Hi, I have a 99 Deville w/4.6 Northstar which is getting the P0741 code pretty consistantly, but the tranny seems to shift very nice. We replaced the TCC solenoid and that didn't make the error go away.

Another problem with the car is that it is missing a little at idle or acceleration. It will do it while parked and the tranny not even engaged. We've replaced the plugs and wires. Cleaned the injectors (no codes for them), and all of the coils seem to be OK, but I don't know the most accurate way to test these.

It has been suggested to me by a mechanic friend of mine that the head bolts may have loosened and need to be retightened, or that there is a head gasket leak. There is no lose of coolant, nor mixture of oil/coolant, nor white smoke.

Would a head that is not tightened down possibly cause the P0741 code? Or are code and the missing separate issues. Where should I go from here besides the dealer?

 

Checked the wire order. It was correct. Today I got a P0440 code too. Checked the gas cap and the vacuum hoses. All seemed to be OK. I reset the code.
Took off and cleaned the Mass Air Flow Sensor. Then cleaned the throttle body with almost a whole can of carb cleaner. It was really dirty. I hoped that would solve the mis-fire. It didn't. But I did get a new code...P0300 (mis-fire). Like I didn't know already. Of course it doesn't tell me the cylinder.

 

For the misfire condition it will in all llikelihood be one or all coil packs, there are 4 packs on your engine each controlling 2 cylinders. Original packs have the cylinder # near each post, replacement don't have this, they cost about $89 in Toronto. You need to isolate which cylinder is misfiring and this may mean taking it to get scanned.

The TCC code is odd given you change parts. Clear codes again and drive.

The head bolt story from your mechanic friend is a terrible joke. Why anyone would send someone to the head gaskets when the car exhibits no symptoms whatsoever seems strange to me.

Forgot about the Evap code...who cares?.... as long as you don't need an e-test. probably needs purging.

Another thing to remember is that your computer will set codes each time an error is encoutered. I tell people this doesn't mean the car is necessarily broken. I get a pretty constant 1527 which is a trans shifter corelation error. It bothered me then I realized that it pops up every time Jr. drives the car. I watched him change gears, you think he was in a speed race cranking the shifter around, no wonder the corelation error shows. Ever get a gas cap error...usually the gas cap isn't tightened.

Look how your microsoft works, about two times a day I have to shut down my sytem and reboot, that's acceptable somehow but when a car's computer has an error we often get tense.