fuel or fire

[Brian Adams]

96 deville 4,6liter northstar hard start rough idle stalls on idle after about 15 minutes replaced plugs wires convertor fuel pressure reg.fuel filter map sensor idle air sensor cleaned throttle body also replaced ignition power control module and egr valve obd 2 codes current 1026 also 0039

any thoughts

[Cadillac Jim]

B1026 Driver Deployment Loop Open
U1026 Loss of ATC Class 2 Communication
P0039 Turbo/Super Charger Bypass Valve Control Circuit Range/Performance

All I see is an air bag code OR a network code, and a possibly CURRENT turbocharger code. Your car doesn't have a turbocharger. My code list may not be correct for this code and your car. I don't see what is going on with the (B|U)1026, either.

Please run the codes again, and note which module is throwing them, and include the letter as well as the four numbers. Of course, which ones have the CURRENT attribute is very important too as you know.

This car should be throwing a P1599 and probably a P0300 if it is stumbling and dying after idling for a few minutes. If this is a hot start, one thing that can cause your problems is a leaking FPR, which won't throw a code. A leaking FPR will cause hard starting when the engine is hot, but an engine will usually start cold OK with a leaking FPR.

You should read the codes through the A/C buttons (<Off><Pass Warmer> together...), not with a code reader. Most DIY code readers only show codes that affect emissions. Although you should have such codes, you will get just about all of them through the dashboard.

Don't throw any more parts at this car until you have a good diagnosis.

To address the title of the thread, "Fuel or fire," smell the exhaust when the car stalls. If the exhaust smells like fuel, either it is running too rich (FPR leaking!) or your problem is spark. If it just smells like exhaust, it may be fuel starvation, or the ISC stepping motor. If it smells like coolant, have the coolant checked for traces of combustion by-products.