Help !! engine sputtering then dies at idle.

[Liberty02sport]

Earlier I thought this might have been a gas/fuel filter issue (could still be I guess). Engine sputters, idles rough, then dies. Just did it twice in a row while sitting in the driveway after about a 15-20 min. trip home.

I had shut of the AC and it was idiling fime while in park, got out opened up the garage door and got back in put it in drive and it immeadiately started idling rough then sputtered out and died. Started it right back up an it was still idling rough but gave it some gas and it started to smooth out, there is also a "ticking" sound when it's idling rough. Pulled it into the garage and put it in park and it began the same rough idle with the ticking sound till it died again. when it's running smooth there is no noticable "ticking" that I can tell, only when idling rough does this ticking happen. No check engine or any other idiot light comes on while this is happening

Per the suggestions in my other thread on possible gas/fuel filter issues I have put some of the Lucas fuel treatment in the tank, replaced the air filter, cleaned the IAC sensor and port as instructed,. The miles are 92K and it had the long block replaced due to a broken valve spring a few years back so only about 3K miles on the new engine. 2002 mode year thanks for any and all suggestions,this is driving me nuts trying to find the cause.

 

[LibertyTC]

When it is running / idling rough what rpm is the engine at?
Have you checked the spark plug condition/gap, & type and have a load test on the battery and what is current reading of battery voltage?
Also see how much voltage is going into battery, the Kj will act very strange if battery is weak!

 

[Liberty02sport]

650-700 on the idle rpm's. The NGK plugs were gapped correctly and have less than 3 K miles on them. Battery was replaced less than a year ago.

 

[Liberty02sport]

It was really screwy.....it drove fine all the way home then started acting stupid when it got back in the driveway. It was doing fine and was idling normally til I put it in drive to pull into the garage then stared idling rough and died. Don't know what the weird ticking noise is when it starts idling rough.

 

[LibertyTC]

Got a battery charger? What is the current voltage of battery?
Next is fuel bad gas from sitting more than a month?, water in fuel? Use a higher octane grade with an ethanol based marine grade fuel stabilizer.
Ticking coming from where? If engine looses rpm it may tick from too low rpm, IAC replacement or internal problem or belt idler/tensioner/assembly?
Does it keep running with gas pedal on? Sure there is no CE light?

 

[Liberty02sport]

positive on the no check engine light. tick seems to be coming from under the hood, only occurs when idle is rough. It does keep running and tries to smooth out if I give it more gas, sometimes settles back into normal idle. No battery charger just a multimeter.

It does sit a bit, but I just added some of the Lucas fuel treatment and had added more fresh gas to the tank.

 

[LibertyTC]

With mulit meter you should be able to see your battery voltage, it should be like 13 volts! A fully charged battery should be 13.25-13.5 with no interior lights on (no drain)
Go easy on that Lucas 2 oz per 10 gallon.
Ethanol fuel left for a while attracts moisture and a ethanol based fuel stabilizer is really helpful to burn off the potential moisture and stabilize stale gas in tank. Go get some or water remover,and put in 91 or 94 Octane fuel and take it fr a good highway boogie!
I like to use and fuel cleaner like Chevron Techron (techroline) that does keep motor & valves clean as well.

 

[LibertyTC]

Regarding fuel if you leave your tank half full it is more likely to attract moisture.
Storage conditions like using the jeep occasionally, or any vehicle is best left full and with the marine grade ethanol fuel stabilizers added to fuel.
Adding a couple of gallons here and there over time does not refresh the fuel.
Stabilizer works to maintain gas over 1 year.

 

[Liberty02sport]

Got a reading of 12.23 V on the battery with the engine off. Had only used half the bottle of the lucas with half a tank of gas. Checked the FSM and it was pretty unclear as to the possible cause of this. Listed faulty coil, faulty crank position sensor, and vacuum leak as possible causes (?). Didn't even mention the fuel system (????).

 

[LibertyTC]

12.23 is quite low for battery. Definitely could use a good charge & then load test.
Most vacuum leaks and CPS & coil will throw engine codes.
With only 3 k of use over a couple of years.....and no battery charging....??
How often did you add fuel without a stabilizer?

 

[Liberty02sport]

Don't let the low mileage on the new engine play too much of a part, I live in a rural area in a small town so my trips are not very long mileage wise. It probably gets driven at least 5 times a month, more so in winter during snow and ice. Never added any fuel treatments of any type till here recently when this bit of trouble came up. Even when not being driven often it still gets started and and washed fairly frequently to keep it in good shape and keeps bug splatter from tearing up the paint LOL.

I'll check the missus's Wrangler battery and see what it reads voltage wise. the low end on my battery might be from it dieing and then being started back up a few times right in a row today. I might try to start it up again and see if it will sttle into a stable idle and let it charge a bit to be sure and then check it again, if the battery is still low might have it checked (still under warranty).

 

[Liberty02sport]

12.72 volts on the Wrangler battery. Just started it back up and couldn't get it to repeat the problem. I did notice while keeping a careful eye on the tach that it seemed to settle into and idle at 700 RPM initially then when placed in drive it would drop to almost 600 RPM, place it back in park and rev the engine a bit (1500-2000 RPM)and it would stop back at 700 then slowly drop back to just about 600, not sure if this means anything or not.

ETA; it did this repeatedly while at operating temp. Like it wasn't satisfied with it's idle and would go up or down 100 RPM, whether in park or drive seemed to make no difference.

 

[LibertyTC]

The IAC controls the idle. The IAC may need replacement.
To effectively charge a battery you need to drive the jeep for 30+ minutes a couple of time per week. You would do your batteries a huge favor and make em last much longer if you use an intelligent charger like the C-Tek. $50 or less. You can leave it plugged in and your battery will always be fully charged @ 13.5 volts. Not the 12.23 I need charging voltage!
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[streetglideok]

If he has 12v with the engine off, then he's about where he should be, unless he has a surface charge. Can be as low as 11.5V and be ok. Now engine running, should be over 13v. How many times has this happened? Does it only do it when you get home into your driveway? Is your driveway sloped? How full is the fuel tank, how old is the gas, and is it E85, or normal fuel?

 

[tjkj2002]

If he has 12v with the engine off, then he's about where he should be, unless he has a surface charge. Can be as low as 11.5V and be ok. Now engine running, should be over 13v. How many times has this happened? Does it only do it when you get home into your driveway? Is your driveway sloped? How full is the fuel tank, how old is the gas, and is it E85, or normal fuel?

Correct.


You can have a good battery and it can only show 12v.If your battery is showing over 13.2 volts alone you got a issue and your cooking that battery.Remember the battery only has six 1.5 volt cells in it,do the math.

Normal idle for full operating temps is 650 +/- 25rpm's,no way to adjust this.I'd start looking at cleaning the throttle body 1st.

 

[Liberty02sport]

If he has 12v with the engine off, then he's about where he should be, unless he has a surface charge. Can be as low as 11.5V and be ok. Now engine running, should be over 13v. How many times has this happened? Does it only do it when you get home into your driveway? Is your driveway sloped? How full is the fuel tank, how old is the gas, and is it E85, or normal fuel?

Happened a total of about 5 times. Seems to happen when engine returns to idle on slowing down for corners and such or when stopping/decelerating, today it happened while sitting at idle in the driveway (which is pretty much flat) seeminglyfor no reason at all other than it was shifted from park to drive. Just started idling rough with the tach needle bouncing a bit then sputtered out and died. When it started to idle rough it began to "tick", after a restart it still idled rough so I tried giving it a little gas and as RPM increased it tried to smooth out, when I let off the gas it returned to a normal idle.

Pulled into the garage placed the shifter into park and it started to idle rough again and ticking then sputtered and died. Waited an hour or two went out restarted it and couldn't get it to replicate the problem even after going thru the exact routine I did earlier that seemed to be causing the problem. Only difference was I never had the engine under any load and it never left the garage. Started it let it come up to operating temp., turned on AC and placed it in drive ...nothing happened. Put it back into park with AC still on and no change in idle. Revved the slightly and let it return to idle..still no change. Turned AC off and shifted from park to drive and back to park, still nothing, revved the engine a bit again while in park everything returned to stable idle.

Only an hour or so before the problem was happening pretty much constantly with any change in the shifter position from drive to park or park to drive, now I can't get it to repeat itself to save my life no matter what I do. The gas level in the tank is a bit above 1/4 of a tank and is no more than a week or so old. Thanks for all the sugestion/input. This is driving me batty since it only happens some of the time and I can't pin down the conditions/cause, other than it seems to occur when the enine comes down out of the upper RPM range and is decelerating, except today it was sitting at idle under no load and just seemed to start having this problem.:favorites68:

 

[Liberty02sport]

Correct.


You can have a good battery and it can only show 12v.If your battery is showing over 13.2 volts alone you got a issue and your cooking that battery.Remember the battery only has six 1.5 volt cells in it,do the math.

Normal idle for full operating temps is 650 +/- 25rpm's,no way to adjust this.I'd start looking at cleaning the throttle body 1st.

It seems to settle in at the lower edge of the tach. needle just touching the mark indicating 600rpm on the gauge. Sometimes up to almost 700rpm, then if you rev it slightly it will come back down to 600rpm.

I'll try cleaning the throttle body tomorrow and see what happens. I only need to clean the exposed "butterfly" and throat area and not disassemble the whole thing right ?? I'll do a search on throtle body cleaning and see what I come up with..

 

[streetglideok]

The noise you hear could be a variety of things, without hearing it first hand, its hard to say what it is. Could be a sticking valve that acts up when its hot, or has heatsoaked, could be faulty ignition coils even. Any codes set or pending?

 

[501]

I'd say get a new battery. Mine would drive great from a cold start, then after about 10 min's of driving it would stall at stop signs & stop lights. I bought a new battery and every thing's fine.

 

[Liberty02sport]

Just got done cleaning the TB and went over the IAC port again too (after removing IAC). TB had carbon buildup around where the butterfly is which wasn't really hard to get rid of using a shop rag with some TB cleaner sprayed on it and wiping it out a few times. Tried to make sure I didn't get any TB cleaner on the plastic intake manifold since TB cleaner warned aginst using it on plastics and I plugged the IAC hole with a shop rag while I gave a few blasts to the front of the port below the TB opening to catch any that might have tried to run into the intake manifold. It was fairly dirty there too.

Put everything back together and started it up and idle went straight to halfway between 600-700 RPM and that's where it stayed. Tried All the same things that got it to act up yesterday and it didn't even act like it wanted to search a little before it settled on what RPM it wanted to idle at, just went straight to 650 RPM and stayed there. If it acts up again I got a bottle of HEET that I'll try on the chance that I may have some bad gas after that I guess a replacement IAC if it still keeps doing it.