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Low idle at startup

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  #21  
Old 04-26-2018, 10:39 PM
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Don't touch any idle screw!
 
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  #22  
Old 04-26-2018, 10:41 PM
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I don't even know where any idle screw is. It would be set at the factory and supposedly hasn't been moved. So any problems you have are not because of an idle screw.
 

Last edited by rockp2; 04-26-2018 at 10:58 PM.
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  #23  
Old 04-26-2018, 10:43 PM
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You are reving your engine really high and and are possibly kicking on the fuel cutoff mode, which protects the engine. Which is possibly why you drop so low in RPM when you let your foot off the pedal.
 

Last edited by rockp2; 04-27-2018 at 04:32 AM.
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Old 04-26-2018, 10:47 PM
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You stated that you didn't think the relearn did anything. You also stated that you must have been wrong about the hot engine flare up because now you notice it. Maybe the relearn did do something? Not sure, but I would put it back together for tonight, let it go through a cold soak and see what happens tomorrow.
 
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Old 04-26-2018, 11:08 PM
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Originally Posted by rockp2 View Post
Don't touch any idle screw!
It's a small torx that controls the "base" of how tight the throttle plate sits. I did adjust it a little, which brought idle yo 750. Just did some test drives, and it was a little too much so backed it off just a hair to 700 which is barely higher that OG. Seems to be more stable and not drop quite so low when coming off accelerator.

Originally Posted by rockp2 View Post
You are reving your engine really high and and are possibly kicking on the fuel cutoff mode, which protects the engine. Which is probably why you drop so low in RPM when you let your foot off the pedal.
Yeah, I did kick into that once or twice, must be around 4500, so no revving higher than 4 anymore...

Originally Posted by rockp2 View Post
You stated that you didn't think the relearn did anything. You also stated that you must have been wrong about the hot engine flare up because now you notice it. Maybe the relearn did do something? Not sure, but I would put it back together for tonight, let it go through a cold soak and see what happens tomorrow.
Agreed. Going to stop messing around for tonight. I'll have to text my son to see how it starts in the morning, should be low 30's... The biggest issue is when it's colder, but spring is now here, haha! So not as big of an ordeal, but just wanting to smooth it out. I'm picky.

I do appreciate the help.
 
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Old 04-26-2018, 11:58 PM
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Originally Posted by Besel53 View Post
I'll have to text my son to see how it starts in the morning, should be low 30's...
Tell him not to put his foot on the pedal and give it gas since he's probably gotten used to that recently. Just turn the key and see if starts and idles on it's own ~1k rpm.
 
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Old 04-27-2018, 02:44 AM
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Howdy,
Here is an excellent material for fuel trims theory:
What I meant is that the difference in between high rpms and idle may be a highly negative and positive fuel trim. So, for example, when You are on high rpms, the trim is negative (adding extra fuel as mixture is too lean), then You release the gas pedal, the engine gets flooded with too much fuel and has to adjust the trim positive.
First things fist :
  • You have posted a fuel trim for one bank, but You got two of them The value change of +/- 10% is nothing big. If Your 2nd bank is same, then I'd say it's ok. A rich mixture is easy to see by taking a look on Your exhaust...
  • I don't like the part You have mentioned "I have cleaned MAF with MAF cleaner". Once i gave some cleaning to my MAF with something inappropriate cleaner and I've ended with similar story. Give it a good bath in a clean alcohol.
  • Another thing that does not add is what You say, that once You take off the MAF plug, everything smoothies up. When engine is cold (the coolant temperature is low) Your engine runs into an "open loop" (afair You have a widget "process" in torque lite for that). That means injectors are not driven by MAF & O2 readings, but go from a pre-programmed values into your ECM. Disconnecting MAF on a cold engine shouldn't make any difference. But
  • if the engine runs rough when cold I would suggest checking the EGR valve. There are two holes, one with a conical pin that should be easy to pressed back with a fingertip or a screwdriver one.
Keep us updated.
Cheers,
Mike
EDIT:
Your idle screw story reminds me those, who want to fix electronics by twisting every potentiometer they see. Like they believe potentiometers have magically moved from their origins. Was Your idle screw loose or You one of those who believe in magic...?

The resistance of Your IAC coils seems ok.
 

Last edited by Mike.308; 04-27-2018 at 02:53 AM.
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  #28  
Old 04-30-2018, 10:40 AM
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Originally Posted by Mike.308 View Post
Howdy,
Here is an excellent material for fuel trims theory: https://www.youtube.com/watch?v=5WnM_NsOtd8
What I meant is that the difference in between high rpms and idle may be a highly negative and positive fuel trim. So, for example, when You are on high rpms, the trim is negative (adding extra fuel as mixture is too lean), then You release the gas pedal, the engine gets flooded with too much fuel and has to adjust the trim positive.
First things fist :
  • You have posted a fuel trim for one bank, but You got two of them The value change of +/- 10% is nothing big. If Your 2nd bank is same, then I'd say it's ok. A rich mixture is easy to see by taking a look on Your exhaust...
  • I don't like the part You have mentioned "I have cleaned MAF with MAF cleaner". Once i gave some cleaning to my MAF with something inappropriate cleaner and I've ended with similar story. Give it a good bath in a clean alcohol.
  • Another thing that does not add is what You say, that once You take off the MAF plug, everything smoothies up. When engine is cold (the coolant temperature is low) Your engine runs into an "open loop" (afair You have a widget "process" in torque lite for that). That means injectors are not driven by MAF & O2 readings, but go from a pre-programmed values into your ECM. Disconnecting MAF on a cold engine shouldn't make any difference. But
  • if the engine runs rough when cold I would suggest checking the EGR valve. There are two holes, one with a conical pin that should be easy to pressed back with a fingertip or a screwdriver one.
Keep us updated.
Cheers,
Mike
EDIT:
Your idle screw story reminds me those, who want to fix electronics by twisting every potentiometer they see. Like they believe potentiometers have magically moved from their origins. Was Your idle screw loose or You one of those who believe in magic...?

The resistance of Your IAC coils seems ok.
Sorry to keep you hanging. Was a busy weekend. Here's where I'm at with it now.

-I was able to start it cold Saturday morning (35F) and it actually jumped up to 1200 right away, then slowly dropped to about 800 for a couple minutes, then settled in at 700. It's almost seeming as if the reset Rock posted, and my very slight turning of that screw has maybe done the trick for starting. No way to really tell until fall I guess, warmer weather is finally here.

-That being said, I will have to look more into this fuel trim. I didn't have time this weekend to mess with it. I will also have to research how to make it better if it's the problem. It does seem to run a little rich by the smell of the exhaust.

-Why would I not use MAF cleaner to clean the MAF? That's what you are supposed to use....leaves no residue.

-The part where I said "If I unplug the MAF sensor, it runs smooth", was in relation to when I have the air intake off so I can get to the IAC. Without the air intake on, it would barely run, surging, so if you unplug the MAF while it's off, it will run off of default IAC settings instead of sensor readings. It also proves that both MAF and IAC were operational and not totally bad.

-I may take the EGR out again and double check it. That's not hard to do. I will put a new gasket on this time when I put it back together.
 
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  #29  
Old 04-30-2018, 12:05 PM
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My experience with the MAF: There is one side you can spray and get clean. The other side is behind a mesh filter of sorts. Spraying it won't clean it. You have to do is remove the torx screws holding the MAF assembly together so that you can get to the wires under the mesh. I take a qtip and spray it with CRC MAF cleaner. Then very, very gingerly rub the doused qtip on the wires of the little sensors. On something with 100K miles, the qtip will turn black where you rub it. I keep changing qtips until they're clean. The wires are very fragile, so you want to put almost no pressure on the wires. In my experience, just spraying them will not get them clean.
 
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Old 04-30-2018, 12:19 PM
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Originally Posted by jacked_72 View Post
My experience with the MAF: There is one side you can spray and get clean. The other side is behind a mesh filter of sorts. Spraying it won't clean it. You have to do is remove the torx screws holding the MAF assembly together so that you can get to the wires under the mesh. I take a qtip and spray it with CRC MAF cleaner. Then very, very gingerly rub the doused qtip on the wires of the little sensors. On something with 100K miles, the qtip will turn black where you rub it. I keep changing qtips until they're clean. The wires are very fragile, so you want to put almost no pressure on the wires. In my experience, just spraying them will not get them clean.
? That's exactly what I do when cleaning any MAFs, and what I did when I cleaned this one. I'm not having MAF issues. Good info, and is correct, but not pertinent to this thread. Thanks though.
 
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