Project Daily Sigma (16V TU)

[darrenjlobb]

Bit of an update to this...

Still got the idle on going saga....

Niall was kind enough to post me his new labmda (which is the correct one for this engine) to see if it made any difference... Oh the fun and games....

Basically before fitting, i had the bosch lambda from the 8v connected...in this setup, the car wouldnt idle at all, other than very occasionally when it randomly managed to catch it with the ICV and work..but a quick throttle up and it would die... but basically everytime you come to idle it will just die, which is a pain in the daily, living with it for now but id really like to fix it... however bar the idle, it ran seemingly ok, I mean ive not dyno'ed it or anything, but appears to pull well, for what it is..

Anyway, fitted the new lambda, and as far as i can tell, there is no changed to the idle at all, behaves identically to before... (have left ecu unplugged for an hour also)...HOWEVER it has a new problem, in that once its warmed up, on "cruise" at mid rpm, it will just start dying on you, and putting your foot down does nothing and nothing until your almost WOT and then it suddently kicks in / is fine again...dosnt seem to effect WOT, just mid range cruising, very odd as didnt do this at all on the old sensor...not sure if its killing spark / fuel, or just leaning / riching it out so bad that it dosnt run hence WOT goes back to base map / bypass lambda and work again? thats my thought anyway??

So the saga goes on, it works, but it dosnt...

The only other weird thing ive found, is that if you unplug the ICV, start it, it will obviously idle (albeit high) due to the static half open position of the ICV, however, if you then plug the ICV IN WHILE its running, after about 40 seconds, the ecu seems to notice it, and bring the idle down...the car then idles like a DREAM, can rev it up / try to stall it, and it always recovers and has a nice steady idle at correct rpm...however after 5-10 minutes of idling, it will just start to splutter and cough, and eventually die, same as if you drive it, works ok for a few minutes, but then you come to a halt and it dies, and thats it, no more idle...unplugging it / repeating the process makes it do just the same...Looking in PP2000, it seems that when you do this, the ICV goes to a fairly closed position, and injection is quite short, but then as its idling, fueling starts increasing, and ICV starts opening, bit at a time (as it would if its getting richer)....From what i can see, the issue is that it keeps doing this richer and richer thing, compensating air with the ICV until eventually the ICV cant open anymore...and thats the point it dies at....

Question is, what on earth is causing this behaviour?