I have been racking my brain on this problem. When I start my car when its cold it runs fine. If I turn the car off when it is in a closed loop then restart it the car will run like it has a cam even though it still has the stock one. And if you are going 35-45mph and give it a little bit of gas it will stumble and shake. But yet if you turn it off and let it sit for a couple of hours (unitl its cold) it will run fine. I thought it might be the o2 sensor so I replaced it this morning.

I did run my car with a sacning program hooked up (WinALDL) and several flags showed up they were Rich flag, EECC Slow o2Rich/Lean flag, DRP Occured flag, BLM Enable flag. I only know what the Righ flag means.

Can you guys please help

Thanks Steve

 

Im unfamiliar with your scanner program but will offer some ideas to begin with.
Its possible you may have leaking injectors.Do you you have a fuel pressure gauge?How about a digital voltmeter to test the resistance of injectors hot and cold?
Thats a place to start.
With the O2 sensors,you sometimes need to check the voltage at the wire and at the ecm to ensure there isnt an open or a short or ground somewhere.

Other possible scnarios is a weak or faulty ignition module,however they usually fail right out.
Another is a bad EGR system...one way to test is to unplug the EGR valve and put a vacuum cap on it and see if the symptoms repeat or not.

I also dont mean to sound like a smartazz...do you have any good TPI tuning and repair books?If not,get some if you can.Reading it through and through really makes troubleshooting the system so easy and faster than what the forum can do.On here,its basically blind troubleshooting as to what may be wrong with the car.With the books you can do your own at home to narrow down and then maybe ask the forum what other ideas to check that the books dont cover.

In the mean time if you can describe anything more from your scanner if you can.

:cheers:

 

Capture some data with it running well; then capture data when the problem is occuring. Then compare the data or come back to report the differences.

Also, have someone shut off the engine while you look into the MAF to see if the sensor wires glow red hot for 2sec after shut off. If not, replace the burn-off relay.

 

check the resistance across the inejectors both hot and cold. When the motor is hot, you may have an injecotr coil that is losing its insulation and breaking down. This can cause them to either stay open, or not open. Either way, you'd have a rough idle/miss. :rolleyes:

 

To check the injectors all you have to do is check the ohms on the two prongs in the injector correct?

Also what should the injector reading be at while hot and cold?