03 Driver s Bank Cylinder Misfiring

[darrahh]

Newish Viper owner here and hoping you guys can give me some advice/fresh ideas on the struggles I've had lately. I bought an 03 with headers, exhaust, intake and tune. The car ran great for over a month, but then the problems started. At first, the car would start fine but within a half mile or so, the driver's side cylinders would start misfiring or not firing at all. If I continued to drive, the problem would correct itself within another mile or so and not return for the remainder of any drive. As time has gone on, the problem has gotten progressively worse until it would happen constantly. When it occurs, the driver's side exhaust will either cut out completely, or sporadically fire/backfire/miss without any regularity. The passenger side always stays constant sound, pressure, pulse, heat, etc.

Here is what has been done so far:
Pulled and cleaned the spark plugs- The problem went away for a day, then returned
Replaced the spark plugs- No change
Put a timing light on each plug wire on the driver's side and monitored- It appeared as though cylinders #1, 5, and 7 were all missing a "spark" occasionally
Put the stock tune back on the car- no change
Pulled positive battery cable and touched to ground to reset PCM- Car ran great for over an hour drive, then back to terrible the next day
Checked connections on PCM- Everything tight there
Monitored battery voltage- Checked out ok
Replaced coil packs and wires- car stopped missing as bad, but still missing consistently and basically undriveable
Pulled sill and checked O2 wiring- Downstream O2 is connected but zip-tied up due to aftermarket exhaust. Upstream is connected, all wiring checks out ok.
Disconnected both driver's O2 sensors- Car runs exactly the same... crappy

I've thought about cam or crank sensor but I'm having a hard time seeing why that would only impact the driver's side. My other line of thought is possibly wiring on the driver's side injectors. That may explain why is runs slightly better after pulling the intake to replace coils. When I pulled the plugs after it was running at its worst, none of them were wet which is what got me going down the injector path.


Sorry for the length, just trying to share as much info as possible. I appreciate any and all feedback anyone may have.
Here's a YouTube video of the exhaust when I was holding it steady just above idle (maybe 1300 RPM)... this is when it was running at its worst, before coil/wire changeout. It's slightly better now but still not right
https://youtu.be/XAmVzNS6Cgg

[Steve-Indy]

I have been following your other thread...and must say that you are going over and above the usual to attempts to solve this issue on your own.

Your notation: "Disconnected both driver's O2 sensors- Car runs exactly the same... crappy"...can only make me wonder how it would run with new O2 sensors and harness.

But, before trying that, I would want to examine the car using Chrysler scan tools.

Sometimes a fresh look by an experienced, well trained Viper Tech solves stubborn issues that befuddle us owner-mechanics.

[darrahh]

Thanks. I'm certainly not against getting a Viper tech to take a peek at it... I think realtime data would narrow it down quickly. I need to try to find someone relatively local that can handle it, but in the meantime I'm just trying to exhaust my options. Being an electrician/mechanic by trade also makes it difficult to give up chasing a problem :D To make matters worse, there's a carbed 528 Hemi sitting right next to the Viper constantly reminding me how much more complicated engine management has become lol

[Steve-Indy]

Tom Sessions is about 3 hours down-coast from you...in Hampstead, NC. He has the proper equipment, has his own shop, and has a ton of experience. 910-228-8477

[Whiskey]

I’d suspect wires. But to change them on a Gen3 you have to pull the manifold. While you are in there....change the coil packs because to replace them...you have to pull the intake manifold again.

[darrahh]

I’d suspect wires. But to change them on a Gen3 you have to pull the manifold. While you are in there....change the coil packs because to replace them...you have to pull the intake manifold again.

New wires and coils went on the day before yesterday. It stopped missing as badly as before, but still bad enough you wouldn't want to drive it

[Whiskey]

Better but not perfect. Sometimes new parts are not good parts. But you could also disconnect the battery for 20min while you reset connections on the PCM, Wires, crank angle sensor.

If that doesn’t do it....I’m out of ideas.

[Florida04]

If you are looking for live data feeds I purchased a scanner named Blu*driver from *mazon. It connects via Bluetooth to your tablet or phone. Records live data streams to share, scans for codes and saves old codes. It has helped me diagnose an O2 sensor that I replaced but was bad. $79 until tonight then back to $99.
Works great on my ‘04.

[darrahh]

Sounds like a good tool to have on hand, even if for other problems down the road. I've tried to datalog with my SCT tuner, but the laptop won't establish communication with the Viper. The tuner works great for uploading tunes but for whatever reason when being a "go between" for the laptop I'm getting zero vehicle info.

That reminds me, I'm also not getting any codes being thrown. Obviously in the video the car is misfiring but apparently the PCM sees no issue

[Rocket]

PCM not seeing/reading any codes is very odd.

[pokeyl]

Do you have any fuel on the misfire plugs? You may have injectors that are sticking, open will be wet plugs, stuck closed plus will be dry.
ABC's of a running engine.
Ignition
Fuel
Compression

One is not right..

[darrahh]

Do you have any fuel on the misfire plugs? You may have injectors that are sticking, open will be wet plugs, stuck closed plus will be dry.
ABC's of a running engine.
Ignition
Fuel
Compression

One is not right..

None of the plugs are wet. When it was at its worst, I pulled the plugs after the engine running for almost 10 minutes, and all of the plugs were dry and looked brand new..as in brand new, no tan color, no discolored ground strap, nothing... there was no combustion happening. Yesterday I made a noid light to test my injector pulses, but didn't have a chance to get into the garage as I was instead fixing a broken aluminum rolling mill all night. I'll be testing injector pulse tonight.

I'm with you on the basics of a running engine, should be pretty straightforward. I know I have compression (tested that last week), so now it's just a matter of why I'm intermittently missing either fuel or spark, and if either are happening at an incorrect time.

Tonight I'll finally have a few hours to dig into the car a little more, and hopefully make some more progress. I'll update the thread with my findings and maybe get some videos of spark/injector pulse... if nothing else it'll help me document my troubleshooting steps.

[darrahh]

So I was able to spend a few hours working on it and I think I'm making progress. Since they're cheap and easy, I replaced the cam and crank sensors and nothing changed... unsurprisingly. I found a hacked up wire on the passenger side downstream 02 and remedied that, which also as expected made no difference (but it's one less potential issue down the road). I then started the car and it was almost as bad as ever, backfiring, misfiring, etc. Shut the car down, disconnected the injectors, plugged a noid light into the #5 cylinder, reconnected the other injectors, and started it. Car seemed to run ok except obviously #5 not firing, but the noid light showed a consistent injector pulse. Connected #5 back up and car ran perfectly. Backed it out of the driveway, and it started to miss again. Pulled it back in the garage, unplugged and replugged each driver's side injector, and the car ran smooth again. I then took it for a 20 minute drive without issue.

So, it seems that it's narrowed down to something with the injector harness on the driver's side. Every time I mess with the injector connections it seems to impact how the car runs. According to the wiring diagram, they all share a +12V common, so maybe the issue is there.

On the upside, tonight is the first time I've been able to take the car out successfully in weeks :drive: It has a slight pop/burble to the exhaust at light throttle, but it was driveable.

[pokeyl]

When you had the intake off were the plastic wire supports for the injector harness good? I think you have 3 on each side. Also check to make sure you have #1 on #1 and so on. I know I got 2 of my plug wires crossed once.

[darrahh]

When you had the intake off were the plastic wire supports for the injector harness good? I think you have 3 on each side. Also check to make sure you have #1 on #1 and so on. I know I got 2 of my plug wires crossed once.

Surprisingly, all the plastic supports/tags were in tact and pushed into the intake flange.

I drove the car another 100 miles or so, and it only gave me issues twice for a total of maybe 10 seconds. Once while at a steady 55 mph cruise and once while launching aggressively. Looks like if I continue to have issues I'll comb through the harness and connections.

[darrahh]

Quick update on the car and it's inconsistent behavior. I haven't had much time to mess with it, but it has gone through stages of running well for a day, then running terrible for a day. I finally got a chance to hook up a wireless OBDII transmitter to my phone and watched some live data. The car was running ok but still missing intermittently, so I started viewing sensor data. Turns out the driver's side O2 was reading a constant 1.0 V with zero variation, passenger side varying from .12-.84 V. While in process of watching data, the driver's side suddenly started reading similar to the passenger's side and the car smoothed out and ran perfect. This would explain why the car is cutting fuel to the driver's injectors if it truly thinks the mixture is that rich. So either the sensor is bad, or an injector is stuck and it's truly running full rich. Tonight I'm going to swap 02 sensors side-to-side and see if that changes anything. I've seen O2 read 0 volts because they failed, but a constant 1.0 is a new one on me.

[darrahh]

Final update... bad O2 sensor. The driver's side was apparently replaced with a Bosch unit that was intermittently failing. Swapped it out with the passenger side and the problem swapped sides. New sensor installed and drove 3 hours down to Kitty Hawk, NC and back today. Smooth, enjoyable, totally different car. Thanks for everyone's suggestions and being a sounding board while ironing this thing out. Still don't understand why I never got any CELs but oh well. Never would've figured it out without realtime data.

[06SRTCoupe]

Wow. I couldn't read all that but if you have a misfire, always replace plugs, then wires, then O2 sensors...in that order. Sounds like you spent too much time on this. Glad you finally got it fixed!