Vacuum leak/Loss of power...Help!

[polarisman14]

Hey all,

Trying to sort out some issues on my turboed Zetec. I had some aftermarket cams on there and I swapped back to stock cams after having lower than ideal power levels and vacuum pressure being off a few inches (thinking the increased duration was killing power and possibly leading to vacuum leaks). With the stock cams in place, even after using the cam timing tool, the car still idles like it has a more aggressive cam and is only pulling 14-15 inches of vacuum instead of the 18-20 it usually does. Any suggestions on what may be causing this? I'll be checking compression, cam timing, and for vacuum leaks, but didn't know if anyone else had prior experience with these issues after a cam swap. Thanks!

[2002red]

Do you have adjustable cam gears ?

If so, try retarding the exhaust cam a little bit (1-2 deg). But I think it sounds more like an intake leak.

[polarisman14]

I do have adjustable cam gears and I'll be trying that soon, thanks for the reassurance...I tried testing for vacuum leaks today just with starting fluid spraying it around the lines but didn't get anywhere--borrowing a friend's vacuum leak tester next week. Keep the suggestions coming, please!

[AcIdBuRn02ZTS]

check the intake manifold seals... throttle body gasket.... and IAC motor seals... all of which can be subject to vacuum leak besides the obvious hoses...

good luck
-AcId-

[polarisman14]

I'll do that also, thanks for the heads up--scott (greentengu) just found an issue with his TB gasket that led to crappy driveability as well. The thing that doesn't make any sense to me is that typically when you have a vacuum leak, doesn't it cause the RPMs at idle to go up? I remember when testing my previous turbo setup a vacuum line popped off and the rpms were about a thousand higher than normal at idle. Currently, they are right at the normal idle rpm but it idles like a lumpy cam. I just don't get it.

[G-forces]

Since it happened after the cam switch, how about the valve cover gasket? Are you confident that is securely in place?

[polarisman14]

Yeah, it definitely is...Not worried about that.

[polarisman14]

I took the liberty of shooting a short video, maybe this can help things along a bit...:

http://s512.photobucket.com/albums/t...IssueVideo.flv

[G-forces]

Nice video, your dash looks ready to roll. Have you checked compression yet.

[polarisman14]

I haven't, and I decided I'm gonna stop being a cheap-ass and start accumulating some useful tools AKA buying a compression tester tomorrow. Tired of waiting on other people for something I should probably have given how often my car is broken, lol..

Thanks about the dash--the e-boost2 is on the other side of the gauge cluster in place of the coin tray, that's the thing that beeps twice

[polarisman14]

I think I eliminated the most potentially expensive item with the compression test...The numbers I got are REALLY good for what I understand. 210, 215, 220, 215. The vacuum tester I'm still not super sure about how to use but it's still only pulling 14-15 inches of vacuum at idle...Is it possible for the compression to be fine but the cams still be out, and would that have an impact on the vacuum pressure?

[G-forces]

It's always good to know your compression and it seems fine, a bit high (at least if it was stock), but good spread.

I can't see how the engine would run/idle if the cams were far enough out to reduce vacuum. I think you should re-time them with a dyno just to make sure you have them where you want them, but probably look elsewhere for a leak.

[polarisman14]

Yeah it is a bit high especially since I'm running 9.0:1 pistons instead of the stock 9.6 ratio. I cranked it over 6 times (it said to do it at least 4) so maybe that raised it up a bit, but the most important part is that there are no outlyers. I need to try and find a smoke machine or something so I can try to locate the vacuum leak...there are a LOT of places that could happen.

[polarisman14]

Update, had a chance to play with the cam timing a bit and did manage to pick up 5psi of compression across the board after an hour or two of tweaking. The car is quicker, but still nowhere near where it should be. Back to thinking it's a vacuum leak, but at this point anything is possible.

[greentengu]

Well, moving on here for a bit because your video made me shudder.

Why, you ask? Because your exhaust sounds pretty much exactly like mine from my Troubled Car: a slight miss, pop pop popping, or as my friend Brian put it, a "half miss".

Maybe take a stethoscope to it and have a listen to the car's innards? Just a thought, even though I have absolutely no idea what that could possibly accomplish.

Again--very telling video that sounds just like my car, which still indicates has knock at idle. Could some sort of knock be causing your car to pull timing somehow? (I'm not even sure you have a program that can pull timing enough to affect things; just fishing for thoughts).

Good luck and please keep posting on this.

Cheers,

Scott

[polarisman14]

IIRC the knock sensors on the zetecs are pretty useless--I believe most people tune around them. I spoke with my mechanic for a half hour today and he says all of the symptoms I have are still associated with improper cam timing...I'll try to zero it out myself and if I can't get it then I will have him do it. I thought it was foolproof but I had him talk me through the process he went through and it was a little different. He suggested advancing the intake cam, which should increase IM vacuum (just to see if that will help). If this works and I can restore the vacuum on stock cams, I may give the aftermarket ones another go.

[polarisman14]

Some huge progress made today...Decided to play with the cam gears a bit more to see if there was more vacuum to be found somewhere and I found out that the cams are WAY out. Not sure how I pulled it off but right now I have both cams retarded 10 degrees according to the adj. cam gears and I have about 16-17 inches of mercury at idle...Car starts quicker, drives smoother under part throttle, goes into boost quicker, and is much quicker under boost...Not where it should be, but I would estimate about 200whp right now based on my previous setups.

As I now know that my issue was cam timing related, I'm putting my FI cams back in (with the same amount of vacuum before, they pulled much harder) and if the cam timing is off upon my reinstall, I'll be taking it to my mechanic to have him time the cams for me.

At that point I should be around 250whp at 9psi--more than enough to spin the tires in the first couple gears. That'll make a decent DD, and I'll be continuing the quest for 350whp on less than 20psi.

[2002red]

Sounds good that your making progress.

[polarisman14]

Fixed it! My mechanic was nice enough to tell me a step by step on how to retime the car and my issue was that I wasn't rocking the crank back and fourth within the TDC stops to help the cam belt tensioner set itself correctly. As a result, last time, it was off by an inch or inch and a half (about fifteen degrees cam timing on both cams). The car rocks n' rolls now