Right chaps, as I mentioned in other threads Im having a bitch of a time with the idle. I've got the 2.4l intake manifold fitted along with the subsiquent EGR blanking and fuel pressure regulator mods, aswell as a set of Piper cams, exhaust and flowmaster air filter etc. Just recently the cars idle has been exccessivly lumpy, far more so than when I first fitted the cams 6 months earlyer.
It seemed to have started after I changed the hydrolic lifters, I had a lazy one that ticked so I stuck 16 new ones in. On the way home from the garage I noticed it was running wrong and when I checked I found I hadnt fitted the coil pack earth strap back on tight and put it down to the bad earth causing the coil pack to miss. Anyway It still didnt seem right, I figured maybe I'd damaged the coild pack by running it without a good earth so I replaced it with my mates good working one and it made no differance. A week or so later we checked the timming and whilst it apeared it may have been out, we reset it and checked it like a dozen times before we boxed the engine back up, theres no way thats wrong now. The problem seemed to get better but its just got worse again.
The car runs fine when you gun it, and it goes like stink at high revs, so I dont think theres much wrong with the valve train or the coil pack as youd expect it to be across all rpm's. I was then thinking the manifold and egr / fpr mods may be causing the problem but everyone else whos done the mod seems to be ok?
So now I've been thinking and I recon it could be the Lambda sensor on the way out. I belive they just get lazy with the build up of silicon and carbon and genral exhaust shit that contaminates them, rather than just fail, so the ECU dosent pick up theres a fault. Now I read more, It would seem that the lambda sensor is ignored for the first 30 seconds or so from a cold start whilst it has time to warm up, and during this time the car idle seems fine all be it slightly higher revs than normal, you can pull away smoothly and have no stutering etc. As soon as the car warms up the idle is lumpy as hell, you can smell the stink of unburnt petrol out the back and its a bit of a pig to pull away smoothly, and if you sit in traffic at idle for 5 minutes or so then it will almost stall when you try to move off. I have to rev the bugger up to clear it out. So does this sound to you like a lambda sensor? Can anyone confirm that when the car is on choke from cold start that it ignors the lambda output? Its looking that way to me but I'd like some second opinions before I spend £65 for one (cheapest I found by the way on autovaux). It does all seem to have started since I did the lifters but how can that cause this trouble? I think and hope its just a coinsidance?
Sorry for the long winded post but I thought the more background info the better.