weird idle and rev limiting at start up; fine later

[nobeconobe]

Hi all, new 2010 Jeep Liberty owner here. I bought it with 147000 miles. I apologize if my terminology is wrong as I describe the problem.

On first start (from overnight, weather is 65F at night, 75F during day), I get a weird sound/feeling during idle. I wouldn't describe it as rough idle (it's not violent at all)... but it sounds like the engine wants to die for 1 second, then it doesn't.. and it keeps cycling through this. It's subtle and cyclic. Hard to capture in audio, too, but the vibration is felt.

At the same time, I cannot rev past 2500 (this is still in Park, coolant temp gauge still hasn't moved from the C) during this time when it's going through this weird subtle cycle of sounding like it's not going to stay on.

After maybe 1-3 minutes, as the engine warms up and is maybe at the 1/8 to 1/4 mark in the coolant guage, the problem goes away, and I can rev past 4000. Things are back to normal.

I've had no problems while driving (can go 90+ in highway, etc), and the problem goes away once the car had been running and is at temperature. Shutting it off and on again does not reproduce the problem if the engine is warm and has been running. It has to be from a "cold" (overnight) start.

If I start driving immediately after a cold start, the car seems to allow me to rev up pretty quickly (e.g. not limiting like when I'm in park). I'll have to run more tests tomorrow or Monday, though (I'll try to drive away quickly after a cold start and see if power is being limiting while driving).

Any ideas are appreciated. There are no codes and no MIL on. I have a cheap code reader - no DTC codes there, either.

Please let me know if you need more information. Thanks!

 

[LibertyTC]

Welcome..
The jeep needs some testing, first off are the battery terminals clean & tight?
Do you have a voltage ohm meter to connect to the battery?
Can you tell us what is the output voltage is while running?
Also what the battery voltage is reading when jeep is off after 20 minutes with doors closed,& nothing on inside jeep?

 

[nobeconobe]

Welcome..
The jeep needs some testing, first off are the battery terminals clean & tight?
Do you have a voltage ohm meter to connect to the battery?
Can you tell us what is the output voltage is while running?
Also what the battery voltage is reading when jeep is off after 20 minutes with doors closed,& nothing on inside jeep?

Hi,

Thanks. I do have a voltmeter. I will try to measure those this afternoon or next week (if I can find my voltmeter!).

I do have a ODB2 reader if that can be used.

I should also say I did a NY State inspection last week and all passed. I believe the shop did a "battery check" then and also when I got an oil change. But I will measure it (I assume I just connect it to the actual battery terminal heads?).

Thanks so far! I've been doing more reading and I read about a "lower power mode" related to the exhaust. Not sure if that's related.

EDIT: also to be clear, I mean "engine power" when I say "power," not electrical. Car starts up fine, normal crank, etc.

EDIT2: My voltometer isn't with me. I won't be able to check voltages with it until next week (unless on ODB2 scanner can read it).

 

[LibertyTC]

Look at the specs of your OBD2 reader to see if it has a gauge package reader included.
If it's real basic ,probably not.
Scangauge & My Autel OBD2 shows voltage etc.

You must be registered for see images attach

 

[nobeconobe]

Thanks so far for the help. I still haven't found my voltometer, unfortunately, but I have more information.

Today, I drove off while it was "hiccupping" as I like to call it during cold idle. Then, flashing check engine came off, then turned off (it did not stay on). I grabbed the code: P0301 Cylinder 1 misfire.

I assume the "rough" (though it's not very rough, it's just a weird cyclical hiccup type of thing) idle is from the misfire, and it goes away once the car is at temperature.

I will do my research: I've already seen it could be the spark plug, it could be the coil pack, it could be fuel injector, etc. But if anyone has any insight on why this may only be happing on cold starts (and by cold, I mean like 70F from an overnight low of maybe 65F), any information would be appreciated.

I'll keep this thread updated.

 

[LibertyTC]

You could also try swapping coil- cyl #1 to another location, & see if code moves with it.
Spark plugs to use for KK are NGK- ZFR6F-11 Gap .043 inch.
Report on spark plug condition, once gaps get eaten away they become out of spec.
Are the correct NGK plugs in there?

 

[nobeconobe]

You could also try swapping coil- cyl #1 to another location, & see if code moves with it.
Spark plugs to use for KK are NGK- ZFR6F-11 Gap .043 inch.
Report on spark plug condition, once gaps get eaten away they become out of spec.
Are the correct NGK plugs in there?

Thank you. I'm not sure what plugs are in there now as I recently bought it and haven't inspected the plugs. I have ordered those exact plugs, though, in case that's the issue.

Here is my game-plan. Let me know if I should do things differently. I think it's important to note that the code does not get thrown every time, even when I feel the "rough idle". I only got it today because I drove off before letting it warm up, and it struggled and through the code. It doesn't throw the code when I just idle (even though presumably, it's misfiring and that's what I'm feeling). I only mention this because it may be a while before I get another code.

Step 1: Swap coil 1 and coil 3 (when looking at jeep standing in front of the grill, the 2 front right cylinders). Do nothing else. Make sure engine starts, etc. Wait overnight, turn on engine tomorrow and see if I still feel the rough idle. If so, I'll try to see if it spits out a code. Hopefully it spits out cylinder 3 misfire, and I have diagnosed it is a bad coil and I will get it replaced. If I don't get a code, but still feel the rough idle, I'm not sure what to conclude until I do get a code.

Step 2: If I swap coils and I still get a cylinder 1 misfire, it must be something else. My next step is to replace the spark plug in cylinder 1 with a new spark plug (and perhaps note its condition and gap), wait over night, and see if the issue is resolved.

Let me know if there's something else I should look into first given that this only happens on first/cold start, then runs smooth (presumably no misfire).

If new spark plugs and new coil does not resolve the rough idle on first start, I'll report back! I'm relatively new to this stuff - I've never replaced plugs/coils, but I've watched a few videos: it seems doable (and luckily is Cylinder 1 - easy access). I have a wrench set and torque wrench I just ordered, in addition to coils and plugs.

 

[nobeconobe]

Oh yeah, here's my freeze frame from my cheap ODB2 Reader:

EDIT: Here is my freeze frame from the code:
DTCFRZF P0301
FUELSYS1 0L
FUELSYS2 0L
LOAD_PCT (%) 43.5
ETC (deg F) 77
SHRTFT1 (%) 0
LONGFT1 (%) 0
SHRTFT2 (%) 0
LONGFT2 (%) 0.8
MAP (inHG) 13.6
RPM (/min) 203
VSS (mph) 0
SPARKADV (deg) 11
IAT (deg F) 79
TP (%) 16.9
RUNTM (sec) 12
EGR_PTC (%) 0.0
EGR_ERR (%) 0.0
EVAP_PCT (%) 0.0
FLI (%) 44.7
BARO (inHg) 29.2
VPWR (V) 14.252
LOAD_ABS (%) 37.3
EQ_RAT 0.999
TP_R (%) 5.9
AAT (deg F) 73)
TP_B (%) 16.9
APP_D (%) 9.0
APP_E (%) 4.3
TAC_PCT (%) 6.3

 

[Johnny O]

Oh yeah, here's my freeze frame from my cheap ODB2 Reader:

EDIT: Here is my freeze frame from the code:
DTCFRZF P0301
FUELSYS1 0L
FUELSYS2 0L
LOAD_PCT (%) 43.5
ETC (deg F) 77
SHRTFT1 (%) 0
LONGFT1 (%) 0
SHRTFT2 (%) 0
LONGFT2 (%) 0.8
MAP (inHG) 13.6
RPM (/min) 203
VSS (mph) 0
SPARKADV (deg) 11
IAT (deg F) 79
TP (%) 16.9
RUNTM (sec) 12
EGR_PTC (%) 0.0
EGR_ERR (%) 0.0
EVAP_PCT (%) 0.0
FLI (%) 44.7
BARO (inHg) 29.2
VPWR (V) 14.252
LOAD_ABS (%) 37.3
EQ_RAT 0.999
TP_R (%) 5.9
AAT (deg F) 73)
TP_B (%) 16.9
APP_D (%) 9.0
APP_E (%) 4.3
TAC_PCT (%) 6.3

Suggest if your reader will do it, take a freeze like this one at start up, then another after the condition “corrects”.

This one shows 12 seconds of run time. So a few others at say 1 minute, when it runs normal, and after 5 minutes of idle will help the gurus. Perhaps one after a good rev too.

 

[nobeconobe]

Hi all,

I decided to change all the plugs and the ignition coils. I used the NGK's suggested here, checked the gaps, etc. I had to use Duralast (AutoZone) ignition coils since that's what was available.

This was my first time ever doing something like this. The spark plug boot broke on the third ignition coil, and I was concerned I would have to have it towed to a shop. But after some elbow grease and pliers, I finally got it off. I hope I didn't damage the engine wall there :/

I was also concerned dirt/dust got into the spark plug hole while the spark plug was out :/ Is this something I should be concerned about, or will whatever got in there burn out?

Car started up fine, idle is fine, no codes have popped up. Everything seems okay thus far. I assume that means I didn't mess anything up installing the plugs/coils?

Of course everything was fine when the engine is hot. Tomorrow or Wednesday morning will be the moment of truth to see if I still get a rough idle/misfire on first start.

Wish me luck!

 

[lfhoward]

Good luck! Let us know how it goes.

 

[nobeconobe]

Oh yeah, Is there a cap supposed to be on this line? I just noticed it's exposed. If so, where can I buy a cap (or what is it called?)

 

[lfhoward]

Yes, that’s an AC line and should have a cap to protect the Schrader valve. I think you can find one at your local auto parts store.

 

[nobeconobe]

So far, so good. Two morning starts and no issues thus far!

 

[Johnny O]

Cool man! A trick I use is after I’ve removed the Coil on Plug, I shopvac the recess before I pull the plug, and then get observant with the flashlight and mirror.