[srich250]

Hello, I replaced my EGR valve, clean the tip of the flow sensor, reset the EFi, and the engine light came back on saying insufficient flow again.

Does anyone know what I can do next?

thank you very much!!

[jjcobm]

Do a search on P0401 on the 80's series forum

And welcome to the P41 club!!!!

By the way, what led you to replace the EGR valve. This code could be a result of four things, bad EGR valve, EGR modulator, VSV valve, or clogged vacuum passages. EGR valve is one of the most expensive things and usually left last to replace. Now that thats eliminated, i would try the EGR modulator ($40) and lastly VSV valve. The chapest thing to do would be try to clear the vacuum passages.

There are diagnostic test to do this if you have the fsm... heres a link to a good writeup also:

EGR Problem???

Don't just throw parts at it, it will cost you alot of $$$

Searching will bring tons more up!

[srich250]

Hey thanks a lot. i really appreciate it. mechanics and emissions tests results are why i was led to replace it. I will do some more searching...thanks again!!

[jjcobm]

80's and their p0401 are a complicated thing

[Proven]

Ah, yes...the most common issue with our beloved Cruisers. You'd do yourself good to buy the Factory Service Manual and flow through the trouble-shooting steps for the VSV (Vacuum Switching Valve) that is located UNDER the upper intake manifold. I suggest testing this BEFORE wrenching anything because it may not be your problem.

I also recommend checking and verifying all the little rubber hoses and pass throughs that control the EGR itself.

In the long run, that little FSM will save you a lot of grief for sure and will keep you from a lot of parts swapping as long as you RTFM.

By the by, what color is your modulator? There were two models of that and it superseded. The best way I know to tell which one you've got is by the color of the stick on the top. I don't think they fail very often though.

[MLX450]

Pics of modulator and VSV:

EGR Modulator

[MLX450]

pics:

[srich250]

Thanks all. I paid the fee and downloaded the FSM and i am moving forward with the troubleshooting.

I really appreciate the feedback! It's helping me move forward.