A dead one will show under 0.1v and not respond to a throttle blip.

[JBliss]

in answer to you're previous reply. I took all the pipes off and refitted.

If you hold the idle slightly higher (by hand just resting on the cable, it is fine). my idle was fine before i took the engine out and i haven't changed anything there!

[andygtt]

probably the cams... mine hunts on idle and it needs a significant amount of mapping to remove it after you go from original to new cams... is it mapped yet? or got a baseline to get you running?
if its not run the cams before then it will need a little more butterfly open than stock (which I think you have said you did).

Im refitting the original engines idle stab valve so that its better controlled on idle.

[Gadgeroonie]

make sure you did not push the map sensor pipe on the intake manifold all the way on

if needs to be pulled back a few mm

[R0162]

I would guess the throttle position has changed slightly, check it is sitting on the throttle stop correctly,the throttle position sensors can be a bit sensitive, so i assume to take the engine out things will have been disturbed.

Did u play about with the idle at all? becasue this is actually a throttle stop and not to adjust tickover, if it moves position slightly you will need to reset the adaptive map, if it moves out of parameters then you will need to adjust the throttle stop to with a certain position and rest again until it will tickover properly, also like Mike says make sure the vacuum pipe under the throttle body isnot pushed on too far, pull it back a little on the elbow.

[Gadgeroonie]

also - did you make sure you put the vacuum pipe back on the fuel pressure reg

can you get the afr checked whilst it is idling

[mgbond]

Bit of a Hi Jack but as the question has been asked:

What should the AFR be for idle and when under 0 pressure?

[Gadgeroonie]

for idle you are looking for 14.7 or lambda of one

however not all engines like to idle at lambda 1, some prefer it a bit richer

the load sites between idle and 0 psi should be in low 14's to low 13's but again it depends on the car

somtimes the afr used is more about heat management than economy or power

[andygtt]

R0162 said:

Did u play about with the idle at all? becasue this is actually a throttle stop and not to adjust tickover, if it moves position slightly you will need to reset the adaptive map, if it moves out of parameters then you will need to adjust the throttle stop to with a certain position and rest again until it will tickover properly

all good advice on stock cams... if new cams and pistons etc have been fitted then you might have to crack the butterfly open a little to get enough air in for the map to be able to control the idle as it will simply stall before the map gets time to respond...

Must admit though I have had the "pushed the pipe on too far" issue before lol

In truth its best to ring your engine builder or mapper

[R0162]

He never mentioned changing came in the op, just had the engine out for gearbox conversion.

[mgbond]

Gadgeroonie said:

for idle you are looking for 14.7 or lambda of one

however not all engines like to idle at lambda 1, some prefer it a bit richer

the load sites between idle and 0 psi should be in low 14's to low 13's but again it depends on the car

somtimes the afr used is more about heat management than economy or power

Ok, mine is set for 14.7 for idle and does reduce as you go up the revs (when off boost). I need to check but low 13's is ok no matter what revs if off boost?