Please Help Vacuum Issues!!

[thundertank2000]

Guys,

I am at a loss. I usually search and am able to find the solution but this one has me stumped. I have low vacuum and a rough Idle. I have done the following and cannot get it better then 12 in Hg:

1. New ECU (old one burnt up)
2. New O2 sensor
3. Boost leak test (no leaks)
4. New timing belt (rechecked timing marks)
5. All new TB gaskets
6. New coil
7. New ISC
8. Cleaned EGR valve
9. New BOV
10. Checked all vacuum lines and replaced a few that were worn looking


I hook up a vacuum gauge to the intake and get 10-13 in Hg. The rest of the RPM range is fine and the car boosts/pulls hard and otherwise runs great. I cannot get it to idle right and get good vacuum. Any help is appreciated thank you in advance. Please help so I don't have to take it to the dealer!!!

 

[ROOKIE1]

Fill in your profile page . Are you stock ?

 

[mitch26753]

search for a vac diagram that will help you out. Make sure everything is hooked! You could have a totally missing vac line in there somewhere. Also if you took any off make sure you cap them with caps. check around fittings. Look at your intercooler piping too

 

[ROOKIE1]

^^^^ good point . The vac lines in behind the intake are difficult to get to .

 

[thundertank2000]

Yeah I am all stock except for the MBC which is hooked up per the VFAQ walkthrough.

I have checked all lines per the Haynes manual. I followed all of them and made sure they were good. I also disconnected one side and plugged to check for leaks.

This is driving me crazy I don't know what else to check. The book said I could have worn valve guides but the whole top end was done on the car a year or two ago and has run well since. It also said to check the injectors but none of them leak and they all tick with a screwdriver on them.

I also forgot to mention that I have done a compression test and had 150 across all cylinders.

Any other suggestions?? Thank you for the quick responses.

 

[vancitydsm]

check your speed idle motor. double check that ## egr valve isnt open. Also check your fuel regulator vacuum hose see if its got some gas in it, plug the vacuum hose as well see if it makes a difference. Did this happen after replacing the ecu or anything? what could have cause this to start happening?

 

[Boost92awd]

http://www.dsmtuners.com/forums/art...-speed-shop-vacuum-diagram-removal-1g-2g.html

 

[awdtsi724]

As we all know finding a vac leak can really be a pain. Ive had the same problem before, i went and bought a can of starter fluid or brake cleaner and spray at near the lines and connections. If the cars idle increases then u found you leak...

 

[DJYoshaBYD]

yeah.. Your motor, if healthy, should have between 17-20 in of vac.. there has to be a hose that isnt hooked up, and the rough idle is telling me that you most likely have a vac leak.. Bust out the shop manual at look at the vac diagrams..

 

[thundertank2000]

Thanks everyone for the suggestions I will get the brake cleaner and go that route again. I tried it before but ran out halfway through, then just went to checking each individual line per the manual.

I will give it another go around and let you all know what i find. Again thank you all and please add any additional info you can think of or similar problems you may have had.