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Discussion Starter · #1 ·
On normal driving, when I floor it, at low revs say 2000-3000 rpm, the gauge goes about a quarter of the way through to the red section, and you feel the kick in the back and even in the dry TCS comes in in 2nd.
But when I try and hold the gears longer to say 5000 r.p.m and change through the gears the boost gauge will only go to 2/3 through the orange section and the car lacks that kick in the back feel.

is this due to the turbo allowing more boost at lower revs as peak torque comes in at 2000 r.p.m ?

so does this lead back to the same old question, will a MBC on my 2.3 DI/APC turbo mean that when I hold the revs longer, the boost level will go always into the red section ?
 

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I think that they all do the same sort of thing, the initial boost is higher, and as you stretch the gear out the boost backs off a bit. My B234R Boosts probabily 3/4 in the red initially and then settles just in the over the edge of the red.

It may be worth you doing an adaption run as discribed HERE . Mine was only boosting to the broken red section until I did this 3 or 4 times.
 

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The procedure is basically the same except ISTR you need to make absolutely sure it's carried out at WOT, however I can't remember which fuse you need to pull- Jason can you help out here?

If you can't find the fuse, disconnecting the battery is an option- as long as you have the code for your radio!
 

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So on my 92 2.3 Carlsson, I would need to disconnect the mbc valve and put the control valve back to normal. Have a tank of Optimax or similar, pull the fuse as mentioned then follow Bills adaption run procedure. Once it has been sorted will it have been a waste of time if put my mbc valve back on?
I have to admit I didn't think adaption runs could be done on pre-trionic cars but I'll give it a go.
Do you have to redue it after each modification that is done on the car? i.e. I've just fitted Aquamist yesterday but haven't sorted out a water supply yet, so would a re-run be required with the water injection operational?
 

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Well the MBC overrides the APC anyway, so adaption would be pointless if your going to run with an MBC fitted. But try the adaption, you may find that you can get enough boost to feel that you can do away with the MBC. Although I admit, adaption mainly seems to affect how the car boosts between 2-4Krpm, above that it does seem that the APC control limits boost to protect the turbo (as the 1992 APC was designed for T25's) and engine.

So if you want boost to hold high levels right up to say 5500rpm, you'll need to carry on using your MBC.
 

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I think the problem is that fuse #5 in the glovebox, labelled APC, only interrupts the power to the APC solenoid rather than the ECU.

A quick look around a few diagrams and observation under my bonnet (although it's Trionic not DI/APC) suggests that the fuse to pull is #9 in the engine bay fusebox, labelled "Ignition system"

Wahey , I've been trying to suss that for ages
 

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Mark in Ireland,

Possibly... it depends if you were having any knock previously, which the system would have adjusted for.

At any rate, it can't do any harm to try.

My pre-Trionic DI/APC tweaked CS certainly needed re-adapting every now and then, and benefitted from it.
 

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Discussion Starter · #16 ·
Thanks for the info, I think I will pull the battery, incase I pull the wrong fuse and do something stupid !

Now I just have to try and find an empty long hill to do it.

I will let you know the results.
 

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Evening all, I tried this on way back from uni tonite. I disconnected the battery and filled up with 98ron gas. I found a nice empty incline and floored it. Now it seems to be a bit more responsive but the gauge still doesent go into the red. I'm thinking that I might have an air leak in the dump valve pipework? as I already have a problem with a high idle speed. (just over 1000 rpm, even after cleaning the idle control valve) I think I will clean the engine and take thorough look under the bonnet.
Billy.
 

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I left it disconnected while I was in the supermarket doing some shopping, so that must have been about 20 mins? I've no idea how long the ECU will remember its previous settings for but it seemed to do the trick.
 
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