Techstream EGR Valve Blockage Data

Exactly. Prevent Maint is cheaper than Rehab maint.

the $1450 included:
Full EGR Clean
Oil Change
Inverter and Engine coolant flush
Water Pump Replacement
Spark Plugs
and a free engine bay cleaning. Shes purty under there now.

 

OUCH! That's a lot of money!

 

Reasonable?

 

Well actually....
Don't we all see a big jump in fuel economy with the warm spring weather?
I know I do, but I don't keep accurate records to nail an exact number. Sometimes it may be ~10%.

Your list of items done does sound like a reasonable price!

All you have to do now is continue with this Ol'Gen3 to see if the head gasket hangs in there for more than 100-150k miles.

 

I appreciate I'm late to the party, haven't read much of this thread, have questions:

The EGR valve degree of open is monitored by the car's computers. It has parameters, say throttle position, rpm and load condition, for when it can open the EGR valve?

How about how much and/or long to open it? Does it monitor rpm drop for example? If there's clogging of the EGR capillary passages in the intake manifold, reducing the results of a certain degree of opening of the valve, does it then open the valve more or longer?

I'm wondering: would a clogging EGR system mean the EGR valve will be opening more or longer, be prone to wear out sooner?

 

Your first comment in this thread was on May 5, 2019.

The ECM doesn't really know how far open the valve is; there's no sensor on the valve. It just has a stepper motor, something like 111 steps from fully closed to fully open.

The ECM can get to where it thinks the valve is closed, by sending it 111 or more steps in the 'close' direction and assuming it must have got there. It can then get to where it thinks the valve is n steps open, by starting there and sending n steps in the 'open' direction. If the valve gets sticky and doesn't move the same number of steps that were sent, the ECM has no direct knowledge of that.

The only feedback the ECM gets on what the valve is doing comes from the effect on the MAP sensor reading.

I'd say the valve is built robustly enough I wouldn't worry much about it wearing out no matter how often it opens and closes. The ailments that it does seem to be prone to are (1) melting a rut through the ski jump, or (2) getting caked up and sticking.

 

Do you really think, it is sticking, because it is "caked up"?

It is absolutely possible, we had here some reports, where the plunger was not moving freely.

Wouldn't it be possible, that it is sticking, while the stopper gets caught in the completely or partially melted rut (apart from opening the valve less than the ECU commands, due to the steps needed to get over the rut itself).

As my old valve was replaced, Toyota mechanics said "it was sticking".
After disassembling the valve, I found the ski jump fully melted through and the valve plunger actually moving free, even, if reasonably covered with carbon residue.

Mat

 

I suppose a partial rut could be one cause of sticking behavior. I consider any sign of rut to be a sufficient reason for replacing the valve in any case; I've never felt a need to settle the question of whether it's the only reason the valve could stick.

I had a used valve apart where I didn't think the pintle moved very smoothly.

 

Yes a factory egr valve can wear out.

 

What part of it did you find to be worn, and how?