Rough idle on a cold startup (10 seconds)

[craigripley]

Hey all,

Got a bit of a mystery going on with my 2014 Ram 1500 5.7L, just started noticing it about 2 weeks ago and haven't had any luck fixing it.

On the first start of the morning or after the truck has sat for about 4 hours or more, the truck starts strong like normal, but then idles poorly to the point of sounding like its about to stall for about 10 seconds, and then everything smooths out and goes back to normal. If I give it some gas while its struggling, it no longer chugs away.

Engine is the 5.7L, has 93,000km on it and running Redline 5W20 or 5W30 in it and have been for a while now. Engine has a Green Racing stage 2.5 cam / springs (factory lifters) done about 25,000km ago, ARH Long tubes, S&B air intake, ATI dampener, e-fan, etc.

Since it's started I've replaced/checked the following since this started:
New Battery
New Spark plugs (all looked normal coming out)
Compression check while doing plugs - All cylinders 210-225psi
New PCV valve
Removed fuel rail/injectors, checked for leakage, found none.
Cleaned air filter
Cleaned throttle body

Not sure what my next step should be...just wondering if the community has any ideas or experience with something similar. I'm about to pull the valve covers I think and have a look, although with good compression I'm not sure if I'll find anything there. Potentially an intake leak or vacuum leak? I've looked for any vacuum leaks and haven't found anything out of place. Any sensors I should maybe replace? Crank/cam position, MAP, etc? No codes present or stored.

Any ideas are appreciated! Thanks!

 

[craigripley]

Changed crank & cam position sensor, as well as MAP and inlet air temp sensor, no change to my problem. The following morning it was actually the worst its ever been and fully stalled after chugging along for about 5 seconds on start. When I started it a second time, it had a big pop out the exhaust and then ran normal.

I've pulled valve covers and looked over everything, looks good. Cranked the engine with the covers off and all the valves appear to move the same, theres definitely no wiped cam lobes like some videos I've seen on here. I even let it sit overnight and checked again in the morning in case it was a lifter bleeding down and not pumping up quick, but it all checked out this morning too. Putting it back together now, but at a loss as to what it could be.

I'm still suspicious of an injector even though I couldnt get any to leak when I checked...or possibly a fuel pump I guess. Theres no service ports on these fuel rails though to check for pressures???

Any ideas are welcome.

Thanks.

 

[Wild one]

Changed crank & cam position sensor, as well as MAP and inlet air temp sensor, no change to my problem. The following morning it was actually the worst its ever been and fully stalled after chugging along for about 5 seconds on start. When I started it a second time, it had a big pop out the exhaust and then ran normal.

I've pulled valve covers and looked over everything, looks good. Cranked the engine with the covers off and all the valves appear to move the same, theres definitely no wiped cam lobes like some videos I've seen on here. I even let it sit overnight and checked again in the morning in case it was a lifter bleeding down and not pumping up quick, but it all checked out this morning too. Putting it back together now, but at a loss as to what it could be.

I'm still suspicious of an injector even though I couldnt get any to leak when I checked...or possibly a fuel pump I guess. Theres no service ports on these fuel rails though to check for pressures???

Any ideas are welcome.

Thanks.

Talk to your tuner,it sounds more like a tune issue then a mechanical issue. Would it be tuned by Chris in Edmonton? If so he's got another cammed truck that's giving him issues to with horrible cold starts.

 

[chrisp2493]

My cam/stroker truck normally has a rough cold start, especially in winter when it’s actually cold. It will run rough until the o2 sensors heat up and the pcm starts reading them. I watched start up logs and it would literally smooth out as soon as the sensors would start reading. You might have any issues somewhere else if it was working fine for awhile then started acting up, but you’ll find lots of little quirks and issues pop up with a big cam. I’ve been fighting mine for months on a slight surging when rpms drop below 1100. It idles perfectly but when coasting at low rpm the rpms keep jumping. Can’t tell if it’s a tune issue, fuel pressure or just having a big cam


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[StoneDude76]

Lifter not pumped up yet. My truck does the same. Stock tune right now. Did it with a Hemifever tune as well.

Sent from my VS988 using Tapatalk

 

[Fitz-0518]

My cam/stroker truck normally has a rough cold start, especially in winter when it’s actually cold. It will run rough until the o2 sensors heat up and the pcm starts reading them. I watched start up logs and it would literally smooth out as soon as the sensors would start reading. You might have any issues somewhere else if it was working fine for awhile then started acting up, but you’ll find lots of little quirks and issues pop up with a big cam. I’ve been fighting mine for months on a slight surging when rpms drop below 1100. It idles perfectly but when coasting at low rpm the rpms keep jumping. Can’t tell if it’s a tune issue, fuel pressure or just having a big cam


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Now I understand why my 6.4 has a bit of a miss on start up at 1000 rpms. When warm up idle drops to 500, it smooths right out. o2 sensor warm up, makes sense.

 

[craigripley]

Not tuned by Chris in Edmonton, although might not have been a bad idea to get done while I lived in the area. Its got a Jay Greene tune currently.

I expect some issues/quirks with a cammed setup, but it just seems odd that I never had this problem after I did the install, and have put about 20,000+km on it and only now am I having these cold start issues.

Lifter not pumped up was one thought of mine, but when I watched the valves this morning I didnt see any that were moving less than the rest (as fast as I could start it and run to look underhood; had no helper).

O2 sensors sounds like it could maybe be it too - I'll throw my scanner on and watch to see when they come alive and how it correlates to the idle. I know I've had 2 O2 failures previously already but they threw codes and had no effect on performance.

I'll hit up Jay and see if he has anything he can try. I contacted him when this first started and he suggested a Wideband install so I'll look into that and see what he can do.

My concern is how this is doing it now in summer on a cold start, I dont want it any worse when its actually cold and winter.

Thanks for the help!

 

[Wild one]

Not tuned by Chris in Edmonton, although might not have been a bad idea to get done while I lived in the area. Its got a Jay Greene tune currently.

I expect some issues/quirks with a cammed setup, but it just seems odd that I never had this problem after I did the install, and have put about 20,000+km on it and only now am I having these cold start issues.

Lifter not pumped up was one thought of mine, but when I watched the valves this morning I didnt see any that were moving less than the rest (as fast as I could start it and run to look underhood; had no helper).

O2 sensors sounds like it could maybe be it too - I'll throw my scanner on and watch to see when they come alive and how it correlates to the idle. I know I've had 2 O2 failures previously already but they threw codes and had no effect on performance.

I'll hit up Jay and see if he has anything he can try. I contacted him when this first started and he suggested a Wideband install so I'll look into that and see what he can do.

My concern is how this is doing it now in summer on a cold start, I dont want it any worse when its actually cold and winter.

Thanks for the help!

There's a another cammed truck north of you that's sorta of doing the same,it ran good for the first 6 months,and just started recently acting up. I think it's had 02 sensors done too. The guy isn't on here,but he is on facebook,if you want me to hook you up with him,to bounce ideas off,message me.

 

[chrisp2493]

If you are using diablo tuners, have you tried using the Dataviewer program? It makes reading live data really easy on a laptop. I hook mine up through my trinity and do all my logging on the laptop


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[Wild one]

If you are using diablo tuners, have you tried using the Dataviewer program? It makes reading live data really easy on a laptop. I hook mine up through my trinity and do all my logging on the laptop


I Bleed Ram Trucks

The 1 I know of is HP tuned,the owner just sprung for the HP platform though,so he'll be able to data log and view issues soon.

 

[chrisp2493]

The 1 I know of is HP tuned,the owner just sprung for the HP platform though,so he'll be able to data log and view issues soon.

I’m wondering if the OP does since he said he wanted to check out the sensors


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