DOESN'T RUN GOOD AFTER DYNO TUNE

[CONCRETEWARFARE]

I had my car dyno tuned and when I brought it home a day or two later I disconnected the battery and now it doesnt run right. It barely wants to run and is running extremely rich. To start it I have to hold the gas pedal to the floor. Is this just a coincidence that it happened after I disconnected the battery or did I maybe reset something. I just disconnected it again to try and reset the computer but any suggestions are appreciated.

 

[Muscleford]

You have cleared the computer. It has to relearn all the sensors. I disconnected the battery in my Dodge Durango for about 45 minutes and it wouldn't idle. I had to hold the accelerator to keep it running then it finally ran. It took about five minutes or so to relearn. It has been fine since. Never experienced this before with any other car. but I have never had a battery disconnected for more than a few minutes before.

Scared me since I didn't do anything but disconnect it to clear a code which I had done before. This time I disconnected it and left it disconnected while I changed the oil.

 

[86bluecobra]

^^ What he said. It is very strange that it has to relearn but its the truth. I believe it even mentions this in the manual for a stock engine.

 

[CONCRETEWARFARE]

yea but I drove it for a couple of miles and still nothing. It would idle at about 750-850 like usual but it was a real weak idle like it was going to die. All the lights were dim and what not. I turned up the idle just before so im going to see if that helps at all tomorrow when I start it up while its cold.

 

[86bluecobra]

Any Updates?

 

[ninety15.0]

How did you turn up the idle? There is a proper procedure for adjusting the idle on our cars...it can be found by searching this forum. You arent supposed to just turn the screw. I think that something must not be right...it doesnt take very long for the computer to adjust after being reset. Pull codes and see what it kicks out.

 

[CONCRETEWARFARE]

Well I reset the idle and everything seems to be ok now. I just cant get rid of this stupid hanging idle. Also, even though my car is non emissions cam and heads do you think I still need the o2 sensors?

 

[795.0pacecar]

Absolutely, the O2s are not there to control emissions like the sn95s.

 

[CONCRETEWARFARE]

So what symptoms do you think I should be seeing due to not running the o2 sensors? I feel like I dont have all the torque I should have could this be part of it? Also with the car running I can see the exhaust like its cold out even though its not.

 

[vristang]

Not sure if I understand that correctly...

You don't have O2's???



jason

 

[bullitstang1313]

You need O2 sensors for the computer to adjust air/fuel ratio. The O2 sensor provides feedback to the computer letting it know if you are running rich or lean. Without O2 sensors, the computer doesn't have any feedback.

 

[Woodrow]

How was the car dyno tuned? Chip, reflash, a/f timing or what?

 

[Red88 RICK]

dude you need o2 sensors so teh computer can fine tune you air/fuel mix spark timing and like everything... i have heard of connectors to show a constant perfect A/F ratio but im not 100% about that. my techer explaines it as say your bowling and there is a curtain at teh end of the ally you throw the ball but have no feedback so you cant perfect the way you throw it... so you take away teh curtain aka add teh o2 sensors and your all good

 

[CONCRETEWARFARE]

sounds good ill pick some up and give it a try.

 

[ninety15.0]

How do you not have a check engine light? You absolutely need to get some O2s in there. What do you having plugging the bungs in the H pipe right now? How exactly was the car tuned? As for the hanging idle...check jrichkers surging idle check list. It has plenty of idle information that may be useful. Also search for that proper idle setting procedure or else its not going to work properly.

 

[$uperstang]

Guys it depends on what type of tune he had done. Was it just put on the Dyno and adjustments made ie.. timing, FP. Or did he have a custom tune done like mine and an SCT or other chip burned so O2 sensors are no longer needed. Like many others you can toss your O2s once a custom chip is burned for your vehicle.

 

[millhouse]

Guys it depends on what type of tune he had done. Was it just put on the Dyno and adjustments made ie.. timing, FP. Or did he have a custom tune done like mine and an SCT or other chip burned so O2 sensors are no longer needed. Like many others you can toss your O2s once a custom chip is burned for your vehicle.

Even with a custom tune the 02 sensors are still required. Closed loop corrections are still present and are required for every day drivability….therefore, unless he plans on driving it WOT everywhere he goes (which I try to do as much as possible anyways) then he needs them in there.

 

[$uperstang]

Even with a custom tune the 02 sensors are still required. Closed loop corrections are still present and are required for every day drivability….therefore, unless he plans on driving it WOT everywhere he goes (which I try to do as much as possible anyways) then he needs them in there.

Incorrect my friend. I have an SCT chip custom tune and no O2 sensors at all.

 

[millhouse]

Incorrect my friend. I have an SCT chip custom tune and no O2 sensors at all.

There is nothing incorrect about it. Removing the 02 sensors (like going WOT) forces your computer into open loop mode which is detrimental to everyday drivability. If you were to reinstall the 02 sensors your computer would go back into closed looped mode and drivability would improve.

 

[$uperstang]

There is nothing incorrect about it. Removing the 02 sensors (like going WOT) forces your computer into open loop mode which is detrimental to everyday drivability. If you were to reinstall the 02 sensors your computer would go back into closed looped mode and drivability would improve.

Yes but you see my driveability is perfect, I have no problems. Installing O2 sensors on a Custom chip tune servs no purpose. They are non-functional at that point.