View Full Version : Low boost...SOMETIMES?!
Hi all, randomly after a bit of driving and only about 1/10 times, my car will only boost to 0.5bar, and not go above it (Normally 1.0-1.2).
If i switch the ignition off and re-start her, it's instantly "cured"?!
Engine check light doesn't come on and everything else seems fine.
Any ideas?! Much appreciated.
Jon
Had a similar problem with my car. Mine was running about 19 psi. When ever it hit that it would then only allow for boost up to about 8 psi. Turning the boost down a touch sorted it out. Not sure why it would only do it occasionaly though.
Sticky boost control solenoid.
Give it a clean out with some carb/brake cleaner.
Edited to say : I've just read your post on Scoobynet and that you have a chipped ECU.
Whats written on the Chip ?
Is it a single chip or an adaptor board ?
You may be running too much boost and it's going into limp home mode due to it thinking it's got a Map Sensor fault.
Read out the Fault codes, to see if it has any.
Code 45 is the MAP Sensor.
If your running any more then 16psi in an early car that may be the problem. The Pre Sept 1994 ECU's don't like being mapped above 16.11psi on the standard map sensor.
Cheers fellas, no faults showing so will try clening the boost solonoid.
The ecu is a SCOOBYECU allowing it to be switched between that and standard. It's only had this problem the last few weeks but had the ecu for months.
Cheers,
Jon
Do you know where you can get a better MAP sensor from then as that may have been the problem with mine?
You can fit a later MAP sensor from a 97> but the ECU needs to be rescaled to use it.
If your using a mechanical boost controller it should be OK though.
How do you mean rescaled?
Ahh i see. Never heard it called that before. How can i get the ECU in my car remapped as it is an early model. Heard that you cant remap the very early models?:Susp: Or were they talking bollocks?
I said re-scaled as that's what you do.
To achieve 1.1bar on the 2 bar map sensor, the boost target and duty cycles are set to the required values.
To achieve 1.1bar using a 3 bar map sensor, the boost and target values stay the same, but you have to adjust the Map sensor scaling, so that the different voltage output from it corellates in order to achieve the same boost.
Once this is confirmed you can then start increasing the boost target and duty to go above 1.1bar .
With regard to not be able to remap early car....yes it's Bollocks ;)...
UPDATE...
When the ECU is switched to normal...the car runs fine, no probs at all.
When the ECU is switched to SCOOBYECU the car will run fine until you floor it, then as soon as it hits max boost it drops to 0.5bar and won't go above it.
I'm guessing this is "Safe mode" or "Limp Mode" although no check light is on???
Gonna have a play with it this morning and see if i can find anything. I'm guessing scott's wins tho! Lol.
Jon
Strange that it's only just started doing it.
You may have a slight boost leak that is causing it to overshoot the target slightly.
Have you changed anything that may of introduced quicker spool or slightly more boost i.e decat downpipe or change of filter.
I used to get this problem on some 93/94 WRX's if they were mapped to 16.5psi. Dropping them down to 15.5psi sorted it.
ok cheers mate i'll have a bitchers at the pipes
jon
Powered by vBulletin™ Version 4.0.4 Copyright © 2012 vBulletin Solutions, Inc. All rights reserved.