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Discussion Starter · #1 · (Edited)
Hi all,

I've been having a problem for about two months now and I'd like to ask You for some help.

My car: 9-3 2000my, b204E stage 2, apc 7 converted car

Each time I hit the pedal to the floor, around 3,5-4k rpm I'm getting overboost and fuel cut off. What I checked:

- It's not possible that apc is faulty, I replaced it to another t7 - the same thing

- I tried cleaning map sensor but it looked ok. Changing to another one, didn't help either.

- when connecting turbo directly to the wastegate I'm getting 0,5 bar of base boost, same thing after unplugging APC

- stage 2 program is set to hit max pressure at 1,35bar (I saw this in t5suite setup) but my readings showed that each time I'm getting cut off, boost is exceeding 1,55bar

- what's interesting - I had a another piece of Ecu from my cousin, bought in England (Maptun stage 1). When I swapped mine to it, the peak pressure was also ~0,2bar higher
than it's supposed to be (it was set to 1,15, and readings showed 1,35)

- in the end, someone suggested that I should unwind the actuator to go back to the stock base boost value. I did that, base boost is now 0,38bar, but max pressure hits 1,45
which is still way too high. There're also massive injection times - at peak boost ~31ms.. (According to simple tune-up stage 2, t5suite set it to 23-25ms at max).

Is it possible that wastegate spring is able to hold the flap and sustain 0,4bar base boost, but it's somehow weak or worn out and it's not releasing enough air to keep 1,35 at max load?

Maybe anyone has and idea, what might be causing this issue?
Please keep in mind that it's b204 so there's no MAF onboard.

thanks
charles
 

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Overboost?

OK, I'm already confused. You are saying that you have a 2000 Model year and no MAF? I suppose I should ask, does the Euro Market 2000 MY car still use T-5. All USA Market 2000 MY vehicles use the T-7 Engine Management with a MAF sensor. Your car has a T-5 ECM and Red DIC, correct?

If this is a T5 Suite car, then I would say that the APC controller is not being triggered by the ECM. The T5 ECM can be modified to work with the T7 APC valve, but the ECM must be modified properly and the connector on the harness changed to accommodate the T7 APC.

Base boost setting is not critical except when the setting is WAY off.

You are certain that the ECM has been properly modified to operate the T7 APC? If so, you are certain that the ECM is still functioning correctly? My T-5 car runs base boost of .5 bar and Max boost of 1.2 bar or 65 inches Absolute Manifold pressure. The base boost being set higher usually only gets the turbo spooled up early and the Boost control valve takes care of the maximum boost pressure. The advantage of the T7 APC is that it is much more accurate and holds the boost to a more constant pressure, closer to the maximum. The T5 Boost control causes a considerable drop back away from max boost when it comes into play. On my T-5 car, I need to be careful to stay away from the point where the Boost control kicks in so that I keep the boost high and engine pulling hard.
 

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Discussion Starter · #3 · (Edited)
Mlynch, thanks for reply.

Yes, for sure it's t5 car. It was made for european market, models from y2000 were still t5 here.

I'd have to check if Ecu was properly modified, but that's what the guy, who made the stage 2, said. He soldered two pins, changed the frequency and cables from the new plug connected to the old, t5 plug. What kind of change on the connector harness You're talking about ?
It's not his first Saab, but who knows. I may try to ask someone to download the soft for me and we'll know everything then.
Keep in mind that the mod was made in both Ecus I've got, and using both, the car still runs on higher pressure than it should. (Bad mod in both Ecus...?)

Ahh, what I forgot to mention - while using the t5 APC before, I was getting same results and I replaced it because I thought it was broken...

Out of curiosity - you're saying that Your base boost is around 0,5bar (so it's higher than stock). What about the soft in Ecu, it's set to 1,2bar and that's what You're getting exactly while readings at max load, anything more than that ?
 

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Overboost?

I cannot tell you the exact tune, the numbers that I am quoting are based on data pulled from the ECM on my data logger. These are observed numbers, not theoretical numbers. These numbers were just recently recorded on a very cool day, about 45 degrees Farenheit air temp. On 91 octane fuel I am seeing 64 inched plus or minus a few tenths of boost. On 93 octane fuel I see just under 67 inches of boost. My understanding of the tune that is on my ecm is that max boost is supposed to be 1.35 bar. The tune is supposed to be the Maximum tune that a "stock" engine and automatic transmission can tolerate without seriously compromising reliability. I was not so concerned about the exact nature of the tune, but the gentleman who did it called it "stage 1" and provided me with the torque and horsepower curves. These "Stage" numbers are all so subjective, so my concern was the real world performance. The performance of the car speaks for itself and is very satisfactory. My efforts have been focused on getting into the boost quickly and sustaining boost near the maximum, without hitting fuel cut. I am using a stock T5 BPC with a bleeder jet in the waste gate supply line. This seems to have allowed me to eliminate the sag in boost as the waste gate control valve comes into play. Previously, when the ECM commanded the waste gate open, the boost would momentarily reach about 65 inches, the waste gate would open and then fall back to between 50-60 inches before stabilizing. The current arrangement seems to eliminate this problem. Not sure if this helps you at all. I would be very interested to see where this all leads.
 

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I would have done the adaptation after the APC valve change. Someone else may have a different view. But that is the point that you started having problems. These systems are somewhat particular in the order that operations are performed. I have two DI Cassettes, one with an 08 date code and one with an 03 Date code. They both seem to run the same. Are you getting any Misfire Codes (P0300 - P0304)? If you are using a "Non-SAAB" DIC, I would be highly suspect. I had nothing but problems with an "Aftermarket" DIC. Bought a Genuine SAAB DIC, troubles ended.
 

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Discussion Starter · #7 ·
DI's been the same from the very begining, since I've owned this car. Looks like original one. And no, I don't have any misfires nor CE errors...

This is stgh reaaaaly strange here.
Being fed up with this looking needle in the haystack, I gave the car to the local mechanic today. They also repair Saabs, we'll see what happens.

I'll post back as soon as I get to know what was causing the problem (if I do)..
 

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Discussion Starter · #9 · (Edited)
Oh dear oh dear,

The first rule for everything, check the basis first as the simplest solutions are very often the right ones..

I described this issue on 4 forums, I wrote to Maptun in this matter, I also asked many people who have Saabs what might have been wrong in my car. They always pointed out injectors, stage 2 program itself, fuel filter, fuel pump, bpc valve, mapsensor or wastegate. These were the same, repeating aswers that didn't ever solve my problem. It took so many months to discover this.

My car is LPG converted (but it doesn't have anything to do with the cause itself) and while the LPG was being installed the mechanics must have swapped the vacuum hooses to the throttle body.................................................
So as a result of this, I've been using the car over 1,5year not knowing that two hooses are routed into wrong places. As I never had any CE light nor any other symptoms I never thought that there might have been anything wrong with them, neither had any reason to check the appropriate connection, what should go where.

Looks like mapsensor nd BPC valve hooses were swapped.

The problem solved, the story ends in this place.
Many thanks for everyone for their time and effort trying to spot the source of my problem.
 

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Overboost?

That is a lesson that I was taught by my father and a very good auto mechanics instructor MANY years ago. I wish more people would remember that rule. On occasion, I slip and "forget" to follow that simple maxim and it almost always bites me in the butt! Glad you SAAB is fixed! Good lesson for all of us, regardless of our experience level.
 

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Discussion Starter · #11 · (Edited)
The problem is not solved!!!

Two hooses that were swapped didn't affect anything as those were the FPR and Map sensor hooses, one fits in the throttle body higher than another. In both cases the underpressure is the same. They were pretty sure that this was the issue but on the road the car was still cutting off.
After a week the service gave up. They didn't find the answer to overboost issue.

Is there anyone who might have an idea what can cause this damn overboost/cut off?
Is this possible that bad/old oxygen sensor is responsible for that?
 
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