Hooked up the GTS to a diagnostic scanner...............

[JH23JOB]

This guy I know has a very expensive Matco scanner, and he was nice enough to come over this evening and plug into my GTS to see if we couldn't pin-point the cause of my Black smoke out the tail pipe upon hard acceleration.

In another post I had, I got great advice from Vipernewbie, Viperzilla, Russ M, Gerald, Fishtail, and TomF&LGoR. The assumsion was that I might have bad O2 sensor(s), map sensor, plugs, wires etc... That's when I decided to call my buddy, and have him come over with the scanner to narrow it down.

At first everything was testing fine, and then we noticed that the TPS (throttle position sensor) was reading low at wide open throttle. The reading was 3.6v @ WOT, and the min was supposed to be 4.0v or greater @ WOT.

Could this be the culprit ?? If it's not reading the min required voltage, what would the performance result be ?? Anyone run into this themselves before ??

BTW....... Everythng else tested out to be Fine. All were within the required specs.

 

[HP]

Dan the TPS sensor reading low will prevent the PCM from realizing that the throttle blades are in WOT position - so the PCM won't do what is required
at WOT conditions - so if anything your motor would never get the fuel required
to run at WOT conditions. I would just clean the contacts on the TPS connector, hook it back up, and look else where for your problem. It maybe that the TPS code doesn't appear again. Code-scanners are great for a lot of things, but some of the basic things won't be picked up in a code scan.
Pull your spark plugs right after seeing smoke and get a reading on them to see if one or more look
electrodes don't have the characteristic gray/light brown color or if there is evidence of gas or oil. And it wouldn't hurt to run another code scan later. Also - don't rule out that oil
isn't playing a role in the puffs of smoke - depending on the completeness of
burn - oil smoke can be black.

 

[Gerald]

have u got a friend that has the same year viper? If so, it takes all but 1 minute to change them (TPS sensor) out. If yours runs great with his in there you'll know that's it!

Gerald

 

[graphiteRT]

Fellas, the TPS sensor doesn't work quite the way you might think. It works off of relative voltage. The PCM registers a "key on" voltage, off idle is defined as a set voltage above the key on voltage and WOT is defined as another delta above the key on voltage. IOW, absolute voltages are not important. The variance in a box full of TPS sensors can be dramatic. It's just not that precise a component. As an example, the TPS sensor on my supercharged 360 registers .44 at key on and ~3.67 at WOT. This is tested with the key in the on position, motor not running, multimeter hooked up to the center wire of the TPS connector. I'm not aware of any "min" value being specified for WOT on the TPS.

The absolute limits of a TPS sensor(in this case for the 360) is .26V on the bottom and 4.49V on the top. That doesn't mean the sensor is expected to operate throughout that full range. In fact, if it goes above or below that it will trip a mil. I wouldn't expect the Viper to be much, if at all different. A factory service manual would be your best reference in this case. Don't rely on aftermarket manuals like the Hayes for information. I have found them to be inaccurate on this sort of stuff.

Dodge typically tunes their motors fat from the factory and I would suspect the Viper is no different. Some black smoke under hard acceleration is not unusual.

Hope this helps.

Bob