Egr valve passage cleaning
 

1999 Camry LE 4-cyl

Where to start cleaning EGR valve passages?

Remove EGR?

I forgot to note that I already removed it, and sprayed some throttle cleaner inside of it to clean out the built up dry carbon if any at all ( black stuff came out ) and let it dry overnight before putting it back in. I still get the check engine light for error: P0401

Possibly be EGR Modulator? Any other suggestions?

I don't know how much built up encrusted carbon there was but I've always had to use different scraping things to remove it, screwdriver, wire brush, etc., as well as carb cleaner and compressed air. You can buy a small dip tank from parts stores to soak overnight but keep vac valve above it. I also use a vac pump to open the valve and clean the valve seat being careful not to damaged it. There would have to be a lot of carbon to get insufficient flow. Did you test EGR by using vac pump to open it while engine is idling? If the engine stalls then you're getting flow. You'll have to check out the whole system, including the exhaust tube, VSV and modulator. Don't discount possible sensor problem.

Likely your EGR VSV. With your engine running in park- rev the engine and see if the EGR pintle moves. If it does- you just verified the EGR modulator works and all of the vacuum lines are intact. Problem is- the EGR valve SHOULDN'T move- because the EGR VSV should be blocking vacuum to the EGR valve until certain running conditions are met. The reason why the valve would move at this point is because the EGR VSV is stuck open- allowing vacuum to reach the EGR at all times. How does this cause an EGR flow insufficient code? Because the ECU monitors MAP sensor readings before and after the EGR is activated. It should notice a drop in manifold vacuum. Since the EGR is already active due to the failed VSV- its doesn't notice the drop and interprets it as a low flow.

CORRECTION- EGR will valve will move for a split second- then become inactive. It it stays on the whole time you have the engine revved- the VSV is stuck open.

JJ

yes, from what I gather on web,,,most people are pointing to the vsv switch and not egr.

I had same egr problem and just got vacuum pump and hook up to egr port with engine running. with the vacuum pump engage and pumped, Engine wanted to die and started to run rough which means that the egr was working. So then I had to get at the vsv switch which control the egr and it was located way at the back of engine block and bottom part against the engine firewall part. It took me about 1hr just to take it out, trying various ways to get it out. finally got it out and tested the vsv switch and noticed it was plugged up with carbon... yeah got a small drill bit (use it by hand, not power drill) and put it in and started to clean it out. And once it was clean, started to blow in pipe on vsv switch by mouth and can now feel the air passing through. After cleaning the vsv switch, I relocated the egr vsv switch assembly to the top right rear side of engine assembly---passenger side and cut some length of vacuum hose and rerouted for easier access for next time--should it require troubleshooting or access.

A lot of people say to buy new VSV switch but its $80 fo rnew one and I am cheap... So try cleaning it first. My car was a 96 camry 4 cylinder. maybe I will take some photos of it and upload.

good luck

thanks guy/gals for posting this info...I bought a used 1996 Camry V6 with 220k miles on body/trans and 60k miles on replaced engine. It still rides good barely any noises I have to replace the power steering pump due to leak from it but no rush this is my beater...when I cleaned of EGR of built up carbon the part that connects at bottom to pipe/tube that I think goes to exhaust got cracked thus now I have a leak causing extra engine area noise anyone know of an online store where I can buy a replacement EGR? It seems the manifold(I think its called that) is all one piece with the EGR am I guessing wrong?

go to your local import junkyard. I got mine there for $15 for whole thing, egr valve, tubing connector part. You still didn't say what code you got.

Thank you!!! It was the PO401 codeand taking EGR valve off and cleaning the carbon gunk all in it was all I needed and warning is gone now. The problem now is the area where 2 screw mount the tubing that leads to exhaust well one was broken and the only good one is now cracked due to overtightening. So now engine noise is more pronounced due to that. So now it looks like I need to get that whole piece again but don't want to overspend that all.