4.0 fast idle?

For the 4 litre guys. What speed does your engine idle at on cold start? Mine is 1300-1400 rpm. I hate dropping it into gear when it's that high, so usually sit & let "calm down" before moving. What's yours idle at?

 

Well... it idles higher when it’s cold and I have the heater cranked....

 

I think mine goes that high on a cold start as well, but I just allow enough time for the oil to really begin circulating before I put it into gear and start driving.

Usually I just take my time finding a song on my phone and put my seat belt on. Give it an extra second and I think I’d be good.

 

That's about normal it's just a warmup strategy for the engine. Let it idle for a minute or so before taking off especially if it's really cold out.

 

These are the ECU's targeted idle speeds based on coolant temp.

Target Idle speed when in P/N:


Target Idle speed when in Gear:


There's also a Idle speed adder that is based off a time switch. This adder, from the factory adds 200RPM for 1sec to the above tables after initial startup.

 

Awsome info, thanks!

 

Is the x-axis deg F or deg C? Looks like C.

 

Oddly, it’s unspecified. I’ve found it to correlate with Celsius in testing however.

 

@JustDSM what's the ECU logic if the temp never reaches the 80c temp when fully warmed up?

I guess since i've been running the mishimoto 160f thermostat my idle engine speed is always at 1100 rpm.

Do these tables need adjusting when running the Low temp thermostat, or what other parameters need to be tweaked ?

 

Dude thats an awesome little nugget of info, thanks

 

I've not had much success with the Mishimoto 160deg T-Stat. Most of the issues arise from the truck never getting up to temp. Frankly I've never seen any reason to run a cooler thermostat in these trucks, but that's another topic all together.

The ECU will target the idle speeds present in the table I posted based on the coolant temp. There are other things that can affect the actual observed RPM as these are just the "Base" figures. You can bump them/lower them per your needs.

There are a few temperature based corrections or switches that are CLT based that can/should be adjusted but I can't recall all of them off the top of my head. I'll come back to this when I'm near my laptop.

 

Can always count on you to drop the knowledge !!!

 

Beat me to it.

With the sleeves, the engine naturally runs much hotter. A lower temp t-stat and upgraded cooling are necessary. I actually prefer the Motorad 160° to the Mishimoto, now that I have had the Mishi for some time. When in the 30's-50's, my engine has a hard time getting over 160°.