Mechanics

CHEVY EGR CODE P0401

1998 Chevrolet Lumina

1998 Chevy Lumina 6 cyl Front Wheel Drive Automatic 150000 miles

I have a '98 lumina with a 3.1 v6. For the last 6 months the check engine light has been on. When scanned gives code p0401 - egr- insufficient flow. First thing I did was remove the valve and clean out the ports, code came back. I then replaced the egr valve and map sensor(even though I couldn't find anything wrong with them, just wanted to eliminate ), code came back with in a day of erasing it , I had the intake manifold completely off last month to do a gasket, recleaned the egr passage, clean out the tube running from the exhaust manifold to the egr. Code still comes back. I'm convinced that the computer is either reading it wrong or another sensor is bad. I purchased an auto xray 6000 scan tool, which will be here tomorrow. What sensor readings, info, ect. Should I look at? I've never used a scan tool before
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Ryan harris
August 18, 2008.




If the scanner has the ability to make different outputs operate, try engaging the EGR valve at idle. If the valve is doing its job, the car will almost stall or will stall at 100% EGR demand at idle.
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Tiny
Jetsa
Aug 18, 2008.
Thanks for the tip, egr works when commanded

got the following freeze frame data w/code

P0401 Frame1 Mod $10

ABSLT TPS 0.0
RPM 1149
Calculated Load 2.7
MAF lb/m 0.61
MAP " HG 8.0
Coolant 194 deg F

STFTRM1 % -14.1
LTFTRM1 % -15.6
Speed 45
Fuelsys1 closed

i won't have time to check more until this weekend
if anyone has some baseline, good readings or knows what the typical readings should be for these sensors and stuff, that would be great as I don't have anything to compare to.

Tiny
Ryan harris
Aug 21, 2008.

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