So yesterday i drive my car to town its acting just fine, shut it off go work for a bit and then go and take it and wash it. I deep cleaned it so i washed underneith really well not in the moter bay just under neath to get it all clean to put some paint on it. After that i let it dry and drive it over to a lift and paint it then pull it off and let it sits though all of that it drives fine. I get in it after i get out of the shop start it and head to the girlfriends when i notice the car has no power sounds like its missing and its chugging along like a freaking fright train and it will contiune to do it untill i punch it then it comes completly normal and ****s and gets. So just at part throttle it runs like total crap. So I check all the plug wires and they are all on and ok so i can't seem to figure out what could be causing this because even after its warmed up it still does it. Like i said it feels like its bogging down and chugging chugging chugging while its part throttle, I have plenty of fuel pressure so its not starving so i am thinking it has to deal with the ignation but i don't know what to check and its throwing no codes at all ! If someone has any ideas throw them out here so i can check it thanks.

 

Check O2 sensors, connectors, and grounds.

Reason being, you are in closed loop at part throttle and open loop at WOT. O2 sensors are what the engine references heavily on in closed loop and ignore them in open loop.

Also, I see that you are running a speed density tune. Is it possible you are not throwing codes because the reporting is turned off or changed?

 

ok well i will check the 02's but once the car is drove for 15 miles it has drove completely fine all day today. Its like when its cold ?

 

That info may actually help narrow it down some. Check the o2 heater wiring when you check the ground.

 

I forgot to add...

After the computer sees the o2 sensors not functioning properly after a given amount of time. It will fail them and stay in constant open loop for that key-on cycle.

If your error reporting is turned off, it will never report a problem.

But, things are a little different when you are running a speed density tune. Unless you are running a OS that is SD specific, the computer may not fail the o2 sensors if it sees the MAF failed.

 

ok which is the o2 heater wire. My o2 has a purple, 2 tans and a brown . What do i need to check with these ?

 

so all in all if this occurs again what can i do to fix this problem ?

 

There aren't two tans. One is pink, but when it is dirty and in dark light, it looks tan also.

Here are the wire colors and what they do:

Tan = Low Signal
Purple = High Signal
Black = Ground
Pink = 12v Ignition Source

To check, you can ohm out the Pink to Black on the sensor. Disconnect the sensor and measure impedance. You should read something lower than 10 ohms, but you should not read open loop (note: 0 does not mean "open loop", it means zero or dead short). DO NOT OHM OUT THE TAN AND PURPLE WIRE. You can damage the sensor and/or pcm.

To check the wiring going back to the pcm, check impedance between black and a chassis point (ground). It should be close to a dead short as possible. If you read open, you have a bad ground connection. The connector grounds all four sensors at a point behind one of the heads (I can't remember which off the top of my head).

Also, has any work been recently done on the vehicle? Do you have long tube headers? If you have headers, did you use a harness extender?

 

I do have long tubes and a guy extended them for me but I never had a peoblem before but I did use a scotch lock for my narrow band air fuel gauage so could that be it ?

 

^^^stop spraying down the car with a pressure washer you prolly got the O2 connectors wet. you said you didnt spray the motor at all so why check the plugs???

 

ya i am thinking in got water in the 02's somehow thanks guys

 

Ok so i drove today and it started to storm real bad so i hurried home to my girlfriends to get the car in the garage and the 02s must have gotten wet again because its running like ****. I think when i had them extended its getting water on the wires so its grounding it out would that be it ? if someone could let me know thanks.

 

That is probable.

A complete visual check should result in you being able to locate the source of the problem.

Check to make sure the connectors are seated into each other properly. Pull them apart. Pay close attention to see if water is inside the connector. Also, check the wiring for burns or damaged insulation.

 

Ok i will have to check that. And after i get them dried out i think i am going to try and put a rubber hose over all of it and plug the ends so it can't get wet anymore.