'92 LC Code 71 (1 Viewer)

[Scota4570]

This is resisting repair. 71 means, "30 seconds from start of EGR operation, EGR gas temp. is less than 100* C (212* F) with coolant temp less than 60*C (140* F) or more, 2nd trip detection logic"

I have replaced the various VSV valves, the EGR temp sensor, and the old associated tubing. I have checked the components with a vacuum and pump as described in the manual. The EGR valve, EGR gas modulator, VSVs, and check valve B all function properly and check out.

The EGR valve is unobtanium, but does test good.

Any ideas on what is going on?

I doubt it is related but when I take the gas cap off after driving I get a hissing noise. That is the evap system? Unrelated?

 

[jonheld]

I doubt it is related but when I take the gas cap off after driving I get a hissing noise. That is the evap system? Unrelated?

That is a clogged charcoal canister causing you to develop excessive pressure in the fuel tank. You're going to want to address this ASAP to avoid the tank fracturing.
As far as the error codes, have you reset the ECU after each replacement to clear codes?

 

[Scota4570]

Yes, I do clear the codes each time I fix something. IT takes about 1/2 a tank of gas to re appear.

 

[Scota4570]

Refer to attached file..........
When I apply air to the tank pipe air flows out both the purge at bottom pipe but somewhat obstructed.
When I apply air to the purge pipe it flow out of both pipes freely
So? it is junk?
Is there a way to repair it or to bypass it?

 

[jonheld]

When I apply air to the purge pipe it flow out of both pipes freely

Sounds like a bad check valve inside the canister. I would replace it. OEM is long discontinued, but you may be able to use an aftermarket unit. If you search on this forum, you'll find 2 possible replacements. However, they are for the 1FZ-FE. The concept is the same, but the mounting location on the 3FE may be problematic.
For the code, both the EGR valve and EGR regulator have diaphragms that break down over time and clog the associated vacuum lines. There are several hard vacuum lines on the left side of the engine that should be inspected and cleared out of any carbon deposits. Make sure they all flow freely.

 

[Scota4570]

I looked into a new EGR valve. My car is a California version. A new EGR is not available. What are the options? Does anyone work on them?

My EGR and VCV do test as good using the tech manual procedure.

I have replaced all the rubber vacuum lines. Find a smoke generator?

I'd take it to a pro but there are no competent mechanics in my area. Not kidding!