moz10

Hi,

Ive just brought my93 wrx and have been loving every inch ive driven, however, when putting my foot down in 3rd, 4th,5th i get a really bad jurk as i hit top of the boost. i am running on optimax with booster (didnt know till reading here on the night i brought it) ive also cleaned the turbo hoses and the thingy that they go in, but, still the same problem. i have noticed that the hks boost gauge goes to about 1.2-1.3 bar in 1st and 2nd but in the gears were i get the problem it only gets to 1.0-1.1 bar and thats when i get the jurk. i think from what i have read that i am over boosting, but how do i get rid of it?
p.s i have no knock link or anything like that.

Neilo

get a dawes and screw it all the way out (so it runs reaaaaally low boost)......see what boost that runs at and the slowly tighten it up until you reach your desired boost.

£40 should see you with a brand new one. problem solved.

Neil.

moz10

cheers neil.

is this a common prob?

also i noticed that the turbo hoses were differnt makes and thickness should i replace them?

Were can i get a "dawes"?

Neilo

to be honest i wouldnt really know if its a common problem, i dont know too much about engines or imports, but i do have a dawes! althogh i use mine to raise boost....not reduce it, but the principle is the same.

The dawes can be obtained from www.j-w-racing.com, it might be worth replacing the pipes, it sounds a little worrying if they are different thicknesses!!

Neil.

moz10

were is the best place to get hoses from adn what sort of price am i looking at?

Dark Blue Mark

I would find out why its overboosting. Has someone played with the restrictor and has it got a standard ECU?

KL is essential too.

MB

moz10

i know nothing about the car. no history or nothing. ecu says its a aa810 if that means anything? how much are knock links and are they easy to fit?

dc911

Could this be down to a knackered maf?

moz10

dont think its MAF coz it ticks over ok.

dc911

It would still tick over ok even if the maf is shot, but your problem seems to be when it is hitting full boost/ torque levels which could point to the maf

dc911

Also still think it could have something to do with your rev counter not working properly as i think that the ecu needs a signal from the rev counter?

Dark Blue Mark

An ECU reset would reveal a knackered MAF, and then it WOULD cause an erratic tickover.
However, on this MY of car, the MAF is pretty reliable and is also unlikely to cause any boost spikes. Lambda is not a culprit either.

If your speedo is a bit out, get the convertor checked. Do a search but it lives down behind the intercooler normally, and may just have come a bit loose.

My bet is there is a variable manual boost controller on there or a changed orifice Doesn't sound like a remapped ECU as the boost cut feature would have been overriden.

MB

NotoriousREV

Has it been de-catted (i.e. loud exhaust) and fitted with an induction kit? Standard boost on a MY93 is 0.85bar, boost cut should be at 1bar, so your boost has been turned up.

My MY93 runs 1.1bar with a remapped ECU and occasionally get det running on just Optimax, so I'd worry about running higher boost than that if you're on the original intercooler, fuel pump and ECU map.

If it's been remapped in Japan on their fuel, I'd be even more worried.

moz10

it has got no cat just big exhaust straight through to a dustbin size back box. it has a hks induction kit on it. it still reads in kilometers. were can i buy a convertor?

richir rich

if your gettin a realy bad jerk leave it alone n play with the car?

Dark Blue Mark

Good Q Rev, think you found the problem

Moz - With those mods you will be skating on thin ice without a remap. Induction kits on scoobs are considdered not needed by most of the experts on here, they can cause the MAF to underread thus causing problems. The HKS has pretty poor filtration too and focuses more on getting more air in. The decat will be affecting the boost, as it naturally increases it a touch. Add all that together with some UK fuel and an ECU mapped to jap 100 RON and you have a bit of a problem...

MB

Leslie

I got overboosting on my MY94 STi after fitting a large bore Power Engineering turbo back exhaust and back box with one free flow cat. The effect was the same as yours when it hit the fuel cut. I also fitted a Dawes and adjusted it carefully to limit the boost to 1.1 bar. That did the trick, the Dawes is very accurate on boost control. I found on my Knocklink that I could run happily on Optimax without booster with no detonation. Shows what a difference a decent exhaust makes. I also fitted an H & S up pipe and I ported the engine manifolds.

Les

moz10

thanks guys for all your help. i am taking the car to scoobyclinic on Monday for a big service. Have been speaking to Adam at scoobyclinic and he has said that they will give it all the once over and offer me the best advice.

Cheers Paul

Scott.T

iTrader: (2)

Probably the restrictor in the boost control return hose. Alot of cars seem to have this removed, as it can give minimal increase in boost. However fitting the decat poushes over the limit.

Check the bottom hose from the boost control solenoid that returns to the big black air intake expansion box. There should be a small brass restrictor wedged into the hose with a hole in it (about 1.2mm I think).

If it's not there make one... start with a 1mm hole then increase it until the desired level of boost is reached.

Fuel cut on that car will be approx 14psi.

If it's standard other then the exhaust it should be running 11.47psi, so no where near fuel-cut.