o2 sensors Gen 1

[martyb]

Trying to figure out a part/full throttle miss on my Roe gen 1. replaced plugs/wires, no change. car runs fine for the first 8-10 minutes, and then developes a miss and full throttle, half throttle or less car still runs fine. I don't want to start throwing money at parts guessing if they are the culprit or not. no CEL or codes thrown. my next thought is O2 sensors. any way of removing and testing them, or should i just buy new ones? was also thinking tps, map, iac.

boy i wish there was a good viper tech in chicagoland!!!

martyb

 

[grcforce327]

Full throttle=open loop!!!

 

[martyb]

grcforce327,

does it at anything more than 1/2 throttle.

 

[grcforce327]

grcforce327,

does it at anything more than 1/2 throttle.

Marty,your first post said full throttle!You can hookup a data scan tool to see if it is happening in open or closed loop.Scan tool will also show the fuel adaptives and if the O2's are functioning properly.You have a Roe,so my guess is you also have a Vec correct??? If so,the issue could also be in the tune.If you were near me,I would be happy to dive in and help try to figure it out!

Guy C.

 

[martyb]

Thanks gforce, yes I have a VEC2. PBJ did the tune, which was spot on, so I doubt that would be the issue. I think I need to find someone with a scan tool, not sure if the local autozone has a scan tool or just a code reader. I appreciate your offer to dive in and help!! I am sure its something simple, I just don't want to start replacing parts if they don't need to be replaced!!

 

[grcforce327]

Joe is awesome.but there still could be an issue with the vec !You can drive all the way down here and we'll hook it up and try to pinpoint the issue!

 

[martyb]

If I could find a damn cable that works, I would be able to datalog since I have the vec software. I think that may be the best bet. Seems there are some issues with a serial to usb cable convertor.

 

[Tom F&L GoR]

I can give you a hint from personal experience. My Gen 1 was having problems (mostly stock engine) and I borrowed a scan tool. The O2 sensors were each giving faulty signals for several seconds at a time but the check engine light never came on. Turns out that the Gen 1 CEL isn't programmed to stay on unless the fault exists for 8 seconds minimum. (I may have that wrong, but it was many seconds!) Since my O2 signals returned to acceptable within that time, it didn't trigger the light. I replaced both and of course, that fixed everything.

 

[IEATVETS]

Chicago is loaded with "Viper Techs" Marty! Contact Tom at Fields dodge or Jon at Roanoke Motors or Scotty Sutker(tooofast) or SVS etc.
Good luck.

 

[martyb]

Thanks IEATVETS.

martyb

 

[martyb]

2 new O2 sensors installed, car is still missing when warmed up. I can tell it is very rich(burns your eyes, popping on decel). Thinking of trying to replace the MAP sensor. Would a faulty MAP, TPS, cam or crank sensor cause a rich condition?

martyb

 

[martyb]

by the way, 1/2 throttle is still fine, only under more than 1/2 throttle does is miss.

 

[Tom F&L GoR]

Popping back is normal depending on your exhaust system.

I don't think it would run at all if cam or crank position sensor were bad.

I'd spend for TPS first.

And another thought. My Dakota had a wire break inside the harness. It was one of the O2 sensor wires, so while the OBD-II and other diagnostics pointed to replacing the O2 sensor, it really wasn't the sensor itself.

 

[99 R/T 10]

I had the same issue(athough on my Gen II) when at high loads at 5000 RPM or greater. Turned out to be the sparkplug wires. They were arcing at the ignition block. Check to make sure they are tight and have the contact grease on them. What wires did you use? ab's wires? (home)

 

[martyb]

99R/T10

Had the MSD wires from Sean, just replaced them with new wires from Tator, along with new plugs and O2 sensors. One thing I forgot to mention, the Walbro 255 pump that pbj installed is really singing once the car warms up. I can really hear it when the car is running, even at idle. Don't know if that would have anything to do with it or not. I hate buying parts chasing the issue, but that may be the route that I go.

 

[99 R/T 10]

Just so you know, the wires that were arcing on me were the MSDs, relatively new too(8 month old). Just saying...........

 

[Tom F&L GoR]

The Gen 1 is non-return, so the pump cannot be suffering from hot fuel returned from the engine. If it is making a different noise, perhaps it is either failing to provide pressure when run for a while, or pushing too hard against a plugged filter. A quick, cheap thing might be to replace the fuel filter.

 

[martyb]

All right, my issue is fuel pressure. I am going to try Tom's suggestion and replace the filter, but I am guessing its the pump. PBJ just put in a Walbro 255 less than a year ago, and I have driven the car about 1800 miles since the install. Are these pumps that weak??

 

[Tom F&L GoR]

Relieve the pressure up at the manifold before you get under the car to change the filter.

In fact, do anything you can to protect your eyes when underneath- there is no good way not to get wet with fuel.

Read up on how the fuel filter ends disconnect from the fuel line.

 

[martyb]

Thanks Tom, yeah, its a fun job for sure!! I am hoping the filter will fix the problem, but I am not holding my breath. If its the pump, I am wondering if it is still under any warranty, hmmmm

 

[martyb]

All right, before I start the tank removal, just wondering if my low fuel pressure could be the MSD BAP? Any way to test it? I would hate to remove the tank and replace the pump, only to find out it was not needed.

Also, any tips on tank removal?

martyb