lowce805

Cant be the Alternator becuase the battery is being charged.. the battery only died because the truck never started enough to self charge.. I drove it an Hr the battery is 100%

00gstang

either reflash the 4.6L PCM with 5.4 data, or buy a 5.4 PCM . I still think your 4.6 PCM is the problem. You can run the 4.6 computer as long as you tune it, or use 5.4 data

00gstang

http://cgi.ebay.com/ebaymotors/2001-...Q5fAccessories

$100 and at least you'll have the right fuel trims and timing for the truck ...

Austin97

Do that.

bob101770

I may be wrong but if the trucks run good twice now, the second time for a hour what makes everone think it's the Pcm. When the engine started it should have run better the longer it ran as it adapted and learned the engine and changed the parameters as much as it could. Yes it will need a flash or pcm to give it the performance it should have because the 4.6 pcm can only give it so much fuel and can't learn how to do some things that must be programmed. I doubt the pcm gets stupid after it warms up.

Austin97

I kinda just mean you need to do it anyway and that one's only $100. Gotta do it eventually might as well do it now maybe it'll fix it maybe not. I think you should take the battery out of the truck completely and put it on a slow charge in the garage all day and get the 5.4 PCM. Rule out anything dumb with a low battery which can cause weird problems and the PCM. I also still think if it ran well before putting the cats on maybe one or more are clogged. It's not that hard to unbolt them and go back to straight manifolds, might as well try it.

lowce805

Bob101770: thats the same logic im on.. Im thinking its a sensor, for example: a sensor that comes to mine is the KNOCK SENSOR since it give info telling the PCM to retard or advance the timing.. so if the PCM resets when the battery is disconnected then after driving 'learns" or "adjusts" it keep retaring or advancing til it stalls.. the knock sensor is doing its job so it doesnt kick any codes.. but I will double check the battery and any other "dumb stuff".
oh and as far as the PCM swap a 2002 has PATS I own a non PATS equipt truck.. I heard you need to be a wiring wiz for 1999 plus pcm on 97 98 trucks.. Im looking for a 98 5.4 PMC

00gstang

you need the right fuel/timing trims, so a 5.4 PCM is a must. It may not fix the problem, but you need it anyway. The truck probably ran like crap after one hour because it started to run in closed loop once hitting operating temp. The PCM can only compensate for so much using the MAF and other sensors.


Here is a 98 PCM for $135 shipped:
http://cgi.ebay.com/ebaymotors/1998-...Q5fAccessories

00gstang

also, it could be the o2 sensors. In open loop, the o2 sensors aren't used to control the fuel. But once you hit operating temp, the system goes into closed loop, and the PCM uses the o2s to adjust the fuel trims and timing trims. so maybe that is why your truck ran bad after driving for an hour. When you disconnected your battery it put the system in open loop, and ran fine, until hitting closed loop. Like I said, regardless of this info, you still need the 5.4 PCM or a custom tuned 4.6 PCM.

lowce805

now it only makes sence that im going to need a 5.4 pcm or a custom tune, but what im trying to do is make my truck run properly before that.. just like everyone elses trucks.. lots of people have said they never even got a tune and their trucks fine.. 8k, 15k, 20k, after there swap with no problems.. 2 have the same combo as I do.. If i swap out the pcm now I will still be in the same situation but $135 less and a few more weeks without a truck..
Ill order the 5.4 PCM if you belive thats the solution..
and ps i really appreciate all your and everyones help..