Boost or No Boost Help Needed

FormulaSuby · Post by **FormulaSuby** » Thu Sep 03, 2009 10:37 am

I posted this in a few places and am hoping those who browse only certain area see it.

I have an EJ20R from a 1996 Legacy GTB in a race car. I have run many events and have been working the bugs out of it. I got to an event where I could really open it up, and started having some bogging issues. I had no gages in it but a tach and CEL. I did some testing tonight and here is what I found.

I added a boost gage to the intake opening on the left intake runner where the power brake booster hooked up. When I start the car, I get a steady vacuum reading around 18". If I accelerate quickly in first or second, and hold it to redline while in gear with wheel raised, I never get below a 5" vacuum reading. It never goes to boost.

When I shift to third and try to load up the engine by feathering the brakes, again, I never see less than 5" of vacuum, and never any boost. It runs smooth to 4500 RPM, then it starts cutting out and dying.

I think I have all the lines hooked up OK. I see the secondary turbo exhaust actuator open up, and even disconnected the vacuum port going to valve that opens the turbo to the intake so it would stay open. All that did was cause a code 66 but no boost.

Is it possible that the boost gage is in a bad area in the intake? I can't see how it would matter as it still ties to the intake.

When the car cuts out, I thought it might be running out of fuel, but I am not so sure right now. I do not get any check engine light or no codes are displayed.

If I am not running off of boost, this car will be scary fast when it does boost.

Any thoughts on this?

Thanks,
Steve

Outback bloke · Post by **Outback bloke** » Thu Sep 03, 2009 3:15 pm

It is possible that you aren't getting a correct reading but you should still be getting some sort of boost reading there. The closer you can get your boost guage to the throttle body the more acurate the reading.

You should have 3 small hoses runnning off the front of the manifold just behind the alternator. One of them will go to your fuel pressure reg which is mounted down below the manifold near the secondary turbo. Have a look, it will be right at the back end of the fuel rail on that side. You can safely T in to this for your boost guage.

If you are seeing the secondary valve on the exhaust open then you must be getting some boost. It opens once the boost controllers sense a certain amount of boost. It is not RPM related. If your boost lines that open/close the valve under the intercooler are incorrect it will not open the valve and let that boost in from the second turbo.

When you drive it and the second turbp starts to make boost you will feel the car do a bit of a splutter (they all do) and then the exhaust note will change considerably and you will get a boost rush.

If you are not feeling the car do this splutter or hear the exhaust change then the valve is not opening while you are driving it.

What ECU are you using to run the engine and boost controller?

What colour are the injectors?

I have got two twin turbo cars here that I can look at to check your vacuum lines but I need to know injector colour mainly. Year model will help some what. I have one of each variant. You say it is a 96GTB, well that could be either as there was a model change that year. If it still has the original oil filler cap you can also look at the numbers under there to get month/year of manufacture.

FormulaSuby · Post by **FormulaSuby** » Thu Sep 03, 2009 9:13 pm

Outback bloke wrote:It is possible that you aren't getting a correct reading but you should still be getting some sort of boost reading there. The closer you can get your boost guage to the throttle body the more acurate the reading.

You should have 3 small hoses runnning off the front of the manifold just behind the alternator. One of them will go to your fuel pressure reg which is mounted down below the manifold near the secondary turbo. Have a look, it will be right at the back end of the fuel rail on that side. You can safely T in to this for your boost guage.

If you are seeing the secondary valve on the exhaust open then you must be getting some boost. It opens once the boost controllers sense a certain amount of boost. It is not RPM related. If your boost lines that open/close the valve under the intercooler are incorrect it will not open the valve and let that boost in from the second turbo.

When you drive it and the second turbp starts to make boost you will feel the car do a bit of a splutter (they all do) and then the exhaust note will change considerably and you will get a boost rush.

If you are not feeling the car do this splutter or hear the exhaust change then the valve is not opening while you are driving it.

What ECU are you using to run the engine and boost controller?

What colour are the injectors?

I have got two twin turbo cars here that I can look at to check your vacuum lines but I need to know injector colour mainly. Year model will help some what. I have one of each variant. You say it is a 96GTB, well that could be either as there was a model change that year. If it still has the original oil filler cap you can also look at the numbers under there to get month/year of manufacture.

Hey, thanks for the detailed reply. I am running stock ECU. I will get numbers tonight. I do have the frame tag off the car. It is a late 96/early 97 with the 3-plug ECU with two rows of pins. WIll also look at injectors tonight, but they are stock as well. I am not convinced that this is still not MAF related, but I cannot get a 90mm Subaru MAF here anywhere. I am using an Infinity Q45 in there now and not sure if the upper end is compatible. I may try to unplug it and let it go into open loop and see if that changes anything. This seems to just have started after I worked out the glitches that were giving me codes 23, and 33.

FormulaSuby · Post by **FormulaSuby** » Fri Sep 04, 2009 8:45 am

Here is an update.

I checked the boost gage location, and it was for the vacuum booster, but there was no valve and it was open to the intake.

After further applying thottle and brake, I was able to get it to read as much as 8 lbs boost. Guess I wasn't loading it hard enough.

That still leaves my main problem. The engine is from a late 96 JDM Legacy GTB with EJ20R and twin turbos running off the factory ECU with no mods. It has yellow topped fuel injectors.

In first or second gear, even with the brakes nearly locked and boost at 7 lbs, it powers right up to redline and I can hold it there (7500), When I go to third or fourth gear and apply load, if I increase gradually, I can get it to redline. If I apply heavy load and try to squeeze throttle, the car just sputters and dies. When it is dying, it feels like it runs out of gas. It is usually at 4000 - 4500 RPM when the car shows boost. If I leave off completely, and car drops down significantly in RPM, I can go right back up. If I try to lift slightly, or mash it to the floor, it continues to die like if I have no fuel. If I keep on it, it will drop right ot 2000 RPM and start sputtering. Sometimes, I can go almost to the floor and it will pick up for a few seconds then die again. I do not have any codes or CEL while any of this is happening.

I am going to try to test fuel pressure under load next to see what happens. If I disconnect MAF or anything to put it in open loop with CEL on, it does not change.

Any other thoughts on this?

FormulaSuby · Post by **FormulaSuby** » Fri Sep 04, 2009 9:49 am

Just checked fuel pressure.

It sits at 46 PSI with engine off.

Starting up, it runs at 38 PSI at idle.
At High RPM, it runs up as high as 50 PSI.
Under mild boost, about 46 PSI.
When it is acting up, it never drops under 44 PSI.
Those numbers are right to what the liberty manual says they should be.

So I am guessing that it is not fuel related, but something driven by the computer that does not create a Code.

Is anyone using a datalog system with this typw and model ECU?

Thanks,
Steve

FormulaSuby · Post by **FormulaSuby** » Tue Sep 15, 2009 9:18 pm

OK,

Back at it last night. Re-checked many of the hoses, cleaned all solenoids and checked them for operation, traced all lines to components and they were where they should be. I think solenoid box is OK now.

Took off MAP sensor hose, replaced sensor with gage and only getting about 5 PSI with little load, but I can still shut it down, so now I am thinking it may not be over boost. I read on some boards, and the solenoid box schematic seems to show that map sensor is after a solenoid in this twin turbo system, and maybe on all.

Tonight I am going to try to rig a test light to the solenoid before the MAP, and pu a meter on the MAP sensor. What I am hoping it may show is sthat if it switches to MAP on secondaries, that I can see the solenoid open up and then watch the MAP readings. I have not checked MAP output up to this point, so it is possible that is bad sensor, wire, or ground.

After that I am going to add 5 gallongs of 107 CAM 2 Race gas to take away any thoughts about octane causing this.

I did notice now when I snap throttle open, I get a pop in the intake manifold almost like a backfire. Does that give any new clues? I had not heard this before.

Gannon · Post by **Gannon** » Tue Sep 15, 2009 10:09 pm

A pop in the intake manifold usually indicates a timing issue. Incorrect would also effect how your engine makes boost

Outback bloke · Post by **Outback bloke** » Wed Sep 16, 2009 7:48 am

Sure would. As soon as I read this I though the timing was out. Pull your front covers off and re-check your timing marks. It is quite common for the belt to jump a tooth or two.

How does the engine idle? Is it dead smooth or is there a slight bump to it.