Need help Gen 2 97 GTS with P0153 code and CEL

[Viper-911]

Hey all, looking to get some ideas on the possible cause of a P0153 code that myself and my shop have not been able to clear up. That code is related to a slow response on bank 2 sensor 1. So far here is what has been done. I've replaced the front 02 sensors with the factory NTKs cleared the code and it came right back. Tried some Denso O2 sensors and that did not work either. I added RT high flow cats in case that would help although I wanted those regardless to lessen the fuel smell. Ironically I wasn't getting any codes for 02 efficiency on the rear O2s even being catless. I smoke tested the exhaust and found an exhaust leak on that side. At this point I was sure I found the problem. I broke two bolts off in the head and at that point I ran out of time and patience and sent it to my local performance shop. They are not super well versed in Viper's but there is one other Viper in my area that gets worked on there (AR Autoservice). There isn't really any good Viper shops anymore it seems in the Portland OR area and this problem seemed relatively straight forward. The shop confirmed the exhaust leak and noted the engine was running lean on that side but not causing a code for lean condition. They got the manifold off and found a burnt exhaust valve on the cylinder with the exhaust leak. The head was pulled on the passenger side to get the bolts machined out of the head and all new valves and pushrods were installed and a new head gasket and exhaust manifold gasket installed. While this was all being done, i had them clean all the injectors in case that was causing any issue. They put it all back together, smoke tested the intake and exhaust and all was good. Then they took it for a drive and the O2 monitor was still not switching fast enough and the CEL and P0153 code came right back. They installed the Denso O2 on that side and the monitor switches faster with that O2. In fact its switching as fast as the drivers side but still setting off a P0153 code. Resistance check on the wires for both O2 sensors is the same. The voltage switching appears to be about the same on both sides yet still the P0153 code comes right back. I'm at a loss and the shop isn't sure what to do to get it to go away. everything appears to be working correctly and the engine is running perfect but still causing the code and CEL. The shop did some of the troubleshooting driving it on a dyno to control the environment and said everything is working right. They even dyno tested the power for me while it was there and they said it put down about 450 whp (I haven't seen the dyno graph yet though) so clearly it runs well. About the only thing left to consider is that maybe its a problem with the PCM.

I'm in a state where i have to pass emissions tests and a CEL is an automatic failure although I've now figured out that since my car is a 1997 and is 25 years old, I can register it as a "special purpose vehicle" and then I only have to register it once and i'm done and no emissions tests. If i can't figure it out, I may just have to live with it but I don't like knowing there is something wrong and that it could potentially result in some other unanticipated issue that will be a problem.

I guess i should list all the mods on the car in case that helps. 1997 GTS: Corsa exhaust, Random Technology (now Belanger) High Flow Cats, smooth tubes, and K&N filter.

[GTS Dean]

Critical key #1. Always use OEM O2 sensors!!!

[Viper-911]

Yes I've read a lot about the OEM sensors and how issues can arise with other O2 sensors. This Code comes up regardless of whether you use the OEM sensor or the Denso sensor.

[Hoonin88]

Might try the trick that utilizes a spark plug non-fouler.

[GTS Dean]

eBay has these cheap:
https://www.ebay.com/sch/i.html?_fro...nual&_osacat=0

[Viper-911]

I'd be hesitant to use a spark plug non-fouer for a front O2 sensor since the front O2 is for engine management. Have you actually done this? I've done this trick on other cars for fooling the rear O2 sensors.

[Hoonin88]

I have not done this on a viper, but I have on old chevy 350s. As another user mentioned, might be a good time to start looking back through the wiring and cleaning up connectors.

[Viper-911]

Yeah I did that already. The connectors looked good too, solid connection, no corrosion. I checked the resistance on all the wiring and it was good and basically the same on each banks front O2 sensors. For whatever reason, when looking at the voltage switching for the O2s, it switches just a tad slower on bank 2 and pretty quickly sets a code. If I switch to a Denso O2 on bank 2, it takes longer to set the code but sure enough it still comes.

I've got myself a spare ECU from another 1997 GTS and i'm going to install that and see if it works

[Hoonin88]

Keep us posted!

I get so furious when scouring through forums for solutions to a problem I am encountering, get to the last page and nothing!

[GTS Dean]

Yep - no final resolution to an important shared problem.

[dave6666]

You don't say you have long tube headers. But if so, that will cause the sensor heating issue.

When Dan Lesser and I were doing some tuning on my car I was having a similar issue throwing a CEL. I believe the solution that Dan came up with was to increase the error count to some unrealistically high number that would never be reached. And therefore no more CEL.

You can also try drilling out the sensor to allow more exhaust flow in to it to in theory, allow faster heating. I did that but ultimately went with the tune solution.

You don't want to put non foulers on your primary sensors esp if you are having heat up issues. Kind of counterintuitive there...

[Viper-911]

You don't say you have long tube headers. But if so, that will cause the sensor heating issue.

When Dan Lesser and I were doing some tuning on my car I was having a similar issue throwing a CEL. I believe the solution that Dan came up with was to increase the error count to some unrealistically high number that would never be reached. And therefore no more CEL.

You can also try drilling out the sensor to allow more exhaust flow in to it to in theory, allow faster heating. I did that but ultimately went with the tune solution.

You don't want to put non foulers on your primary sensors esp if you are having heat up issues. Kind of counterintuitive there...

The car does not have long tube headers. At one point in the car's history it did have Belangers on it for awhile but the previous owner removed them. Currently I think it has the more recent OEM tubular headers that were in the later run of Gen 2 cars rather than the stock manifolds that were present in 1997. Not sure if that would potentially cause this. Your idea about drilling out the senor is interesting. This is exactly why I experimented by putting in a Denso sensor since those have many more holes in them already. I know from reading this forum that using anything but the stock NTKs usually causes problems rather than solves them but I was curious for the heating effect. I like your idea of simply tuning this issue out and i wouldn't mind putting a custom tune on the car anyway to take advantage of the mods on the car.

[Viper-911]

I got the other PCM installed and drove it around and the P0153 code has so far not returned! It usually comes back pretty quick so maybe that was it. Unfortunately this PCM does not have all the OBD monitors activated that should be. The misfire monitor shows up as not supported. To clarify it is not the case that it just isn't ready and just needs to be driven more to set the monitor but that it shows up as unsupported. Since I live in an emissions testing required area, this monitor must be on. Any ideas on this? Seems I've trader one problem for another. As far as I know, the misfire monitor is just a signal from the crankshaft position sensor. Maybe I just need to talk to a tuner and see which of these problems is easier to solve via tuning?

[usmcfieldmp]

I got the other PCM installed and drove it around and the P0153 code has so far not returned! It usually comes back pretty quick so maybe that was it. Unfortunately this PCM does not have all the OBD monitors activated that should be. The misfire monitor shows up as not supported. To clarify it is not the case that it just isn't ready and just needs to be driven more to set the monitor but that it shows up as unsupported. Since I live in an emissions testing required area, this monitor must be on. Any ideas on this? Seems I've trader one problem for another. As far as I know, the misfire monitor is just a signal from the crankshaft position sensor. Maybe I just need to talk to a tuner and see which of these problems is easier to solve via tuning?

For emissions testing, most places only see it as a fail if it says "Not Ready". YMMV. An unsupported system typically just means that system is monitored by the ECU, which usually isn't a neg against you. I suppose it depends on your state's level of sophistication.

[Viper-911]

Yeah that's exactly my experience "unready" is usually the issue which is fixed by drive cycles. Unsupported isn't going to change. Any chance an unsupported misfire monitor is just how the vipers came in 1997? Anybody else got a 97 that has the misfire monitor showing as "ready"?

Another thing I noticed when I switched ECU is that the ECU that came out is a part number for a 1996 vehicle. The replacement I put in is a part number for a 1997 vehicle. I assume these aren't supposed to be interchangeable? Wonder if that had something to do with my prior problems.

[GTS Dean]

I'm not aware that a misfire detection routine was built into the 96 board or software. It is possible you have a sensor that wasn't present on the 96 and the JTEC is having trouble resolving an unsupported input.

[usmcfieldmp]

If I remember to do so when I get home today, I'll check the System Readiness readouts on my recent Texas Inspection.

[goggles Pizano]

If I remember to do so when I get home today, I'll check the System Readiness readouts on my recent Texas Inspection.

Almost read Texas Instruments.

If I get a chance, I will check out the readiness on the scanner.

[Viper-911]

Would be great to get some confirmation. Looking forward to what you guys find.

[dave6666]

If you think you may have an unsupported sensor issue, or a PCM compatibility issue, then talking to all of us forum PCM hillbillies is wasting your time. Call or email Dan Lesser @ Viper Specialty Performance.

I've done quite a bit of tuning and PCM related work with Dan over the years working on both stock n/a and f/i Roe. When going from a 1-bar MAP to a 2-bar or 3-bar MAP with injector multipliers and everything else that we did, you will never get to an emissions readiness state. My inspection stickers were of Mexico origin. BUT, I never expected P0443 purge solenoid to pop up every other time I started the car.

Over the 10 or so years I lived with that code I replaced the purge solenoid and everything else that you can do to the car to test or fix it. Finally, I called Dan and asked for advice since he knows the car. There was a mid year code change to the PCM for that nugget and I had an early that year PCM but needed a later that year PCM. He hooked me up.

Summary: I should have called Dan 10 years ago.

Also, if you are talking about drive cycles, you need to be aware of just how complex the definition of a drive cycle is. Here is a good read about what a drive cycle is.

https://www.justanswer.com/chrysler/...html#re.v/287/

[Viper-911]

If you think you may have an unsupported sensor issue, or a PCM compatibility issue, then talking to all of us forum PCM hillbillies is wasting your time. Call or email Dan Lesser @ Viper Specialty Performance.

I've done quite a bit of tuning and PCM related work with Dan over the years working on both stock n/a and f/i Roe. When going from a 1-bar MAP to a 2-bar or 3-bar MAP with injector multipliers and everything else that we did, you will never get to an emissions readiness state. My inspection stickers were of Mexico origin. BUT, I never expected P0443 purge solenoid to pop up every other time I started the car.

Over the 10 or so years I lived with that code I replaced the purge solenoid and everything else that you can do to the car to test or fix it. Finally, I called Dan and asked for advice since he knows the car. There was a mid year code change to the PCM for that nugget and I had an early that year PCM but needed a later that year PCM. He hooked me up.

Summary: I should have called Dan 10 years ago.

Also, if you are talking about drive cycles, you need to be aware of just how complex the definition of a drive cycle is. Here is a good read about what a drive cycle is.

https://www.justanswer.com/chrysler/...html#re.v/287/

Well based on your experience it sounds like my original problem I started this thread with may just have been an issue of running a 96 PCM in a 97 MY GTS especially given the fact that it immediately went away when the 97 PCM was installed. I'm not actually sure if the 96 PCM also had the misfire monitor unsupported since I never was paying attention to that. In any event, I'll give Dan a call and see if he can shed some light on that issue. I'd like to get some tuning done for the car as well and seems like he can help out with that as well.

I've also managed to solve the "passing emissions" issue by using Oregon's loophole for antique and collector vehicles to register the car as a special interest vehicle which must be at least 25 years old to qualify (so 1997 and older vipers qualify). Not only do I not have to worry about passing emissions every other year, I don't ever have to pay registration fees ever again. I get a permanent plate for the vehicle. The limitations on the registration are that it is to be used for car shows, club events, and "maintenance driving". Maybe other states have this exception as well.

[usmcfieldmp]

Glad to hear you got it sorted... because I was coming back to give you the bad news that since mine turned 25 as well, my Texas inspection changed to safety only - so I didn't have any system readiness data.

Granted, I do have an HPTuners cable and could probably have just read them myself.