boost pressure, hows it holding?

[nello]

When you launch your sy/ty does the boost level stay consistent or pegged (say 14.5psi) until you let off the gas or reach your desired speed? My truck, can't figure out if it’s the boost gay-ge (VDO) or I'm loosing boost pressure somewhere. I had a 93 turbo Mitsu Eclipse and the boost was pegged at max on full acceleration always. WTF.


It got me sniffing for problems and I figured out that my intercooler is not working right, busted pump, I hope. It’s got about 60k on it.

Only my first launches are somewhat respectable. All other launches after the first are week. Put truck in maintenance mode and the IC pump never turned on. Even on the first launch it never held a level of boost, goes down as fast as it goes up.

So I'm pulling the intercooler out this weekend and installing a new pump, flushing the whole system too. I hope this solves my problem. Anybody have diagrams of the intercooler setup? Man, it better be the pump.

 

[Black Knight]

Re: boost pressure, hows it holding?

Make sure to get a bigger pump, reroute hoses, hot wire I/C all the good stuff, that could be a big part of your problem all your doing is forcing hot air in there.

 

[dhorsman2000]

Re: boost pressure, hows it holding?

So you got me confused, does your truck go to full boost on a launch, or does it have no boost on a launch??? Your intercooler pump isn't gonna make a huge difference on how much boost you have. It could be a wastegate issue. Give us some more info, ie. if you hold the brake and give it gas (boost launch) where is your boost pressure at, at WOT and a full load (driving down the road in drive) what does boost do?

 

[QUICK STORM]

Re: boost pressure, hows it holding?

more info please

 

[nello]

Re: boost pressure, hows it holding?

more info please

At WOT my boost shoots up to about 11.5-12psi (thats what the VDO gauge says, never hit 14 before) but then starts to drop back down to 0 even though I've still got my foot on the gas. I had a problem with a crimped guage line, I fixed it (boost was only going to about 7psi before the fix), now I'm up to 11and 12psi of boost, but like I said it drops really quick.

I'm changing the IC pump because I couldn't get the pump to turn on when in maintanence mode and the heat exchanger and lines never got hot. I never saw water moving in the CAC, felt any vibrations from the pump, or pressure in the lines. I hope I made a little more sense.

 

[QUICK STORM]

Re: boost pressure, hows it holding?

intercooler operation will not affect boost unless its leaking. do the bike tube test and see if you have any vacuum leaks. tb shaft is an extremely common leak. intercooler operation will affect KR and if KR happens the ecm will pull timing.

 

[nello]

Re: boost pressure, hows it holding?

intercooler operation will not affect boost unless its leaking. do the bike tube test and see if you have any vacuum leaks. tb shaft is an extremely common leak. intercooler operation will affect KR and if KR happens the ecm will pull timing.

What KR mean again, sorry its late.

So anyway, I tried the tube test and heard a lot of hissing going on, I was having idle issues at that time. What is supposed to happen? I mean since the valves are open the air is just going to flow out the exaust right. I have replaced the plenum gasket twice, once myself and once by my mechanic. He says its not leaking.

I was thinking waste gate like dhorsman2000 said. Whats a good way to test, or replacement WG, anyone have any recommendations?

Oh, I have never seen boost build from doing a brake launch so I just stop doing it. I'm waiting to get a deep pan on the tranny. Thanks buddieeez.

 

[gjp]

Re: boost pressure, hows it holding?

Hissing is probably comming from the TB shaft. Common problem. No IC working will cause KR even at low boost levels.(dont ask how I know)

 

[nello]

Re: boost pressure, hows it holding?

Hissing is probably comming from the TB shaft. Common problem. No IC working will cause KR even at low boost levels.(dont ask how I know)

Ok, I won't ask how you know but you guys lost me with KR...whats that mean again?

 

[Jimmy]

Re: boost pressure, hows it holding?

First of all let me say "welcome" :cheers:
I'll clear things up for you.
First of all,if the boost is leaking off when you are WOT,then you obviously have a boost and/or vacuum leak.How many inches of vac is it pulling at idle?

Check the ic to tb clamps and rubber coupler for leaks. Check the turbo to ic hose for cracks.

This hissing you heard might be vacuum leaks.
Replace all your vacuum lines.They are dryrotted and cracked and the reason for your hunting idle.

Keep your foot out of it until you have it running right,or you may throw a rod through the side of the block.


KR is knock retard.It kills engines.

 

[blk00z28]

Re: boost pressure, hows it holding?

How loud is it hissing? Check the hose going from the pass side pcv valve up to the intake. Mine was off and it would his loud. But I never had boost problems. :dunno:

 

[nello]

Re: boost pressure, hows it holding?

How loud is it hissing? Check the hose going from the pass side pcv valve up to the intake. Mine was off and it would his loud. But I never had boost problems. :dunno:

The hissing was never heard when driving, only when I tried to pump air using the bike tube test. But I figured the noise was coming from the air blowing through the valves and out the exaust. I mean it doesn't hold any pressure right?

So far the truck has run strong with the exception of my falling boost. The idle is a little bit rough but nothing compared to when I first got it. It was ticking about 2 to 3 hundred RPMs back and forth easy.

So, I am replacing my vac lines, ic pump, turbo to CAC hose, and PCV hoses, and probably the PCV valves too. How bout the waste gate, is it pretty complicated and expensive?

Any recommendations on VAC lines would be nice, where to get, order. I've tried before but nobody has what I'm looking for. Are they all pretty much standard? Thanks again, keep the info coming please.

 

[Black Knight]

Re: boost pressure, hows it holding?

For vac lines you just have to go to a parts house and purchase some lenghts and cut to fit, there are diagrams on file here, seach for vac stuff.

If your still stock turbo your wastegate is going to be inside the turbo, the actuator will be external, so complicated would be up to your level of experience.

It sounds like your on the right track but still hard to understand what is going on. The truck will make 14psi but once it does it just starts bleeding it off to 0? If its making boost and then not, I mean it has to be going somewhere wastegate stuck open, another leak?

 

[nello]

Re: boost pressure, hows it holding?

For vac lines you just have to go to a parts house and purchase some lenghts and cut to fit, there are diagrams on file here, seach for vac stuff.

If your still stock turbo your wastegate is going to be inside the turbo, the actuator will be external, so complicated would be up to your level of experience.

It sounds like your on the right track but still hard to understand what is going on. The truck will make 14psi but once it does it just starts bleeding it off to 0? If its making boost and then not, I mean it has to be going somewhere wastegate stuck open, another leak?

Exactly right, boost jumps from 0 to 12psi and then starts to head back to 0 in a hurry, like its leaking. I got to do more testing because I've been real easy on her. I'll be back on this topic after the weekend. Gotta make some changes before I can go further.

 

[gjp]

Re: boost pressure, hows it holding?

This is the kit I got. It worked out for me and so far I am happy with it.
http://cgi.ebay.com/ebaymotors/Plat...ryZ33601QQihZ002QQitemZ120040257342QQtcZphoto

 

[Black Knight]

Re: boost pressure, hows it holding?

Did you get the black kit? I know you can get the stuff in red and wondered how it would look with it all red?

 

[QUICK STORM]

Re: boost pressure, hows it holding?

i doubt you have an exhaust leak, can you hear the compressed air thru the tailpipe or near the exhaust manifolds/turbo. like i said tb shaft is a common vacuum leak. check turbo shaft play in/out and up/down. if you have excessive up/doen movement turbine bushing needs to be replaced. basically rebuild turbo.

 

[nello]

Re: boost pressure, hows it holding?

i doubt you have an exhaust leak, can you hear the compressed air thru the tailpipe or near the exhaust manifolds/turbo. like i said tb shaft is a common vacuum leak. check turbo shaft play in/out and up/down. if you have excessive up/doen movement turbine bushing needs to be replaced. basically rebuild turbo.

What I mean by leak out the exhaust is, using the bike tube test, would pumped air in just go throught the intake, then the exaust valves and then out the exhaust pipes? So no pressure would be built up right? You just have to listen for leaks, and my loud ass air compressor pretty much rules that to be impossible.

I did pull my intercooler system out today...WOW! So far this is the easiest job I've ever done on my truck. Pump looks to be totally shot. Got one on order from Mike Lee so it should be here any day. Replacing all the IC hoses as well.

Checking for turbo play means take the air intake pipe off and move the impeller around right?

 

[QUICK STORM]

Re: boost pressure, hows it holding?

rather than compressed air, smoke tester is the way to go. yes pull turbo intake boot off and move impeller around.

in a sense your not really putting the intake system under compression, your justb lowing compressed air into the intake system and listening for the air to to take the shortest path out i.e. vacuum leaks.

 

[Black Knight]

Re: boost pressure, hows it holding?

Well Branden since he said he can't hear anything because of the compressor ( nello you can't move the truck away from the compressor and just use the hose? ) wasn't there a post on here awhile ago about putting a smoke bomb in the TB so you could see where the smoke was coming out of and then pressurize?

Checking for turbo play means take the air intake pipe off and move the impeller around right?

Yes, should have a minimal amount. Hey Branden is it in/out or up/down thats really bad I can't remember?