Is the SES light on? If so, what DTC's are in memory?

Engine at idle, coolant at operating temperature, all accessories turned off, trans in neutral or park:
TPS voltage should be .47 volts. Normally if there's a problem with TPS it will set a DTC in memory and turn the SES light on. It's rare, but possible, for TPS to cause a stumble and not set a DTC or turn the SES light on.

Usually a stumble or misfire is caused by a fault in secondary ignition or low fuel pressure. If there is a misfire, the PCM will detect it and turn the light on. Another possibility could be that camshaft retard is out of adjustment. If it's off far enough, P1345 will set in memory and turn the light on.

 

the only code in the computer was misfire #5 but its a old code just have not had it cleared yet. in the last 24 days I have been driving it I have not seen SES light on.

 

Wouldn't hurt to check TPS voltage and camshaft retard. Camshaft retard must be checked with a scan tool, (not all scan tools will access it though).

 

I sure miss my Snap-on MT2500 scanner... I used to run circles around the dealership and there big diagnostic machines back in early 90's

just curious does a PCM have control or effect tranny shifting, and the cam timing?

 

The PCM controls all shift points. Cam timing is not adjustable. Camshaft retard is adjusted by rotating the distributor. It synchronizes the camshaft position sensor with the camshaft.

 

I wondered how much the PCM had effect on the engine.

today driving home I was trying to watch when the transmission shifted.

on a easy take off under 2000 rpm it shifted from first to second at about 12 mph then it shifts from second to third about 20 mph.

at a moderate take off at 2000 rpm it shifted from first to second at about 16 mph then it shifts from second to third about 22 mph.

I think when the transmission was put in, it really shifted hard! I took it to the GM dealership and they adjusted the collector or something like that? it was better than when I took it in but first to second was still a little hard shift.

so would a tuned PCM take care part of hard shifts? and the pinging I going on?

I think some of the pinging will go away with fresh new plugs, wires, cap and rotor, since all of it is still all factory installed equipment.

from what I have be told and understand plugs should last 100,000 miles, cap and rotor on today's engines I truly don't know what their life span is.

since I am planing a moderate size trip in about 59 days and want to have the best mileage and performance out of it. so I am trying to get a lot of work that is over due done and over due maintenance done.

also it's new to me and now my everyday driver. so I do the little stuff about every night. and the bigger stuff on weekends. and I have to have it be done before memorial day weekend.

I figure by next weekend to have the tune up done (plugs, wires, cap, rotor) The thermostat is done and made quite a bit difference in mileage so far, and I am still checking mileage this week and next. in 2 weeks it will be sitting on new rubber, and aligned. with all this done will a tuned pcm make enough difference to for go the cost of the programming?

 

New AC Cap & AC rotor & Autolight plug wires, AC plugs (Iridium) installed now. And Yes #3 plug is a S.O.B. it took about two hours to do all of it. Everything was original to the truck 132,000 miles

Results:
I didn't notice much on starting about the same as it was before, but drive ability is night and day smoother acceleration, smoother running down the road, It seems to have more power accelerating than it had in a while. (note: it's amazing what we can get used to)

Conclusion:
yes it did make a difference in it. It didn't take all of the dog out of it but did build a fire under it's butt and made it run better, a lot better. glad I did it.

I might later decide to do a tuned PCM. If would make as much difference as the tune up did I would jump on that wagon for sure.

 

checked the mileage today 16.9 mph. next weekend I will give it a good highway run.

 

Check out blackbearperformance.com. his website is really good at explaining what a tuned pcm can do. Justin is very knowledgable, most people want there shift firmer but I'm sure he can make it softer.

 

Ok I will check out blackbearperformance.com maybe in a few weeks I want to see how if does this week and next weekend to set a baseline from. I spent today putting in a heater core for about 6 hours. I think I need a weekend off, work all week at work this spend the weekend working on my blazer. (I had a boat like that.)