EGR sanity check

[Mike Gallion]

I have had this 93 ATX since April this year and am just getting around to repairing the EGR issue that is throwing a CEL after the car warms up. (Been busy chasing the more relevant issues such as motor mounts and electrical issues) That CEL is really annoying at night!

I believe I can verify functionality of the DPFE by removing the Reference and Hi pressure inputs and applying the EGR valve vacuum to the Reference side of the DPFE sensor leaving the hi side vented to atmosphere. Of course, the hard lines that spew hot exhaust gas into the engine bay would have to be capped.

Unless I am way off base, this will tell my whether my DPFE is faulty (i.e. continued CEL issues) or will point to the more probable issue of clogging within the intake.

By no means is this intended to be a permanent solution, merely an aid in identifying the problem area.

Any alternate paths would be greatly appreciated.

 

[Slo-Sho]

Pull the codes instead of guessing.

 

[TopGunnYFZ]

Is there a way to get rid of it? Both of my ATX's throw the same 332 code ive just been driving them as they show no loss in performance or fuel consumption. The light is annoying indeed

 

[projectSHO89]

Perform a "suck test" on the EGR valve at idle. If it stumbles, it's likely the DPFE sensor.

If it doesn't stumble, the EGR ports are clogged.

That will cover 95% of the 332 faults.

It is relatively easy to perform a bench test of the DPFE sensor. There's a specific response curve for the output voltage vs input vacuum. All you need is a small handheld vacuum pump with gauge and a voltmeter.

EGR insufficient flow faults won't affect fuel economy normally, but it will cause increased NOx emissions which is a particular concern if you are subject to a tailpipe sniffer emissions test.

See my post from six years ago.... http://www.shoforum.com/showthread.php?t=13813


Steve

 

[Mike Gallion]

Sorry for not properly filling in the blanks. I had pulled my codes earlier in the summer and the only one related to the CEL was 332.

Swapped in a spare DPFE, cleaned the devil out of my intake, EGR valve as well as all the associated hard lines. Blew them out with compressed air (NOT the DPFE though!) Nasty looking gunk came out of the nostrils (or at least it seemed to come out of both....)

New silicone tubing on the hi and reference inputs to DPFE.

EGR valve moves with vacuum applied. Idle does not change with vacuum applied to EGR

I did go ahead and bypass the DPFE as described in my initial post last night and the CEL did not illuminate, so I'm pretty sure the DPFE is functioning. reinforced by the fact the motor does not stumble with vacuum applied to the EGR valve (Thanks again projectsho89!)

Looks like I need to take some time this weekend and swap in that freshly cleaned intake I had put on the shelf this summer!