Need Help......91 AWD has 10 vac!!!!!!!!!!

[Justins99GSX]

Hello again... lately i have been driving around in my 91 TSi AWD for the past two weeks and have had my boost gauge around 10 vac at idle... This is starting to drive me crazy the past two weekends i have taken the intake apart and leak tested it several time.... this is what I have found out... I do have a bad Brake booster.... plugged the hole for the line got a little better but would still creep back to 10 vac... shaft seals are also bad but i don't think this would cause that much of a vac leak... and thats it I am gonna take it to Satan this week and see what they can find out but i wanted to post on here first to see if anyone had an idea... not even the local DSM guys here have any clue what else it could be WTF


ps. i did do a search on bent valves but my car doesn't suffer any of the problem like they state a bent valve would have... I am lost and don't have a pile of money to send to Satan to get my car running right again

Thanks again
Justin

 

[ddavisaf]

By shaft seal do you mean the turbo seals are bad?

It definately sounds like a boost leak. Soapy water everything when you do a boost leak test. Test it to 20 psi and it should hold for at least 30 seconds. Post back and let us know about the boost leak test.

 

[Justins99GSX]

By shaft seal do you mean the turbo seals are bad?

It definately sounds like a boost leak. Soapy water everything when you do a boost leak test. Test it to 20 psi and it should hold for at least 30 seconds. Post back and let us know about the boost leak test.

sorry by shaft seals i meant the ones that hold the throttle body shaft in place... i tried getting them replaced but mitsu dosen't have a part number for them... as far as the boost leak I have done it several times... I am only able to get 15psi and that doesn't even hold for very long.... i have a special leak detector thats better than soapy water and still can't find anything...

keep the ideas coming
thanx
Justin

 

[BOBS90TURBO]

Hey, Have you checked all around the intake manifold gasket, it is a hard place to check, I had one go bad and found it by spraying carb cleaner around it(at idle) and listen for engine change. Also, does the car run good/fine/normal, could it just be a bad gauge??

 

[BudmannG]

Throttle body shaft seals do play a big part. Do a boost leak test and then try moving your throttle open and closed. See if it leaks more or less through throttle movement.here is a link that might help you http://www.ca.dsm.org/faq/tb-shaftseals.html .

 

[ddavisaf]

Throttle body shaft seals do play a big part. Do a boost leak test and then try moving your throttle open and closed. See if it leaks more or less through throttle movement.here is a link that might help you http://www.ca.dsm.org/faq/tb-shaftseals.html .

I agree with everything here ^^^

Can't hold 15 psi is all bad. Replace the seals, then re test for boost leaks. Continue until you can hold 20 psi for a decent amount of time. Special tester or not, you have a boost leak.

 

[Justins99GSX]

Thanks again guys! I am beginnnig to think I am goin to have to replace the TB shaft seals and check again.... I just want to make sure that I don't have a bent valve.... I'll probably try to get the seals this week and work on it this weekend (again )... Thanx again guys.....

Justin

 

[Justins99GSX]

Thought i would ask another quick question..... I noticed today that while i was driving around that at 750-850rpm vac is at 10-11...but if i slightly step on the gas and get the rpms to 1000-1100 vac drops to 15-16 does that help anyone on diagnosing my problem?????

thanks again
Justin

 

[Defiant]

Hello again... lately i have been driving around in my 91 TSi AWD for the past two weeks and have had my boost gauge around 10 vac at idle...

Just for starters, where are you measuring vacuum at? Where are you tapped-in?

 

[Justins99GSX]

I have my vac gauge tied in before the Fuel Pressure Regulator Solenoid .... I have a question also when at idle what should the TPS sensor be??? (mine says roughly %10) And at idle should the throttle body be completely closed????

 

[Old Mitsu Tech]

A couple of things came to mind. First, I would get a known good vacuum gauge to compare with. I never trust any one gauge if I get a weird reading. If that's not the problem then I would do a compression test to see what turns up there. Also if the timing belt is off one tooth that could cause low vacuum. If that's the case then immediately change the belt as you well know these are interference motors. When you get the rpms up then chop the throttle the vacuum would naturally be higher due to the higher rpms. Other than that, checking for vacuum leaks would be the norm as has been suggested.

I hope this helps. Old Mitsu Tech

 

[ddavisaf]

I have my vac gauge tied in before the Fuel Pressure Regulator Solenoid .... I have a question also when at idle what should the TPS sensor be??? (mine says roughly %10) And at idle should the throttle body be completely closed????

10% is normal.

No, it shouldn't be compltely closed, but I mistakenly say it is on ocassion. As steve said in another thread, it's not possible, otherwise you'd get no air, and without air there will be no combustion....

Start with the boost leak test after the tb shaft seals and then we'll go from there.

 

[Justins99GSX]

Well to check up on things I did find that the intake gear is off 1 tooth........ Anyways is there any ways to get it to go back without doing the whole timing or should i put some tension on the tensioner and loosen the belt?????

took it to emissions the other day and failed Hydrocarbons by 2!!! Idle standard is 220, I got 222. WTF Anyways it look likes my vac. leaks and timing needs to get fixed asap..... I'll get on it this weekend............

Thanx again~!!!!
Justin

 

[Justins99GSX]

Hey there thought I would update this and gladly say that it was my timing... Spent all day this past saturday and reset the timing.. My only problems:
Satan wouldn't sell me a efin tensioner tool

Anyways I passed emissions yesterday (With no cat or EGR) WTF I also have since turned the beast up to 14 pounds on my small 16g... This is why I love these cars.... Just don't know when it will break again

Justin