So I'v been running into this problem for a few months now where on cold starts my engine takes a number of cranks to start, then idols pretty high (1.5k) followed shortly by sputtering and coughing of my engine for several minutes; its completely un-drivable when its like that. I have found that de-flooding the engine before start solves this as well as playing around with the tps while it idols; also some strong revving right after start up fixes it (but i hate doing that). Once the engine is warm however start up is no problem. I'm not entirely sure how I can fix this. I have heard that this can possibly be leaky injectors, however I have noticed overall performance lately has been sub par. At certain spots in my rev range I notice a big drop in power followed by a burst, but its almost a pulsating thing. High end is great but you can definitely feel it on the low end at times.

Some details to know:

13b N/A

short ram intake

5-6 port are stuck halfway open at all times due to insufficient back pressure

my spark timing is accurate, i have checked it

no visible vacuum leaks

i have played around with my tps and pressure sensor as well as the screw on the throttle body trying to find settings that might remedy the issue.

everything else is very stock aside from the removal of that unnecessary air pump.

Sorry to make a long question, but I try and give as much detail as possible, any feedback would be appreciated.

 

Might want to test the TPS range as it should run from 1 volt at idle to 4.5 volts w/the TPS piston fully extended when engine is completely warmed. There should not be any bumps in the voltage reading as the throttle is slowly opened, but a completely smooth and progressive climb from the lowest voltage vaule to its highest. An analog needle meter is best used for this puropse of identifying dead spots in the TPS range.

You also might want to check the Water Thermosensor. And make sure the Fast Idle Cam is set properly. And the rough idle could also be poorly conditioned fuel injectors or perhaps a tired, old engine.

 

Interesting, well the engine we rebuilt around 40k miles ago, im told it still has several years left. How do I know if the Fast Idle Cam is set properly once i find it?

 

The FSM details how it should be set.