Erg Being A Pita - Toyotas that aren’t Corollas - Corolland: the Toyota Corolla Forums

Is it just me or is the search button missing?

So my CEL has been on for quite some time now and I've slowly been tinkering with things in hopes it would go out. It first came on months ago intermitently and gradually stayed on longer and longer until it's just always on. Now that my Inspection is due I Need to git er done.

The code is P401? (or something like that) for EGR insufficient flow. I checked the Egr valve and the vacuum switching valve operation and cleaned out the egr valve but the light stayed on. (VSV ichecked flow/no flow as is and with 12v applied it clicked and the valve switched states. The egr valve seemed to open ok with a slight vacuum and maintain the vacuum over time so I'm fairly comfortable there's no leaks in the diaphram. It also held fluid (sea foam) fine until vacuum was applied and then it seemed to flow fine.)

I replaced the modulator valve and after 3 drive cycles the CEL went out. Perfect!

UNTIL literally the next afternoon the CEL lit up again and sure enough it's again egr insufficient flow with the same code pending ???

Oh, this is a 99 camry by the way, 4 cylinder.

PS if anyone knows the engineer who designed the VSV and ERG valve in their locations on thes car .. I'd like to have a few words with him/her. Gogo Gadget Rubber Arms. I'm an engineer and if I ever design something that hard to get at without a damn good reason ... Please shoot me.

Search entry box - top right corner of the page. On my browser, has a little magnifying glass icon in the search field.

Yeah, location on of the EGR system is a PITA. If cleaning the EGR and the modulator didn't work - might be a vacuum leak somewhere (given that the light did go out after changing the modulator valve). My 3rd gen Camry started to do the same thing as yours, after several months of on/off battles with the EGR - I just replaced it. Been good for over 5 years now.

Well i see the search box now ... different computer, different browser.

sounds like i should replace the valve.

is it supposed to get hot back there (intake manifold/egr area)? ... i mean, not like instantly burn hot, but hot like i can keep my hand on things for more than a few seconds -- even the modulator valve was pretty warm. Didnt seem to me like it would be that hot. but of course it IS the EXHAUST Gas Return.

Thanks for the help Fish.

The intake manifold does get pretty hot - typical underhood temps are around 160-170 degrees on most cars. EGR only mixes in a small portion of the exhaust gas, but even so - that exhaust is well over 600 degrees - just via convection, lots of head can get transferred.

I put the new valve in the other day ... no change in the status of the CEL (after several "drive cycles") and Advanced Auto's code reader gets the same P0401 current and pending.

What "measures" the flow through the EGR valve? could it be something to do with some sensor somewhere?

I'm also going to get some little spring clamps or something because some of the vacuum hoses feel a little loose.

The CEL is triggered if the ECM finds that the manifold absolute pressure sensor is reading higher that what the ECM suspects.

Here is a link to the diagnostic page for the EGR system on a 2001 Camry (5S-FE engine) - same generation as your 1999 - so they should be applicable.

EDIT: Opps, help if I posted the link. http://www.justanswer.com/uploads/skyvisions/2008-08-23_150358_01_camry3.pdf

Possible that the MAP sensor is bad, pretty hard to believe, but anything is possible. I would suspect a dying VSV valve and bad hoses, before I suspect the MAP sensor went bad. The VSV on this generation have a bad habit of working fine one minute and acting up another. Even after being replaced, they still act up.

The only two thinks left are the MAP sensor and ECM itself - both are behind the EGR, as far as potential culprits that would necessitate replacement.

Sounds good ... I'll pick up a new VSV and some hoses tonight on my way home from work.

Thanks

-Ian

Update: This problem is fixed. Seems like it ended up being a combination between the Modulator valve and the VSV. I had replaced the modulator valve which temporarily cured the problem (see above), after some more fooling around I put a new VSV valve in ... still had problems. But once I started re-checking I found a vacuum hose on the VSV was not connected ... whoops.

Sweet. EGR and related systems can be a major pain to work with, great to hear that you got this resolved.