1998 Chevy Lumina EGR valve/replaced. Check engine light sti

Tiny
DAVE MAVERICK
  • MEMBER
  • 1998 CHEVROLET LUMINA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
In the last 4 days, I have replaced this item twice, (150, just for the part)sprayed cleaner down the ports as well as the exaust tube. Yes, when I took it apart to put the 1st one on, it was carboned up with some hard deposits. Iwas even able to stick the clener tube in all the way, and I used the whole can. Please help me, because I am getting terrible gas mileage. Thanks.
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Monday, June 22nd, 2009 AT 5:40 PM

6 Replies

Tiny
DOCFIXIT
  • EXPERT
Hi
Need the code in P0xxx format to help diagnose.
Please post will advise
Thanks for donate
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Tuesday, June 23rd, 2009 AT 8:59 AM
Tiny
DAVE MAVERICK
  • MEMBER
Hi guys. Took me a while to get the code you requested. Here it is--P-0401. It reads egr insuficient flow.W

We both know that's not the problem, as I said 2 new ones were put on. HOPE YOU CAN HELP. THANK-YOU.
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Friday, June 26th, 2009 AT 7:23 PM
Tiny
JALOPYPAPA
  • MEMBER
If you're sure the intake manifold port is no longer plugged up (and I've seen them plug up again after relatively few miles) two other possibilities remain: (1 -- most likely) Whatever EGR control system this car has has failed. All in some way monitor engine back pressure to modulate the vacuum to the EGR for engine load conditions. (2 -- less likely) the exhaust riser itself is plugged with carbon.
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Sunday, June 28th, 2009 AT 6:34 AM
Tiny
DAVE MAVERICK
  • MEMBER
Thank you, guys.I will try both, but if the system has"failed"as you said, does this mean Ineed to replace a computer board that controls the egr valve?Thans again.
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Sunday, June 28th, 2009 AT 8:12 AM
Tiny
DOCFIXIT
  • EXPERT
Yes make sure intake ports clean. Also EGR flow rate is monitared while watching MAP changes. So MAP can cause code to set. Try cleaning MAP no P0401 set so MAP is not too far out of range.
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Sunday, June 28th, 2009 AT 12:56 PM
Tiny
JALOPYPAPA
  • MEMBER
There are a number of different EGR systems; I only meant that if yours has a backflow transducer, which usually feeds an electronic signal to a solenoid in a vacuum modulator in turn connected to the EGR, that part of the system can cause problems. But now that I look it up, I think you may have what GM calls a digital EGR, which apparently (I haven't worked on one) gets its signal directly from the computer, which, as docfixit says, reads the manifold absolute pressure from its sensor (on the back of the manifold. I should think replacing the computer would be a costly last resort and therefore only if indicated by a scan readout.
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Monday, June 29th, 2009 AT 8:44 AM

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