Low idle at startup
#11
Problem: When I start it, it never initially idles up. Immediately after starting it idles at around 5-600. If it is cold, it will die right away unless I get on the gas to get it idled up for a little bit. Additionally, if I rev it high, like 5K, then drop off the gas, it will almost die before recovering to about 500 rpm.
The "bold" part sounds exactly as a fuel trim reversal looks like.
Cheers,
Mike
#12
The PIDS you want to record are; 1)IAC Counts, 2)Desired RPM, 3) RPM, 4)Desired Throttle Position, 5)Throttle Position.
With the ohm meter your looking for 40-60 ohms across pins A&B and across C&D. Then infinite ohms across pins A&D and B&C.
Might as well try those IAC relearns (one at a time) before you do any testing. Be nice if that solves the problem right there...but I'm not betting on it.
With the ohm meter your looking for 40-60 ohms across pins A&B and across C&D. Then infinite ohms across pins A&D and B&C.
Might as well try those IAC relearns (one at a time) before you do any testing. Be nice if that solves the problem right there...but I'm not betting on it.
I only have torque lite for my BT dongle, and it doesn't have IAC counts, desired RPM, or desired TP. Maybe there's a better app? Did the relearns, didn't really seem to make a difference. I guess I was wrong about 500, it idles right around 650 like it's supposed to, but when I get the A/C going (not working yet), that may drop. Fan, radio, and lights drop the rpms by about 50.
With engine warm, and air intake off, there is a LOT of suction going through the iac air hole. (See pic). Is that right? It will barely run, surging up and down with the air intake off.
#13
#14
Hey guys, I have to backpedal a little bit... Usually when I start this, it's cold, and it never initially ramps over 700 before dropping to around 600. Now that the engine is good and warm, I'm realizing that it does in fact ramp to 1K right away (when warm) and drop immediately to about 500, then level off at the 600 to 650. Just want to make sure I'm posting facts. It still drops too low (IMO) after a high rev 4-5K, it will drop to about 400 for a sec, stumble sometimes, then level back off at 650. I edited my initial post to reflect this, sorry.
I'm appreciating the input, thank you.
I'm appreciating the input, thank you.
Last edited by Besel53; 04-26-2018 at 08:43 PM.
#15
Hey guys, I have to backpedal a little bit... Usually when I start this, it's cold, and it never initially ramps over 700 before dropping to around 600. Now that the engine is good and warm, I'm realizing that it does in fact ramp to 1K right away (when warm) and drop immediately to about 500, then level off at the 600 to 650. Just want to make sure I'm posting facts. It still drops too low (IMO) after a high rev 4-5K, it will drop to about 400 for a sec, stumble sometimes, then level back off at 650. I edited my initial post to reflect this, sorry.
I'm appreciating the input, thank you.
I'm appreciating the input, thank you.
EDIT: I think the fuel trims you are looking at are both ST fuel trims. Though I'm not real familiar with the app. See if there is another PID that specifically lists LT.
Last edited by rockp2; 04-26-2018 at 08:58 PM.
#16
While the truck is stumbling, unplug your MAF sensor and see if anything changes.
#17
Sounds like your IAC is moving the pintle in and out then. I would next consider the ECT sensor. Also, maybe take your MAF off and make sure you didn't accidentally break loose a side of one of the little resistors from the bars in there while you were cleaning it. With my eyes, I need a 10x loop to see it clearly. Will your tool show you MAF g/s and MAF volts? Will it show you ECT volts?
EDIT: I think the fuel trims you are looking at are both ST fuel trims. Though I'm not real familiar with the app. See if there is another PID that specifically lists LT.
EDIT: I think the fuel trims you are looking at are both ST fuel trims. Though I'm not real familiar with the app. See if there is another PID that specifically lists LT.
#18
Yep, if I have the air intake off and it's stumbling bad, if I unplug the MAF, it smoothes right out. I'm thinking I'm just going to raise the idle using the screw just a hair, maybe 700 or so.
#19
Yep, if I have the air intake off and it's stumbling bad, if I unplug the MAF, it smoothes right out. I'm thinking I'm just going to raise the idle using the screw just a hair, maybe 700 or so.