clogged egr tube

[twocontours]

Is there a flow test for a clogged EGR tube. Manifold was cleaned as part of UIM cleaning. EGR valve swapped with a known good one. I've checked everything else but still get code 332 on KOER test. Car is 95 2.5.

 

[BrApple]

well I have never heard of this happening. have you tested the egr valve? my guess might be the DPFE sensor .... it has to be metal and I bet its rusted out ....

 

[twocontours]

Replaced DPFE, EGR tested good but I swapped with my other car's EGR valve, still same problem. Replaced computer. When I pull a vacuum on the EGR the car stumbles but the DPFE output only goes from .6 to 1v. When I put a vacuum on the DPFE ref port I get 4 or 5 volts. I doubt it's the problem but I'm out of ideas so I guess I have to pull the tube and see if it's restricted.

 

[Rogerm60]

When I pull a vacuum on the EGR the car stumbles but the DPFE output only goes from .6 to 1v. When I put a vacuum on the DPFE ref port I get 4 or 5 volts.

If the EGR orafice was blocked you would get higher than expected DPFE output.

Clean the EGR passage in the UIM. This time run a coathanger from the hole under the TB over to the EGR mounting flange and blow it out.

 

[twocontours]

Already had the manifold off and ran cleaner through the passages, put a wire brush through it and blew compressed air in and felt it blow out the vacuum port in the manifold. Still getting low flow code.

 

[Rogerm60]

The DPFE measures the pressure drop across an orafice.

The upstream DPFE port is exposed to exhaust pressure (<1psi.).

The downstream DPFE port pressure is supposed to be a split between the orafice size and the EGR valve pintle position.

When the EGR valve is full open (~5.5 in. hg.) the DPFE should be exposed to something like 10 in. hg. differential and give about 4.6 volts output.

If the DPFE is new and the EGR valve is the correct one and it is opening, then a low output means that there is a reduced vacuum at the downstream DPFE port. This can be caused by low engine vacuum, a restriction between the EGR valve and the intake vacuum, or a leak in the EGR tube between the downstream DPFE port and the EGR valve.

Have you checked the EGR tube for rust-through?

Do you understand how the system works?

 

[twocontours]

Yes I understand all too well! EGR passages are clear, I even swapped valves with my other contour. Intake manifold cleaned, tube looks good, replaced rubber hoses, replaced DPFE. Problem now appears to be in the harness as I can't force code 337 per the diagnostic procedure. DPFE disconnected reads 327 when shorted or connected to Vref.