View Full Version : Overboosting like a loony!
andyedwards
19-02-2003, 10:51
Hi,
My 20VT Ibiza is being peculiar again, having fitted a boost gauge recently I can now see the problem visually. As you put your foot down instead of the boost peaking at about 14 psi it flies all the way round to 20 odd and in cuts overboost protection and limp mode for a while until it sees fit to revert back (anything from 1 min to 20). It doesn't do this all the time on full throttle but lately it's happening almost every drive. When it works okay it is peaking at about 15-16 psi though (I would have thought this still a little high for a chipped car).
Is the above indicative of the cold weather or does my boost control seem all over the shop!?
Cheers,
Andrew
(AmD Chip, Full Miltek Exhaust and Cat)
Is it an early AmD map? about mid 2001?
Mark
andyedwards
19-02-2003, 11:22
A little later, 19th Jan 2002
Originally posted by andyedwards
Hi,
My 20VT Ibiza is being peculiar again, having fitted a boost gauge recently I can now see the problem visually. As you put your foot down instead of the boost peaking at about 14 psi it flies all the way round to 20 odd and in cuts overboost protection and limp mode for a while until it sees fit to revert back (anything from 1 min to 20). It doesn't do this all the time on full throttle but lately it's happening almost every drive. When it works okay it is peaking at about 15-16 psi though (I would have thought this still a little high for a chipped car).
Is the above indicative of the cold weather or does my boost control seem all over the shop!?
Cheers,
Andrew
(AmD Chip, Full Miltek Exhaust and Cat)
Jammed/broken wastegate???
the reason i ask is that AmD 'finished off' their maps after the first ones were done.
Dave's (one of the first to be done) was a keen overbooster.
Might be worth asking geoff to see if he'll do a new map? (mention the words "Free of charge")
Mark
ibizacupra
19-02-2003, 12:20
Or..
N75 valve is playing up.
Bill
Andy,
I am (was) having the same issue with my car. I've installed a dawesdevices boost controller and the boost is constant like hell, car pulls massively! I think the problem is related to the N75 valve and wastegate. The dawesdevices is a very cheap and effective way of curing this (surging), however it has its own (non desired) side effects too. Sadly my car is sitting in my garage wrecked at the moment, so i can't finish my experiments, but i have got a quite good (i think) solution for running dawesdevices without any problems. Will make a complete write-up and article as i soon as my car's back on the road again (~1 month).
andyedwards
20-02-2003, 09:57
When you say none desired side effect do you mean the fact your car is wrecked!? Pretty hefty side effect! I was thinking of something like that, a mechanical boost limiter so to speak. After playing last night it seems it only overboosts badly when the engine and intercooler etc are relatively cold.
Well, if i would have the N75 controlling the boost, i'm not crashing my car, that's for sure! I may blame the MBC yes, but not because it was bad,.... no, the car boosts like hell now and that was the problem. Imagine stepping on it in second @ 38Mph and wheels spin until 50Mph.. and that was the problem...
The non desired side effect is a different story.Basically when you use partial throttle, the ECU requests just a few amount of boost, lets say (0.4bar), but the dawesdevices still provides 1.0 bar. The ECU will recognise this as a fault and closes throttle body/vents boost through the DV. This means that dawesdevices works good only at full throttle. I have a simple solution for this, but i'm not about to reveal it yet ;).
my'n is peaking 21 psi, and i dosent have overboosting....
cheak your n75 valve like bill said.
Christoph
24-02-2003, 09:22
ECSTuning is supposed to be working on a limp mode eliminator circuit due to overboosting for 1,8T engines, release date early to mid spring. I have the same problem using their ECS N75 valve together with the Green Twister XL as opposed to the smaller standard twister...limp mode everytime I hit the pedal a little stronger.
regards
Chris
andyedwards
24-02-2003, 09:54
Mine seems fine lately, hasn't maxed out past 16-17psi at all! Seems to peak and then come back down to 14-15psi. Seems that it was either something to do with the provoking boost on a warmed up, but relatively cool engine (ie cold days, hard acceleration after some very mild tootling around) or a mysterious mechanical fault that seems to come and go.
Bit odd, but as long as my engine doesn't pop I'll live with it for now.