Please help!
I have 855 model '95 2.3 T5, manual gearbox, catalyze free, sport air filter (green), rest - stock. I have chipped it to 0,9 bar. But the problem is that turbo boost is 1,2 bar, not 0,9 like it is programmed) and it is fluctuating: it boosts 1,2 bar, then drops to 0,4 bar (service regime, DTC 4-1-4 boost pressure too high), then again 1,2 bar and so on (its because ECU turns service regime on when it boosts). You can clearly see it in this video: http://www.youtube.com/watch?v=42v88dxnDBc
I tried to solve problem with manual boost controller (MBC), turbo holds boost steady (tried @1-1.1bar), no fluctuations, but there occured very strong jerkings >100km/h (there is everything ok using 2nd gear, I can pull up to 6000rpm without any problems, jerking occurs only using 3rd gear and upper gears at full throttle). But I think that's related to boost fluctuation while driving without MBC, because MBC did not solved a problem.

When ECU was programmed to 1 bar, it boosted nearly this, but fluctuating, it was also programmed to 1,2 bar - the same, it is now programmed to 0,9 bar - boosts 1,2 and fluctuates... When ECU was stock, no fluctuations occured, also tried another stoch ECU - no fluctuations.
What could be the reason? All sensors are working well (I do hope they do), no DTC errors (except mentioned 4-1-4), no dashboard information about system's failure.
May it be because waste-gate is not adjusted to higher pressure? O car don't get enough air because of stock intercooler?

Can you (who had ECU upgrade) write whether you have everything all-right after chipping, what also made after chip?

 

I had an IPD tuned ECU in my 850 and it was set to 1 bar. I did not have any of the issue that you are having with this tune. The only two things that I can think of that could be causing this issue would be either an issue with the tune itself or you BCS is going so it can't hold the higher boost.

Oh, one other thing that I thought of could be a weak spring in the CBV. This would allow the boost to bypass and cause you turbo to loose boost pressure. I have a feeling it is the CBV.

 

Turbo holds boost, but ECU turns service regime so that's why it fluctuates. And when I installed MBC turbo holds boost, but with enormous jerking at full throttle... Can it be that MBC could solve these problems that might be (which you mentioned)??
Can problems with BCS or CBV cause computer to not allow full boost?

 

I had an IPD tuned ECU in my 850 and it was set to 1 bar. I did not have any of the issue that you are having with this tune. The only two things that I can think of that could be causing this issue would be either an issue with the tune itself or you BCS is going so it can't hold the higher boost.

 

Copy and paste FTW

 

Two things come to mind...

1. Your hitting the fuel cut off.
2. You need a tune up.

I have run into both. The IPD ECU removed the fuel cut off problem and a tune up solved the missing at high boost.

IPD ECU, IPD Wires, Bosch Cap and Rotor and Iridium plugs....Problems gone.

 

Stock turbo?
Who tuned the ECU?
Did they remove the fuel cutoff?
Also are you running a wideband O2? If so what are your numbers?

 

Damb you beat me to it!!! LOL

 

Turbo is fully stock, everything is stock, except ECU. It was tuned by one guy in Lithuania, he tuned >500 various cars.
I don't know whether he removed fuel cut off.

What is wideband O2??

 

15Gs are known for boost fade, might be part of your problem there. Also 1 bar is about 14 psi IIRC, so you shouldn't be loosing efficiency, although you're close to it. I would try a full tune up. And if he didn't remove fuel cut, then you may be hitting that which is at 15 PSI, which would make complete sense, and to me sounds like a very good possibility.

Wideband measures your AFR's (air/fuel ratio), recommended whenever you start tuning a car.

 

BCS is ok, I've tried another one, but no effect -fluctuations remained.

 

what about MAF? Doesn't it do the same as wideband?

And how to install wideband? Maybe you have a scheme?

But if I do not use MBC, just ECU, which is tuned to boost 0.9 bar, but it boosts 1.2 bar? what about it? Couldn't it be the issue with fluctuation (that smth is wrong so it boost too much and fluctuates)?

 

AEM wideband AFR gauge


And you may just be experiencing a boost spike, which is normal. And what you do you mean fluctuation?

 

wideband o2 FTW, and does sound alot like fuel-cut i used to get it all the time in my 89 dodge spirit turbo until i put a boost contoller on my map sensor.

as for it being boost spike does the car over boost past .9 bar for just a second or does it try to hold the over boost? if it tries to hold the over boost the it isnt boost spike. but it could very well be just a boost spike if it when you start gaining boost it jumps past .9 for a brief second. during boost spike is when my spirit would get fuel cut and i solved it by buying a "G-Valve"(simple/cheap boost controller but helps hold boost VERY well.) i had an electronic apex-i boost controller on it and thats the only time the car would boost spike other then when when the spring in my G-Valve would become weak. dont know if this helps but i hope it does!

 

I believe he has already tried a MBC, see his original post.

 

i beeeelieve i read that and i wasnt saying that would cure his problem i just said thats what fixed mine. ok? just tryin to help lol.

 

Sorry if I offended, not my intention. I run a MBC as well for the exact same reason.

 

The 15G is pretty useless after 15 PSI. You said you are hitting 1.2bar which is over 17 PSI. That is a little to much for the 15G. I think it might also be the fuel cutoff you are hitting.

If you have a fuel pressure gauge you can connect it and test drive and see if the fuel pressure cuts out when it acts up.

Also if the ignition parts are old it can cause that as well.

What did you gap the spark plugs to?

 

I have talked to someone who works with volvo cars, so he explained, that the reason for fluctuation is the DTC 4-1-4 boost pressure too high. ECU then drops pressure and that's why fluctuation occurs.
Can anyone tell what might be the reason for that DTC 4-1-4? Diagnostic does not show any other faults.

 

If you are running the stock BCS then the waste gate might be out of adjustment or the vacuum lines are ran wrong.