EGR Tips and Tools

[Daniel M. Dreifus]

EGR Tips and Tools

Seems I've solved the check engine light on the '94 Camry 4 cylinder with 193,000 miles (code 71 - insufficient exhaust gas temperature at the EGR valve) with some very helpful comments from the lead service technician at the local dealership and wanted to pass along the experience to others who may benefit.
The technician - this is California, so California version cars if that makes any difference, -- he said they used to disassemble and clean the EGR valves, but now just remove the throttle body and use a wire to clean the EGR port. After doing this I can see why this may be. On my '94 the EGR port is almost directly opposite the PCV valve hose - so oil laden crankcase vapors are prone to mix with the incoming exhaust gas at the EGR. I found this to be so. The port was nearly completely plugged with crusty carbon deposits. Do remember to use a well placed rag when cleaning to prevent carbon bits falling into the intake runners nearby.
He also said, that if they do not also replace the vacuum switching valve for the EGR, the check engine light is usually back on within a month.
I should mention that I've seen others mention finding carbon in the EGR tube and connector to the EGR modulator, but I found the flexible line between them seemed clear. Maybe using Redline fuel additive and Lucas fuel treatment continuously (first one then the other) had some effect?
What the lead service tech did not say, is that two tools are essential for changing the EGR VSV. 1) a hinged head ratchet handle (found mine at Kragen Auto Parts) and 2) a 3/8" extension with a "wobble" end (also Kragen)
The EGR VSV is on the back of the engine block above the rear engine mount on the 5S-FE and access is very limited. I needed a shop light and flashlight plus a large block of wood for a head rest to prevent neck muscles from becoming exhausted.
With lots of patience, the job is not difficult - just awkward. Seemed turning the steering wheel all the way out to the side helped.
The electrical connectors release by squeezing at the top. This had me puzzled for a while, since the release lever is not obvious.
That wobble extension with a 12mm socket was also indispensable for getting the bolt back in after reaching my right arm in to the shoulder to hold the new VSV. I had never used a wobble extension before, but found it moves enough to work around angles, but unlike a universal joint, still holds straight enough to really aid in removing and reinstalling bolts. Same too with the hinged head ratchet handle - don't think this job would have been possible without it since clearance is very limited.
Cleaning the EGR valve port in the intake manifold did help a lot. By "babying" the throttle (EGR is off at light throttle conditions) I could keep the check engine light off.
I did not find an obvious fault with the old VSV. Had read posts elsewhere that they are a known and common problem, so if nothing else, preventative maintenance at nearly 200K. I connected battery voltage to the terminals and heard a click and also found flow of air through the valve was there, but perhaps not as strong as it should be when open. (seemed noticeably less than through an unrestricted section of vacuum hose)
There is an air "filter" on the end of this VSV assembly, so I wonder if over time, the internal passages become somewhat restricted.
Someone more adventurous than I might try shooting solvent through it to clean and save the replacement cost, but I didn't want to risk doing the R&R twice.

[Airjer_]

I run into plugged EGR ports fairly often on those older corrolas as well. Apply vacuum to the EGR valve and no or little RPM change = Pull the throttle body (I like to pull the EGR tube thats bolted to the intake as well) and start scrubbing. I like to stuff a rag as far back as possible and carefully chip away at the big chunks. Then finish the cleaning with a good carb/choke/throttle body cleaner. Don't forget to clean up the throttle body while its off as well.

[Brian R.]

Good posts. I will put them into the FAQ thread.

[Daniel M. Dreifus]

Turns out after four days the check engine light came back on (then went out again) setting a 71 code (EGR exhaust gas temperature insufficient) - so the EGR valve will have to be cleaned or replaced.