Oh joy, P0401 is back... (and how 80's fail emissions)

[Crash]

Aren't the 80 series OEM air filters all washable? I've read that they are good for 10 or more washings and that ought to be at least 10 years worth, or close to it, eh?
Tim, fresh gas and some hiway miles to blow out the cobwebs sure wouldn't hurt. Also, it seems to me that with close to a 10% ratio of ethanol to petroleum fuel per gallon at the pump, adding heet or other water absorbing products is sort of overkill, isn't it?

 

[Uncle Ben]

Kevin what kind of tires are they- are they AT's? could I borrow them? My 255 Maxxis sounded like hell on those rollers, everyone in the place looked over to see what was making all the noise and shaking the earth when the guy had it up to speed... it got squirrely a couple times too I was worried he was going to lose it. Maybe a little less rolling resistance would be a good thing for the numbers too?

Stock Michellins on stock 97 80 wheels...I think... Of course you can borrow them....

 

[Tch2fly]

Tim, just put your 35s back on and tell them that was how they tested it the first time through ...it worked for me They balked but measured them and they were under 34" mounted on the truck, so away he went
It ran better on the dyno with the 315s then it did using the 265s off my Taco or the 285s I had on 2 yrs ago.

 

[Hulk]

I couldn't pass until I replaced my catalytic converters. Once they were both replaced, I passed with great scores. I also replaced both of the O2 sensors with OEM units.

 

[bh4rnnr]

A long shot, but what about spending some good time on the highway before the e-test. Get that sucker nice and warm. Did this back in 08 after it failed the first time. Passed with flying colors after driving it on the highway the 2nd time.

 

[Corbet]

Tim, do you have the Landtank mass air flow mod? I don't recall but if so cold that be causing a slightly lean mixture and higher combustion temps? Thinking out load and remembering how happy I am to not have to do tis every year like you front ranger folk.

 

[Crash]

Easy catalytic converter test, per BVB, is to get the engine up to temp and then run it for a minute or so at 1500 rpm. While at that engine speed with a temp gun check cat inlet and outlet temps. The post-cat temp should be something like 300 or more degrees farenheit higher than the inlet temps. If the inlet/outlet temps are similar, then the cats need to be replaced.

 

[nakman]

Easy catalytic converter test, per BVB, is to get the engine up to temp and then run it for a minute or so at 1500 rpm. While at that engine speed with a temp gun check cat inlet and outlet temps. The post-cat temp should be something like 300 or more degrees farenheit higher than the inlet temps. If the inlet/outlet temps are similar, then the cats need to be replaced.

Ok I think I've got one of those at work, so just point the dot at the exhaust pipe huh? If I can find the gun I'll report back what numbers I see. And yes Steve the new air filters are washable, but I have had questionable success with that.. usually the air gun doesn't blow all the dirt out, then the water just turns the dust to mud, then the whole thing looks terrible, especially when compared to a new one.


Yes I do have the Landtank MAF mod.. am hoping to get through this without undoing that though. My plan at this point is drive the heck out of the 80 for the rest of the week, and just hope I don't get pulled over again. On Saturday I'll clean out my tuna can, put in my new air filter, maybe wipe out some dust from inside the big air tube, Try to get 1/4 tank into new tank before the next test next Monday. If I fail again, then we'll have to get further into this, but I feel like I was so close to passing that I should probably just try to take the test again.

Maybe we'll have a new legislation about air quality in 2 years so I don't have to go through this again..

 

[powderpig]

Well I did not pass today. I was turned away the first time with my 34.5 tires, because the paper said no tires over 34".
anyhow My NOX was 14.75. I was even allow to keep my car running to keep the cats hot, what a hoot. I used UB thermogun and saw that one cat was dead even in and out (584 degrees F) the other was 630 in and 700 out. Anyhow new cats on order, direct bolt in from Bosal on line for 200/per cat. So much cheaper than stock. I did not even want to mess with cut and weld yet. I want to build my own exhaust when I have time. Yes I could of gone with many other compaines that do a cut and weld, but I did want to retain the bolt in bolt out feature. Who know what will happen to the shells of the old cats.
Tim, carbon on top of pistons will also cause high NOX. It might be worth to pick up some additive that will help burn some of that off. Redline addtive will help, as will sea foam, and some of the other gas additives. Also running the piss out of with some additives will help. Like keep it in lower gears, higher RPM's will help.
You are not that far off in the grand schem of things.

 

[60wag]

My 80 got tested not too long ago with the Landtank MAF sensor in it and passed just fine. NOx at 0.55, CO at 2.3, HC at 0.05. With both the NOx and CO high on yours, I'd bet on weak cats - although a functional EGR wouldn't hurt.

 

[nakman]

Ok I measured my cat temps just now.. 344 going in, then 290 out, then 250 going into the second one, then 300 going out. Measured 400 right at the Y pipe.. oh and someone set this thing to Celcius, sorry about that I can convert later I'm cooking dinner right now.

Oh and it gets better, my CEL came on at lunch today. I think my little solder job on the temp sensor wire must have come undone, it was cold out when I did it and I am a terrible solderer anyway.. I will pull the code later tonight once the kids are in bed to see if it's 401 again, if it's 402 then I've got the other side to the EGR issue now, and if it's 420 then I need cats right? stay tuned...

 

[60wag]

Here's a good primer on catalytic converter operation - its from Toyota

http://www.autoshop101.com/forms/h64.pdf

It also gets into oxygen sensors too.

At the end of the article it describes a test comparing the signals from the O2 sensors upstream and downstream of the cats to determine the function of the cats.

 

[nakman]

So do you think I need new cats Bruce? I just checked and it's 401 again, I fixed those wires together better this time am about to take it out for a spin to see if the CEL stays off.

 

[60wag]

There are a bunch of things that can cause high NOx. There are several things that can cause high CO. To get high CO and high NOx at the same time, I think there are few possible causes - weak cats would do it. The TWC efficiency test decribed in the article looks pretty simple for a shop that has the diagnostic gear. It should determine whether its the cats, the sensor(s) or something else. Also the temp rise you measured seems pretty weak. You want to see 750F (400C) for efficient cat operation.

There is also a comment in the article mentioning coolant contamination as being bad for cats. You've pushed a few quarts of coolant through your exhaust, haven't you?

 

[nakman]

Ok I just got back from driving 35 miles, about 45 minutes. Front of the first cat is 615° F, then 616°. the second cat measures 607° then 673°. While I was at it, both diffs measured 97°, the transmission pan 109, oil pan 165 and t-case drain plug 118.5. Once you get under there with the laser thermometer it's hard to control yourself..


I read through that article, thanks for that. I didn't see any numbers in the 700's though.. maybe since it's cold out? Sounds like I probably do need new cats.. they are original (168,400 miles) plus they may have been gently rubbed upon rocks a few times. I've got a rattle somewhere too, and adding more hose clamps didn't completely fix it last time I was messing with it.

Yes I did burn some coolant, probably a gallon of it over a month long period. That would have been just before my head gasket was replaced July 2002 with 111516 miles. then in November of 2002 and 114247 miles I had a P0420 CEL, and received two new O2 sensors.

 

[Crash]

[QUOTE=nakman;<snip> And yes Steve the new air filters are washable, but I have had questionable success with that.. usually the air gun doesn't blow all the dirt out, then the water just turns the dust to mud, then the whole thing looks terrible, especially when compared to a new one.
<snip>

I feel the same way about washing a paper air filter, never having had a washable paper filter element before. They don't look bright and shiny when the element dries and they are mighty wrinkled. Robbie, or anyone else, have any comments about repeated washings of the OEM paper air filter for an 80?
BVB informed me that the differences between the cat inlet and outlet temps should be two or three hundred degrees if it is working properly. I wouldn't think air temps would drop the exhaust temps much at all when everything is operating properly. The burning of the NOx and other emission contaminants by the cat is what causes the inlet/outlet temp variance and if the temp difference is less than 100 degrees, then there isn't much catalytic conversion going on. Hope that isn't too redundant.

 

[nakman]

Last thought, is if I need to get new cats then I may as well just get all new exhaust from the Y-pipe back, right? Then I can get the fancy over the frame deal that UB and Romer have... who do you guys recommend again?

I am presuming the shop would have a good way to test the current O2 sensors? And I've never bought a muffler in my life, what kind of muffler do I need? This is starting to feel expensive, I'm glad I got that fridge last week otherwise it would have never happened!

 

[wesintl]

This is starting to feel expensive..

P.O. box in..

 

[Bikeman]

I woud look to see if the VSV is bad before throwing $$$ at the cats. I have 170K on the cats on the LX and the Nox and CO were low. I can post the #'s, but the NOx was at 5 or 7, and Brian indicated the EGR was flowing well.

 

[nakman]

I think my VSV has been replaced, when the 401 issue was dealt with a couple years ago. I'll have to check my folder of receipts though.

What do you guys think of this setup http://forum.ih8mud.com/ih8mud-com-vendor-marketplace/323450-fzj80-exhaust-upgrade.html