How much control does the wastegate solenoid have?
- Thread starter litdog83z
- Start date
any way to test the solenoid?
i did an injector and chip change, and then my boost shoots up uncontrollably when i get on it now
It's supposed to be set to 15 or so psi by the chip, but boosts over 20. So either it's a big coincidence that it failed, i pinched a wire somewhere doing the injectors, or something else... i checked for cracks in the wastegate hoses and if it was hooked up wrong, and it worked just fine before the swap, so i dunno...
if i unplug the vacuum line to the wastegate solenoid and plug a host straight from the turbo to the wastegate actuator, it should boost 10psi right? i would put my stock chip back in to test, but i just installed 50lb injectors and dont want to swap those back
i did an injector and chip change, and then my boost shoots up uncontrollably when i get on it now
It's supposed to be set to 15 or so psi by the chip, but boosts over 20. So either it's a big coincidence that it failed, i pinched a wire somewhere doing the injectors, or something else... i checked for cracks in the wastegate hoses and if it was hooked up wrong, and it worked just fine before the swap, so i dunno...
if i unplug the vacuum line to the wastegate solenoid and plug a host straight from the turbo to the wastegate actuator, it should boost 10psi right? i would put my stock chip back in to test, but i just installed 50lb injectors and dont want to swap those back
- Joined
- Nov 24, 2001
Hey bud-
I would suggest that you try doing what you were saying, take the hose from the turbo to the wastegate, and it should get about 12psi. it might creep to 14 depending on wastegate and intercooler.
It actually might be more boost depending on how rich or lean it is and if the wastegate is adjustable.
Rjc will get you the fastest spoolup, and you can email eric marshall in my signature and ask him about what his chips can do for boost control.
BW
I would suggest that you try doing what you were saying, take the hose from the turbo to the wastegate, and it should get about 12psi. it might creep to 14 depending on wastegate and intercooler.
It actually might be more boost depending on how rich or lean it is and if the wastegate is adjustable.
Rjc will get you the fastest spoolup, and you can email eric marshall in my signature and ask him about what his chips can do for boost control.
BW
northern87gn
trbolvr
- Joined
- Mar 27, 2004
I may be totally wrong but I didn't think the computer received an actual boost level signal. Thought it controlled the solinoid via the MAF reading. I remember talking to some buick guru that stated the only thing the map sensor did was drive the boost gauge. Gurus can take it from here. 
The stock 2 Bar map sensor only controls the stock boost gauge on the dash.
The waste gate solenoid is controlled by the ECM in open loop. That is to say the the ECM pulses it between 0-100% duty cycle without knowing what the result is. At 100% duty cycle (DC) the boost will be approximately 7 psi above the base mechanical setting. The solenoid will not be used until the MAF passes a set value, stock is 55 g/s (from memory). Once past this flow rate, boost mode is engaged. The ECM sets the DC from 2 main tables, it picks a value in % from a table varying over RPM, the factory values being approx 60% over the whole RPM range. It then scales it by % TPS, it then further scales down if the you are in third gear and by a lower amount if you are in 4th gear. This lowers the boost in upper gears or if your foot is not fully on the floor. To prevent boost spikes, the factory settings only allow the selected value to be ramped up over about 1.5 seconds. This is why the factory style chips have soft smooth rise in boost. This is all done beacuse the ECM does not know what resulting boost actually is, it only knows indirectly be seeing higher MAF levels.
The stock chip operated at about 60% DC. If the solenoid failed open it could raise the boost about 2-3 psi beyond normal. Most aftermarket chips use 80-100% duty cycle so if the solenoid fails open the boost can only rise 1-2 psi more.
One exception to this is the Thrasher chips which use a fast spool feature but in a ridiculous way. Unless your VSS reads 0, your solenoid is chattering away at 100%. When an internal load variable goes above a certain value it uses normal boost settings like 80%, if you are simply cruising, the solenoid is going crazy al the time. It only stops when you stop moving. I am sure the Thrasher causes solenoids to wear out.
Other chips have fast spool features but they do not chatter the solenoid all the time when cruising.
The waste gate solenoid is controlled by the ECM in open loop. That is to say the the ECM pulses it between 0-100% duty cycle without knowing what the result is. At 100% duty cycle (DC) the boost will be approximately 7 psi above the base mechanical setting. The solenoid will not be used until the MAF passes a set value, stock is 55 g/s (from memory). Once past this flow rate, boost mode is engaged. The ECM sets the DC from 2 main tables, it picks a value in % from a table varying over RPM, the factory values being approx 60% over the whole RPM range. It then scales it by % TPS, it then further scales down if the you are in third gear and by a lower amount if you are in 4th gear. This lowers the boost in upper gears or if your foot is not fully on the floor. To prevent boost spikes, the factory settings only allow the selected value to be ramped up over about 1.5 seconds. This is why the factory style chips have soft smooth rise in boost. This is all done beacuse the ECM does not know what resulting boost actually is, it only knows indirectly be seeing higher MAF levels.
The stock chip operated at about 60% DC. If the solenoid failed open it could raise the boost about 2-3 psi beyond normal. Most aftermarket chips use 80-100% duty cycle so if the solenoid fails open the boost can only rise 1-2 psi more.
One exception to this is the Thrasher chips which use a fast spool feature but in a ridiculous way. Unless your VSS reads 0, your solenoid is chattering away at 100%. When an internal load variable goes above a certain value it uses normal boost settings like 80%, if you are simply cruising, the solenoid is going crazy al the time. It only stops when you stop moving. I am sure the Thrasher causes solenoids to wear out.
Other chips have fast spool features but they do not chatter the solenoid all the time when cruising.
I've been using a Thrasher for years, and reading the info on several of the Buick boards for years, and this is the first time I ever heard the suggestion that the Thrasher keeps the waste gate solenoid "chattering away at 100%". I'm aware that the Thrasher has a "lean cruise" mode, which also helps in quick spool, but I don't think that involves the waste gate solenoid. Also, at 100% duty cycle, the solenoid would be continuously OPEN, which is somewhat different from chattering.
- Joined
- Nov 24, 2001
Well, if you loop your wastegate to compressor and get 17 psi of boost, then someone has cranked the rod down and thats why your getting too much boost.
Is your wastegate rod adjustable???????????????
BW
Is your wastegate rod adjustable???????????????
BW
stock wastegate actuator, hasnt been modified adjustable yet, but if it had i would have gotten more than stock boost with the stock stuff.. i'm thinking i'll just take the wastegate solenoid out of the picture and make the rod adjustable... is that a good idea?
- Joined
- Nov 24, 2001
I will think outloud here:
I doubt the wastegate puck is stuck causing the overboost issue.
Try and loop the wastegate to the compressor and see where the boost is at.
Delete the Y and let us know where the boost is at.
If you get 17 or so psi, then the problem is the wastegate asssy.
Since yours is not adjustable,Either the wastegate diaphragm is bad or someone drilled a hole in the wastegate to raise boost seen it, or the hoses you have are not allowing the pressure to the wastegate allowing the wastegate to do its job.
Do the loop, compressor to wastegate,let us know the boost.
BW
I doubt the wastegate puck is stuck causing the overboost issue.
Try and loop the wastegate to the compressor and see where the boost is at.
Delete the Y and let us know where the boost is at.
If you get 17 or so psi, then the problem is the wastegate asssy.
Since yours is not adjustable,Either the wastegate diaphragm is bad or someone drilled a hole in the wastegate to raise boost
seen it, or the hoses you have are not allowing the pressure to the wastegate allowing the wastegate to do its job.Do the loop, compressor to wastegate,let us know the boost.
BW
Ormand said:
If you have Direct Scan, watch your WG DC hit 100% as soon as you start moving. If you are in garage with your hood open roll forward and you can hear it if your exhaust isn't too loud, its definitely chattering, not stuck open. 100% DC is not simply held wide open its actually still pulsing.
The lean cruise mode is separate from the wastegate calculations. In the Thrasher, under certain light load conditions the ECM will go open loop and lean the mixture very slightly. Its nowhere near as lean other lean cruise chips out there if gas saving is your thing. The stoich ratio in hex is 111 and the Thrasher leans out it out to 110 (from 14.7:1 to 14.9). Other chips will go into the 16:1 range. By the time your foot gets anywhere near the floor, lean cruise has long since kicked off.
- Joined
- Nov 24, 2001
could be blown fuse at ecm solenoid on the under dash fuse panel, of course you would get a ses light/ check engine light... does yours work? do you get a code on your direct scan?
My guess its the solenoid, did eric burn that in the chip?
for the same money, rjc sells a bleeder vavle will get rid of that setup.
BW
My guess its the solenoid, did eric burn that in the chip?
for the same money, rjc sells a bleeder vavle will get rid of that setup.
BW
The solenoid is almost a year old, i bought a new one because i thought i lost it a while back.. i think i have the old one i can try still. I think the chip is burnt for it. if it's not burnt for it is it possible that's the problem?
i'll probably just get the manual boost controller. Then i dont need an adjustable wastegate rod, right? I adjust boost on my turbo minivan with just a grainger valve,
i'll probably just get the manual boost controller. Then i dont need an adjustable wastegate rod, right? I adjust boost on my turbo minivan with just a grainger valve,
- Joined
- Nov 24, 2001
I use BSTC and never told eric how i control my boost-
You need to varify if that wastegate sole/ fuse is good or bad, if its bad, the check engine light will come on and you will get code 31 for the solenoid because it does not provide power. Ground go thru the tranny.
I would first assume the solenoid, but after reading this thread, seems you have a new solenoid, and the very next thing you changed was the chip...
I have never installed the Y fitting backwards,... i dont know what would happen if that was the issue, been awhile.
compressor strait thru to the solenoid, the extra odd end goes to the wastegate.
BW
You need to varify if that wastegate sole/ fuse is good or bad, if its bad, the check engine light will come on and you will get code 31 for the solenoid because it does not provide power. Ground go thru the tranny.
I would first assume the solenoid, but after reading this thread, seems you have a new solenoid, and the very next thing you changed was the chip...
I have never installed the Y fitting backwards,... i dont know what would happen if that was the issue, been awhile.
compressor strait thru to the solenoid, the extra odd end goes to the wastegate.
BW
- Joined
- May 9, 2002
I believe you'd have about 10 PSI of boost if you reversed the "Y" fitting. If you're going to use a manual boost controller, leave the wastegate solenoid hooked up, because the ECM monitors its electrical function.Quick6'n'-K.C. said:
leeb
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