Down on boost, no CEL, no changes... what's up with that?

QuickDrive · Post by **QuickDrive** » Mon Feb 21, 2005 6:34 pm

Ok so the car hasn't been messed with aside from an oil change last week.

Aside from a gigantic drop in temperature over the last few days, nothing has changed...

Car Idles fine, but isn't getting full boost.. only gets up to around 7psi max as opposed to 12 normally.

Highway tested today, and just didn't have the push it normally did.

I haven't had a chance to Really check things out but nothing looks out of the norm under the hood.

It's too damn cold to troubleshoot today, but I think I'll be reverting to stock (lose the IC and MBC) to see what happens there.

I think it may be a boost leak, but the car doesn't sputter or pop, just low on boost.

Oh, and I noticed the Vacuum reads all the way in the -30 on my gauge when I'm off throttle in anything above 2nd gear. Normally it didn't read below 25 unless I was going over 60mph...

Any thoughts on what I should look at assuming I get a chance to get out there...

I"m not pleased when things just "happen" but that's cars huh...

vrg3 · Post by **vrg3** » Mon Feb 21, 2005 6:41 pm

I think your gauge might be at fault. There's no way your engine is producing an almost perfect vacuum (atmospheric pressure is about 29.9 inHg). Even the healthiest motors coasting from redline can only pull about 23 or 24 inches.

That wouldn't explain the car seeming less powerful, but maybe that part was psychological or something. I dunno.

A clog in the intake (like an old air filter) or exhaust (like a bad catalytic converter) can cause boost to drop.

QuickDrive · Post by **QuickDrive** » Mon Feb 21, 2005 6:46 pm

I thought of that too..

Catylitic or Air filter.

My K&N hadn't been touched (IE Cleaned) since purchase in May of 04...

My Cat on the DP is stock.... that could be the culprit...

I'm pretty sure it's not in the noggin on the loss of power... I know the kick the car has, and it just didn't have it today.

The gauge isn't the best, that I know...
I'm going to be testing it with your scantool if I can get my hands on a laptop.

At least I know the car isn't damaged in any way, it runs and idles fine, just seems to have a slight case of asthma.

azn2nr · Post by **azn2nr** » Mon Feb 21, 2005 8:43 pm

maybe your boost control solenoid went bad.

QuickDrive · Post by **QuickDrive** » Mon Feb 21, 2005 11:20 pm

Maybe...

But I've got an MBC in place of it.

THAWA · Post by **THAWA** » Mon Feb 21, 2005 11:42 pm

About the bad gauge. If it's liquid acutaed couldn't the liquid have compressed from the lack of heat? That would've caused the needle not read more to the left.

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 12:18 am

I don't think it's liquid...

It's a base model Autometer Phantom.

Seemed more spring actuated when I last remember seeing the guts of it...

vrg3 · Post by **vrg3** » Tue Feb 22, 2005 12:21 am

Bourdon tube, most likely.

It still sits at zero when the engine's off, right?

THAWA · Post by **THAWA** » Tue Feb 22, 2005 12:42 am

hmm, well metal contracts too. so I guess taht's also a possibility, but who knows how far I'm stretching that

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 12:43 am

Sits more like -1.5 but it's been like that since day one... I dropped the damn thing as soon as I took it out of the box...

vrg3 · Post by **vrg3** » Tue Feb 22, 2005 12:44 am

Oh.

In that case, you really have no idea what the manifold pressure is doing. Bourdon tubes don't take well to physical shock.

You should get another boost gauge first and then try to figure out what's happening.

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 12:57 am

As I mentioned I'm gonna test it out with the scantool... that should give me an accurate boost reading... assuming that the ECU sees boost from the manifold and not from the solonoid that is plugged in electronically, but not vaccuum. Otherwise then the scantool is pointless too..

I can almost guarantee that the guage is, although reacting strange, not the problem.

I'll test out the butt dyno again tonight, I don't feel the umph that it had prior to today.

vrg3 · Post by **vrg3** » Tue Feb 22, 2005 12:59 am

Yeah, the scantool should help. It does measure boost from the manifold. I'm not saying the gauge is definitely the problem, but it is a problem, and fixing it will help diagnose the rest of it.

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 1:06 am

Cool, lose the mbc, back to the solonoid, then scantool.

Then I'll go from there.

thx again v

vrg3 · Post by **vrg3** » Tue Feb 22, 2005 1:06 am

No -- don't switch back to the solenoid.

First set up the scantool and figure out what your boost level is right now.

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 1:24 am

Will do.

/me goes to find a laptop to use.

mikec · Post by **mikec** » Tue Feb 22, 2005 1:36 am

FWIW, my junky Autometer is working fine in these subzero-north-of-the-border temperatures, even when the rest of the car feels like its full of molasses (including the bits that aren't liquid filled).

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 2:40 am

Thx mike....

Well I just got back from work

And I had a passenger agree that there's deffinately a few ponies missing.

Mind you the car does still pull.. but more like a stocker than the slightly more power than I had.

It just feels like where it's supposed to kick in to full boost.. it doesn't.

As for the gauge, I think, even though it's not reading perfect, it's still giving off the right readings. aside from the -1.5 off when the car is off....

So I'll try the scan tool tomorrow night or wednesday morning and go from there.

free5ty1e · Post by **free5ty1e** » Tue Feb 22, 2005 2:40 am

I've got the same cheap-ass autometer phantom boost gauge, and luckily I didn't drop mine. It reads 0 at atmospheric, -21 during deceleration in gear, and -18 to -19 at idle. It also correctly read 6psi and 9psi at the proper times when I had the stock boost control hooked up.

Good thing we've got that scan tool available to us huh?

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 2:43 am

free5ty1e wrote: Good thing we've got that scan tool available to us huh?

Yes, damn good thing, also damn good thing it's software provider is also still available to us

mikec · Post by **mikec** » Tue Feb 22, 2005 2:48 am

QuickDrive wrote:
free5ty1e wrote: Good thing we've got that scan tool available to us huh?
Yes, damn good thing, also damn good thing it's software provider is also still available to us

Agreed!

Good luck with your explorations with it. Hopefully you figure out what's wrong.

vrg3 · Post by **vrg3** » Tue Feb 22, 2005 3:49 am

QuickDrive wrote:As for the gauge, I think, even though it's not reading perfect, it's still giving off the right readings. aside from the -1.5 off when the car is off....

It can't be. There is no way your engine is pulling 28 and a half inches of vacuum.

free5ty1e · Post by **free5ty1e** » Tue Feb 22, 2005 4:45 pm

if you've got your engine pulling that much vaccuum without a bad gauge, please tell us how because thats a healthy engine!

QuickDrive · Post by **QuickDrive** » Tue Feb 22, 2005 6:18 pm

Heheh ok ok.... I'll get actual vaccuum and boost with the scan tool tonight.

As for boost, it's back.... Cars performing back to normal today.

I guess it was on vacation yesterday or the snail was sleeping.

Wierd......

legacy92ej22t · Post by **legacy92ej22t** » Tue Feb 22, 2005 6:39 pm

free5ty1e wrote:I've got the same cheap-ass autometer phantom boost gauge

Hey now, I have a Phantom Series, Autometer boost gauge and I love mine. It works perfect everytime and it looks good too. Plus the green bulb condom is the perfect color for our gauges.

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Down on boost, no CEL, no changes... what's up with that?

Down on boost, no CEL, no changes... what's up with that?