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Forced Induction All questions and problems regarding Superchargers, Turbos, NOS, ZEX, intercoolers, water injection, etc.

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Old 07-17-2006, 11:49 AM   #1
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Well, added a new H to the stable over the weekend (takin my dear sweet time on the tranny rebuild, for obvious (I hope) reasons). 95 LSS (L67)... a beater for sure, but a nice beater.

Anyway, the guy I bought it from said the check engine light has been on for about 2 years now, and being a '95 (and himself being completely incompetent) getting it scanned was a no-go (even knowing the hybrid issue, I couldn't find a free read in grand rapids).

So today, back at work (shutdown is over now...), I threw on a Tech2, and found a QDM1 fault. I've been reading up on the various posts scattered across BC history, and for an */c car, it seems it'* either tcc, boost solenoid, or evap purge (or canister... memory is a bit short today).

The problem is, I don't have a boost gage, so I have no idea if I'm building the proper amount of boost. My gut tells me that I'm *not*, as my L67 doesn't feel any faster than my L36 LeSabre - and while the LeSabre feels nice and strong to me, it seems like there should be some performance difference between the two.

Anyway, the light always clears on turning the car off, and will stay off when you start it up... it comes on seemingly at random intervals, and will occasionally turn off during a drive. My TCC engage is just fine (though the disengage can get a bit shakey, but not really all that different from my LeSabre), and there has been at least one time I saw the light come on while I was still <30 mph, in 2nd gear... so the TCC shouldn't have even been trying to engage.

So... my butt says I hope it'* a boost solenoid, but I'm wondering if there'* a good way to actually check both components. I've got a Tech2 at my disposal for the remainder of the week (though not officially), and I've got a decent multimeter that I'm fairly handy with... what should I be checking?

<edit> sorry... probably should be moved to 92-99... followed a searched thread and posted new topic, not realizing it was in the forced induction forum...
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Old 07-17-2006, 01:32 PM   #2
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Boost gauge wouldn't tell you a darn thing.

The 95 SSEi I had developed that very same code. Since boost was fine and obviously working 100% I went after the other items. Evap purge soleniod and TCC soleniod.

TCC wasn't going to be changed unless the trans was out.. so that'* a no go. However..you can test it.

Watch the RPM'* if you have a tach at about 50-55, gently tap the brake and watch the tach jump a couple hundred rpm. TCC working 100%

Evap purge requires the car to be warm and running for X amount of time..blah blah. Properly waiting and testing it tough as I lost paitience. It was fine.

So with all three things seemingly fine.. why was there a code?

On a whim I nabbed a BCS from a JY car and swapped it. Poof.. no more light ever.

I found a post by someone and it was the same issue and same result. That'* why I gave it a whirl.

Although the issue could be any of the three.
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Old 07-17-2006, 01:37 PM   #3
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Quote:
Originally Posted by BillBoost37
Boost gauge wouldn't tell you a darn thing.

The 95 SSEi I had developed that very same code. Since boost was fine and obviously working 100% I went after the other items. Evap purge soleniod and TCC soleniod.

TCC wasn't going to be changed unless the trans was out.. so that'* a no go. However..you can test it.

Watch the RPM'* if you have a tach at about 50-55, gently tap the brake and watch the tach jump a couple hundred rpm. TCC working 100%

Evap purge requires the car to be warm and running for X amount of time..blah blah. Properly waiting and testing it tough as I lost paitience. It was fine.

So with all three things seemingly fine.. why was there a code?

On a whim I nabbed a BCS from a JY car and swapped it. Poof.. no more light ever.

I found a post by someone and it was the same issue and same result. That'* why I gave it a whirl.

Although the issue could be any of the three.
Ahh... this actually has the smoothest TCC engagement of any H I've driven as of late... I just thought the code might be for more than proper apply. That narrows it to evap and BCS...

What'* the proper procedure for checking the evap purge?
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Old 07-17-2006, 02:48 PM   #4
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If anyone is curious, the p/n for the BCS is 12480246, and you're better off getting it at a yard.

GM PART # 12480246
CATEGORY: All
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $381.46
OUR PRICE: $226.14

er, or that may be the BCA. I'm not really sure which does what (new to */c land), and the parts guy I was talking to was at a loss, as neither showed up under their appropriate names for him... he finally found this under the title 'wastegate'. It'* the part that the vacuum line and pressure line from the */c run in to, with the slider arm... so is this the BCA?

<edit x3> okay, the part print calls it an actuator, so I guess that'* what it is. So how does one check the BCS for proper operation?

<edit x4> okay, finally figured out what had me confused the whole time. I'm okay now I'll be taking a look at the BCS as soon as work gets over (not fast enough, as it were, for the first Monday after two weeks off)
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Old 07-17-2006, 04:07 PM   #5
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The BCS should be no more than about $30

Proper operation is boost kicking in when you are on the pedal. The one on my 95 worked 100%.. but it also kicked on the CEL.

Not sure how you could test it other than replacement.
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Old 07-17-2006, 04:18 PM   #6
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bah!

that'* an issue, because I really don't know if my boost is kicking in... I mean, I can hear the whine, but if it'* all being dumped, I don't really have any way of knowing. Suppose I'd be better off just trying to find another solenoid, and trying it out, eh?
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Old 07-17-2006, 05:10 PM   #7
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bah!

that'* an issue, because I really don't know if my boost is kicking in... I mean, I can hear the whine, but if it'* all being dumped, I don't really have any way of knowing. Suppose I'd be better off just trying to find another solenoid, and trying it out, eh?

You have whine..you have power....you have boost
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Old 07-17-2006, 05:35 PM   #8
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Measure the resistance across the two terminals of the solonoid. It'* easier if you remove it first.
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Old 07-17-2006, 10:57 PM   #9
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Will do.

For kicks, I hooked up the Tech2 today, and was able to command the BCS to open and closed positions without fault or throwing codes. On the other hand, my purge solenoid, when commanded to full on, only made it to 50%.... so it sounds like that might be the real issue?

I'll still get a resistance reading off the BCS, but it'* pouring cats and dogs out right now, so it'll have to wait until after work tomorrow.
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