I want to replace the 3way solenoind boost control valve that fits 6mm ID hoses. What is available? The stock boost control valve on my 1997 Saab Turbo is a bleeder type valve. The bleeding contributes to boost lag.

I want to eliminate boost lag while maintaining ECU control. I have an aftermarket ECU that provides a high degree of integration between boost, fueling, and ignition that I want to retain so manual boost controllers and stand alone EVCs are out of the question. The bleeder valve seems to be the heart of the matter.

SLAAB's web page

 

Like I said, I do not want an MBC. Temperature in Tampa varies from 30 to 110 degrees. Installed properly, you will need to adjust the MBC to compensate for temperature and elevation variation. All of them are adjusted with screws. My ECU does temperature and altitude recalibration in real time, recalculates fuel maps in real time, plus uses the electrode potential across the spark gap as an in cylinder ionization sensor .

Piggy-back EVCs (boost controllers) are also out of the question. The electronics won't be as well integrated as my ECU (already boosting 21 psi), plus I'm not about to pay hundreds of dollars for a $50 part.

Are the solenoid valves from the EVCs sold separately? All I want to change is that stupid valve they installed at the factory to a non-bleed valve.

 

Yes, I love my ECU. But my ECU is far from state of the art. For example it does NOT use AMM (air mass metering). Here is a clearer explanation.

Its a speed density system, that uses RPM's, absolute pressure, temperature to determine the air mass flow and maps fuel accordingly. The volumetric efficiency is accomodated within the O2 sensor adaption loop. The fuel mapping will trim to changes in humidity etc via the same method. This level of adaption accomodates variabilty in sensors and will also take changes to intake and exhaust in stride. So this is the ideal system for making mods.

The ECU system also analyzes the combustion process by using the spark plugs for measuring ionization within the cylinders. A weak voltage is applied across the gap of every spark plug after each combustion stroke. The current flowing back to the control unit is dependent on the number of ions that have been formed, which provides a measure of the combustion in each cylinder. Ionization measurement reveals whether the fuel/air mixture has ignited and burned correctly. If not, the system adjusts the fuel quantity, the Direct Ignition timing or the boost pressure. The Direct Ignition timing is also monitored separately in each cylinder. The Saab Trionic system can control each cylinder individually, which is a more accurate way of controlling the engine than by using averages of measurements carried out at only one point. This continuous monitoring enables the fuel energy to be put to optimum use. The result is a reduction in fuel consumption and exhaust emissions. Each fuel injector is controlled individually and the air mass entering the engine is calculated from measurements of pressure, temperature and air mass flow. The processor is so fast that it even checks during the injection phase whether any factors have changed, making in-cycle corrections if required by varying the fuel pulse from a minimum of two milliseconds (1/500th sec) to the complete four-stroke cycle. This makes the control of air/fuel ratio significantly more accurate and permits octane levels from 85 to 104 RON.

When the ECU sees a boost level that is above the max setting it has calculated as appropriate, it will engage fuel cutoff as a safety feature. Max boost is variable. Running 94 octane on cool days it will permit 21 PSI. Heat soak the intercooler by letting the car sit in the sun, get the temperature up to 120 degrees and run 87 octane, max boost will fall to about 8psi. No, you cannot disable the pressure sensor for the ECU as it will totally screw up the air/fuel mix. You want to make sure that boost is always below this max level, so MBCs need to be constantly adjusted to the level expected by the ECU.

What I want to fix is called boost lag.

The ECU controls the valve that actuates the wastegate on my turbo. This is a 3 way valve that has a feed from the throttle body, a line to the wastegate actuator and a vent to the intake. These 3 way valves are slow acting and contribute to boost lag (as opposed to turbo lag)... turbo spools quick but boost comes on slow. Presumably they did this with the stock valve to smooth throttle response and extend clutch life.

What I want to do is keep the ECU and swap out the bleeder valve with something that will act more quickly.

 

Dave,

I think we are at an impasse here.

Yes you are right, only in that the MBC will solve the boost lag problem

BUT other problems are created. As stated before I cannot use an MBC because the ECU always wants to adjust the max boost level. See the earlier comments about fuel cutoff. 21lbs of boost is engaged when the ECU allows the equivalent of the 'scramble mode' from EVCs. This max setting is not a permanent state. Both the ECU and boost control valve have to be in harmony to achieve maximum boost w/o fuel cutoff.

Does any one know if the solenoid boost valve from EVC kits are sold separately? Please help me out here.

 

If you are looking for just a solenoid valve, get one from any factory turbo car.....one notible unit is a 1988 Pontiac Grand Am turbo.... 2.0 turbo i had one that tought me everthing about turbos.

or a 86 transam turbo 4.9
sunbird turbo

GM stuff is used by alot of the stand alone ecu companies so thats why is use them....i've had my TEC II on 3 cars with 6 different setups.

 

Do you know which ones do NOT use bleeder type valves and fit 6mm ID hoses?

Thanks

 

ah, this is not a bleeder type !to my knowledge! it is a one in and one out. However it does have a third nipple with a foam filter i forsee that this is a simple solenoid used for several possible functions......GM likes to do that.

I have some at home i can take a pic of. i'm stupified by the "bleeder type" you mention

on my drag car i use the old school blitz unit, would you classify that as a bleeder type(i guess i would since it lies to the vacuum assisted spring to adjust boost) with this in mind i dont know what kind of solenoid you will find that is not a bleed type , thats what controls boost pressure from a wastegate is pressure/vacuum on the actuator. unless its a variable vane controller or some shoot