viper gts with only 1 oxy sensor ??????

[madbrian]

i have tried everything possible to fix the low speed surging on my 99 viper.

i am now out of ideas and it almost feels that the left bank of pistons are out of balance with the right bank.
the car has brand new OEM sensors.
i know i 'm probably talking through my **** but i am starting to lose it.

is it possible that the right bank is getting a different air/fuel mixture causing the car to surge until about 3000 revs when driving through traffic.
if i nail it the car runs strong and smooth but while cruising at low speed i get surging that causes noise ,clunking etc from the drivetrain.

this is making the car a nightmare to drive and totally spoiling the viper experience.

is it possible to run all cylinders from 1 oxy sensor to prove if this is my problem ?

 

[ViperGeorge]

Does the 99 have dual throttle bodies or just one? If two, the cables may be misadjusted causing the surging.

How did you determine that the right bank is not in sync with the left? That, it would seem to me, to be very difficult without a real time data acquisition system that could look at O2 voltages left and right and Fuel Maps left and right. If you really think this is the problem find someone with a real time data monitor.

 

[madbrian]

Does the 99 have dual throttle bodies or just one? If two, the cables may be misadjusted causing the surging.

How did you determine that the right bank is not in sync with the left? That, it would seem to me, to be very difficult without a real time data acquisition system that could look at O2 voltages left and right and Fuel Maps left and right. If you really think this is the problem find someone with a real time data monitor.

it has dual and both are adjusted correctly with the drivers side opening slightly before.

i am just guessing as i have tried and replaced everything that would normally cause this problem.

 

[Dom426h]

typical newb complaint. There is drivedrainslop. This is normal for a viper, it is the nature of the beast. Once your foot learns how to be extra sensitive on the throttle(which is hard since the wobbly pedal *****) you will be fine. Also, more assertive ON of OFF throttle is better than trying to feather part throttle.


-This is Not an O2 issue
-Some people say that the Throttle bodies get out of sync, but i dont see how that would happen unless someone was screwing with it.
-Some say replace motor/trans mounts with stiffer/poly versions, but this can cause other unwanted side-effects like excessive vibrations.

I say Fix the driver

 

[madbrian]

typical newb complaint. There is drivedrainslop. This is normal for a viper, it is the nature of the beast. Once your foot learns how to be extra sensitive on the throttle(which is hard since the wobbly pedal *****) you will be fine. Also, more assertive ON of OFF throttle is better than trying to feather part throttle.


-This is Not an O2 issue
-Some people say that the Throttle bodies get out of sync, but i dont see how that would happen unless someone was screwing with it.
-Some say replace motor/trans mounts with stiffer/poly versions, but this can cause other unwanted side-effects like excessive vibrations.

I say Fix the driver

perhaps it is me , but i doubt it.
i have driven approx 6000 miles so surely i should be able to get it right by now

 

[ViperTony]

Give the Viper Wizard a call at 914-763-3136. Chuck can help you diagnose this.

 

[BOTTLEFED]

i have tried everything possible to fix the low speed surging on my 99 viper.

i am now out of ideas and it almost feels that the left bank of pistons are out of balance with the right bank.
the car has brand new OEM sensors.
i know i 'm probably talking through my **** but i am starting to lose it.

is it possible that the right bank is getting a different air/fuel mixture causing the car to surge until about 3000 revs when driving through traffic.
if i nail it the car runs strong and smooth but while cruising at low speed i get surging that causes noise ,clunking etc from the drivetrain.

this is making the car a nightmare to drive and totally spoiling the viper experience.

is it possible to run all cylinders from 1 oxy sensor to prove if this is my problem ?

Put a OBDII scanner on it that can read real-time data. Check the LTFTs of each bank and make sure they are close to 0 (±3%). This will tell you if your fuel trims are correct for each bank. Other than that, check for codes of misfiring or lean/rich bank. After all that, have the compression checked if you are still worried.

 

[Russ M]

Changed plugs? Wires?

Reset the ECU? Check if the cats are plugged?

 

[1TONY1]

Changed plugs? Wires?

Reset the ECU? Check if the cats are plugged?

How old is the battery ? (JD)

 

[RTTTTed]

I have a problem with a connector and that is causing my af mixture to run all over the place. 14 to 1 is fat, but runs great. 16 and 17 to 1 cause bad hesitation although the only surging I get is under about 1200rpms in gear trying to drive too slow in traffic or speedbumps and that is a 708 camshaft (large overlap) causing that to happen. That is the reason the camshaft got changed for the 200 and up creampuff engines. The newer engines run smoother and don't have the slight surge, rough running problems. Lots of threads on that problem. Gen 1 to '99 problem

 

[Russ M]

14 to 1 is not fat even light load you should not be leaner than that. These motors are not designed to run leaner than 14 to 1.

 

[Dom426h]

+1 Russ

What are you talking about TeDD none of us should be running 16-17

around 13 is a good target for NA.(WOT)

 

[RTTTTed]

In response to your question about 1 oxy sensor, the car is designed using 4 oxy sensors. 2 sensors for the ECU to adjust the fuel mixture (you have no control)at less than 3/4 throttle and 2 sensors that monitor the efficiency of the Cats.

The ECU adjusts the mixture as you drive and uses the front oxy sensors to do this. If you tried using only one side to feed the sensor info to the computer I would expect that would probably not be a good thing.

My GTS normally adjusts itself between 14 and 15.1 to one af when cruising down the freeway.

Lately it develops a problem and the mixture goes way off, then it runs badly. I'm guessing a bad connector as I get it running good and then it eventually goes to bad.

Ted

 

[Russ M]

That is much too lean, these motors do not like being there. They start to run hot, stumble, miss, etc..

Driving down the highway you should never be leaner than 14:1 your car will thank you if you keep it in the mid to hi 13's, and under heavy load hi 11's-low 12's if you are NA.

 

[Jack B]

If you are in closed loop and high vacuum the PCM is going to force the engine to run at close 14.7. If the wideband O2 algorithm is a *high cycle count type you should see the a/f cycle to both sides of 14.7. that will not be the case when the throttle is being varied or under deaccel.

Max hp at wot in general is between 12.4 and 12.8. Max torque will always come at the low side of that number.

*many of the wideband O2 sensors on the market are not good at showing instantaneous reading because their firmware is not fast enough. The a/f ratio is constantly changing (even sub cycle) and if the logging firmware/software is not polling fast enough the overall a/f readings will suffer. In other words by default they are averaging which is not ideal.

Turbo cars are another issue, if the O2 sensor is too close to the exhaust, there will be a general loss of accuracy. that accuracy loss is more pronounced at wot.

Cars with modified exhausts that have minor leaks will also read inaccurate if the leak is to the engine side of the O2 sensor. In addition, if the sensor is too close to exhaust exit there will be a loss of accuracy. This is why the tail pipe sniffers that are used at most dyno shops are worthless. Maybe worthless is too strong, inaccuarte may be more correct. I have run the tailpipe sniffer and changed to the oem O2 position on a cat-less car and there is a difference.

 

[bigmack339]

As a 99 GTS owner myself, Sir, the SCT tuner software caused mine. Once I reset the ecu to stock, it was fine.

over

 

[bluesrt]

sell the car