ok, this is an issue that pretty much only happens when the engine heats up and very rarly when the engine is cold,...heres the problem...under boost/acceleration it cuts out on me, sometimes vigorously and cant fiure out whats going on but sitting still and reving the engine everything is fine until i am under leao.... heres the actions i have taken: cleaned MAF sensor,regapped my plugs,checked all my inter cooler piping and couplers, checked all my vacumes, spark plug wires, cleaned air filter,closed my boost controller (cuts out worse when boost controller is open), new fuel pump, is there anything else anyone knows of that i can check out to kill this problem,... i want to enjoy my 15 lbs. going to be upgrading to a mitsu te05 soon but i would deff like to kill this problem before i put the new turbo on, please help...

 

leao=load

 

i guess no one knows huh...

 

cat converter clogged? Trans slipping, hot coil cutting in and out (would make since w/ no power under load), bad fuel injector relay/wiring, flame trap clogged???

 

So are you running higher boost? If so, these cars have a safety that cuts out the fuel if boost rises to about 14psi. That would make it buck. Normal boost is around 7psi. You can short the switch, but that would be unwise unless you have done so other mods to safeguard against knocking. That's a good way to throw a rod. Later B230FT's have way strong bottom ends, but they aren't invincible.

I would also check that the waste-gate actuator line is not leaking.

What type of boost are you developing when this happens?

 

cat is gutted out with a higher flow muffler, trans mission is perfect working order, hot coil? whats that? where is it? main coil is new aswell, as for the boost cut at 14 lbs, its only happening around 14 lbs and my wastegate actuator hose is new and i had checked it so i know its not leaking but i have noticed that it seems to get worse when the engine heats up..., i have a couple friends with 740s and 940s all in which are producing 18 lbs, esspecially the 940s there 1994 and up so yeah they have the stronger bottom end, but i only want 15 to 16 lbs i dont want 18 lbs... but i dont want the cut,,, so how do i do this to fix it to where it stops the cut, i had asked a couple friends today and they all said they baught the car that way so which means the fix was already done, if someone could tell me how to fix it to where it stops the boost cut at 14 lbs please let me know..

 

i had tried to do research on the zener diod mod and cannot find much info , theres different sizes, i need to know what size, and how and where to install it...

 

I have no idea what the zener diode mod is and I'm having a bit of trouble understanding what you're saying. However, I think you say that at 14psi it cuts the power right? So you are running higher boost and that's what's making this happen. There's a switch that is opened by pressure that kills power to the fuel. All you need to do is short the switch. You can jumper across the plug that goes into it. Really it just grounds on one side. So you can ground the hot side, I believe. This will kill a designed safety system in the car and you do this at your own risk. In my 740, the switch is located on the pedal carrier under the dash. It reads manifold pressure by the same line that brings pressure to the turbo gauge. Look for a tee in the line. There will be a few other vacuum lines going to pedal switches for the cruise control, just ignore them. You could probably just plug the line the the switch too. If for some reason it is not there, just find out where the rest of your vacuum lines (from the intake manifold) go and it will be at the end of one of them. I say this because my claims are based on the a Volvo 740.

Have fun, but watch that engine. An EGT gauge may be a good idea as well as other mods. Good luck.

 

Titan Joe, Im having a similar fuel cutout on my 91 640 turbo ...I have my boost /vac aux. gauge hooked up to the same line as my in dash boost cauge ...could this be causing my problem where and what is this device you mentioned on the line and what does it look like thanxz Ben