RT

John, so the fueling is based on the MAF readings then? Not the solenoid duty cycle? Now that I think properly about it, should be. If not all Electronic Boost Controllers won't work...

[Edited by RT - 6/1/2002 5:45:21 PM]

Matt_Davies

A mates got an MY98 that we think is overboosting. Sometimes (but not always) on full throttle the car will "stutter" quite violently. You'll be goin flat out and then it will hesitate, go, hesitate, go again, all very quickly. Resulting in the driver of the car your overtaking laughing quite histerically and whiplash for driver and passengers. Suffice to say overtakings know out of the question just in case the car decides it aint playin'

A well known local(ish) company has the car this week but there not sure if its overboost or not as on the occasions they've taken it out it's been fine. They reckon its running a constant 14psi.

Does this sound like overboost? How do you cure it?

Cheers Matt

Edited to say: Apologies as im sure this has probably been done to death bit the search facility is'nt working.

[Edited by Matt_Davies - 5/29/2002 1:17:12 PM]

NotoriousREV

It sound like what my car does, but I'm still not sure if it's overboost!

Mine's worse if I hold it at high revs on a light throttle (i.e. waiting to overtake) then floor it, it prefers to be held at lower revs then brought into boost as the revs rise, which makes sense to me that it may be overboost, maybe?

Stuart Taylor

Try cleaning out the boost control solenoid and relevant pipework with brake cleaner. This may solve the problem. Also check all the pipes to make sure they are not split. If this doesnt work you could increase the size of the hole in the restrictor.

Stuart

DAVE O.

Mines doing this also.

Not had the car long, where is the boost control solenoid situated??

Thanks

Dave O.

Matt_Davies

About half hour before the first time it did it we were waiting in second gear to overtake something... floored it and nothing. It was as if it had lost the boost pressure altogether. Changed to third and it flew!

Dont know about revs. Might try and provoke it holding it at high revs and then hoofin it. Havent really been overtakng a great deal in case it doesnt go (so no holding at high revs). Just been overtaking when theres a big stretch of road and hence not flat out anyway. The car must look funny to anyone you pass when it starts playin up. Certainly feel daft.

Stuart, Solenoid has been cleaned and checked by ABP motorsport and it still does it so assume it aint that.

Is it a case of a boost controller or something like that?

Someone must have had an overboost problem surely. Thought 98's were notorious!

Matt

TonyBurns

iTrader: (3)

You could try cleaning the pipe to the wastegate, that caused me some probs.
Also what sort of mods have been done to the car??
more info needed please

Tony

nom

this could well be the 'low noise test' thing rather than anything more sinister (revs held at somewhere between 2 & 3k & then WOT responds with no boost to keep noise levels low).

TonyBurns

iTrader: (3)

You should only suffer from overboost in 3rd 4th and 5th gears as you dont get full power in 1st or 2nd, will agree with last post and it could be the built in emissions test thing, blip the throttle before you overtake, kicks it out

Tony

Matt_Davies

Cheers Fellas.

Cant say i've ever noticed what gear it does it in. I'll ask my mate. It has only lost the boost once though. And since doing that it has started this jumpin on full throttle.

Tony, Mods are only a full Blitz Nur Spec R exhaust with back cat out. Apart from a sound system a set of wheels and a big disc conversion of course Have noticed that the exhaust is doin alot more "popping" than usual on over run. Some quite loud old people scarin ones actually

I think (but will also check) that the pipe to the solenoid has also been cleaned. ABP motorsport again. They have had the car all week and aint phoned back yet!

The problem is it only does it when ot feels like so when they take it on a test drive it behaves. Would puttin it on a rollin road be of any use. I suppose it would have to do it then tho?!?

Cheers so far, Matt

RICH WILD

Sounds like overboost possibly, but could be other things too.

I had a similar problem on my car once, turned out to be a cracked coil lead. Check the leads for damage and also check the plugs, how long ago were they swapped. Could be just a plain and simple misfire.

You could look at fitting a boost gauge (if it hasn't already got one) to see if the boost flies up irregularly when the symptom occurs. I'd say a boost gauge is essential really on a modded car.

As said above though, check all your hoses too for filth and pressure leaks. If a hose isn't on tight, it may leak at high boost pressures intermittently.

Cheers
Rich

Matt_Davies

Plugs and leads were the first thing we checked and i'd assume that during the course of this week (the time ABP have had the car) they'd have checked them also. Aparrantly when one of the lads took it out he said it was the nicest uk car he had ever driven

A boost guage does sound like a good idea tho! Matey will get in touch with them tonight and see what they have to say about the car and then perhaps ask them to sort one for tomorrow when he collects it.

This car is supposed to be goin on your rollin road day rich. Hope its sorted by then.

Matt

NotoriousREV

Mine is also de-catted (full Scoobysport jobbie, according to the previous owner), I need a cheap boost gauge!!!

Would a Dawes Device help do you think?

RT

"this could well be the 'low noise test' thing rather than anything more sinister (revs held at somewhere between 2 & 3k & then WOT responds with no boost to keep noise levels low). "


What you're getting is the "feature" to pass the noise test.
Gosh, we must bring this up at least once a week!

Basically, 50kmh, gear 2, hold for 5sec. WOT immediately, you get 0.5bar boost. Happens every time.

Matt_Davies

At least once a week hey.... And i still was'nt aware of it!! I dont usually visit this part of the board.

At least i know what it is now when it does it future. Cheers nom

RT, i thought that might have been relevant to the problem. Have you any suggestions as to what its doing and how to cure it ???

Matt

NotoriousREV

Hey, it's not our fault the searched is fcuked

RT

Quote:
"Mine is also de-catted (full Scoobysport jobbie, according to the previous owner), I need a cheap boost gauge!!!
Would a Dawes Device help do you think? "

I never tried personally, but I would think as a Dawes takes the control of boost away from the solenoid, it might be a work-around this noise test thing. However, I hope that the car is "smart" enough to know that altho it is pulsing the solenoid for 0.5bar boost, fuel/timing will still be for 1bar (or whatever you set the Dawes to). If not you'll be running seriously lean!


Matt, I didn't "cure" mine. What I did was just to open the throttle "briskly" instead of "immediately". After a few tries, you should be able to gauge just how fast "briskly" is. You are not any slower, and you'll get your 1bar boost.

Alternatively, you could spring for an Autronic or MOTEC.

john banks

The Dawes does fix it and it fuels fine.

NotoriousREV

Excellent, my boost gauge will be here next week, might as well order a Dawes to go with it

john banks

Fuelling is MAF based and on MY99/00 OK up to fuel cut. Since a MY98 has (I believe) smaller injectors you have to watch you don't max them out - Select monitor.

boyband_pete

Your not the Matt Davis, are you?
I which case hello we used to kart together in Super one.

Katana

No it doesn't. Trust john banks on this one. If not, my car is going to be in bad trouble (guess where from?). JB is an electrical engineer thus knows what he's talking about.

The boost solenoid only controls the wastegate when a certain boost is achieved. Here's another one, MAP sensors also don't have any affect on fuelling.

john banks

I'm not an engineer, I'm a GP and a part time tuner. But that doesn't stop me argueing with engineers

Katana

Eh? I thought you were an electronics engineer. You know more about electronics than me and I take engineering. Shows how I failed those two electronics paper eh?

john banks

I probably should've been an engineer instead. A non-overall wearing one At least I don't wear a white coat any more

Katana

But chicks digs doctors. I wanted to be a gynacologist ones, but after thinking it through I decided not to. You see, its like being a **** star, you go through the non fit ones first before you get hold of the fit ones.

I better stop there or I'll end up muppetising this thread. I'll look at that "****" thread instead. :P

Matt_Davies

Sorry been away!

RT, The problem we are having is NOTHING to do with the low noise test thing. That came into it because it did it once before the real problem started so i mentioned it incase it was relevant. The problem is the car hesitating and going again on full throttle in quick succession much in the way a learner driver will jolt back and forth as they try to master the clutch. Only difference is your flat out doin 50-60mph. I am trying to find out what it is and how to make it stop!

Regards, Matt

Boyband pete; I am THE Matt Davies Just not the one you used to go kartin with

RT

I see. Then the problem you're having is different from the noise test thing. The latter feels flat, but definitely not learner driver jerky.

Matt_Davies

It all happens really quickly with sharp breaks in the power, so it throws you forward as the power stops and then goes again chuckin you back in yor seat. This happens until you change up a gear and stop accelerating.

It has'nt done it all weekend. Doubt its cured itself tho.

Matt.

Mike Nolan

Matt,

I am getting the same problem with my MY98 WRX Wagon (Import). Under acceleration it seems like the power cuts for a split second - really quite dangerous. Happens in 3/4/5 gear, but intermittantly.

Mine only started doing this after a recent service - I had a new lambda sensor put in to replace a faulty unit that was causing a hesitation, and the problem started a week or so after that.

I run my car usually on Optimax, but switching to 97/98 RON seems to improve the problem, but it is difficult to be conculsive as it tends to be intermittant.

I am going to book the car into Power Engineering when I get back from Le Mans, and if I find anything out I'll let you know.

I must have done something bad in a previous life as this problem is a serious pain in the harris.

Mike