andrewv

My car seems to stumble when trying to accelerate. It appears like it happens only after it has warmed up. I have not taken out my uego sensor yet but I have tried it twice now after the car has sat for 24+ hours of not running, just turning the key to ACC. The gauge does the usualy start up then says P00 then it stays at 14.7. After sitting there it will slowly makes it way accross to lean and when it hits around ~16 it quickly shoots over to almost full rich once then goes back to ~16 and works it way back to full lean.

Does that sound like the sensor is going bad? Can they be cleaned or so or usually you just replace them?

Let me know what you guys think

Thanks

o'malley_808

There is a test on youtube where aem tells you how to test the o2 sensor. Google search it. He basically sprays brake clean on a rag and sticks it over the sensor and it goes full rich, removes it from the rag and it goes full lean.

gettin it

I take it your sensor is connected to the aem ems?

s2000442

Try running in open loop and see what happens.

andrewv

yeah it is connected to my ems, I doubled checked the connections and it is hooked up fine. I saw the test on you tube, I just need to get home and disconnected it and try it. I just thought it was weird that as it was going lean it goes full rich then finishes up going full lean and stays there.

As far as setting it to open loop how do I go about that in the aem ems series 1?

o'malley_808

Turn off O2 feedback. Its under the fuel section in AEM or go under sensors-->O2--> then you should find a checkbox to enable or disable it (not sure if your using series 1 or 2)

andrewv

Tried disabling it and still having the same issue. It seems to do it at about 2-3k and then again a little later on in the rpm's. It does it wether you floor it or just slowly accelerate.

Anyone think it could be a bad tank of gas? My gas gauge is reading just a few bars below half a tank. My boost gauge reads -21 vacuum at idle, If I had a boost leak would this be different?

andrewv

I just went out and reseated the map sensor, made sure my vacuum lines were on good. I even tried opening the gas cap. It still has the same issue. It seems to run fine when it warming up then after about 10 or so minutes and when its warmed up it starts to stumble wether you floor the car or gradually accelerate.

It was running fine the only think I changed out was to a slightly larger vacuum line and changed the oil from 10w-30 to 5w-40 turbo diesel. Also the oil on the dipstick is slightly higher than the full mark. Could that be the issue right there? I swapped out the vacuum lines back to what they were so the only two factors that it could be is from changing the oil or the change in themperature since when it was running last.

o'malley_808

How long have you had this tune/setup?

indi00

Check fuel pump hose. What kind of clamp?