notanymore

i dont know exactly how to explain it all so ill just list some of the problems.
-hard to start cold - something in the cold start system i know
-trouble idling when cold, will idle fine when first started, but will drop and idle below 500 and eventually die.
-after somewhat warmed up it will idle about 800, but will be a rough idle
-once fully warmed up the idle will raise to about ~1500

now i am having a cel for a knock sensor short which i will be able to fix next week. i dont drive my truck everyday but tomorrow i need to drive 200 miles home and need to try and resolve this very soon.

notanymore

come on anyone? i need to leave later today and if i can get this somewhat resolved that would be good.

rdlsz24

How is your timing? The 2nd symptom sounds like my truck after my headgasket replacement when my timing was off.

Rob

pat24

i have the same problem i have no fin idea what it is but the truck runs fine once she warms up i dont get it !!

rdlsz24

Yours sounds more like the cold start system.

Rob

thook

Cold start injector time switch and engine coolant temperature sensor.

notanymore

the cold start injector thing has been a problem for the last few years and i never really got around to fixing it, but you think the coolant temp sensor might be bad? and i dont remember where exactly its timed but unless it magically changed itself i timed it to stock when i rebuilt the engine about 5k ago.

84sr5yoty

Cold start injector time switch for the extended cranking problem.

Dirty, clogged, or bad Auxiliary Air Valve or Air Valve passages clogged from the throttle body to the Air Valve for your low cold idle problem.

notanymore

nothing should be dirty of cloged, i recently rebuild the engine and cleaned everything out pretty good. but i went ahead and made the trip and it made the trip as a gutless wonder, but i just found out that my rad has a hole in it why cant things just work sometimes.

thook

That's a question through the ages.....and no one has the answer. Not that I've met, anyway. Some guy named Murphy seems to have a view on it.

Anyway, it COULD be the coolant sensor. It works on resistant and voltage. The lower the coolant temp, the higher the resistance and voltage. The warmer, the lower. So, the ECM reads that as a sign to richen or lean out the fuel mix. And since your problem seems related to engine temp, that is my first guess. It's even one of the first culprits in the FSM troubleshooting guide.

The ECT sensor has a relationship to timing in that the more fuel is needed (as determined in part by coolant temps) the more the timing is advanced (by the ECM), and the less fuel the timing is reduced. If the coolant sensor is blinking out, erroneous signals are being given to the ECM and erradic behavior results. This wouldn't affect base timing, just timing advance. But, the coolant sensor may not be the problem....you'll just have to test it.

I don't suppose there's any handy-dandy codes being thrown is there....besides the knock sensor one?

85BigBlue

I have an issue related to this.. If the coolant temp sensor was unplugged, I should be able to get the engine started yeah? I recently replaced the head gasket and put everything back together about 2 weeks ago. I noticed the ECT connector was loose and about to break. The engine was running decent. I noticed fuel injector #2 was dripping lots of fuel. I removed the EFI manifold and fuel rail (again). Replaced the o-rings in all 4 injectors (#2 was shot). Put everything back together and the connector on the ECT broke. I have not been able to get the truck to start since. I can't figure out what I did wrong.. I double checked the hose connections and injector wiring. The new sensor is being shipped fedex, but won't be here till the 31st. Anyone have any ideas? If I spray starter fluid up the air intake the engine wants to start. Feels like engine is not getting proper fuel. Is this all related to the sensor?

85BigBlue

I guess I'll answer my own question since nobody else added any thoughts. The problem ended up being my fault. I wired up my own starting switch to bypass the ignition key switch. The starter was getting juice, but the computer wasn't getting signal that the engine was cranking thus did not tell the injectors to spray fuel. I tried starting with the key and problem solved.