umrpunter

Hey I did a pretty long data pull. If anyone has some time could they help me get a hold on my issues?

Car is running rough, missing, and very rich on right side (spark plug pull). I have checked fuel pressure, it held 38lbs (reg still hooked up) for 2 hours and didn't lose a LB.

I have noticed the MAP is low and the right 02 strongly lags the left. Just not as variable over the whole spectrum.

Car misses under load (hit gas on highway), you can see it in the knock count at the end of the run.

umrpunter

the previous ZIP was an excel dump. Here is the .uni if that helps. Thanks for any help!

FrankieD

Looks like your Left O2 sensor is lazy. I would replace this first. Yes, the right side is very rich. Once you replace the Left O2 datalog again and we can analyze it again. Also, check for any spark missfire on the right side.

umrpunter

Thanks for the help! Do you mean the right O2? It is much less active than the left. Only reason I am asking is I am just now learning to digest all this information from datamaster and want to make sure I am reading it correctly. In the meantime I'll get a sensor on the way!

FrankieD

Left O2 sensor needs to be replaced, then datalog again.

umrpunter

Update. I have replaced both o2 sensors (they were like $12 it turns out so why not). I cleaned the ground location on the transmission. Here is the new data log. Still getting some pretty crazy results. Looks to me the right O2 is either getting completely flooded out or is not sensitive. Considering it backfires and smells rich on the right side I am betting on fuel washing. Thoughts? It stumbles and dies now, and when you give it throttle it hesitates and sometimes dies. You can see it on the RPM log in the files below. It doesn't die once it goes closed loop and relies on O2's btw, you can see that also on the RPM data. It is really hard to keep running until it goes closed loop at about count 2000. Also I noticed the O2mv on the left just continuously went from ~200 to ~900 just climbing up and down all the time in a very predictable fashion (RPM was constant). Like I said weird. Any help would be appreciated.

umrpunter

here are the logs in .uni and excel

umrpunter

Just so I don't leave yet another thread that has a question with no answer. The car is running great now!

What I have done.

• Replaced both O2 sensors
• Replaced Fuel Filter
• Replaced Fuel Pressure Regulator
• Cleaned grounding points on transmission and under battery on frame (decently corroded) by grinding to clean metal and cleaning terminals
• Made a new ground strap that goes from under battery frame ground to the transmission ground (8 gauge car audio power wire)
• Put anti-oxidation dielectric grease on all ground points and terminals
• Coated all ground points with under body coating (aerosol can) after bolted down (prevent corrosion and rust where I ground to clean metal)
• installed new FIC Bosch III injectors (great to work with)

I took it down and did all of this because the car is getting older and I knew all these parts had years/mileage on them. So I knew it wasn't a loss to throw in a few new parts that weren't bad yet. After work was complete I am fairly certain the main issue was a bad fuel pressure regulator, a slightly clogged fuel filter, and corroded grounds.

After doing this I recommend doing the above to your car as well, you will be amazed what you find.

all hesitation has left this beast and it runs really well now! On to the next step

Cliff Harris

It's supposed to do that. That's how the ECM takes a very non-linear device and makes it look linear.

The ECM richens the mixture slightly by increasing the injector pulse width. It then looks for the O2 sensor to go rich. When it does the ECM leans out the mixture and watches for the O2 to go lean. Then the ECM makes the mixture rich again. It does this continuously all the time the ECM is in closed loop mode. It takes roughly 1 second for the cycle to complete.