help me ID these parts please

[HD_DUALLY]

The ECM is a generic for all suburbans or trucks,etc.The PROM is for your suburban particularly.If you changed the ecm I hope you got one with the same part number,mine is 16197427,yours might be the same but the PROM(mine is BMHM)is what must be kept with your vehicle.I hope I explained that correctly and hope it makes sense.

BTW,the PROM is what all the programmers modify when they talk about ''chipping'' a vehicle.I've always been afraid to try it because with my luck I'd make it so bad it might blow up lol.

ok that's what i thought, ya i got a 16197427 as well, probably didn't need to though, just another part i threw at it trying to fix this issue. thanks again for all of your help. if this thing keeps acting up it might end up for sale. its a sharp truck i just need perfection in my vehicles lol

 

[grampadirt]

Have you checked for vacuum leaks where the intake manifold meets the heads?

 

[HD_DUALLY]

Have you checked for vacuum leaks where the intake manifold meets the heads?

no i haven't, how should i check that, spray something around the edge of the gasket? and would that type of leak change as the engine warms up?

 

[grampadirt]

no i haven't, how should i check that, spray something around the edge of the gasket? and would that type of leak change as the engine warms up?

You can pretty much spray anything that will change the idle characteristic,I use brake parts cleaner,some use WD40,some water.It won't take much to make the idle change.You'll notice maybe a little stumble,maybe it will rev a little higher or lower,depends on what you use.Spray everywhere,around the base of the TBI unit too,hoses included.

 

[smdk2500]

when you set your timing did you disconnect the advance wire? If you didn't that might be part of the reason it didnt seem to change much.

 

[HD_DUALLY]

when you set your timing did you disconnect the advance wire? If you didn't that might be part of the reason it didnt seem to change much.

yeah i disconnected it, I'm getting pretty good at adjusting timing thanks to this truck.

 

[grampadirt]

Got an Idea,it may sound crazy but just try it ...before starting your truck put the TC in 4low then got through the startup routing including putting it in gear.I'm wondering if the lower gearing would put less pressure on the engine.Maybe,if you can,put it in gear without your foot on the brake to let it roll if it wants to.

 

[HD_DUALLY]

Got an Idea,it may sound crazy but just try it ...before starting your truck put the TC in 4low then got through the startup routing including putting it in gear.I'm wondering if the lower gearing would put less pressure on the engine.Maybe,if you can,put it in gear without your foot on the brake to let it roll if it wants to.

you are on the right track, if i put the truck in gear without my foot on the brake and let it take off it doesn't stall hardly at all, its when i hold the brake and the engine has to hold that load that it really stalls. I'm going to look at the 2 different IAC valves after work and see what i come up with. it will probably be this weekend again before i get to mess with it again though.

 

[grampadirt]

you are on the right track, if i put the truck in gear without my foot on the brake and let it take off it doesn't stall hardly at all, its when i hold the brake and the engine has to hold that load that it really stalls. I'm going to look at the 2 different IAC valves after work and see what i come up with. it will probably be this weekend again before i get to mess with it again though.

OK,sounds good.Maybe making some progress

 

[HD_DUALLY]

OK,sounds good.Maybe making some progress

i bought the 12mm IAC and put it in, no real change. FYI what i have figured out is that the 10mm has a single taper and the 12mm has a double taper end if that makes sense. they both measure exactly the same. I'm going to remove it and start the truck with it still hooked up to see if its even moving any.

if not, i think I'm going to try to make a jumper harness straight to the ECM in case i have a problem in the factory wiring. how would i go about finding which pins on the ECM run the IAC, so i can tap into them.