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Discussion Starter #1
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?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Check your spark plug wiring against the diagrams - the correct coil-wire-plug connections are critical. Hope you used ACDelco wires and ACDelco #41-950 Platinum plugs.

DON'T MESS WITH THE HEADBOLTS !!!!!

Your TCC is a different problem.

Google "waste spark ignition" to read up on what your system does.
 

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2010 DTS
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Would a head that is not tightened down possibly cause the P0741 code?
Absolutely not.
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.
The only way head bolts come loose is if the threads pull and tightening them will not help. If your coolant level is not dropping, I think the gaskets are OK. Have you cleaned the TB?
 

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Deville
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Discussion Starter #4
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.

btw...why do I need to use specifically AC Delco parts for wires and plugs. Do they conduct current better? Or is there something else I'm not aware of?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Over the years it has become apparent, from the number of posts concerning aftermarket plugs and wires, that the Northstar is not happy unless it runs on the OEM parts. Many have used other brands and are satisfied, but more have experienced missing, poor economy, and power loss. There's no rational reason for the differences, but they are definitely there. So the logical recommendation to someone unfamiliar with the Northstar and its quirks is to stick to OEM replacement parts. There are no magic spark plugs and no magic wire.

Carb cleaner eats the finish off the throttlebody interior. Use the spray designated as "Throttlebody and choke cleaner". Different solvent.
 
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