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I have a 1991 Toyota Tercel and my check engine light came on with the code 71 (OBD1 Question is I got the code 71 (EGR System) I know it has something to do with the EGR System but what are the things to check/diagnose?
I did take out EGR Valve and cleaned out the carbon build up the best I could and also tested the diaphragm on it and it still works. But in case the light comes back on what other things should I check/do?
Thanks.
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Ok…Check engine light came back on, so I did some checks today… VSV- Vacuum Switching Valve, Vacuum Modular, Tested Egr Valve with hand pump and all are fine.
I have not yet tested the EGR Gas Temp. Sensor, is there anyway to test that?
Also what are some other things to test?
The temp sensor can cause this issue… there should be an ohm spec on this, but I have no idea what it should be on a car this old…
Karl
Got it Karl
Your code is actually for the EGR temperature sensor no change when valve commanded open.
I do recommend doing like college suggested, start car using vacuum pump open valve, engine should try to stall. If it does, do this next test.
Here is the heat to resistance tests for the sensor.
https://www.dropbox.com/s/tbt2tep3vw19z45/EGR%20temp%20sensor%20trouble%20tree.pdf
Is there another way to test it? I seriously don’t have the type of stuff to heat motor oil up with….
No sorry. Its not to hard get a cheap volt/ohm meter and grab an old sauce pan and candy thermometer. You can get everything at wallyworld for about $20.00 (ten for the meter, six for the thermometer). Any oil will do fine and you don’t need much, just enough to cover the thermocouple (the part under the threads).
http://www.walmart.com/ip/Innova-3300-Equus-3300-Hands-free-Digital-Multimeter/14644665
“With the car running apply vacuum to the egr does the car
stall or stumble?”OK, I applied vacuum to the EGR valve (at Idle) and at operating temputare and I did NOT notice any difference in how the engine ran it did not stumble or stall same RPM, it does how ever hold pressure and I know the diaphragm is not punctured or has any leaks in it…
Is that normal?
Sounds like the passage from the EGR into the cylinder head is clogged up somewhere.
Take the valve back off. You are supposed to have a passage from the hole between the studs (where the valve bolts up) all the way into the intake. I have a feeling you will find the passage is blocked up with carbon.
[quote=”SDMAN1981″ post=81500]”With the car running apply vacuum to the egr does the car
stall or stumble?”OK, I applied vacuum to the EGR valve (at Idle) and at operating temputare and I did NOT notice any difference in how the engine ran it did not stumble or stall same RPM, it does how ever hold pressure and I know the diaphragm is not punctured or has any leaks in it…
Is that normal?[/quote]
If the car did not stumble or stall and the diaphragm did raise.
Then you have a clog either to the valve or after the valve.I like to use a pick set (looks like dental picks) and just work on preaking the crud up and drawing it out.
It is a very common problem
A small screw driver to dig with and a couple cans
of carb cleaner. see if this helps.That video was to clean the EGR valve its self, is that also how you clean or clear out the EGR port(s) on the intake manifold too?
OK, tried unclogging the egr ports on the intake for the egr valve and the engine almost died after I tested it with a vacuum pump, so I must of unclogged it.
My question now is if the check engine light does happen to come back on what are other things to check in the egr system? I checked the VSV, modulator, EGR Valve but have not checked the EGR sensor, is that the only thing left to check as far as the EGR system goes?
The check engine should not come back on… I’m hoping that cured it.
Anyways thanks for the help.
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