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Cold Start - strange high idle until warm

Rob_I

Elite Explorer
Joined
June 19, 2020
Messages
163
Reaction score
45
City, State
New Hampshire
Year, Model & Trim Level
2013 PIU 3.7 NA
On a cold soak start, I see this very odd idle until the engine warms up. Feels a touch rough. I hate it. Freaks me out. With any other vehicle, this would be cause for a serious investigation of a problem.

-Cold engine
-Crank
-1500
-1100 with slight bounce
-800
-600 (at normal temp)

I've read and heard this might be normal due to some sort of new emissions calibration? I've never had any other vehicle do this. Even my office's '19 Transit cranks and idles to 600 immediately. Perhaps it's to get the cats up to temp quickly? If I goose the throttle slightly it idles back down to 800'ish and only goes to 600'ish when its at temp. Warm engine start idles at normal 600.

Before I heard this might be 'normal' I did a complete 100k pre-winter maintenance with the hope of correcting this issue. Oil, PTU fluid (its leaking so replacing it asap), plugs, O2s, PCV, upper intake gasket, cleaned MAF, new air filter. All the normal stuff. I have a new throttle body coming today. That might be a little overboard but why not. I would have replaced the IAC if it had one; the classic Ford fix-all. Was going to go deeper with cam and crank position sensors, coolant temp sensor, but thought maybe I should ask before.

IDS shows no errors, all tests show normal performance. Acceptable long and short fuel trim. Can't find a single thing wrong. All module calibrations up to date as of IDS 119.03. There were a couple that were older.

Apologies for the strange reflections. The odd action mostly ends at the 1 min mark. It settles to normal idle at 5:30. This is just for watching the RPM. Yes I know my tire is low.

 



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What you are describing has been normal in every EFI vehicle I have owned. Initial high idle, and it comes down as heat is produced. I'm sure the 5th Gen owners will be able to tell you for sure if it's normal for those vehicles as well.
 






Yikes and this is the first EFI vehicle I've ever encountered that does it. Between family and company cars. Maybe 20? 30?
 






Or I should say, I've never had it THIS pronounced to where it holds 1500 for such an extended period. And the idle hunting. That's what had be me concerned than anything.
 






On a cold soak start, I see this very odd idle until the engine warms up. Feels a touch rough. I hate it. Freaks me out. With any other vehicle, this would be cause for a serious investigation of a problem.

-Cold engine
-Crank
-1500
-1100 with slight bounce
-800
-600 (at normal temp)

I've read and heard this might be normal due to some sort of new emissions calibration? I've never had any other vehicle do this. Even my office's '19 Transit cranks and idles to 600 immediately. Perhaps it's to get the cats up to temp quickly? If I goose the throttle slightly it idles back down to 800'ish and only goes to 600'ish when its at temp. Warm engine start idles at normal 600.

Before I heard this might be 'normal' I did a complete 100k pre-winter maintenance with the hope of correcting this issue. Oil, PTU fluid (its leaking so replacing it asap), plugs, O2s, PCV, upper intake gasket, cleaned MAF, new air filter. All the normal stuff. I have a new throttle body coming today. That might be a little overboard but why not. I would have replaced the IAC if it had one; the classic Ford fix-all. Was going to go deeper with cam and crank position sensors, coolant temp sensor, but thought maybe I should ask before.

IDS shows no errors, all tests show normal performance. Acceptable long and short fuel trim. Can't find a single thing wrong. All module calibrations up to date as of IDS 119.03. There were a couple that were older.

Apologies for the strange reflections. The odd action mostly ends at the 1 min mark. It settles to normal idle at 5:30. This is just for watching the RPM. Yes I know my tire is low.


Mine does the same thing it runs perfect other than that I’m not sure why it does that
 






Slight possibility of a vacuum leak otherwise looks like normal operation to me. Cold start and open loop the ECM will request high idle to prevent stalling. As the ECM goes into closed loop and the coolant temp increases it will settle down the idle. If the engine quickly goes into closed loop and there is no vacuum leak I would suspect this is normal operation. My 2004 and 2014 both start very similar to yours. My Grand Prix, converted to run on E85, I have to dump a ton of E85 fuel at cold start so it takes a couple seconds longer to settle down or it will hard start and want to stall.
 






The more I read, the less concerned I'm becoming. Still annoyed though. However, this may be perhaps a good test case to make SURE there isn't something off. Winter is coming (my best Game of Thrones voice) so I want to ensure I don't have something that will bite me in the middle of a New England blizzard.

On any other vehicle I am would suspect a vacuum leak, I did, and may still. Since the computer shows totally free of codes and all PID values look normal, it would be minuscule. The first thing I did after I got the vehicle was the vapor purge selonoid/valve. No particular reason except for preventive maintenance. Went over the vacuum system when I did the plugs, pcv, etc. Checked clamps, hoses and connectors. Nothing was dirty though I wasn't too crazy about a buildup of oil when I took off the upper intake. Maybe it's normal for the 3.7. Been a 4.6 guy all my life. I haven't investigated with starter fluid yet. See picture below of oil on gasket. Yes I put on a new one. I'm tempted to do a lower intake gasket but not crazy about what needs to come off in order to do it. Starter fluid...

Besides what I've already done, any other 100k things to eliminate? Since I don't have complete
maintenance history, was a PD car, I'm resetting the clock on all the stuff that may go at this age. The vehicle was very well maintained. I get the feeling I did a lot of totally unnecessary replacements. The O2s and plugs looked good, almost new. Did them anyway.

When my PTU is replaced, I'll do the tranny. Heard that can cause odd behavior especially with idle bouncing. That bothers me.
 

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The more I read, the less concerned I'm becoming. Still annoyed though. However, this may be perhaps a good test case to make SURE there isn't something off. Winter is coming (my best Game of Thrones voice) so I want to ensure I don't have something that will bite me in the middle of a New England blizzard.

On any other vehicle I am would suspect a vacuum leak, I did, and may still. Since the computer shows totally free of codes and all PID values look normal, it would be minuscule. The first thing I did after I got the vehicle was the vapor purge selonoid/valve. No particular reason except for preventive maintenance. Went over the vacuum system when I did the plugs, pcv, etc. Checked clamps, hoses and connectors. Nothing was dirty though I wasn't too crazy about a buildup of oil when I took off the upper intake. Maybe it's normal for the 3.7. Been a 4.6 guy all my life. I haven't investigated with starter fluid yet. See picture below of oil on gasket. Yes I put on a new one. I'm tempted to do a lower intake gasket but not crazy about what needs to come off in order to do it. Starter fluid...

Besides what I've already done, any other 100k things to eliminate? Since I don't have complete
maintenance history, was a PD car, I'm resetting the clock on all the stuff that may go at this age. The vehicle was very well maintained. I get the feeling I did a lot of totally unnecessary replacements. The O2s and plugs looked good, almost new. Did them anyway.

When my PTU is replaced, I'll do the tranny. Heard that can cause odd behavior especially with idle bouncing. That bothers me.
My 14 FPIU revs like this on a cold start and quickly returns to a low idle between 600-800.

Were you planning on replacing the whole tranny?
 






Oops, no I meant I'll service the tranny fluid.
 






On a cold soak start, I see this very odd idle until the engine warms up. Feels a touch rough. I hate it. Freaks me out. With any other vehicle, this would be cause for a serious investigation of a problem.

-Cold engine
-Crank
-1500
-1100 with slight bounce
-800
-600 (at normal temp)

I've read and heard this might be normal due to some sort of new emissions calibration? I've never had any other vehicle do this. Even my office's '19 Transit cranks and idles to 600 immediately. Perhaps it's to get the cats up to temp quickly? If I goose the throttle slightly it idles back down to 800'ish and only goes to 600'ish when its at temp. Warm engine start idles at normal 600.

Before I heard this might be 'normal' I did a complete 100k pre-winter maintenance with the hope of correcting this issue. Oil, PTU fluid (its leaking so replacing it asap), plugs, O2s, PCV, upper intake gasket, cleaned MAF, new air filter. All the normal stuff. I have a new throttle body coming today. That might be a little overboard but why not. I would have replaced the IAC if it had one; the classic Ford fix-all. Was going to go deeper with cam and crank position sensors, coolant temp sensor, but thought maybe I should ask before.

IDS shows no errors, all tests show normal performance. Acceptable long and short fuel trim. Can't find a single thing wrong. All module calibrations up to date as of IDS 119.03. There were a couple that were older.

Apologies for the strange reflections. The odd action mostly ends at the 1 min mark. It settles to normal idle at 5:30. This is just for watching the RPM. Yes I know my tire is low.


Dirty throttle body? You should see a Toyota 3.5L rev. High and long
 






I have a new throttle body staring at me. Gonna put it on tomorrow for kicks. Will report back.
 






Oops, no I meant I'll service the tranny fluid.
The tranny fluid is really easy to service and I've heard of that being a potential fix to RPM surging issues from earlier threads! I've been been able to do it in the past without having to jack the PIU up, which is really convenient.
 






Yes, I've read the same about the tranny fluid and surging hence why it is on my list. It would have been on top of the priority list until I discovered the PTU leak and it's impending detonation.
 






Yes, I've read the same about the tranny fluid and surging hence why it is on my list. It would have been on top of the priority list until I discovered the PTU leak and it's impending detonation.
I'm also looking into getting my PTU fluid changed (as well as the RDU). I bought it at 103K miles, and it's almost at 140K now, so I hope the fluid change will go smoothly.
 






Do the PTU sooner than later.

My current dilemma:

 






Do the PTU sooner than later.

My current dilemma:

I know, I've read through multiple PTU threads. I don't have the expertise to install a new PTU on my own, so I hope changing the fluid will be successful.
 






New throttle body made a world of difference. Start and idle are what I would consider to be "normal" in my opinion. No more hunting. Values are dead on (position requested vs actual).
 

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New throttle body made a world of difference. Start and idle are what I would consider to be "normal" in my opinion. No more hunting. Values are dead on (position requested vs actual).
Do your revs still start off high on a cold start?
 






Cold start at 1300 for a moment, then quickly settle to 600. Whole process is 8 to 10 seconds long. Not 5 minutes like before.
 



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