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CVSVO666
05-04-2012, 02:42 PM
I'm having some issues with my 1984 Svo, after setting timing to factory specs car still idles rough, I ran compression check and everything seemed fine, when I hooked up a vacuum gauge the needle bounced between 8 and 10, when reved vacum drops like normal then shoots back up into the 19 20 range but falls back to 8/10 imidiatly after, i know that average healthy vac pressure should be around 17-20 at idleDoes any body know what could be causing the lack of vacuum? And needle bouncing at idle?

NotBud
05-04-2012, 03:49 PM
Bouncing needle - First off, it's a four cylinder engine. Not gonna be as even vac as more cylinders. And the bouncing greatly depends on the amount of gauge damping. Could be a sticking valve, but that's almost impossible to diagnose with just a vac gauge and you would have other symptoms. If the RPM is above idle and the throttle is closed, vac will increase briefly. That's expected.

MOST rough idle issues are related to intake side air leaks. Could also be fuel supply/condition issues.

As usual - start with the basics and make sure everything you can get to is proper: new spark plugs, wires, cap, rotor, etc. New fluids, replle vac lines. Check for intake manifold air leaks. Check fuel delivery and pressure. Use fresh petrol.

What cam is installed?

Fix as needed.

CVSVO666
05-04-2012, 06:47 PM
Thanks for the input bro, well first the car has been sitting for 15 years haha a d this is only my second turbo car, my first was a supra. I have another couple questions if u don't mind. First is what's the best way to check for leaks on the intake side? Second one is what's the compression readings suppose to look like on the 2.3 for normal and healthy engines, and as for the cam question I'm assuming it's stock, I re checked the timing and ran some sea foam through the car and it smoothed out a bit, but vacuum didn't change.

Jay4hand
05-05-2012, 05:49 AM
The easiest way to check for a vacuum leak is to get a can of break clean and spray all the vacuum lines one at a time, you are looking for a noticeable increase in RPM, if it rises, you have found your leak, if you do not, then spray around the intake manifold, small areas at a time, gaskets first, hose fittings, ect. Do this slowly, then move to the turbo, lastly the vacuum booster both under the hood and under the dash. I believe 150psi is optimum on the compression test for these motors.

mrzw70
05-06-2012, 05:22 AM
You could use WD-40 in place of brake clean and get the same results. I've never used brake clean for this, will it discolor the metal?

Jay4hand
05-06-2012, 05:41 AM
Use brake cleaner.. Brake cleaner will not discolor the metal because it has an extremely high vaporization rate, and you will only be doing small spurts at a time. If you use too much, it may possibly discolor old rubber hoses, but that will be ok if you use armor-all on it afterwards.

scenario
05-06-2012, 08:01 AM
Absolutely do the brake cleaner thing!

There is a GOOD chance its a vacuum leak and if so I am sure it will solve your idling problem. I had a similar prob with a V6 and it was an intake vacuum leak.

I am just getting my 1986 SVO back from a 15 year sitting out as well, I am not sure how many vacuum hoses there are but look everywhere and check the intake manifold gasket with spray as well!