M35 0.8 Boost Issue

[burkash]

Hi to all, new to this forum but already have read a lot.

So in short, my Stagea has terrible fuel economy during active city driving (~30 liters per 100km) and has bad reaction on the throttle pedal (not always, though).

What has been done already: new maf, new o2, new knock sensor, whole new timing mechanism including both vtc pulleys and all chains, new injectors, new fuel pump with filter and many others.

Has a bigger intercooler, slightly highflowed turbo, 3 inch cat back, a/t transgo kit and cooler.

No leaks in the intake system, checked. Compression ok.

So the main problem is that the car runs 0.8 boost instead of 1.0 pactically all the time, and sometimes (mainly if started up in cold, but not strictly), first 10 minutes after start and warm up it goes 1.0 and pulls really hard.

My idea is that 0.8 boost happens because the car runs some kind of safe map (maybe knock map??), and for the same reason handles the throttle slower and smaller? Does anyone really know, how exactly a signal of knock affect the m35's behavior?

P.S. Sorry for bad English, not my native.

Edited August 26, 2012 by burkash

[scotty nm35]

It definitely sounds like a fault, no way you could be using twice the fuel without the ecu protecting itself.

Does the engine light light up at any time?

[PN-Mad]

First of all, what fuel are you using? 91, 95, 98? With knock, you would see the ecu pull timing, not adjust fuel, I believe. It sounds like you have spent a load of money trying to fix it, which is sad. Might be worth asking one of the guys for a spare stock etc, and swap it over- see if it does the same thing. Could be a bad solder or something in the ecu itself.

As Scott asked, and check engine lights?

Lastly, how are you measuring consumption, and what kind of driving are you doing?

[Daleo]

It's interesting that you mention the low boost thing; as I saw this while at the drags this week.

Normally I can stall the car against the brake, and the turbo will spool up to 15psi at around 3200rpm. It pushes hard against the brakes, churns the rear tyres, then takes off like a cut cat.

At the drags; the car would struggle to get to 2500rpm, and boost gauge was still in vacuum (it normally has around 5-7psi boost at that point). Once I'd done my run; I pulled over on the return road and was able to stall the car up as I can on the street.

As the engine was fully up to temp, I believe it is some kind of gearbox protection when cold; and it either retards the ignition timing or valve timing (or both) to limit boost. Once I was off the brake it would allow full boost. Throughout this I had full opening of the throttle.

It also does another thing, if I give it too much of a hard time when cold; it will limit boost to 7psi (regardless of RPM or throttle application) until I pull over, switch off the ignition & restart the car. Then it will give full boost.

I'm assuming this is an extension of the gearbox protection, as the engine will be at operating temp, but the car may not have been driven very far, thus a cold gearbox.

Is there a gearbox temp sender that could be giving erroneous feedback to the ECU, and limiting boost, retarding ignition timing and/or valve timing and giving you woeful fuel economy & performance?

[scotty nm35]

There are two gearbox temp sensors, but they would only go back to the gearbox controller. I know what you mean though, there is definitely a connection between gearbox temps and the throttle/boost.

[burkash]

It's interesting that you mention the low boost thing; as I saw this while at the drags this week.

Normally I can stall the car against the brake, and the turbo will spool up to 15psi at around 3200rpm. It pushes hard against the brakes, churns the rear tyres, then takes off like a cut cat.

At the drags; the car would struggle to get to 2500rpm, and boost gauge was still in vacuum (it normally has around 5-7psi boost at that point). Once I'd done my run; I pulled over on the return road and was able to stall the car up as I can on the street.

As the engine was fully up to temp, I believe it is some kind of gearbox protection when cold; and it either retards the ignition timing or valve timing (or both) to limit boost. Once I was off the brake it would allow full boost. Throughout this I had full opening of the throttle.

It also does another thing, if I give it too much of a hard time when cold; it will limit boost to 7psi (regardless of RPM or throttle application) until I pull over, switch off the ignition & restart the car. Then it will give full boost.

I'm assuming this is an extension of the gearbox protection, as the engine will be at operating temp, but the car may not have been driven very far, thus a cold gearbox.

Is there a gearbox temp sender that could be giving erroneous feedback to the ECU, and limiting boost, retarding ignition timing and/or valve timing and giving you woeful fuel economy & performance?

What you're talking about -- it's tranny overheat protection, I saw this several times before installing tranny cooler. This happened each time after driving very severely with flooring after each stop and rushing through traffic with lots of kickdown. The boost became limited to 0.5, and moreover the manual shift mode was unavailable.

Does the engine light light up at any time?

No, if that was so, it could be easier to dig in.

First of all, what fuel are you using? 91, 95, 98? With knock, you would see the ecu pull timing, not adjust fuel, I believe. It sounds like you have spent a load of money trying to fix it, which is sad. Might be worth asking one of the guys for a spare stock etc, and swap it over- see if it does the same thing. Could be a bad solder or something in the ecu itself.

As Scott asked, and check engine lights?

Lastly, how are you measuring consumption, and what kind of driving are you doing?

The fuel is 98. strictly, and from different stations. Even tried some additives, no difference.

I didn't say, but I've already tried to change the ecu, overall the car goes better, but the problem stays.

I measure the consumption in the right way, driving full tank to empty, and then seeing how much fuel gets into there.

As I've said -- I do rather active city driving, but to compare, recently I used a w211 e320 for about a month (3.2 liter diesel engine, 500+Nm and 180Hp), flooring it very often and maybe going even faster than on my Stagea -- I had 11-12 liter per 100. The car weighs nearly the same and has a similar stupid 5AT, of course it is diesel, but not so much difference..

Edited August 26, 2012 by burkash

[Daleo]

What you're talking about -- it's tranny overheat protection, I saw this several times before installing tranny cooler. This happened each time after driving very severely with flooring after each stop and rushing through traffic with lots of kickdown. The boost became limited to 0.5, and moreover the manual shift mode was unavailable.

As I've said -- I do rather active city driving, but to compare, recently I used a w211 e320 for about a month (3.2 liter diesel engine, 500+Nm and 180Hp), flooring it very often and maybe going even faster than on my Stagea -- I had 11-12 liter per 100. The car weighs nearly the same and has a similar stupid 5AT, of course it is diesel, but not so much difference..

I don't believe the issue I had at the drags was an overheat condition. Car had been sitting stationary, turned off for 45mins each time at the track; not a chance it was overheated. Also; my manual shift was unaffected. Also, the problem was reduced once I deliberately soaked some heat into the system; just not enough unfortunately.

In any case, I run a large external cooler; and the car had only driven a kilometre or so.

Comparing your Stagea's fuel economy to that of a Turbo Diesel Merc is not even close to a fair comparison.

[scotty nm35]

To be using over twice the fuel you must be blowing a fair bit of black smoke out the back, either that or you have a fuel leak...

[burkash]

To be using over twice the fuel you must be blowing a fair bit of black smoke out the back, either that or you have a fuel leak...

That was not me who said twice

Not twice, I suppose 18-19 liters according to the car weight and my driving habits.

Have got no leaks and no petrol smell..

And no black smoke, I mean no smoke that could be seen in the rear view mirror.

Edited August 26, 2012 by burkash

[burkash]

And to be mentioned, the car also starts very poor, but not always. Sometimes it starts instantly, but mainly requires to hold the key for 2-3 secs. Didn't notice any connection with temperature or any other things.

Edited August 26, 2012 by burkash

[scotty nm35]

What fuel pump did you install? New stock injectors?

[burkash]

What fuel pump did you install? New stock injectors?

Yes, injectors are stock, 16600aa500

The fuel pump is Walbro, but frankly I don't like how it fitted into the case -- it was 1cm too long, so required some additional work to be installed.

Glad you asked about the pump, please tell me, what pump fits perfectly?

Edited August 27, 2012 by burkash

[scotty nm35]

Did you do a search before fitting it? There are a few mods required to the pump for it to fit like a glove. I generally use the 342.

The reason your car is running like crap is probably because you never ran direct power to the pump. Walbro pumps require 14v continuous, and the factory fuel pump only gets 8v or so at idle and cruise. Use the original pump wires to power a relay and run some nice thick power wire down to the pump. Make sure you fuse it.

[burkash]

Did you do a search before fitting it? There are a few mods required to the pump for it to fit like a glove. I generally use the 342.

The reason your car is running like crap is probably because you never ran direct power to the pump. Walbro pumps require 14v continuous, and the factory fuel pump only gets 8v or so at idle and cruise. Use the original pump wires to power a relay and run some nice thick power wire down to the pump. Make sure you fuse it.

Thanks, will try to do this today.

Just to save some time, don't you remember the color of wires powering the pump?

BTW, the problem didn't occur with walbro install, it was the same with the factory pump.

[scotty nm35]

The factory pump may have been shagged. Not saying this is the only issue but I have seen many problems with the Walbro's run at lower voltage.

The power wires to the pump at the tank end are black with a yellow line (+ I think) and green with a red line (negative). They are the two thicker wires to the plug.

[PN-Mad]

Where do you live?

There is the option of going for a drive and Logging your ECU including Injector Pulse Width, and then comparing to other cars. Some people have the powers

As long as you don't think your the next Shumi...

[burkash]

The factory pump may have been shagged. Not saying this is the only issue but I have seen many problems with the Walbro's run at lower voltage.

The power wires to the pump at the tank end are black with a yellow line (+ I think) and green with a red line (negative). They are the two thicker wires to the plug.

Thanks, Scott. Will try to do this today. Just to bla-bla, you mean in some situation the car lacks fuel and determines a knock, then falls into safe mode?

Where do you live?

There is the option of going for a drive and Logging your ECU including Injector Pulse Width, and then comparing to other cars. Some people have the powers

As long as you don't think your the next Shumi...

I'm from Russia.

But this could be a good idea, thanks.

[scotty nm35]

Possibly, the o2 sensor should try to compensate to some extent, but generally the Walbro's will make the car run like crap when the pump goes into its low voltage setting. Hopefully the rewire makes a difference for you.

Have you checked all the breather and cooler piping for leaks? Perhaps a pressure test of the intake is in order...

[PN-Mad]

I'm from Russia.

But this could be a good idea, thanks.

Always wanted to go to Russia! I'll log, if you fly and put me up!

My walbro isn't direct wired, but my car is tuned for what it is at the moment, and being a non return,is different anyway.

[Commsman]

Russia? Would Eugene be able to help?