Driveability issue

[slipknot51]

Well to start off this morning I let the car warm up like normal and when I got in the car I noticed that my idle was sitting at around 550 which I found weird put it in gear the car drops down to 350 and almost dies or ties to. I took and started to drive the car and noticed it had really poor driveability the car would accelerate slow then go back to normal. Then when I got into boost and let off the throttle I get alot of turbo flutter which I'm wondering if all this stuff would be caused by a fault Bypass valve. I noticed my vacuum dropped off a little and that when I took and tried to adjust the fine idle screw nothing changed when it was turned out or in so I set it back to were it was set

[kimokalihi]

Don't ever adjust that screw. It's not meant to be adjusted. You probably have a vacuum leak.

[slipknot51]

Ok noted. Would a vacuum leak cause a turbo flutter thought when letting off throttle after boost. I figured that I would have noticed other issues like brakes being harder to apply but that didnt change.

[Legacy777]

Yes, check for vacuum leaks.

You may also want to check and see if there are any codes stored in the ECU. Instructions on how to pull the codes are on my site.

www.surrealmirage.com/subaru/engine.html

[slipknot51]

Could a faulty bypass valve/dump valve/air bypass valve cause a vacuum leak internally. I have a adapter plate with a 90 degree fitting right off the intercooler running to the bov inlet and then the outlet runs from the valve back to the intake track just before the turbo. The vacuum line is coming right from the manifold like it did from the factory. I double check the valve itself and saw that the arrow is facing the right direction. Now the real question is should pressure be able to leak from inlet to the vacuum and vise versa from the vacuum line to the inlet. Im guessing its not so im sure the valve is toast

[Legacy777]

Under engine vacuum that valve should be open. So what that's saying is that when you're cruising along the turbo is more or less just free spinning and air could take the path through the turbo or the bypass valve to the engine. You could essentially think of it as a single pipe. But once the valve sees atmospheric or higher pressure it closes.

[slipknot51]

So in theory i should be able to take a vacuum pump and apply vacuum to the vacuum port and be able to blow thru the bov i know that when i apply air the the inlet side of the valve the vacuum port blows out air. Im wondering if thats normal or does the bov work of a differencial pressure theroy when you have a low pressure on the control side and a higher pressure on the other side it doesnt allow air thru it but when the pressure equilized or is greater on the control side it will allow air flow. Also should the control side be able to hold vacuum. Im thinking that the diaphragm is damaged on my bov

[Legacy777]

Umm....the vacuum reference port should be completely isolated from the actual valve. If you can blow air through one end of the valve and it comes out the vacuum reference port, then yes it's toast.

[slipknot51]

That what I thought but I just wanted some one else's input on the subject. It was weird I have been noticing that the valve has been leaking once I was above 8 pounds of boost I could hear a hissing or almost sounded like a fart to be honest. But for sure now I know its bad when I can blow air in to the inlet of the valve and its blows out the vacuum port aka the control side

[kimokalihi]

I've got one or two laying around in my garage...

[slipknot51]

So thanks kimokalihi for the valve worked out great now my gauge is reading 20/21 inches of vacuum. But the weird thing is the car for some reason when its cold runs great no idle issues but once it gets hot the car start to hunt for idle like changing from 700 to 300 to 500 ext im sure you get the point the car is driveable it runs and shifts fine bov is now going off like it should and car is pulling more then 20 crusing around and on decel. Now the question is could there be a IAC issue causing this problem or could I try to take and reset the computer start run the engine and let it do the relearn prosses

[Legacy777]

I'd try and do the ECU reset first, and then see how things work.

[slipknot51]

Well reset my ecu over night and re hooked it up today let the car do the relearn and once it got up to op temp it was doing the same thing as before. Its still doing the same thing as before idling like crap when in drive or in park and when going under boost and letting off throttle its like the bov doesnt work and the turbo is fluttering. I still have my boost gauge routed into the same vaccum line as the bov vac ref is and im getting 18 inches at idle and over 20 on decal. Im guessing its now a vacuum leak or intake leak any common spots to check

[2.2TLegacy]

Just follow the intake piping and search for any cracks or loose connections. Also make sure to check all of your vacuum/boost lines for damage as well. Depending on how long it has been since you replaced everything, it would be a bad idea just to get some bulk line and have at it.

[slipknot51]

Well did some investigation pulled both the intake and my tmic and found the 90 degree turbo inlet boot that I have has a nice crack in it that doesn't look repairable and look like it could be leaking enough and could be causing the issue but I also check the vacuum lines/ pvc lines and every thing that side seems to check out good I did replaced most of them when I got the car. Could that intake leak cause the turbo flutter noise I hear once I let off the throttle after boost plus it does sound like I have a small leak once I get into boost more then 10 pounds i guess i could pressure test my tmic to see if that is holding pressure properly

[slipknot51]

Well update on the car. I got the new 90 degree inlet elbow in and im still having the same issue. I did pull my intercooler and inspect my vacuum lines and the intake manifold and every thing does check out good and no issues. I checked all the intercooler piping and that check out good and now my 90 degree elbow is good too. I did get the car back togeather today and ran the car my brake light was on and I did notice that when i pumped the brakes my vacuum dropped the car did stumbble a little then vacuum increased again and once it got warm it got worst once i pumped the brake. plus im still having the issue with the turbo flutter. Im just starting to get frustrated with the car any ideas

[kimokalihi]

Get a pressure tester from siliconeintakes.com that fits your turbo inlet and pressurize it with a bike pump or compressor with regulator to 15 psi or so and see if there's any leaks between the turbo and intake manifold. You'll need to block off the intake side of the of the system.

[slipknot51]

Well took and ran my car yesterday and once the car warmed up and started to run like crap I took and played around with some of the smaller vacuum lines around the canister and I noticed that when i took and unplugged the vacuum line from the manifold to the Tee the car ran worse then like night and day the car ran better I was playing around by the maf sensor and baro/boost control solenoid and the check engine light came on I pulled the codes and i got codes 23 and 45 Im guessing i could take and do a resistance check on both the maf and baro sensors to see what there resistance is and see if one of the sensors is bad

[Legacy777]

Yeah that would be a good next step.

For the turbo cars, code 45 is both the MAP sensor and the pressure exchange solenoid. So check both of those

[slipknot51]

Well did a little more investigating tonight and found that then I wiggle the wiring going to the tps,coil and iac the car stumbles really bad and then I let off it still idles like crap Im guessing that im having a issue in the wiring harness were the iac might be receiving some voltage from the ignition coil or tps causing it to open more then the computer is commanding it to be causing the idle issue and possible flutter issue. Idk how the iac is control im guessing by PWM im guessing the higher the duty cycle the valve is closed and the lower the duty cycle the valve opens. I guessing this could make since and would support my theory. Any other suggestions before I try to find a complete engine harness

[Legacy777]

The IAC valve has an open and close signal. Yes they are PWM, but you'll probably get a combination of lower and higher on either side of the open & close coil to obtain idle.

If wiggling the wiring does cause hiccups, then I would certainly start there and check the resistance of the wiring from end devices IAC or TPS to the ECU. Also, check that appropriate voltage is reaching the sensors.

[slipknot51]

So I have done a little reading on there and I was looking into swapping out the engine intake harness since I found issues with the harness. Now the question is would I have to repin an N/A harness to make it work with my turbo car I know about the coolant temp relocate which is fine. Plus is there a difference between the manual and automatic harnesses I remember reading that the automatic iac is different then the manual one as in 3 pin vs 2 pin. The place I usually get parts thru has a whole lot of N/A harnesses laying around but no turbo harnesses. Other wise the only other opption is to pull the harness and repair the damage which might be the same amount of work.

[Legacy777]

The non-turbo & turbo harnesses are different, as are the 90-91 harnesses vs. the 92-94 harnesses. On the three plug harnesses, 90-91's and the turbo harnesses, the third plug is pretty much just ground pins.

I'd recommend trying to find a 90-91 non-turbo engine harness with three plugs. All you should need to do then is depin that third square plug and pin them to the round plug from your turbo engine harness.

There is no difference between manual and automatic engine harnesses.

[slipknot51]

Oh I was just checking I have my 91 turbo and I do have the 3 plugs 2 square and 1 rectangleish square one. I was going to get the same year harness in the na and was just wonder besides the coolant temp sensor relocation is there anything else needed to do or will it be plug and play at that point

[Legacy777]

Ok, that's right....the 91 turbo does have the same three square plugs as the 90 & 91 non-turbos.

Nope, nothing else is different other than the location of the coolant temp sensors.