overboost query
21 March 2004, 01:55 AM
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overboost query
ive got a 93 wrx and i think its overboosting.......
is there a safety cut off that will only accept a certain amount of boost and then cut it?
thanks.
is there a safety cut off that will only accept a certain amount of boost and then cut it?
thanks.
21 March 2004, 11:36 AM
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Yeah, it's called fuel cut. If you get it you'll know about it from the steering wheel shaped bruise in your forehead.
I'm not totatly sure what pressure it kicks in, about 1.3bar I think, though it may be less.
I'm not totatly sure what pressure it kicks in, about 1.3bar I think, though it may be less.
22 March 2004, 10:29 AM
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Why do you think it's overboosting? What are your symptoms? Do you have a boost gauge? As Zhastaph says, you'd know about it if it was hitting fuel cut. However, it's possible that the previous owner raised, even removed 
, the fuel cut. Hence my original question...
, the fuel cut. Hence my original question...
22 March 2004, 04:06 PM
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What symptoms are you getting exactly?
To find if the limit's been removed, do one (or all) of the following:-
- Fit the boost gauge. If your boost levels are going to crazy figures, and you're not hitting fuel-cut, then you know it's either been lifted or removed.
- Check around the ECU for some sort of fuel cut defender, which will be a small device attached to one of the wires. It'll stick out like a sore thumb.
- Check the engine bay for a mechanical FCD, which would be somewhere in the hose between the manifold and the MAP sensor (similar to a manual boost controller).
- Speaking of MBC, whilst your head's under the bonnet, check around the turbo to wastegate actuator hose for one of those.
- Lastly, there could be a chip upgrade in the ECU itself. I don't know much about those though...
Couple of questions:-
1. What fuel you running it on?
2. Have you got a knocklink?
To find if the limit's been removed, do one (or all) of the following:-
- Fit the boost gauge. If your boost levels are going to crazy figures, and you're not hitting fuel-cut, then you know it's either been lifted or removed.
- Check around the ECU for some sort of fuel cut defender, which will be a small device attached to one of the wires. It'll stick out like a sore thumb.
- Check the engine bay for a mechanical FCD, which would be somewhere in the hose between the manifold and the MAP sensor (similar to a manual boost controller).
- Speaking of MBC, whilst your head's under the bonnet, check around the turbo to wastegate actuator hose for one of those.
- Lastly, there could be a chip upgrade in the ECU itself. I don't know much about those though...
Couple of questions:-
1. What fuel you running it on?
2. Have you got a knocklink?
23 March 2004, 08:49 PM
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Fuel cut's set just under 1 bar on early imports. (14psi i think) if everything seems to be in place, no electronic tweekery or brass lumps in the boost/vac hoses, locate the 3port boost soleniod on the drivers side strut tower and remove the bottom hose, the other end is conected to the air expansion box on the intake. it should have a brass restrictor inside (just before the first bend, soleniod exit) if it's missing refit straight away.
Roy
At a guess you'll be hitting boost cut when loading in 4th and 5th on cold days.
Roy
At a guess you'll be hitting boost cut when loading in 4th and 5th on cold days.
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