Turbo Problem

[sporty]

I have just bought a mr2 turbo and the turbo seems to be

running a little wrong, 75% of the time it gives full boost,

but then sometimes it dose'nt.

any ideas anyone

[Karma Supra]

anything else???? when is it not giving boost???? and strange noises, smoke???????

I'd hazzard a guess at a knackered actuator

[sporty]

It ok lads, I just give the car a full service and it was a seriousley blocked

air filter, its amazing how a little thing, can have an affect on a car.

thanks anyway

[Dame]

I have the same problem, it's not a filter, and only seems to happen on colder mornings. At first I though it was the ECU reducing boost to compensate for cold air outsode. However, it's not been cold enough recently. I'm thinking knackered actuator. Any idea how much one would cost?

[Bibbs]

I assume by your avatar you have a rev1/2 ..

The car will limit boost to 7psi unless it's happy. Then the VSV (i think) will open and allow an extra 3psi is it's all okay.

It's why when you add a G-valve you block off the VSV so it has no effect on boost.

[Jimlad]

I noticed my boost is sometimes limited ( obviously not happy for some reason ).. then other times it's fine. It's a pain in the ***** ! I'm also looking to get an uprated actuator.

If you override it with a G-Valve.. isn't that bad ? Obviously it doesn't want to hit full boost for a reason.

[Dame]

Hmm, I think it's more a case of the system being too cautious. But Jimlad is right to ask the question: Would fiting a G-Valve have a potentially dangerous effect on an 'unhappy' system? How much are these things? If memory serves around £70 - £120, which would you reccommend? Also could I fit one to a standard setup, or would I need to carry out further supporting modifications? I presume it's down to how much you open the valve i.e. you can determine how much boost the car will run at? Though any higher than standard and the FCD will activate :(.

If this is so, looks like I might be needing that accurate boost gauge sooner rather than later. need some way of accurately monitoring boost levels.........

In the meantime, I think I'll check the diagnosis computer for any faults. I've noticed that resetting the ECU will give me full boost again. I thought it may be the knowck sensor, but usually the boost restores itself to the max level without having to reset anything. If I understand correctly when knock is detected, full boost will not be restored until the ECU has been reset?

P.S Yes the car is a Rev 2. :)

[MattMR2Turbo]

I was going to ask about this.

I've got a rev3 turbo and when I first got it, it had a bleed valve on (opened up) which was reading boost over the max on the boost gauge. Now I've closed the bleed valve until I get a proper EBC and the most it boosts to on the standard gauge is about 3 quarters??? WTF??

[Dame]

Ah in that case, I believe you need to open the bleed valve a little more. However, I'd want to see an accurate gauge reading before doing this. A little turn might not hurt, you can see if it increases boost levels....

[MattMR2Turbo]

Yea I agree that it would be fine to open it a bit so that I get full boost on the dash gauge, but shouldn't it be getting that anyway without the bleed valve?

[Dame]

Thinking about it, Matt you're right, all the bleed valve does is bleed a little air away so the ECU thinks the turbo is making less boost than it really is. Closed should be stock??

[wraith car]

OK lads chill....there is one major likley reason for the iregular change in boost...

ye ecu sences the octin level on a jap car because of theyre 100 ron rated fule we struggle in england..wat u will find is if u put 95 ron fuel in u will only reach 7psi ..but put optimax or bp ultimate in and u will reach 12 psi as mine doe every time.

[Geri]

How does the ECU sense the octane rating of the fuel? I find it difficult to believe that it can do this.

[Dame]

Anyone know if you can delete double posts on this forum??

[Dame]

but put optimax or bp ultimate in and u will reach 12 psi as mine doe every time.

Sorry to dissapoint you mate, but I've been running it on Optimax (or the equivilent) for the past five years!

I've been looking into the temperature restricting boost, and I believe that it is almost certainly this that is causing my problem. It only ever happens on cold mornings, throughout the summer it has been fine, and TBH, I tend to drive carefully in the winter months, so haven't really noticed this before.

I've been searching around on the net, and believe I have found a solution. Once I have the money to buy the parts required I'll work on resolving this issue.

Thanks anyway.... :)

[Jimlad]

someone said you block a pipe going from the alternator ?? Not sure who or where... but sounds easy enough.

[Dame]

When I get around to it, I'll send you a piccy of the engine from the workshop manual. It should show you exactly what it what. TBH, I haven't looked at it yet....