F1nd3r05

Hi everyone. To make a long story short, I modded my car with a lindsey super 75 turbo and supporting mods. The problem I am having is that i cannot achieve full boost. When i connect the boost line from my intercooler pipe to the wastegate with no manual boost controller, it will hold at 5psi perfectly through the gears. When i put a manual boost controller on it it will also hold up to about 10 psi as if all is perfect until i try to turn it up and then and then bam when i try to go over 10psi my boost gauge needle shakes and it wont let the car boost more. NO it doesnt shut off, Yes it has the appropriate chips and injectors and fuel pressure regulator. Also, what i also find to be the EXTREMELY WEIRD part of this...When I clamp the wastegate line, which in theory would cause the car to boost with no regulation, It will go to that maximum of 10-11 psi and still have the same outcome. PLEASE HELP ME I JUST WANT TO DRIVE MY CAR!

travisgreen

What wastegate do you have

rlm328

CHeck for vacuum leaks

travisgreen

If everything is hooked up properly and the cycling valve etc is bypassed as it should be, then u have a severe boost leak. My guess is if the turbo is brand new it may be leaking at the seals. Did you tighten the bolts up before you installed? Lr doesn't torque them before sending them out which is real dumb. Do a pressure test and see if that's the problem,

doabarrelroll

The stock boost is 10-11 psi IIRC. If you don't delete the cycling valve, that's your boost ceiling.

If you don't have a bigger/dual port wastegate, that doesn't help either.

travisgreen

That's what I'm thinking as well, so most likely if you are still using your cycling valve then the rest of your vacuum routing is wrong too. If you don't have a dual port wastegate, then that's your max boost with or without a manual boost controller

F1nd3r05

hey sorry for the delay in response, thank you all for making an effort to help me. i deleted the cycling valve using a manual boost controller (bleed type not ball and spring) also, I am using my stock wastegate. When i run the line directly from the intercooler/charge pipe to the wastegate with no mbc, it will hold 5psi and pull through the gears boost fine. when i use the mbc, as i begin to turn it up it still holds fine up until around 9-10 psi. if i leave it there, i can pull through to redline solid psi no issues. once i go to turn it up past there it just whacks out and the car stops like something is momentarily blown off. the weird part is that when i let off on the throttle (even gradually and keep it right under the 11psi limit as i go through the gear) there is no issues in acceleration or boost. just when i go to pull past that psi it happens. When you talk about those bolts @travisgreen TRAVISGREEEN via the turbo, which bolts are you talking about? I feel as if i have checked literally everything but the turbo at this point although it acts perfectly before that limit. vacuum is between 17-18in/hg at idle btw 20-21in/hg when i let off throttle in gear. Thanks again for your answers everybody!

blown 944

you are probably hitting boost cut. What pressure do you hit when this happens?


If it just cuts out hard then it's not a boost leak.

What chips do you have in there?

Whe you say "supporting mods" what do you mean? Be specific

Tom M'Guinn

Are you using stock chips in the DME / KLR? Stock chips have an over-boost protection feature that feels like a brick wall when triggered -- it's designed to prevent you from running more air/boost through the system than your chips/maps are able to handle.

Tom M'Guinn

Posts crossed, but +1 on this.

F1nd3r05

its right about 11-12 psi according to my gauge. I have lindsey racing chips made to work with lindsey super 75 turbo dry turbo setup, 65lb injectors, 3.0 fpr, cycling valve delete, mbc, spec 6 puck clutch. other things but literally besides of this the car runs perfectly fine. im trying to think would it be a good idea to take a video of the gauge to show you guys what is happening? also, i spoke to dave lindsey and he said that his chips do not have a cut off like that. that with the wastegate line clamped that i should be able to achieve a very high psi way beyond what im doing at the moment. i just cant understand why if it were a vacuum leak it would hold so well until that pressure every single time

Tom M'Guinn

You changed both chips, right? One in the DME box and one in the KLR.... Assuming so, it's possible your wastegate is just weak or broken and just can't hold more than a certain level of exhaust pressure. You could rule that out by physically blocking the flow of exhaust to the wastegate, using a sheet of copper or steel in lieu of a gasket for testing. Just be careful as the boost may well shoot up to the moon quickly -- don't let it shoot up to 20-30 psi etc -- your only boost controller will be your right foot. How does the car behave right after the boost cuts out -- all good with less power or does it flood/stumble etc.? Sometimes intake couplers will hold up to a certain pressure, but let go like a safety valve when they reach a certain pressure point. Pressure testing the intake is rarely a waste of time. Also, have you tested or blocked off the bypass (blow-off) valve to make sure it's not letting go? If that's all ok, might check the diagnostic port for blink codes and confirm the DME is getting the full-throttle signal from the KLR when you floor it.

A video would be helpful!

F1nd3r05

so you're saying that if i literally remove the wastegate completely and block off the inlet from the crossoverpipe that i can somehow test it without blowing it up? sounds like an idea to me...also yes i replaced both chips. the car functions perfectly after it happens. i mean literally perfectly the second i let up even for a second. i can let up and immediately floor it and as long as it doesnt exceed that amount of boost pressure its as if its a perfectly running car. id like to avoid doing that with the wastegate if possible, but if worst comes to worst ill try it.

F1nd3r05

maybe it is the wastegate. would it be possible even though when a direct line is ran it holds 5psi perfectly? also, when i clamp that direct line it should technically overboost to the moon right? because when i do it it has that blow out affect that even makes a slight pop sound to it as well. could that be the wastegate diaphragm/spring giving out at a maximum pressure? i tried the test of when you start it up to see if the outlet pipe gets warm and it stays cold.

blown 944

Might also be something weak in the ignition system.

Need to narrow down whether it will even build boost, or if it is shutting down because it hits a certain pressure.

By your description, it sounds like the wg is functioning normally with a weak spring.