19963.4lsr5
New member
To me your LTFT a -3.9 looks good. My 97 runs around 0 but -5 to 5 is ok and some manufactures say operating within -10 to 10 is normal.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
P0420
- Thread starter 2ndhandyotaman
- Start date
2ndhandyotaman
Member
I got the new sensor today- it didn't exactly go very easy. Both studs snapped off at the mounting flange. The first one I did at my storage unit, so I knew the 2nd one was going to snap as well. I drove to the maker space that I use for fab projects, parked on the side of the building out of site and snapped off the 2nd stud, then dropped the pipe and went inside.
I found that both flange gaskets were badly deteriorated and I found a small hole on the top of the pipe where the hanger is welded on. More than likely this is the cause of the CEL. The Oxy sensor looked ok, no big build up of carbon and no rust/physical damage. I used the vertical mill to face off the mounting surface of the sensor, then drilled out the broken studs and re-tapped the holes for M8. I MIG'd the rust holes shut then re-installed the pipe along with the new sensor. The 'Runner seemed to idle a little better (not that it was bad before).
I used a IR thermometer to measure temps on the cats ( at 2500 RPM), the 1st cat was at 550° inlet and 525° outlet (average) and the 2nd cat was at 425° inlet and 375° outlet (average). The 'Runner seemed to drive ok on the way home, no noticeable difference from before. I'll go for a run up the interstate tomorrow morning and see if the CEL comes back on and I'll data log while driving.
It looks like I'll be needing a rear cat soon just because of the thin metal from oxidation. I bought myself some time with the weld repair but who knows how long it will last, of when another hole will open up.
I found that both flange gaskets were badly deteriorated and I found a small hole on the top of the pipe where the hanger is welded on. More than likely this is the cause of the CEL. The Oxy sensor looked ok, no big build up of carbon and no rust/physical damage. I used the vertical mill to face off the mounting surface of the sensor, then drilled out the broken studs and re-tapped the holes for M8. I MIG'd the rust holes shut then re-installed the pipe along with the new sensor. The 'Runner seemed to idle a little better (not that it was bad before).
I used a IR thermometer to measure temps on the cats ( at 2500 RPM), the 1st cat was at 550° inlet and 525° outlet (average) and the 2nd cat was at 425° inlet and 375° outlet (average). The 'Runner seemed to drive ok on the way home, no noticeable difference from before. I'll go for a run up the interstate tomorrow morning and see if the CEL comes back on and I'll data log while driving.
It looks like I'll be needing a rear cat soon just because of the thin metal from oxidation. I bought myself some time with the weld repair but who knows how long it will last, of when another hole will open up.
2ndhandyotaman
Member
I went for a 35 mile trip on the interstate averaging 75MPH this morning, no CEL or any hiccups. The truck seems to idle smoother and accelerate a bit better, so that's some good progress. I had the scan tool viewing live data during the drive, the only difference that I noticed was the the long term fuel trim seemed to be staying between zero and +2. The only time I saw it dip below zero was during idling after the interstate run when I snapped a pic of the screen.
I have no idea if it's "fixed" or if I've only postponed some more trouble shooting. I know that I'll go to get emissions tested on Friday as long as the light stays out, I can at least get that off of my back for 2 years.
Thanks to everyone that has posted in this thread, the opinions are always helpful.
I have no idea if it's "fixed" or if I've only postponed some more trouble shooting. I know that I'll go to get emissions tested on Friday as long as the light stays out, I can at least get that off of my back for 2 years.
Thanks to everyone that has posted in this thread, the opinions are always helpful.
19963.4lsr5
New member
Your readiness monitors will need set maybe as part of your smog test. That scanner should tell you if they are set.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
TheDurk
Elite Member
http://mde.maryland.gov/programs/Air/MobileSources/Documents/OBD%20II%20Readiness%20Monitor%20VEIP%20Requirements%20_Revised_%20for%20Website%20_4_.pdf
Here are the Maryland readiness rules. (one son had Md Plates for four years.) You can fail catalyst if ALL other monitors show READY, but only ONCE. Next time it must show READY.
19963.4lsr5
New member
That sucks that they remember it wasn't set. In PA my 97 can have 2 not set and pass the smog scan. My 04 grand Cherokee can only have 1 not set. And around 2007 all have to be set to pass.
Sent from my iPhone using Tapatalk
2ndhandyotaman
Member
Thanks for the info about the 'rediness monitors', I'll have to fiddle with the scanner and see if I can find where that info is hidden. I've only used this scan tool since my buddy lent it to me so I'm still trying to figure it out.
I drove the CRV today in the ice/slush, it does surprising well for being a total 'hands off' system. It just has crappy fuel mileage for a vehicle that is ,90% of the time, front wheel drive. 21 MPG is average combined, I'll see maybe 24 on a long highway run. This is the main push to get the 'runner going strong, so that I can sell the CRV and get a DD sedan for fuel economy and use the 'Runner for fun/crappy weather driving.
I drove the CRV today in the ice/slush, it does surprising well for being a total 'hands off' system. It just has crappy fuel mileage for a vehicle that is ,90% of the time, front wheel drive. 21 MPG is average combined, I'll see maybe 24 on a long highway run. This is the main push to get the 'runner going strong, so that I can sell the CRV and get a DD sedan for fuel economy and use the 'Runner for fun/crappy weather driving.
19963.4lsr5
New member
My 2002 Saturn SL1 manual shift is my DD at 38-45mpg. My 4Runner is bad weather and pleasure driving, My Cummins is woods firewood hauling.
Sent from my iPhone using Tapatalk
Robb235
Senior Member
I have that same Actron scanner. It does read the readiness monitors. Going from memory, I believe it's under I/M Monitors or something like that.
Sent from my iPhone using Tapatalk
2ndhandyotaman
Member
Thanks. I found the file that you mentioned and guessed that was the info I was looking for on the reader. Everything looked to be functional so I took it for an emissions test last Friday and it passed. They just plugged in and looked for codes, no tailpipe sniffer. I actually asked if they could do a sniffer test just because I'm curious about what it's actually coming out of the tailpipe. The tech just looked at me and said 'no'. LOL
I'm down to 1/4 tank now and I'm at 200 miles, so the mileage has improved slightly. No CEL so far, fingers crossed.
19963.4lsr5
New member
The 1/4 tank mark on my 97 is 12 gallons to fill
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
because you had an exhaust leak the PCM with the o2 sensors reporting too much oxygen then dumps more fuel into the engine.
if this did not get fixed the converter will get damaged from too much fuel .
the down stream sensor with the exhaust hole indicated a high voltage.75 .. after the leak fix down to .25v so that is why no code return.
if this did not get fixed the converter will get damaged from too much fuel .
the down stream sensor with the exhaust hole indicated a high voltage.75 .. after the leak fix down to .25v so that is why no code return.
gtxtom
New member
So I can't make my own thread, but I'm having a similar problem. Over the past year I have replaced the AFS and O2S. P0420 came back on on my way home from work yesterday. Plugged in a scan tool this am and graphed the 2 sensors. This is what I got. Cats done for?
Car is a 2002 4Runner with roughly 115k miles on it. I do have an exhaust leak at the muffler, but I smoke tested the exhaust system when I replaced the AFS and didn't notice any leaks before the O2S.
Car is a 2002 4Runner with roughly 115k miles on it. I do have an exhaust leak at the muffler, but I smoke tested the exhaust system when I replaced the AFS and didn't notice any leaks before the O2S.
19963.4lsr5
New member
Fix your exhaust leak. Reversion will pull fresh air into the exhaust.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
2ndhandyotaman
Member
Exhaust leaks between the 2 sensors will definitely work against you, as well as old sensors. When I took my 2 cats off last week, I found more rust holes in the upper part of the tubing, a corroded flange not sealing properly as well as the temps on the cats indicating that they weren't flowing properly.
I installed a Bosal "premium" load for the first cat ( it was actually cheaper and it came ID'd for CA emissions) and the regular Cat for the 2nd one. I got new gaskets for the sensors and flange mounts, some new SS hardware for the flanges and got it done. I'm already seeing an improvement in fuel economy as well as overall performance.
I had my 1st long road trip yesterday, about 3.5 hours of driving. The truck ran much better and the CEL stayed off. It's not even showing up as a "pending" code, so I'm starting to feel better about spending the $$ for the parts.
@ gtxtom: from what I remember, my voltages were similar to what yours is showing. I didn't condemn the Cats until I hit them with the IR temp gun and saw that both of them were showing temps around 150 ° hotter on the inlet side compared to the exhaust side. at 2500 RPMs.
I installed a Bosal "premium" load for the first cat ( it was actually cheaper and it came ID'd for CA emissions) and the regular Cat for the 2nd one. I got new gaskets for the sensors and flange mounts, some new SS hardware for the flanges and got it done. I'm already seeing an improvement in fuel economy as well as overall performance.
I had my 1st long road trip yesterday, about 3.5 hours of driving. The truck ran much better and the CEL stayed off. It's not even showing up as a "pending" code, so I'm starting to feel better about spending the $$ for the parts.
@ gtxtom: from what I remember, my voltages were similar to what yours is showing. I didn't condemn the Cats until I hit them with the IR temp gun and saw that both of them were showing temps around 150 ° hotter on the inlet side compared to the exhaust side. at 2500 RPMs.
Last edited:
