I read the thread on IAT relating to MPG performance during winter weather. I have possibly a similar issue and was wondering if anyone else has experience or if anyone might know what is causing it. Just a piece of mind thing more than anything. 

Set Up:

02 cummins, 6speed,  102k miles, with Edge EZ and RV275's

 

Symptoms: 

I have confirmed that during cold weather usually below 50-55 degrees I have a noticeable hesitation around 1400-1600 rpms when I get down on it. My version of a romp does not involve spinning up a $1000 set of michelins so just know that I don't hammer on my stock clutch like that. It usually happens in 5 and 6 gear. Especially in 6th if I'm low on the rpm band when I give the beans. It's usually even more noticeable if I do that at the bottom of a fairly steep hill and about mid ways up the pull as I increase throttle heavier, I can feel it cut out a couple times. Feels like two or three quick bumps. I have not noticed this at all since we've had warmer weather. 

 

Causes:

Could this be a air/fuel ratio issue? I am going to pull my IAT and see how nasty it is as a first cause. Anything else that I could check to help figure out the cause would be very helpful! 

 

Another vote for timing issue.  

 

I would take a look at your IAT and verify it is reading correct and not low.  

Optimal IAT temperatures is 100-140*F below this range the MPG's drop approximately 1 MPG for every 10*F. As the IAT temperature falls the timing is advanced more. 

 

 

So if you adding cetane booster on top of winterized fuel plus colder IAT temperature you have a mixture for over advanced timing. You need warm air for optimal ignition quality colder air retards the ability to ignition the fuel being you are attempting to ignite fuel with cold air you need more timing to get enough time for the fuel to pop. 

 

As my gauge is marked for optimal IAT temperature. Below 60*F MPG's fall rapidly. Why else does the MPG fooler work so well at 143*F IAT temperature...

 

Edited December 8, 20168 yr by Mopar1973Man

I don't run any additives. Just Edge EZ, RV275's, winterized fuel, and some 2 cycle. That's it. 

I am going to check out this IAT sensor and see if it's reading properly. Just need to find out what kind of resistance a good sensor should run at. I appreciate all the responses and I'm a problem solver by trade (mechanical designer in the Aerospace Department at Virginia Tech) so this has been a fun problem to solve and learn about. Just hope it doesn't end up costing me $$$. Regardless, I have another reason to love summer the way I do. Truck runs better!!!!!!

Hook up a tool and measure the IAT and the ECT at key on they should match... No removal needed...

will a regular scan tool do this thru odb2?

 

Just using a OBDLink LX...

http://www.obdlink.com/

 

You can use a smart phone or tablet...

I was able to use my buddy's can obdII scan tool and take some live data. At key on the coolant temp and the iat was the same. I ran truck until it got up to coolant temp 187-188 normal and the iat ran about 68-72. Is that normal for 30 degree temps outside? I was def not reading 95-130 degrees on iat and I have stock filter box remember. So would that mean it's reading too low? Bad sensor? 

Sensor is normal. Nothing wrong. Typically it's about +40*F over outside temp. 30+40=70*F so its working normally nothing wrong.

Funny I didn't notice the stumble as much especially as it got warmer on coolant temp tonite. seems to Be worst when truck is working harder. I.e.-pulling steep hill while on it hard in 5-6 gears. 

I really noticed it back in October towing camper about same temp as it is tonite and I was not quite up to full operating temp and it was really herky jerky on interstate. I like problem solving but this might be just a sneaky gremlin that I'play just hafta live with! 

14 hours ago, Mopar1973Man said:

Optimal IAT temperatures is 100-140*F below this range the MPG's drop approximately 1 MPG for every 10*F. As the IAT temperature falls the timing is advanced more. 

 

 

So if you adding cetane booster on top of winterized fuel plus colder IAT temperature you have a mixture for over advanced timing. You need warm air for optimal ignition quality colder air retards the ability to ignition the fuel being you are attempting to ignite fuel with cold air you need more timing to get enough time for the fuel to pop. 

 

As my gauge is marked for optimal IAT temperature. Below 60*F MPG's fall rapidly. Why else does the MPG fooler work so well at 143*F IAT temperature...

 

So what is better IAT for power vs economy? Is 100* more optimal for power? is 143* better for MPG? My truck likes to run 105-137 IAT depending on ambient temp and whether I have AC on or not. Also, what is this live data tool you are using?

100-140*F is good for both power and economy. Any where between 100 to 140*F IAT temperatures. So that's basically 60-100*F outside temperature. 

woodtrucker remind me.....  Did you try disconnecting the Edge to see if your stumble goes away?  NOT just turning it down either but full removal from the engine and electronics.

No but I plan to do that this weekend. Although, I did have it hooked up before the injector install for about 2-3 weeks and never noticed a single problem. I put the injectors in with the tuner and then started having the cold weather problem. Summertime it runs like gold. 

Thanks for hanging with me on all this. I've not been able to pinpoint any iat sensor or code issues at this point so I'm moving on to other issues. I want to run the EDGE a few days while it is cold and confirm the problem is still happening when pulling the normal grades around home and then I'm going to yank it off for awhile and see what happens. 

 

TJRocks 

 

On 12/8/2016 at 11:42 AM, Mopar1973Man said:

Just using a OBDLink LX...

http://www.obdlink.com/

 

You can use a smart phone or tablet...

 

You need the MX version for iphone I think. It's actually $80 but the android version is only $50. 

Just unhooked the edge EZ. 

Gonna run out today and see how it does pulling. I definitely noticed that it was far worse at 20 degrees outside than it was at 28 degrees the other day. So one characteristic is that as the outside temp goes colder the issue worsens. 

I've seen where weird issues occur with Edge EZ because of the module being under the hood and the circuit board getting wet and corroded. You might want to unhook it and open it up and inspect for water issues. 

Just unhooked the edge EZ. 

Gonna run out today and see how it does pulling. I definitely noticed that it was far worse at 20 degrees outside than it was at 28 degrees the other day. So one characteristic is that as the outside temp goes colder the issue worsens. 

You going to have to get a hold of a live data tool and watch the data from you temp sensors and see what's going on. 

Ran it unhooked and no issue so it's definitely present with tuner and no problem without tuner. 

you think I should run temp data with and without tuner? What exactly could be learned if I did that? I guess I feel like when I checked the iat/coolant temp at key on and it was the same means iat is working right. I don't understand how tracking temps without tuner would make any difference but I guess I'll check it out. 

Would a S-03 smarty give me more control over how much timing is present? I also noticed with tuner unhooked  the truck just sounded like it ran better and much less valve clatter but obviously far less power too so...I'm stumped...

The smarty is pretty timing aggressive.  The only tuner that allows for timing change based on user input is the quad.

I'd let Edge know what you discovered.....