Need some help - codes 121 and 172

[rio95]

So here's the problem. My car is running great at WOT, but has a few bugs at part throttle. About half the time I drive my car it will essentially have NO power are part throttle (seems worse when it's hot out, but not sure if that is a certainity or not). When I say part thorttle I mean literally having the pedal in just enough to stay at cruising speed. It will shudder a bit and it feels like there is NO power whatsoever, but if I push the pedal further it instantly goes away and the car will actually jerk as the power comes back. If I keep holding the thorttle in the spot where it acts up, it will ocasionally pop through the intake.

So I pulled the codes and got the following:
172 - O2 sensor lean (bank 1)
121 - Throttle position voltage higher or lower than expected OR signal voltage inconsistent with engine intake airflow

I just removed my PMAS MAF to clean it and it appears to be spotless. I have also started to check and clean wiring connections. I haven't found anything alarming yet. Also, I checked the TPS voltage and its at 0.99V closed and 4.18V fully open. I think the TPS is fine.

As for vac leaks I haven't found any. I have 15 in. at idle and all vac lines are zip tied and in great shape.

Any ideas would be GREATLY appreciated.

Also, I'm thinking about taking my car to Alternative Perfomance to get tuned by Lidio this summer in hopes of improving driveability and see how much power its putting down with my current setup. I'm thinking about having him tune my car in open loop as it seems that I am having O2 sensor issues etc. Any thoughts on open loop vs. closed loop for my setup?

p.s. I have no exhaust leaks and the O2 sensors are OEM and about 2-3 years old, so I would think they'd be good, but who knows. Also, the CE light come on and off while driving.

Thanks

 

[HISSIN50]

Did you happen to watch the TPS reading through the entire range to make sure there's not a dead spot? An analog voltmeter makes this easier (with a digital meter you have to go really slow and watch the numbers the whole time).

You could swap your O2's, clear the codes, and see if the O2 code follows that one particular O2 sensor.

Good luck.

 

[rio95]

I did test the range and it was fine. Although, for some reason if I went too fast my digital meter would kind of flash and not read for a second. If I went really slow it never showed a dead spot. I'm not sure why the meter flashes like that if I go too fast, but I've seen in act like that everytime I have ever checked my TPS.

I was thinking about swapping them like you said. I can try that when I get my MAF and stuff back in the car and it stops raining.

I might try to figure out where the o2 wires go and do a continuity check on the wires to make sure they're good the whole way, because they travel all around the engine bay. Although I'd probably not be getting good readings if I had a problem there.

 

[HISSIN50]

I'd just read the O2 signal with the DMM. It should be Pin 43 for the left side and 44 for the right side.

If you wanna do a continuity test, the wires start at the O2's obviously and go to the EEC pins listed above.

 

[rio95]

I cleaned the maf and all other o2 and maf connectors etc. The 121 code came right back, but I have probably 50 miles on the car and the 172 code hasn't returned yet. Most improtantly I didn't fix anything. The car still hesitates at very light load and pops through the intake every now and then at part throttle. But like I said WOT is just fine. I actually just went to the track and ran a best of 11.79 at 122 with a really bad clutch. New one is on the way though!

Could this be tune related at all? I'm still thinking that when it's colder outside this isn't as much of a problem. That might point in some direction. Not sure!

 

[rio95]

well I just had my car apart due to some bent valves and push rods and put it back together thinking that maybe I would have accidentally fixed this issue. But nope, same exact issues. It still is worse when it is hot out, but it is also very random. It might run pretty good for one drive and then pretty bad the next. Same with the idle. Sometimes it idles just fine and other times it decides to surge a bit and just randomly shut off. I don't understand why things aren't more consistent.

 

[rio95]

OK 172 came back and now the other bank is throwing the same code, I think like 164. Should I just try new o2's. Seems logical I guess.