Hey everyone, I just changed my MAF sensor with oem bosch item and both knock sensors. Put everything back together reset the ecu and went for a test drive as soon as I floor it I heard a slight pop and the car was not boosting and would not go over 15mph. Got home pop the hood and noticed the hose that connects to the throttle body came off, so I put it back on and double checked and re-tightened all the intercooler hoses etc.. Now the car idles fine and drives fine but only boost between 4-5psi??? Any ideas why? I put my old MAF sensor in just to check and same thing. The only thing I can think of myself is my intake manifold is missing one bolt on the corner (timing belt side) that's it, could that cause it?

Thanks for all the help

95 850 turbo, mesh grill, lowered, 17" t5-r wheels, spoiler

 

how old are your hoses? check for leaks, check all clamps, i had a similar issue with my wagon and my hoses were old and i was getting boost leak wouldnt get past 6 replaced the hoses with silicone ones and it helped significantly

 

When you did the MAF did you remove the air box from the engine bay or did you do it in place ??

 

sounds like a boost leak. How do you know you're only boosting 5psi? Do you have a boost gauge? If so, what's your vac numbers? Sounds like a boost leak. And with all the possibilities, why do you think you're missing in intake bolt? And if you think that's the problem, did you try fixing it?

 

I have a aftermarket boost gauge, and the vac reads between 20-22psi. the bolt on the intake manifold is missing because I dropped it and could never find it so I just left it off

 

You don't have a vac leak then. And come on, if you're missing a bolt on the intake manifold replace that before asking why you might have a boost leak. No, I doubt that's your problem, but still. I would check all of your vac lines and hoses for any cracks that are opening up when you go into boost.

 

+1 with gabe on the bolt!! Its there for a reason...
Have you checked your BCS?
What Lines are you using for vac lines.... Replace them with silicone..
Have you checked you waste gate?

 

Yeah Ill get the bolt on the manifold in place this weekend when I get time. I am not sure how to check if the BCS is working or not. Its all connected and they are all upgraded silicone hoses from previous owner. And I am not sure how to test the wastegate without the tool from ipd.

 

You can make the IPD tool pretty easy if you already have the handheld vac pump.

If not some parts stores loan the handheld pump and you can at least attach it and see if the pot holds vacuum and the arm moves and returns. You may not know the PSI it opens at but seeing that it does function rules out some possibilities especially if you haven't messed with the rods adjustment recently. Or you can add the tubing and gauge and just use the loaner handheld pump and actually test it for the specified Vac opening.

You can take the arm loose from the wastegate actuator and see if you can manually move it further than the actuator in case the actuator isn't letting the valve seat properly.

You might have to pull the turbo at some point though to make sure the bypass valve isn't stuck slightly open. That or pull the down pipe and get in there with a mirror to see if it's seated.

The reason I asked you if you removed the air filter housing when you were in there was to see if you might have disconnected a hose from the BCS. You never answered that but you did post your BCS is hooked up and you have quality hoses and I'm assuming you put the clamps back on so .... moving on.

 

+1 on the bolt..+1 on the BCS.. Also IAC to TB hose, located on to of the idle control valve going to the throttle body! And yes check all your Vac lines and hoses!