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  #1  
Old 04-27-2005, 06:59 PM
lee lee is offline
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Question FSM owners - please check something for me

I use Alldata, and they state to check the EGR function one should apply about 8" vacuum to the line going to the EGR. The result Alldata describes is the engine should stumble, but the vacuum should hold steady. When I test my EGR I can't get the vacuum to hold, so I'm wondering if I have a leak. I can pump away and feel the EGR valve moving in response so the valve itself is at least partially OK - I just don't know if the alldata info is right.

So, could someone with a FSM check the section on EGR function testing and let me know if the Alldata info is correct?

tia
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  #2  
Old 04-28-2005, 04:36 PM
oab_au oab_au is offline
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Quote:
Originally Posted by lee
I use Alldata, and they state to check the EGR function one should apply about 8" vacuum to the line going to the EGR. The result Alldata describes is the engine should stumble, but the vacuum should hold steady. When I test my EGR I can't get the vacuum to hold, so I'm wondering if I have a leak. I can pump away and feel the EGR valve moving in response so the valve itself is at least partially OK - I just don't know if the alldata info is right.

So, could someone with a FSM check the section on EGR function testing and let me know if the Alldata info is correct?

tia
Gidáy Lee, the manual does not give this info.
The line that runs from the EGR solenoid, to the EGR valve, also goes to the BPT valve (thats what the book calls it, don't know what it means), this unit modifies the amount of vacume that is applied to the EGR, in accordance with the gas pressure that is in the exhaust manifold. This unit bleeds air from the throttle body, into the vacume line. So you won't be able to hold a vacume level in the EGR line.

Harvey.
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  #3  
Old 04-28-2005, 04:52 PM
lee lee is offline
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thanks Harvey

BPT is Back Pressure Transducer - pretty fancy moniker huh?
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Old 04-28-2005, 05:27 PM
oab_au oab_au is offline
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Quote:
Originally Posted by lee
thanks Harvey

BPT is Back Pressure Transducer - pretty fancy moniker huh?
Yea that makes sense. as it regulates the EGR flow to account for Exhaust gas pressure.

Does that answer your low vacuum?

Harvey.
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  #5  
Old 04-28-2005, 07:05 PM
lee lee is offline
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I got some things to check, but here's the text as it appears

"Disconnect vacuum hose from EGR valve. Run engine to normal operating temperature. Attach a vacuum pump to EGR valve. With engine idling, apply 8 in. Hg to EGR valve. If vacuum holds and idle becomes unstable or engine stalls, EGR valve is functioning properly. Reconnect vacuum hoses. Increase engine speed to 3000-3500 RPM. Ensure EGR valve opens."

I have been testing by pulling the line from the BPT to the EGR, and applying a vacuum to that line. I use a small hand vacuum pump (MityVac by brand name) that works quite well - I can test by putting my finger across it's opening and the tool holds the vacuum. But when I hook it to the EGR and apply vacuum, I have to keep pumping away, it simply won't hold any value, but I can feel the EGR valve open a bit as I pump, and it does stumble like it should. So either I have a leak or the info above is just wrong, or (of course) operator error.

Beav did tell me some EGRs have a small port/vent at the valve itself, I need to run new line to the EGR and retest making sure that's covered. I was hoping the FSM had a specific EGR function test described as the part isn't cheap (and I am ).
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Old 04-28-2005, 07:56 PM
oab_au oab_au is offline
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It depends on which line you are on. The vacuum line from the manifold, runs to the EGR solenoid, then it splits, one to the EGR valve, the other branch, to the BPT valve. The BPT valve is the one with the small port to vent some of the vacuum away.

If you connect your vacuum pump to the EGR valve itself, you should hold vacuum. If you are connecting the pump into the line from the EGR solenoid, it won't hold vacuum, as it will bleed away through the BPT valve.

Harvey.
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Old 04-28-2005, 10:08 PM
lee lee is offline
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thanks for the insight, I need to look at the vacuum diagram once more - it may well be I was using the wrong line to test
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  #8  
Old 05-08-2005, 08:36 AM
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Any news lee? I think I need a new valve, I was going to do process of elimination...egr solenoid then valve but I hear they are very difficult to change due to the bolts rusting. Can I start by cleaning anything? I only get a code once and a while.
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  #9  
Old 06-16-2005, 07:10 PM
lee lee is offline
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Quote:
Originally Posted by michael
Any news lee? I think I need a new valve, I was going to do process of elimination...egr solenoid then valve but I hear they are very difficult to change due to the bolts rusting. Can I start by cleaning anything? I only get a code once and a while.
Problem solved - turned out to be three things - a couple small intake air leaks in the plastic housing between the MAF and the throttle body, bad Bosch spark plugs (+4 type), and finally a bad ignition coil.

Alldata has a bad description of the EGR system. I found out somewhat the hard way, or at least the semi-expensive way. "semi" because I went and bought a bunch of parts from a wrecking yard....now I have a spare ECU, TCU, TPS, EGR BPT, 5 good ignition coils, and an igniter - oh well, at least this yard was "semi" cheap - all that set me back only $150.

To test the solenoid and vacuum system all you need is a partner, have them rev the car up/down (idle to say 4K rpm) while you put you fingers in an opening on the rear side of the EGR valve - if you feel something inside moving up & down in response to throttle changes, then the solenoid and vac system is OK. My EGR valve isn't rusty at all, but then I don't live in the rust belt either, so....

Last edited by lee; 06-16-2005 at 07:13 PM.
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