OVERBOOST why is my 94 impreza wrx boosting to fuel cut at 14.7 psi
 

Bought a 1994 impreza wrx with an overboost issue thinking i could fix it easily, i tryed connecting the pipe straight from the turbo to the actuator and its supposed to run at half a bar but instead goes to 12 psi in 1st,2nd and 3rd but in fourth at fifth its goes to 15 psi and hits fuel cut! Getting very confused now and running out of ideas

what mods has the car got? has it been mapped?

I would test the actuator now, a split in the inner diaphragm would cause this.

Ps are you using a decent boost gauge?

It has a td05 turbo and i believe its supposed to have a td04 and as far as i no apart from that the car is standard i havent owned the car long and bought it has a standard car, how do i find out if its been mapped?

wrx will be a td05 16g. Best bet may be to get it to a tuner to look at and diagnose, could chase it all round the engine bay and not solve it

Not sure what boost gauge it is mate i assume its pretty accurate because when its gets to 15 psi it hits fuel cut and thats supposed come in at 14.7? I tryed testing the actuator by pulling the pipe off and using a pump it seemed to start open nearly straight away is that the way to test?

I no i was thinking the same im a mechanic myself but never had any dealings with subaru turbos before, just thought i would put it up incase it was a common problem. And i was told the wagons have a td04 and the saloons had a td05 is that bull****? I have a wagon btw

pretty sure 15/14.7psi is not normal for this car so something has changed, get it looked at ;)

varies from year to year but on a 1994 saloon td05 1994 wagon td04

I no i thought it should be running at 8 psi? Im going to have to otherwise i will be wasting a lot of time and money, cam you recommend anywere in the west midlands? Thanksfor your help

TDR at Warwick or API at Harbury.

http://tdracing.co.uk/

http://www.apiimpreza.com/frames/company/contact.php

Not a difficult problem to fix, as suggested could be a split in actuator diaphragm. Pump it up and see if it creeps closed. Another thought maybe too much pre load on the actuator?
Also make sure the wastegate arm moves freely.
Also make sure the actuator is standard and not a stiffer one.

Could be someone has wound the actuator up far too tight.
I had a Pre MY96 arrive to be mapped many years ago and I could not get boost under control. Turned out the actuator was set so tight it was running over 1bar under mechanical control.

The actuator should be set so that it just needs a slight tug to drop onto the wastegate pin.
Without tugging it should 1/2 align over the pin.

Does the car have an induction kit fitted? Just wondering if it could have had the pipe with the boost pill in removed..

With the pipe fitted between the turbo nipple and the actuator nipple you shouldn't be seeing more than about 7psi with a standard actuator.
If you are the that would suggest an issue with the actuator.

Managed to sort the problem it a non adjustable td04 actuator iv been told so i got one off a td05 and iv got no more overboost but it now only boosts to 9 psi and i have been told off a lot of different people it should be boosting to 12.7 psi i have tryed adjusting the actuator rod but still no difference any ideas???

Ant the wastegate seems to sound like it is rattling now aswell

Smashing. How much preload have you got on the actuator rod? Should be about half a hole.
Then you will need to bleed off to raise boost, either though factory boost solenoid or a MBC

Checked it and it was way off so I adjusted it so it was half a hole it now boosts to 12 then instantly back down to 9?

Ecu controlled through ecu boost controller? How is it piped?

Not far out then. Could do with a turn or 2 more tightening.
Last 1994 target is 12.7psi, early is 11.47psi.

Got yet another problem with this f***ing car, when i get to 5000rpm there seems to me something holding it back a little bit in every gear its not a misfire for such it seems like its choking a little bit and then the red check engine light came on for about 20 seconds and then went off again and hasnt come on since tryed checking the codes but because my battery has been dead all night i think it may has reset the ecu

Sounds like the cars needing a bit of money spent on it.
New battery for starters

Have a good look at the coil packs -they tend to crack inside where they fit onto the spark plug.


Mick

Checked out the coil packs all look good put a new batterry on it, the check engine light came back on i plugged the 2 black connectors together and it had 3 slow flashes and 2 fast flashes which i believe is 02 sensor is that right? And i no it probably isnt but could that be anything to do with the low boost? Thanks for all of your help. Ben

The actuator i had on my car i borrowed off some i know to test it i had to give it back so bought the right one now i get boost spike to 14 psi in every and then just in fifth it creeps up with the revs till it hits fuel cut any ideas?