20Vt running troubles
 

Well I have been trying to get my car up and running with help from the S2 forum and thought I would add my problems here too for 2nd opinions/ brainstorming.
The old beast has been off the road on SORN for almost 6 months as is the norm and taken the opportunity to get the charge cooler fitted, turbo overhauled and installed 2 stage chip for trial etc. Came to start up and ticked over perfectly, tried to open throttle and lots of complaints and almost stalling. Not really an issue once warmed up though. Went through wiring and found a broken wire to the N75 boost valve and thought that was issue, but then took the car down the road and only boosting to 1.1bar (should be 1.4) and went into limp mode almost immediately, back home and traced plumbing and found a tiny leak on vac line at back of inlet, back down road and amazed to find boost just passing 1.2bar but ECU still going into limp mode though not as quickly. Cannot see any leak and think I need a diagnostic. Paul (S2Central fame) is returning my standard ECU just to confirm it is not his old trial ECU but after that am going to be stumped. Like to get fixed before I have to find funds to pay experts like Tim Cooper to get it right. As most people at the moment, I am on a tight budget...
When it is on boost it certainly flies now with this new chip set and even at 1.25bar it covered the 40-60 in 3rd in 2.5secs so no slouch. But no good if it keeps going into limp mode...Doh?! So near yet so far!
MAF is my next item, but will have to wait until I get paid in 2 weeks, not leaving much time before it is due for its MOT and re-tax for 6 months. Poo!:razz:

if it's going into limp mode, there will be a fault code. The code will tell you what's up

how old is the fuel? 6 months wont do you any favours either:idea:

humm... wish i knew something about turbo cars.. so i could have something to add. but i have nothing. :(

Yes, considered that which is why I am taking it up and down the road late at night to get it as low as I dare before putting fresh in. Would not cause the 0.2 bar drop in boost however or limp mode to cut in.
Strange progress last night as I wound the wastegate spring in a full turn and on its trip out it did not go into limp mode, might be coincidence, but might be worth exploring further if same happens tonight... noticed boost very slightly higher too but that might be down to lower air inlet temps last night... :hmmm:

You could do with popping VAG COM on it. Has it still got the diag plugs connected?
Use measured value blocks (if ECU late engough to support them) to measure specified and actual boost levels. this would show any leak or at least that it is asking for full boost but cannot supply it. Also, check the N75 is working properly, I know you said a wire was broken but they can stick open if left for a long time, the ReCirc valve and it's control valve can do the same. These engines use the ReCirc valve as much as the N75 to regualte boost (it hasnt been replaced with an atmospheric dump valve has it??? - they're bad!) Also, ensure the diaphram for the wastegate isnt in bits.
I know it sounds obvious but if it violently cuts into limp mode under heavy load then double check for boost leaks.
Either an air leak or failed air mass meter could give the same fault as the ECU cannot correctly adjust fuelling if it "thinks" the wrong volume of air is getting in, same applies if the air mass has acounted for air being drawn in but it escapes before getting into the engine.

Paul now sent my original ECU back and as suspected it still cuts to limp mode. N75 new and fuel almost down to zero now so will be putting in some fresh super unleaded in before car goes up to Tim Coopers. Hope he can sort on the day. 1st May and the start of my 6 month fun period not far away...:crazy: