OBD II Problems

yikes · Post by **yikes** » Sun Apr 17, 2016 4:09 pm

Having some troubles with the MAF and driveability. It was running fantastic last Friday. Saturday morning before heading out to Barstow it started idling rough and began stumbling on the way there. Got worse as the day went on. Engine hesitates and cuts out severely while driving, idles rough, smokes, smells rich, codes say lean. Unplug the MAF sensor and it stumbles off idle, but no longer hesitates. Scanner says low input voltage. Replaced the sensor, but no change. Anyone else experience this before? I'm at a loss.

Phoenix0783 · Post by **Phoenix0783** » Sun Apr 17, 2016 4:22 pm

TPS can cause all sorts of driveability issues. Any O2 codes? How old is the fuel pump?

Does it do any of this while still cold (when it's not reading O2 sensors) or only when warm?

yikes · Post by **yikes** » Sun Apr 17, 2016 4:28 pm

Fuel pump is new. Pressure is 34lbs at idle; 40 without vacuum. I was thinking the TPS as well, but thought it would throw a code. Throttle position did seem to have an affect, but everything was so erratic, that I couldn't definitively single it out. Maybe that's it.

Phoenix0783 · Post by **Phoenix0783** » Sun Apr 17, 2016 4:36 pm

TPS will eventually throw a code. OBD II is a little more 'self learning' when it comes to the TPS sensor. You want right around a volt with the throttle closed. I can't remember if it's 4 or 5 volts at WOT though.

yikes · Post by **yikes** » Sun Apr 17, 2016 5:02 pm

Thanks. I'll check it out.

Post by **SteveG** » Sun Apr 17, 2016 7:48 pm

What's the fault code?

Ghostwhite · Post by **Ghostwhite** » Tue Apr 19, 2016 1:29 am

How does it run at WOT? I had a bad O2 sensor and it had the same symptoms but would pull fine when WOT(open loop, doesn't use the O2 reading at WOT).

yikes · Post by **yikes** » Tue Apr 19, 2016 6:30 am

SteveG wrote:What's the fault code?

P1074/1075/1021?? I'm going to clear it and check again. Somehow I think this is all related to the wet weather. Something might be getting shorted out. Yesterday it ran much better, but still with the MAF unplugged. Idles normal. RPM drops a bunch when it goes into gear, as if the convertor is locked up, which could be just another symptom of a bad, water laden connection. Will check the multi-connector at the trans too.

yikes · Post by **yikes** » Tue Apr 19, 2016 6:33 am

Ghostwhite wrote:How does it run at WOT? I had a bad O2 sensor and it had the same symptoms but would pull fine when WOT(open loop, doesn't use the O2 reading at WOT).

Problem exists at all throttle positions.

Phoenix0783 · Post by **Phoenix0783** » Tue Apr 19, 2016 9:30 am

I can't find anything for 1074/1075/1021. 0174/0175 are O2 sensor rich/lean codes. 0121 is a TPS code.

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