These are the TPS and IAC sensors. I didnt have any problems with them before the rebuild, i find it odd that as soon as i connect the engine up and try and crank it over it would die unless i kept my foot on the gas. I did considerable research on this forum about the TPS and IAC and believe that to be the problem.

I disconnected the IAC and as long as i kept my foot on the gas the truck ran great (until i noticed smoke coming off the grounding wire see other post lol).

I took the IAC apart and it did have a ton of carbon build up on it, the question is.. what is the chances of both sensors failing once i tried to connect it to the new 408 i put in there. (i did flash the ECM with the custom tune). The truck was running fine before with the two old sensors. I just find it odd that i would have to buy both the TPS and IAC with the new engine. Any thoughts? the truck wont stay running unless i have my foot in the gas a bit. I thought it might be a vacuum problem, but everything is connected right (from the labeling i did). I think i have good fuel pressure, the injectors are brand new.

There are no miss firing codes in the computer, just the TPS and IAC. Thoughts?

 

try replacing them, see if it helps
i always replace any sensors like that when i do a motor swap

 

I would check like your intake gaskets for a vacuum leak there or maybe a leak down test to see if your loosing it some where else?

 

it might be just one of them failing, and the other code may be false. my recommendation is to buy a new set and move on. if it fixes the problem, then maybe spend time to swap them and determine if one or both may be ok. i think its good to just have a spare set.

 

might be that you need a bit more air to establish minimum idle you might have to adjust the throttle plate set screw open a bit to keep her idling.

Are you reusing a stock TB on a 408? Are you running too small an exhaust for that thing?

 

okies, well i was a little hesitant to buy two new sensors because prior to the rebuild they worked perfectly. But i am not gonna argue with you guys, you are on here all the time giving bang on advise and i wasnt gonna leave anything to chance.

I bought a new TPS and IAC sensor plugged them into my stock 360 TB and son of a bitch, the damn thing turned over first crank and didnt stall out!!!! I will take the truck for short runs to get the new computer used to the new sensors. I am not sure how/what the performance shop actually did with my sct tuner, it is probably gonna need some tweaks, but the truck sounds mean as hell!

My only question about this, right as it starts up, it puffs/back fires once and then purrs like a cat.... well rumbles like a lion is probably more accurate heh, any thoughts? i checked the DTC's no error codes.

edit: as for the exhaust i removed the Cat, have 3" cat back to a glass back muffler and a 4" tip, its says redneck with class lol. PS aims, love the sig

 

been there done that. one of your old sensors is likely still good. you'll just have to put them back one at a time to figure out which one. and sometimes you put both the old ones back on and it keeps running fine. that's when you pull your hair out and throw ****.