low vacuum/low boost help...

[Jay Drew]

i was idling in a parkin lot gettin ready to leave work, and all of a sudden the sound from the engine changes a bit, and my boost gauge was showin a vacuum of only 9-10 in/hg at idle. drivin home i push it a little to see what it does, boosts consistently to 10-11 psi, boost control was set to 15 psi.

after a quick look at the engine, nothin was visibly wrong. i didnt see any vacuum lines that might have falled off, although the line from my boost controller to the wastegate might have come off, i couldnt see and didnt think to check it at the time. could that cause somethin like this or would the effects be different? any ideas?

[Chao C. Yin]

Low vacuum? check for leak "after" the throttle body.

But I am sorry to say, your description sounds like a jumped T-belt.  If you hear some pinging at low-mid revs and lost of power, check and see if the timing marks on the cam sprockets line up or not.  

Don't worry, your valves are still ok.

[Jay Drew]

i dont hear any pinging, and it drivability is the same as it was before, just with a bit less top end, kinda like when i had it set to 10 psi before this. would the timing belt jump at idle? i hope thats not it, cuz i really dont have the money for anything that costs any money to fix right now aleady the clutch slips pretty bad even at low rpm launches, and the brakes shake like hell above 80kmh, really dont need to add another big thing to the list  :cry:

[Chris Andrews]

The T-belt could easily jump a tooth at idle.  

Rotate the crank by hand to get #1 cylinder TDC, then remove the timing belt covers and make sure all the marks line up.

Hopefully you have a timing light. If you skipped a tooth, quite often the base timing goes to hell, and this is a quick check.

When I had a faulty t-belt tensioner, this happened several times.  My driveability did get worse. Engine seemed a little rougher.... but your symtoms may vary....  

Hope its a loose hose/bad gasket or something....

[Jay Drew]

hmm. i dont have the greatest hands-on knowledge with this sorta stuff, but im pretty sure i did it right... :roll: anyways, heres a pic of my cam gears

does that look like its jumped a tooth?, it seems like theres no way the 2 middle marks would line up.. or am i supposed to be looking at the outside marks? anyway, if any of you smart people can tell if theres anything wrong in the pic, thatd be great. also, assuming the timing belt did jump a tooth, how hard/expensive is it to fix? and is it safe to drive on for now?

[Chao C. Yin]

Bingo...one tooth jump, no wonder your car doesn't drive too bad now (mine had jumped 2 or 3 once, and it was pretty obvious)

First to find out why it jumped?  Brokent balanceshaft belt, AC belt are possibilities.  Or bad tensioner, or whatever.

If your timing belt is more than 60,000km old you should replace it anyway.

The belts are not expensive, but the tensioners are, and you need some new seals, pulley bearings, a waterpump etc.  They add up. :cry:

[Jay Drew]

the timing belt was done about 40k ago. i'l probly make another appointment with lowell then pretty soon, but is it safe to drive with it as it is now for a few days?
and is it much extra work to have the balance shafts removed while the timing belt is being done?

thx

[Chris Andrews]

Jay, if you just leave the front shaft in, just to block the oilers in the bearing, and have the rear shaft cut and machined, it would be about $60 for machining, some replacement gaskets ($80?) and a little bit of labour (an hour?).

I would DEFINITELY change the tensioner.

[Troy Simkus]

there's a deal at eastway chrysler in ontario (Adam Clay on ca.dsm.org) for timing belt kit, includes everything you need for a timing belt change for $318 i think.

[Jeff Armstrong]

Maybe we can get an even better deal with a group buy.  That's a wicked deal.  Does this come with a waterpump?  
I'm sure L&R can use a few for on the shelf when an emergency timing belt replacement walks in the door.

[Troy Simkus]

well thats the november deal for dsm members, dunno if you can get better than it.

[Jay Drew]

well after talking to lowell on the phone, he gave me a few suggestions first and told me how to do it properly, looks like it didnt jump a tooth after all


#1 is at TDC for sure now, and the marks line up perfectly.. anyone got any ideas now?

[Chris Andrews]

So what were you doing wrong?

Anyway, back to the drawing board then.   Check compression and pressure test the intake.  I would still check base timing with a timing light.

[Jay Drew]

in my mechanics class today, i reset the ecu and took apart pretty much to whole intake. put it all back together, tightened everything down really well, and fired it back up. vacuum was back to around 17"hg, boosts back up to 15 psi. i dont see why taking apart and tightening down the intake side of things would have made a real difference, if somethin was gonna blow off or start leakin i figured it woulda done it under boost not while idling. oh well, seems back to normal now. if resetting the ecu caused it to go back to normal, anyone think the original problem may have had somethin to do with leaky capacitors? i dont know if they've ever been replaced