Low Vacuum but drives great?

[flaatr]

OK I did a search and everything associated with low idle vacuum usually follows with drivability problems... I don't have that.

Car starts instantly cold or hot and when cold does the normal fast idle until warm... drives/pulls great... BISS is set... idles normal when cold or hot *except* when I pull off a freeway after an extended period. In this case the idle fluctuates a bit more than it should. The only thing I see is that idle vacuum is around 10-12 in.Hg where according to the factory manual (and others) say it should be 20'ish.

Engine is still basically stock... cams, turbo, all smog equipment except cat removed... 3" turbo back. Could the low idle vacuum be due to the no cat and 3"? Under deceleration vacuum goes to about 22-24in.Hg

Any thoughts?
-Raffi

 

[flaatr]

Did you end up figuring out what the problem was?

Not yet... I f'ed up big time on the way and am now fixing stuff that wasn't previously broken. 15 test is now several hours of repair just to get back to where I was.

FML... More details later.

-Raffi

 

[Boostdriven]

Not yet... I f'ed up big time on the way and am now fixing stuff that wasn't previously broken. 15 test is now several hours of repair just to get back to where I was.

FML... More details later.

-Raffi

Sorry to hear that you're still having problems but don't give up man, its just a car. Given enough time, research, bloody knuckles and sweat I'm sure you will get it figured out.

FML are the famous words of a friend of my. I always tell him that the attitude like that just discourages you from looking forward. Problems are part of owning a DSM but in the long run you can learn allot of things. I had DSM cars since 1999 and since then I've always been a fan. Sure you can have problems here and there but once you get it right there isn't a better car to mess with and build then DSM.

Don't know what problems you're fixing now but good luck and hopefully you get it fixed. If you need an advice on something let us know, we will be glad to help.

 

[Xploitn]

It can't be as bad as dropping a nonmagnetic bolt down an open spark plug well into a cylinder!

Good luck fixing it!

 

[flaatr]

It's close...

First I removed the upper timing belt cover to check the cam timing and while the engine was running I dropped a 6mm Allen wrench that took an odd bounce and got sucked in to the belt between the belt and intake gear... The engine still ran with the key wedged between the gear and lower cover so I shut it down and tried to remove the wrench... It feel into the lower cover. Pissed of I walked away.

A few days later I removed a few of the screws on the lower cover and was able to fish out the Allen wrench but now the cam gear skipped a tooth... Time to order the tensioner tool from Jay Racing... I order the full kit with the parts to hold the gears in place and while using them I drop a part of the kit even deeper into the lower belt cover!!!... I walked away again.

Now I've got the mount off, the all the pulleys and lower timing belt cover off... I got the tool back and now I'm still not back to square one. Since I have it torn apart I'm installing new idlers and a tensioner and Gates Racing belt that I had along with a new lower timing belt cover... I'll reset the timing and put everything back together and pray I didn't bend a valve.

Like I said... FML

-Raffi

BTW, I never give up!!! I walk away sometimes to chill but I refuse to lose!!!

 

[flaatr]

Got it started back up last night with a bunch of new parts... Gates Racing timing belt, new idlers, etc. I was there and I had them to put in. The exhaust cam skipped a total of 1 tooth so I don't think I've done any damage, I got real lucky

I need to check and set base timing, verify CAS and up the BISS by 25-50 RPM and then I'll start the investigation... again.

-Raffi

 

[EVO9_Inside]

dont get too worked up, i just had a thread about this, my vacuum is at 15in/hg at idle or decel, still trying to find time to boost check mine though.
My car runs fine, but i only drive it on weekends.

 

[flaatr]

dont get too worked up, i just had a thread about this, my vacuum is at 15in/hg at idle or decel, still trying to find time to boost check mine though.
My car runs fine, but i only drive it on weekends.

Mine is an occasional weekend car as well. I'm not overly concerned with the vacuum situation... I would prefer a smoother idle that I think the vacuum would get me but even then I don't really care too much about it. It is what it is until I get around to building a new motor.

I just wanted to check the obvious stuff and I thought you all would enjoy hearing how lame I am

-Raffi

 

[Diamond Star Werks]

dont get too worked up, i just had a thread about this, my vacuum is at 15in/hg at idle or decel, still trying to find time to boost check mine though.
My car runs fine, but i only drive it on weekends.

Mine is at 16.x. but I have low compression. Altitude and cam profile will affect both cranking pressure and engine vacuum.