vacuum leak...?

barlar · Post by **barlar** » Wed Mar 08, 2006 10:53 pm

Hello again,

when putting the engine back in my car it runs like pure d*ng. I thought I had an air leak of some sort as the boost gauge shows just a little less than -1 bar at 1000 rpm's above this it's spot on the -1 bar. So I checked every hose (which are new), sprayed everywhere with starter gas and removed the EVAP system just in case (don't do this if you don't want to manufacture a whole new front end to hold the bumper, that was a day well spent).

I THINK it's a bit better now, but it still can't hold the vacuum properly. The needle rises about 2 maybe 3 mm. My question is, is this necessarily an air leak or could this behaviour be normal?

Hope I can sort this out because I REALLY want to know how the car goes now.

Cheers

martinholmesuk · Post by **martinholmesuk** » Thu Mar 09, 2006 2:45 am

Aftermarket boost gauge? Mine (after market) shows neg while at idle.
does spike if u blip the throttle but shoes no boost unless engine is drivng the car.

not sure if that's what u want to know!

robin_xr4i · Post by **robin_xr4i** » Thu Mar 09, 2006 8:33 am

What are the revs like at idle?

If the idle is too high i guess the boost gauge would read less than -14 psi (-1 bar)? This could indicate a sensor fault (TPS, Idle control valve, AFM etc) or an air leak on either a boost pipe or vacum pipe?

Tighten all hoses and fiddle about with the sensor plugs, see if that helps!

barlar · Post by **barlar** » Thu Mar 09, 2006 10:48 am

Thanks for the reply's, but the thing is that. I can't find any leaks on any hoses and starter gas gives me nothing. Throttle switch is OK, and I think the idle valve is OK. But just in case, do the idle valves leak when faulty? It's one of the few possibilities I have left.

The gauge I'm referring to is the original boostgauge. So noone has experienced the loss of vacuum when everything should be OK? D@mn it....

Looks like I need some more work, but I frankly don't even know where to start....

I'll keep in touch,

Lars

martinholmesuk · Post by **martinholmesuk** » Thu Mar 09, 2006 7:56 pm

So what's it idle at?? (RPM) does it go up and down the revs?

Look at the idle valve, off it is a black disc looking thing! The valve inside can split and cause idle/leak problems

remove and see if you can blow through it.

if you can then it's fooked.

barlar · Post by **barlar** » Thu Mar 09, 2006 9:14 pm

Right thanks, I will do this tomorrow. But A few months back I did check the idle valve, by the way, mine's T-shaped with a "rotating" valve inside what does yours look like? The revs are quite stable it's running a bit like an old truck goes a wee bit up and down, very quickly, but I'll spend the day tomorrow on jiggling with the modded MAF and see if I can get a few things sorted.

When I first started the engine again it ran like crap and I thought maybe I'd put the cambelt on wrong, but I checked it and it was OK. The markings lined up. But has someone got experience of putting it on wrong? What are the symptoms?

And as every time I'll appriciate all the tips you can give me on ensuring me that there are no airleaks.

Will keep you updated, thanks again,

Cheers

clio_rsi · Post by **clio_rsi** » Sat Mar 11, 2006 1:03 pm

if youve put the cam belt on wrong, it either wont start at all, or you'll hear the lovely sound of your valves hitting the top of your pistons, like i did the first time! lol. sounds like idle valve to me?

robin_xr4i · Post by **robin_xr4i** » Sat Mar 11, 2006 4:10 pm

clio_rsi wrote:you'll hear the lovely sound of your valves hitting the top of your pistons, like i did the first time!

Ouch i bet that was expensive!

barlar · Post by **barlar** » Sat Mar 11, 2006 4:24 pm

OK! so I can't have the cambelt on wrong if the engine is running? This sounds good to me! I've been at the garage yet another day and today I broke one of the pipes on the solenoid valve.........yet another problem to fix. But I'm hoping the new gaskets will give better result regarding the air leaks. So hopefully I can start it up tomorrow again and see how it runsWill keep posting, thanks for all the help.

Cheers

clio_rsi · Post by **clio_rsi** » Sat Mar 11, 2006 8:14 pm

@ robin, yeah it was but while i had it off, i had a stage 2 port and polish with new valves.

martinholmesuk · Post by **martinholmesuk** » Sat Mar 11, 2006 9:08 pm

I'll spend the day tomorrow on jiggling with the modded MAF

Why do you have a modded maf? Are you using a 10K potentiometer on it? Your idle T valve is the old type. Anyone here got the T shaped valve and able to get a picture?

Cheers

barlar · Post by **barlar** » Sun Mar 12, 2006 3:34 pm

I've got different injectors, and Rich modded the MAF so I didn't have to put the MAF in a bigger tube to match the injectors. Yes I have the T-shaped idle valve, and I think there already are a couple of pics on it on this forum.

But again, can you put on the cambelt wrong and still have the engine running? I'm going back to the garage now to test the car......fingers crossed....

/Nervous....

clio_rsi · Post by **clio_rsi** » Tue Mar 14, 2006 5:56 pm

yes you can get it to run with the belt timing out slighty, had mine out by one notch, still ran but very rough and you could hear the valves just touching the top of the pistons. if its more than that it prob wouldn't start at all.

Williewammes · Post by **Williewammes** » Thu Mar 23, 2006 7:15 am

Hehey,

Again a problem wich I recognise. I never had a boost gauge in my car, till last week. I noticed that with the engine off, the boost is 0 (normal atmospheric pressure). When I start the engine, the boost gauge will hit the -1 point and stay there when idling. Only when I'm at full throttle the needle will go into the yellow zone above 0.

Is this normal or does it indicate a vacuum leak?

Sometimes the car is feeling a lot less powerfull too, expecially in higher revs. like it doesn't want to work hard. It can be that an hour later, when I start it, there no problem at all.

Also, at idle it regularly seem to misfire or something, wich gives a little shock through the car. But again, it doesn't always do that.

Any ideas guys? I konw, quite a lot of problems at one time.

Thanks