I was out playing with the car (MY96 UK) at the weekend and discovered what may or may not be a problem...

I was in 3rd, with the revs at about 5k when I thought it would be a good idea to change up to 4th. Naturally enough, I lifted off the throttle - I thought slowly and smoothly - however, the result was like hitting a brick wall! I didn't see any spiky boost, but I did see the boost gauge almost hit the pin round on the vac side - normally it will stop about 20-25 inHg.

Up to just over 4.5k this behaviour doesn't happen.

I read in the SIDC FAQ about the "ECU bug" Is this it, and is there anything I can do about it? Or is it a dump valve issue? (OEM naff plastic one...)

Any help gratefully receieved, as I don't really have time to be dismantling the car to fault find this week!

 

David,

sounds very much like fuel cut by the way you say you hit the windscreen! could be something weird, like the pressure sensor playing funnies!? I know you cleaned out the pipes the other day, maybe you are spiking on change?
have you had a chance to log the boost from the ECU during this blipp ?? just the parameter to see what it's actually doing?

my vacume goes to over -800mmhg at times, which I think is too much (no idea what it should be!) but that's on overrun, so it's sucking hard than tickover (-600mmhg)

dump valve is more likely gona give low boost, leaking boost, than a sudden fuel cut type event.

ecu bug, isnt a BUG as such, its a bodge, to get round the emmisions law. if you hold the car, in second at about 3k for about 3-5 seconds (or longer) then boot it, you will only get 0.5bar boost. lift of and slam it down quickly and it will go back up to normal (or change gear & you feel like you've taken off!)

hope you can sort it out! I'd log it !

Steve

 

Thanks

Not had a chance to log the boost yet. I tried it again while watching the boost gauge, but didn't see anything... A log would help to diagnose the pressure sensor, as a funny from it won't show up on a boost gauge... When I get some more data I'll post it up.

My computer got sick, and I lost some of the select monitor stuff I was working on - the install file for the com port I was using, now, I can't remember the name of it It could have been a lot worse...

Maybe I can get Nic. to do the recoding (and improvement) for me...

I'd like to have a drivable car for my advanced driving test!!

Time for some testing on Millitary Road then

BTW - how are the brakes now you've had a chance to get them run in?