Recently converted my younger brothers mk2 driver to a GTI using a PB engine, loom, ecu and associated parts. All has been fine for 2-3 weeks until 2 days ago with no sign of anything going wrong the car has started to hesitate/hold back at around 3000rpm. It does not appear to be a misfire as it just hits a wall and will eventually pull through, any ideas will be gratefully received.
did you set the timing, and if so did you forget to do up the 13mm dizzy clamp bolt. mate of mine managed that
will double check cam and ignition timing, changed plugs today along with the whole ignition system noticed the plugs i took out had gone white (running too lean?)
Cam and ignition timing are correct, i have the bottom pulley timed to the mark on the belt vover the cam pully is timed to the rockercover/cylinder head from the mark at the back of the pulley i have borrowed a timing light and the timing is at 6 degrees at idle. Could the fault be something to do with the airflow/vane meter?
Those `white` plugs are not good ... need to get the CO / mixture set. Does it only hesitate `on load`?
hi it doesent seem to matter how hard or soft you accelerate at 2500-3000 rpm no matter what gear you are in there is a big flat spot/hesitation ist fine once it clears through and pulls well between 3500-6000rpm One other thing to note it wont do it for the first 5-10 mins of driving. not 100% on the CO only had wide band so got it to lambda 1 which im told should be fine adjustment on the air flow screw seemed to make little to no diffrence though.
Hello there, I have this exact sane problem with mine, after driving around when the engines heated up it seems, the engine hesitates briefly for a second or two under hard throttle around the 3000 mark. I had my MOT last week and it failed on the emissions, the CO being 1.5% above the legal amount If I remember, the guy told me he'd put it through anyway but I need to look in to why it's doing it. As "JamesA" posted, the CO/mixture could need setting up but I have no idea as to how to do this so it's two people in one thread who need help here. Josh.
Sorry to hear about your car too, I feel your pain[:^(] If anything this now appears to be getting worse still rougthly at the same rpm but its really starting to jerk around too and its much harder to try and drive through it. Really need to get this cracked now.
Which is when it is `on choke` and overfuelling via the cold start injector, it then appears to `lean off` hence the hesitation and white plugs. Have you a spare WUR to try ... the fuel control pressure could be affected. Have you taken the rubber boot off the top of the air flow meter and checked that the flap is moving freely ? ... just realised, is this a Digifant system as I`m focusing on KJet ?
lol cheers john just realised how stupid iv been, any ideas why it ran fine for 2-3 weeks before though?
unless the timing adjusted itself I have no idea, but i do know you'll want to get that tuning guide looked at to start with then work from there ideally ask a garage to do the co though, the diy ones are pants. print out my guide and show it to them but maybe cut off the muppet garages comment
Cool john i did work to your guide but seem to have got it wrong it was 2 in the morning when we finished putting it all back together the dizzy was playing up so ended up going to derby at 12am to get one off a friend. anyways will go through your guide again and read it properly this time. Will report back to confirm a fix or not. With the CO will setting it on lambda not be good enougth its a good wide band i borrow/use (Motec plm). Cheers
Cheers John you have made a lot of sense, will get the ignition timing set properly first. Thanks Jay
Ok developments are, set timing properly now 6 degrees @2250rpm with ect sensor unplugged, decided to check fueling again and discoverd it was seriously lean showing around lambda 1.7-1.8 on idle. Adjusted the hell out of the airflow meter and finally managed to get it to lambda 1.0, when the car is then driven instead of getting richer under load it actually gets leaner. I now believe the problem all along to be the fuel pump is failing. im sure this would explain why it was fine for 3 weeks and suddenly went wrong.
are the idle and wot switches working? it should switch to wot map when the switch on top clicks. easy test is hold the throttle just off idle so rpm is around 1500, then press the wot switch on top. the revs should fall then rise again when you release it. that being said digi injection is pretty poor at te best of times, lean running is what they do
Will check those next then john. Think im going change the fuel pump as well got a mk3 here that i can nick it from as the mk2 is already on a mk3 tank (if that reads correctly).
hmm, so how are you supplying the mk2 pump, via a mk3 main pump? mk3 gti/16v/vr6 pump would be a good upgrade either way, you'll just need to bin the mk2 main pump and fit the mk3 filter + carrier in its place
