A few tips for running monitors to completion
I watched the OPUS IVS Stubborn Monitors & Drive Cycles Presentation by Keith DeFazio this past Wednesday. The link to the replay says the video is not ready.
I gleaned some tips and I would like to give a couple of them too.
I focus mainly on Toyota, Honda, GM and Ford vehicles at my shop. I am often asked to run readiness indicators to completion for customers that have failed their smog inspection for incomplete monitors.
My favorite scanner to view CAN Generic OBDII vehicle data is the Toyota Techstream scanner. This scanner will pull Mode 1 data from the makes I had mentioned and most other CAN vehicles. The data will include monitors and their enable status. Monitors are part of Mode 1, but for some reason, most scanner manufactures place monitor information separately from the other data. Techstream will also work with most Asian pre-CAN vehicles. Techstream does not play well with VPM or PMW vehicles. It doesn’t seem to like late model Chrysler vehicles either.
A 2008 Nissan Altima failed its smog inspection for a lit MIL and a code P1148, P0133, and P0130. All of the information pointed to a faulty A/F Sensor. I replaced the sensor, cleared the codes, adjusted my dyno for 5hp, and drove the vehicle with the intention of setting enough monitors to pass the smog inspection. My plan was to complete the CAT monitor first. The Altima has a catalytic converter and a catalytic adsorber. If you had only planned to run the diagnostic pattern for a P0420, the monitor would not complete. The diagnostic pattern for a P2423 is completely different from a P0420. The information I used came from Alldata.
Initially, I ran the P2423 diagnostic pattern. The first scan is the vehicle being driven at 50 mph for 3 minutes and then decelerated to 0 mph. SI recommended that there be a pause of 10 seconds, and I made sure the vehicle went into fuel-cut as seen in the scan. It also mentions that it should be done 3 times. I believe the PCM wants to fill the cats with O2 and to see the full range of the O2 sensor excursions. During one of the decelerations, you can see the O2 Sensor monitor completing. During that whole time, I tried to keep the monitors “enabled”. You can see the monitor jumping in and out of being enabled before it completed.
The second scan is the vehicle coming down from 50 mph. SI says for a P0420 you’re supposed to rev the engine up to 3500 rpm in park or neutral for 3 minutes, bring it back to idle for 5 seconds and then rev it up to 2500 rpm for another 3 minutes. I believe that first 3 minutes is to make sure the system is warmed up, and the cats are full of O2. I figured I had performed the warm up with the 50 mph run, so I stopped the vehicle, brought the engine up to 2500 rpm, and watched the CAT complete.
The first tip is to use a capable generic OBDII scanner such as the Techstream that allows you to see all of the OBDII pids and monitors. Seems like most scanners will not display all the OBDII generic pids available in the PCM, nor display monitor information along with the data. There is a lot of information on the generic side you don’t get with the enhanced side. There are other scanners that do Mode 6 and Mode 9 better than Techstream. My favorite for Mode 6 and 9 is the android OBD Fusion scanner app.
The second tip is to read SI for the code test criteria for the device or system monitor you are trying to complete. I won’t say that I don’t use drive cycles. I kinda have LA4 memorized and I’ll try that if SI is lacking information.
What is "LA4" Danny? Can you do a 30 sec video, of how to get Techstream set-up, like in your screen shots?
Hi Geoff, LA4 is a drive cycle that I would execute on my SnapOn/Sun EIS. There would be drive trace drawn on the monitor, and all I would do is follow the car on the screen. I've performed that drive cycle so many times, I can do it by memory. Here's a description of the LA4 drive cycle. dieselnet.com/standards/cycl….php When I go back to the shop on Tuesday, I'll…
"LA4 is a drive cycle....Here's a description........" interesting! Thank You. So after you're done playing video games, do you still have time to FIX anything? Just kidding, Uncle Danny. :-)
Good stuff Danny. The only thing I think I would do differently is, I generally do not put more than a 1 HP load on the dyno. I pretty much just spin the wheels. I find it is easier to match load and speed (especially on Chrysler/Jeep) I either use Techstream or Shop Forman Pro. I can’t count the times another shop sends me a vehicle with monitor issues because I have factory tooling! But I…
Thank you. You're correct about trying to match the load to run the cat monitor on Chrysler products. There have been a few times where I'm adjusting the dyno controls trying to match RPM, TP, Load and gear selection according to SI. For the most part, 5hp has been the best starting point for me. I agree, Generic OBDII has the best information to run monitors to completion.
Hey Danny- does the Techstream or the Fusion app decipher the typically stubborn Nissan …ish) Mode 6?
Techstream doesn't do Generic CAN Mode 6 very well. The OBD Fusion app displays great CAN Mode 6 reports. I didn't look at the Mode 6 on that Nissan. I usually look when there's a problem running the monitor. I find that most manufactures follow the rules CARB has for CAN Mode 6. I'll post the Mode 6 report when a Nissan comes in for a smog inspection. Edit: the typically stubborn Nissan…