abrupt momentary shut off of engine

I decided to change how I had my boost control hooked to vacuum. I was getting vacuum from a "T" on the intake manifold. (This "T" also is connected to the brake booster.)
Into this hose an I installed another "T" which has two more hoses attached to it, one of which goes to the mechanical wastegate control which continued to the waste gate can. The second hose went to the pcv which was attached to the valve cover spigot. As I thought it worked, vacuum closes the pcv and holds the wastegate closed at the same time. When boost gets high enough it opens the wastegate. I wondered if the pcv opening caused a poor signal at the can because boost is also pressurizing the crankcase.

I isolated my boost control directly to the spigot coming from the intake by the fuel rail, so it is on the same circuit as the map sensor, boost gauge and fuel pressure regulator. So I tested it this morning. Boost went to 14 psi, indicating to me that previous readings might be wrong because it never went hat high before but when it got to that point everything, apparently fuel and spark, abruptly quit. I figured, OK its going into over boost. I went back to my garage and changed the boost control to less spring pressure. tested again, same thing. I put the weakest spring in the boost control, screwed it way out for least pressure, same thing. Another condition was that I didn't have my laptop hooked up to the ostrich. That shouldn't make any difference, the tune is on the Ostrich but I went out hooked it up, tested, same thing. 12 psi...shutoff.
I verified that all vacuum lines were properly connected. Also the port on the "T" left open I capped with a rubber plug.

Maybe the control needs to be installed on the throttle body spigot. Should the boost control ball and seat be pointed at the wastegate can?
I'm stumped,
Jeff

I put everything back the way it was and it worked properly again. I also tried taking vacuum off the throttle body, that worked as well.
I hope someone can explain this to me. It doesn't make sense.

Not sure what kind of boost controller but, Yes, you are correct having the laptop connected to the Ostrich makes no difference as the program is on the Ostrich.

I have a grainger valve.

It started to do this again so I Ran an MPscan, boost going all the way to 14.7 and likely beyond. I suspect that somehow the wastegate can is hanging the waste gate shut. Have to wait till its cool to be able to reach under there and check the rod movement.

hook up a air spray nozzle.
https://www.harborfreight.com/pistol...gun-63568.html
to a regulator
https://www.harborfreight.com/150-ps...uge-68223.html

set it to about 20 PSI. and hit the wastegate with the air.

you should be able to see and feel the rod move.

I have since put back everything along with putting the weakest spring into the Grainger valve. It doesn't over boost but runs at about 11psi and holds so the can is good. I just don't understand why, all of a sudden it became so sensitive to spring strength. I had the black spring in it before which is longer and stiffer than the yellow spring have in it now. Mistifying.

The ball in the grainger faces the side that is connected to the vacuum. The spring side is connected to the wastegate (and ideally a small vent). That way boost pressure pushes the ball that compresses the spring and when boost overcomes the spring tension, pressure is sent to open the wastegate.

With an LM, can I turn off the over boost function? I do have my grainger installed correctly and it has a vent.

You can raise the limit. There should be a section in the cal about overboost. Look at the values and in the description should help tell you which one to change. Set it to a psi value well before you run out of fuel.

Quote:

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Originally Posted by jeff1234

I have since put back everything along with putting the weakest spring into the Grainger valve. It doesn't over boost but runs at about 11psi and holds so the can is good. I just don't understand why, all of a sudden it became so sensitive to spring strength. I had the black spring in it before which is longer and stiffer than the yellow spring have in it now. Mistifying.

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Uh, have you CLEANED you Granger? I've had several go erratic over the years. CLeaning with TB or carb cleaner fixes them.

BTW, it should be a SHORT DEDICATED vacuum/boost source that isn't shared.

I looked for that before but somehow missed it. Does increasing the number raise the the overboost point?
Thanks

That last sentence caught my attention, particularly the SHORT DEDICATED. I will definitely change that, at present I had it back on the hose to the valve cover. The most obvious is one of the ports on the throttle body, the question is which is best to use. I think they are both behind the throttle plate. I had planned to check out the bleed hole to verify that it wasn't plugged as well.

Quote:

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Originally Posted by jeff1234

That last sentence caught my attention, particularly the SHORT DEDICATED. I will definitely change that, at present I had it back on the hose to the valve cover. The most obvious is one of the ports on the throttle body, the question is which is best to use. I think they are both behind the throttle plate. I had planned to check out the bleed hole to verify that it wasn't plugged as well.

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See where the large vacuum source goes into the brake booster? There usually is a capped off barb on the check valve the hose connects to, I've used that one many times.

Quote:

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Originally Posted by jeff1234

I looked for that before but somehow missed it. Does increasing the number raise the the overboost point?
Thanks

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Yes. The number is the psi where over boost cutout starts. So if you set it for 13psi then overboost will happen at 13psi. I'm not sure which LM cal version your working with but it probably is under "OB, Speed, and Rev Limiter" the value "OverboostFuelShutoffEnablePointFromMap_Timer" .

Bringing the car to Jackson's on the 25th?

Jeff Chojnacki
87 LeBaron 2.2 T2
88 Caravan 5-spd 2.2 T2

Jeff, Yes, I will be at Jackson's with the car. I found overboost and sure enough it was set at 13.29 psi. My scans showed me 13.3, so that was the problem. I would like to talk with you at Jackson's and pick you brain about your tuning experiences about this and other subjects.
Thanks again!

There's 2 damn overboost settings in at least the 87 Turbo2 code. That one got me for a while.

So you're using the grainger valve with all the different springs huh? I have one. Never used it as the normal one has always works for me. I do have a couple "Normal" ones that have a spring that doesn't release till 21psi. Be good for a diesel :)

Glhnslht2, hmmm, I have the 87 T2 LM in my car. What's the story on the two different settings. Where are they located? I have found one location. As far as the spring thing I will probably go back to the black spring although It is somewhat of a mystery as to why I had boosted to 13.3 so many times without over boost and then a Change of hose location suddenly everything goes wacky. Weird.

The PCV valve probably isn't air tight. I wouldn't use that as a vac/boost source. The actuation level at the grainger will be different depending on where you have it getting it's source from. Off the turbo comp housing will be different than directly off the intake manifold.

As for the 2nd spot it's been so long since I've messed with any calibrating that I couldn't tell you where it was. But it's there. I set each one I could find to 14.7 or FF which shuts it off. With a stock garrett on the car I could set the boost level at 14.5psi and the ECU would control it like a grainger valve was on the car. As soon as I went to a S60 turbo the ECU couldn't control it anymore :(

I've got a hybrid so probably best to stick with grainger. See you on the 25th.