94 FZJ80 95k
Check engine light come on and then goes away, pulled codes and get a "71" EGR malfunction

EGR valves tests out fine

I noticed on start up the vac line to egr starts the suction to engage egr valve, WTF?

My understanding of the EGR system is that it is only suppose to engage when engine is warm. at higher Rpm's and when you are traveling at a constant speed???????

Now the question is what sensor tells it when to engage? is my problem caused by a simple bad sensor or a screwed up computer?

Any thought would be helpful, next step is off to the dealer for quick $100's an hour ankle grab

Buzz :confused:

Originally posted by chliansh

Any thought would be helpful, next step is off to the dealer for quick $100's an hour ankle grab

Buzz :confused:

---hahahahaha aint that the truth! lol! i got no clue...but that was too true!:rasta:

Buzz,

Correct on the EGR is operating under warm temp, normal cruising, partial load.

Haven't messed with the later FJ80's, but suspect they are similiar to the 3FE system.

Did you check the VSV? The computer controlls the VSV. Normally open (vented to the air cleaner), it will close when the power is applied to the solenoid. Vacuum is always applied to the EGR & EGR Vacuum modulator, the job of the VSV is to ensure the EGR is not used when the engine is cold or at higher rpm.

The computer will use the air flow meter, throttle position, and water temp sensor to determine when to open and close the VSV.

Sorry for being so general,, but wanted to just get you pointed at a few things to look at?

Uh, how many miles on the engine? Just wondering about carbon build up in the EGR passage?

Tom :usa:

Originally posted by chliansh
94 FZJ80 95k
Check engine light come on and then goes away, pulled codes and get a "71" EGR malfunction



I would start by finding out what the "71" code means. I know from OBD II engines that a number of different faults will set an EGR malfunction code and it doesn't only mean the the valve is not working. It could be something like a vacuum leak or one of the O2 sensors on the three way catalyst out of range. The number will tell you which specific sensor is out of range.

You might try just clearing the error and see if it stays away. Some of these error situations are transient.

The mechanics at the dealer's often don't know and more importantly, they don't care. They just replace stuff and the more stuff they replace the more money they make.

Find a local "independent" Toyota mechanic that has the equipment/mnuals to run the codes.
The dealers are now mostly populated by jiffy lube skill level "parts changers".

Thanks for the reply, I have some more questions.

1. Vacuum is suppose to "always" be applied to the egr actuator?
I assumed when vacuum was applied it started the egr process?

2. I assume the egr flow is from the exhuast manifold through the egr valve (when open) into the air cleaner box to be filtered, and so on ?

3. the vehicle has 95k miles, The passages I see look quite large and almost impossible to be carboned up?

4. What is the VSV valve, location or look like?

Thanks for all the help.

Chad

Originally posted by chliansh
Thanks for the reply, I have some more questions.
Chad

Chad... Answers a below. Remember I am more familiar with the earlier (2F & 3FE) setup, but most of the Toyota's follow along the same lines.

1. Vacuum is suppose to "always" be applied to the egr actuator?
I assumed when vacuum was applied it started the egr process?

Vacuum is always present. There are two vacuum ports taken off the throttle body for control, but basically you always will see a vacuum at the EGR valve. Yes, this seems backwards than most vehicles, but Toyota will apply a vacuum then use a solenoide VSV to vent the vacuum to the atmosphere to disable the EGR.

2. I assume the egr flow is from the exhuast manifold through the egr valve (when open) into the air cleaner box to be filtered, and so on ?

No. EGR is ported from the exhaust manifold back into the intake manifold. The evaporate emission lines will go back into the air cleaner, etc.


3. the vehicle has 95k miles, The passages I see look quite large and almost impossible to be carboned up?

If the engine has excessive wear, & oil consumption, even those big lines will get clogged up! Correct for more normally running engines with regular oil changes, the passages should be fine.

4. What is the VSV valve, location or look like?

Vacuum Solenoid Valve is just small thing with one or two vacuum lines on it, and two wires attached. There should be about four of those sitting on the fender well. Each one is about 1/2" x 1/2" x 2" long or so. You should have a diagram of vacuum lines under the hood. On the EGR valve there will be two of three lines attached (not sure if you have an EGR & EGR modulator or just an EGR valve present). One of those vacuum lines should go to the VSV.

Thanks for all the help.

You're welcome

Tom :usa: