OBD II quirks

[GTS Bruce]

NY state No sniff test but plug in to verify systems working,Headers,no cats,corsa,syms.No check engine light and no problem passing for years.UNTIL the computer or battery is disconnected.Then the cars system knows the O2 sensor heat up is not working correctly and it refuses to do the 2 evap tests even though there is no check engine light.Instead of cruising with friends this weekend.Install high flow metal substrate cats from JON B and the o2 sensors I kept in a plastic zip lock.Yep the sills are a lot hottter again.Immediately checks and passes o2 sensor warm up.Then runs the evap tests and passes those too.Too much of a hassle to switch back and forth.Car is a little quieter.Can converse inside.Tone is deeper.Car runs smoother and seems a little mor torky.Pull the cats and use syns and you won't have a problem UNTIL the battery/computer is disconnected. GTS Bruce

 

[2000_Black_RT10]

On other OBD2 cars there are 02 sensors before and after the cats. Do all Vipers only have 2 or are there those that have 4?

Maybe Chuck Tator can shed some light on this?

 

[Camfab]

On other OBD2 cars there are 02 sensors before and after the cats. Do all Vipers only have 2 or are there those that have 4?

Maybe Chuck Tator can shed some light on this?

Actually I believe he is referring to the second set of 02 sensors. Your 2000 has in fact four 02 sensors. The two primary sensors before the cats are used to correct for variations in fuel delivery while driving after warm up. The two 02 sensors after your cats are used to check the differential of 02 in the exhaust post catalytic action. Another words if they sense no change in 02 levels the cats aren't working, and thus a check engine light is set. He had removed his cats, and that required the 02 simulator he was referring to as syms.

 

[2000_Black_RT10]

Makes sense, thanks. I didn't realize they were that far back on the tailpipe, just looked and there they were..

 

[dave6666]

NY state No sniff test but plug in to verify systems working,Headers,no cats,corsa,syms.No check engine light and no problem passing for years.UNTIL the computer or battery is disconnected.Then the cars system knows the O2 sensor heat up is not working correctly and it refuses to do the 2 evap tests even though there is no check engine light.Instead of cruising with friends this weekend.Install high flow metal substrate cats from JON B and the o2 sensors I kept in a plastic zip lock.Yep the sills are a lot hottter again.Immediately checks and passes o2 sensor warm up.Then runs the evap tests and passes those too.Too much of a hassle to switch back and forth.Car is a little quieter.Can converse inside.Tone is deeper.Car runs smoother and seems a little mor torky.Pull the cats and use syns and you won't have a problem UNTIL the battery/computer is disconnected. GTS Bruce

The space bar is that big wide key down at the bottom. Can be used after periods (.) if you want to promote others to spend their time reading your post.

 

[vprtech]

I have never seen a Viper with O2 sim's pass the O2 heater tests. The ecu sends a biased voltage through the signal wire on start up, and as the sensor warms up the resistance drops thus the voltage drops, this is how the pcm checks to see if the heater is up to spec. With the sim's, as soon as the key is turned to the run position, they are sending a switching signal back to the ecu, so the ecu never runs the heater test.

- Chris

www.dcperformance.com

 

[Hoosier Daddy]

Oh contraire, mine has been working for years even with a battery disconnect yearly!!

 

[vprtech]

I should clarify something, I have never seen one pass, but the car does not fail either. The OBD2 "heater monitor" test just never runs. Of the many vehicles I've seen with downstream sim's, it's always been the same.

Remember also, that if you were to take your vehicle into a smog test (obliviously you would not be smoging a vehicle with missing smog equipment, right?) you would not fail because of one OBD monitor not passing. Over here in CA, if you complete three out of five, and you don't fail any of them, that will get through the OBD portion of the smog test.

- Chris

www.dcperformance.com

 

[GTS Bruce]

In NY you pass if you fail 1 test.You need 4 out of 5 but there is no sniff test.In my 01 when the heater monitor test wouldn't run neither would the 2 evap tests.With the high flows and after cat o2 sensors in place it immediately passed the heater monitor test and after a short drive ran and passed both evap tests.Had to do a lot of checking with a DRB before plugging into NY again to check and make sure everything was running.Got a lot of errors before figuring it out.Test not run(coolant temp too high)Wrong voltage signal(tank too empty or full).The bottom line is it simply wouldn't run the evap tests until after the heater monitor tests ran. GTS Bruce

 

[2000_Black_RT10]

How soon did you get a check engine light with no cats?

 

[vprtech]

In NY you pass if you fail 1 test.You need 4 out of 5 but there is no sniff test.In my 01 when the heater monitor test wouldn't run neither would the 2 evap tests.With the high flows and after cat o2 sensors in place it immediately passed the heater monitor test and after a short drive ran and passed both evap tests.Had to do a lot of checking with a DRB before plugging into NY again to check and make sure everything was running.Got a lot of errors before figuring it out.Test not run(coolant temp too high)Wrong voltage signal(tank too empty or full).The bottom line is it simply wouldn't run the evap tests until after the heater monitor tests ran. GTS Bruce

GTS Bruce, I understand what your are saying about the evap test, to be honest, I hardly ever let the car run that test by itself. Did you know that you can force the car to run the evap and purge flow OBD test together with the DRB? When I'm doing a smog repair, and checking all of the OBD monitors, I will cold start the thing and let it idle to pass the heater test (no reving), then LDP test , it's under menu one "system test's" I believe. After those three have passed, I will drive the car on the street or the dyno, following the pre-test sections in the OBD menu of the DRB for the O2 test, and Cat efficiency. Some cars can be a real pain.

- Chris

 

[GTS Bruce]

2000 black RT 10:Never got a check engine light because I immediately upon removal of cats installed syms at the same time.Never got a check engine light even when it refused to run the heater test because it always got a signal from the syms. Chris we tried that and my car just flat out refused.Actualy its slightly quieter.Has a better tone.Just wish those side sills were cooler.Reason I left them out initialy was to save a few bucks at the time. GTS Bruce

 

[Viper Specialty]

Bruce- running into the same BS with my car right now. I HATE the OBD-2 crap here in NY, it would be easier to smog the damn thing...

I have passed all but the O2 Heater and Evap, same as you. Failed today as I knew it would, just wanted the 10-day extension as this car has an 06 sticker!

I am going to try a quick fooler on the system tomorrow by plugging in the rear O2's while the car is off, and then doing a quick drive to pass the 02 heater, but I wont make the drive long enough for it to check cats again. (then again, O2's in open air will read lean anyway and should pass cat efficiency...assuming it doesnt pop a rationality DTC first) Question is, will it check O2 heater on warmup or cooldown? manual states cooldown, posts here say warmup... we'll see. Once the heater passes, I can plug sims back in, and it should run evap and pass it as well.

 

[Viper Specialty]

Well, plugged in the rear O2's, dangled in open air, started car for about 1 minute and shut off. Left off for about 5 minutes and checked- 02 heater passed. Plugged back in the sims and i'm good to go, heater remains ready even with the sims plugged back in. Evap should run on next drive cycle.

PS- O2 heaters checked on shutdown as I expected them to be.

 

[vprtech]

Well, plugged in the rear O2's, dangled in open air, started car for about 1 minute and shut off. Left off for about 5 minutes and checked- 02 heater passed. Plugged back in the sims and i'm good to go, heater remains ready even with the sims plugged back in. Evap should run on next drive cycle.

PS- O2 heaters checked on shutdown as I expected them to be.

Sorry, you are incorrect. To paraphrase DCX service bulletin 25-02-98 :

Front wheel drive vehicles (SBEC) heater monitor will run when the key is turned off and open throttle timers have elapsed.

Rear wheel drive vehicles (JTEC) heater monitor requires a cold start. The test will only run with an ambient temperature between 0 – 100 degrees F, and the engine temperature must be within ten degrees F at startup.

In my experience the O2 heater usually runs within the first minuet or so from cold start. The monitor is most likely to fail in borderline situations (headers) if the car is not driven immediately after a cold start.

- Chris

www.dcperformance.com

 

[Viper Specialty]

Sorry, you are incorrect. To paraphrase DCX service bulletin 25-02-98 :

Front wheel drive vehicles (SBEC) heater monitor will run when the key is turned off and open throttle timers have elapsed.

Rear wheel drive vehicles (JTEC) heater monitor requires a cold start. The test will only run with an ambient temperature between 0 – 100 degrees F, and the engine temperature must be within ten degrees F at startup.

In my experience the O2 heater usually runs within the first minuet or so from cold start. The monitor is most likely to fail in borderline situations (headers) if the car is not driven immediately after a cold start.

- Chris

www.dcperformance.com

Dont know what to tell you? The manual states shutdown, and the monitor remained Not Ready for the entire time the key was on. It flipped to Ready on the next Key On. Its certainly possible there is another reason for this, but there is certainly conflicting information here pointing in different directions. if it makes a difference, I am dealing with an NGC controller, not (just) JTEC.

 

[vprtech]

I was under the impression that we were talking about Vipers. As far as NGC goes, I really don't know, but for JTEC the test runs with start up, and with the older SBEC3, SBEC3+, etc, the test runs when you shut the car off, thats the only point I was trying to make.

 

[Viper Specialty]

I was under the impression that we were talking about Vipers. As far as NGC goes, I really don't know, but for JTEC the test runs with start up, and with the older SBEC3, SBEC3+, etc, the test runs when you shut the car off, thats the only point I was trying to make.

I probably should have specified- there were two vehicles in this conversation. One indeed was a Viper, the other was a Hemi (NGC). Both had the same issue, and both were fixed in the same manner. I did monitor them both, and they both appeared to pass on the next key-on (shut-down testing?), as they did not pass when running. Ironically, both manuals also state they are tested upon shutdown.

Is it possible they actually passed on key-on? sure. is it possible one passed on key on, the other on key-off but they didnt display until later? also sure. Either way, there is still conflicting info.