Extremely Rough running need some ideas

[Dirtnap30]

shortly after figuring out my no start issue I ran into this rough running condition. Car will not idle for long and has extremely sporatic idle until it stalls. driving the car is awful because it just misses, hesitates until it stalls. checked for vac leaks, made sure plugs were good, enough fuel, clean maf, checked all sensor connections. Its a m52 ran obd1 with a 413 and turner tune for 3.5 maf, 21.5lb injectors, s52 cams, pulleys etc. Some advice would be greatly appreciated, its so close to being done

[drez14]

Any CEL's?

BTW, what was your start issue, this might help diagnose.

[Dirtnap30]

my no start problem was a combination of bad cps and dme. got it running now but its extremely choppy like i said. its throwing a cel for an oxygen sensor. however I have a brand new bosch one and it seems to be sending a voltage signal back when I record live data with a scan tool

[Dirtnap30]

update, signal from the O2 is weak and the value isnt changing much goes between .42 and .47 volts.

[dsobering47]

You check all your grounds? Make sure you have good contact with un-painted metal. Also absolutely sure you dont have any vacuum leaks? Particularly around the throttlebody/intake boot area.

[Dirtnap30]

I'll re-check my ground. I re-located my engine ground strap to the driver's side hopefully thats not the issue. Also I checked for vac leaks and found nothing. nipple on the throttle body is plugged, pcv and fpr vac lines are good and also large vac hose going to booster is good. Drove better earlier, seems to idle much better but still breaks up and backfires and hesitates at higher rpm

[Beej '86 325es]

update, signal from the O2 is weak and the value isnt changing much goes between .42 and .47 volts.

Check the other two wires...Is it getting 12V for the heater?

[Boostesi]

on my swap recently i had a similar issue with the irratic idle and stalling because i put a universal check valve in my brake booster and ran a new hose to the intake and i guess it wasnt a perfect fit in the grommet on the booster so i had a massive vacuum leak that was easy to figure out because i had just put the faulty piece in and the car ran fine with a cap on the intake port before. how did you check for vacuum leaks? i dont have an 02 sensor in my car right now and it runs pretty good and idles smooth. try unplugging it and see what happens

[wheelies247]

I had some what the same problem and replaced the o2 sensor and cleaned the maf sensor problem fixed.. Also make sure your o2 sensor is located a little far back from the engine mine is located behind my seat in the pipe to get a good reading.. Is there a converter on the car ?

Thanks J

[Dirtnap30]

I have raceland headers and no cats. right nown the o2 sensor is in the first bung closest to the engine, I'll move it farther away and see if that improves the voltage signal.