Very Rough Idle When Cold
Thread Starter
|
Cruiser
Joined: Aug 2009
Posts: 126
Likes: 8
From: Maryland
Very Rough Idle When Cold
2007 Street Glide with 110
Only when the engine is cold, when I first start it up it sounds like the engine is galluping, idles very rough. Hard to explain, but after 2-3 minutes when the engine warms up the idle and engine will smooth out and all is fine. This problem has been going on for a few season. Reminder this only happens when the engine is cold both in the summer and winter, abviously a little worse in the winter! This has been happening for 60K miles or so. Thought I would try to get it fixed finally. Just incase this might answer a few of your questions as you are thinking about my issue, I have done the following over the past few seasons.
Thoughts?
Only when the engine is cold, when I first start it up it sounds like the engine is galluping, idles very rough. Hard to explain, but after 2-3 minutes when the engine warms up the idle and engine will smooth out and all is fine. This problem has been going on for a few season. Reminder this only happens when the engine is cold both in the summer and winter, abviously a little worse in the winter! This has been happening for 60K miles or so. Thought I would try to get it fixed finally. Just incase this might answer a few of your questions as you are thinking about my issue, I have done the following over the past few seasons.
- Voltage Regulator
- Stator
- Starter
- New Battery
- Traded in old thundermax ECM for new one.
- Spark Plugs
Thoughts?
HDF Community Team
Joined: Nov 2012
Posts: 6,189
Likes: 2,419
From: USA
A few useful tricks to zero in on things when it's cold and running rough.
Timing light in the spark plug. Does it flash? Obviously this is easier with two timing lights, one on each plug line. If one doesn't work, it's ignition and on that circuit.
Disconnect one fuel injector, then the other. If one doesn't make any difference, be suspicious of that injector/wiring. A noid light on the injector plug will tell you of the injector is getting a signal or not. If it is getting the signal, but not responding when cold, it's the injector. If the signal is missing when cold, you've more diagnostic work to do further upstream.
This may take you a few tries as inviariably the engine will warm up and start running right.
Timing light in the spark plug. Does it flash? Obviously this is easier with two timing lights, one on each plug line. If one doesn't work, it's ignition and on that circuit.
Disconnect one fuel injector, then the other. If one doesn't make any difference, be suspicious of that injector/wiring. A noid light on the injector plug will tell you of the injector is getting a signal or not. If it is getting the signal, but not responding when cold, it's the injector. If the signal is missing when cold, you've more diagnostic work to do further upstream.
This may take you a few tries as inviariably the engine will warm up and start running right.
Cruiser
Joined: Apr 2005
Posts: 234
Likes: 2
From: Midland NC
just a guess but is the engine temp sensor output correct? with power vision i can monitor my temp. Don't know if the ECM looks at eng temp to determine if it should be in closed or open loop. If the ECM thinks the engine is at temp it might not be putting enough fuel when cold.
Club Member
Joined: Apr 2013
Posts: 5,815
Likes: 3,812
From: Cape Cod
Clean IAC......inside throtle body at the 12 oclock position.......stuff shop towel in throttle body........turn on ignition but dont start..........rock kill switch back and forth while using that straw on (I use brake cleaner) cleaner and spray...moving it around inside orifice.......will probably be pretty dirty.......
Grand HDF Member
Joined: Jan 2012
Posts: 4,458
Likes: 2,876
From: Oklahoma
"Galloping" and "rough" imply different things to me. By galloping, do you you mean the rpm cycles from low to high and back down again? For that, the IAC guess is a good one. By "rough" do you mean the the engine is shaking much more than normal but the rpm as fairly constant? When you changed plugs, how did they look? Was one significantly different from the other? One being extremely clean may suggest an intake air leak that causes misfire when cold. You made an excellent try to include all of the vital information, but plug condition might answer the question. And clarifying "gallop" and "rough" would help also.
Thread Starter
|
Cruiser
Joined: Aug 2009
Posts: 126
Likes: 8
From: Maryland
Both plugs looked identical when I pulled and changed them. Your second on how the engine runs is correct. The RPM stays steady, doesn't flucuate at all.
Trending Topics
Grand HDF Member
Joined: Jan 2012
Posts: 4,458
Likes: 2,876
From: Oklahoma
Does the cold idle rpm seem lower than normal warm idle or a faster, more normal warm up idle rpm but just very rough? Have you checked for any stored codes?
Last edited by btsom; Feb 27, 2019 at 08:58 PM.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Thread Starter
|
Cruiser
Joined: Aug 2009
Posts: 126
Likes: 8
From: Maryland
I did a data dump from my Thundermax ECU and upon the technician reviewing the results, this is what I was told.
"QUOTE FROM THUNDERMAX"
There is an issue with the IAC motor and TPS setting. The TPS should set at a value around 10-12 degrees if you link and pick monitor and look at the Throttle Position gage. The TAC value should show 85. Once the bike starts the TAC value should go down and yours goes up way up to around 120 steps. Like it is lost then after a couple of minutes it starts going down and the bike starts to come around and idle well. This is not something that can be adjusted at the ECU level but I believe should be adjusted at the throttlebody.
Any ideas here on what I should do next?
"QUOTE FROM THUNDERMAX"
There is an issue with the IAC motor and TPS setting. The TPS should set at a value around 10-12 degrees if you link and pick monitor and look at the Throttle Position gage. The TAC value should show 85. Once the bike starts the TAC value should go down and yours goes up way up to around 120 steps. Like it is lost then after a couple of minutes it starts going down and the bike starts to come around and idle well. This is not something that can be adjusted at the ECU level but I believe should be adjusted at the throttlebody.
Any ideas here on what I should do next?