93 4Runner SR5 V6 Fail on emissions test @ NO(PPM) 15mph
#1
93 4Runner SR5 V6 Fail on emissions test @ NO(PPM) 15mph
93 4Runner SR5 V6 Fail on emissions test @ NO(PPM) 15mph. Pass @25mph
Max Avg Meas
356 113 747 @15mph. FAIL
533 150 280 @25mph. PASS
Timing @ 11
any info at this time would help
Max Avg Meas
356 113 747 @15mph. FAIL
533 150 280 @25mph. PASS
Timing @ 11
any info at this time would help
#2
Registered User
Join Date: Sep 2007
Location: San Francisco East Bay
Posts: 8,254
Likes: 0
Received 822 Likes
on
649 Posts
NOx is controlled by the EGR system. That's what it does. That's all it does.
NOx is slightly affected by the Catalytic converter, so look at HC and CO while you're at it. If they'reboth low, then concentrate on the EGR.
In addition to the testing in the manual, http://personal.utulsa.edu/~nathan-b...77exhaustg.pdf, you should consider that your plenum (upper intake manifold) may have so much "gunk" in it that it is constricting the tube into the plenum from the EGR. If completely blocked the EGR temp sensor should throw a code, but if just restricted could easily cause your problem. In my case, it was difficult to pull the tube out of the plenum because of the build up (should be about 2mm clearance all-around).
NOx is slightly affected by the Catalytic converter, so look at HC and CO while you're at it. If they'reboth low, then concentrate on the EGR.
In addition to the testing in the manual, http://personal.utulsa.edu/~nathan-b...77exhaustg.pdf, you should consider that your plenum (upper intake manifold) may have so much "gunk" in it that it is constricting the tube into the plenum from the EGR. If completely blocked the EGR temp sensor should throw a code, but if just restricted could easily cause your problem. In my case, it was difficult to pull the tube out of the plenum because of the build up (should be about 2mm clearance all-around).
#3
Thank you SCOPE
Yep! All other emissions are way low. Recently replaced both head gaskets a few months back after blowing the RS HG. Could not figure out how to get the sensor you mentioned out of the Intake Manifold. What do you suggest? and yes that sensor looked gunked!
#4
Registered User
Join Date: Sep 2007
Location: San Francisco East Bay
Posts: 8,254
Likes: 0
Received 822 Likes
on
649 Posts
It's not a sensor. The part I'm referring to is part of the assembly labelled "EGR valve" here: http://personal.utulsa.edu/~nathan-b...68cylinder.pdf The part that extends into the plenum has a "union" connecting it to the valve. Once you unbolt enough to get some wiggle room, you can remove that union and the nuts holding the pipe to the plenum. It should come right out, but if there is enough gunk on it you may have to slide it back and forth until you knock off enough.
If you have that much, you'll need to remove the plenum to clean it. I suggest removing the "freeze plugs" at the ends so you can get inside (I didn't, but I should have).
If you have that much, you'll need to remove the plenum to clean it. I suggest removing the "freeze plugs" at the ends so you can get inside (I didn't, but I should have).
#5
Registered User
Might be good to also make sure all the vacuum lines for the EGR are hooked up correctly and not cracked or damaged. If they are wrong, basically your EGR isn't recirculating the gases like it should be.
I don't know if this will help either, but if the catalytic converter is cold during the test you'll get higher HC reading since heat helps convert it. If it's hot, you'll get higher NOx readings. Doing the test with the engine cold will get you lower NOx readings (and higher HC) but not that much to fix your current issue.
I don't know if this will help either, but if the catalytic converter is cold during the test you'll get higher HC reading since heat helps convert it. If it's hot, you'll get higher NOx readings. Doing the test with the engine cold will get you lower NOx readings (and higher HC) but not that much to fix your current issue.
#7
yep its the Cat EGR was clean. The part that goes into the exhaust manifold was caked took a bit to clean out the manifold. gave the engine better response at lower rpm still lacking in power in high rpm. retest came back still high NOx only at 15mph and that's all that was high
Trending Topics
#8
Registered User
You might also find this page helpful, taken out of the FSM:
http://personal.utulsa.edu/~nathan-b...72systempu.pdf.
But yeah, if the EGR is good and you're still getting high NOx, the cat isn't doing its job.
http://personal.utulsa.edu/~nathan-b...72systempu.pdf.
But yeah, if the EGR is good and you're still getting high NOx, the cat isn't doing its job.
Thread
Thread Starter
Forum
Replies
Last Post
kawazx636
The Classifieds GraveYard
34
10-06-2021 03:03 PM