Hard to start and very rough idle

LennartfromAustria

LennartfromAustria

Member
Joined
Mar 31, 2020
Messages
72
Location
Austria
Hey,

unfortunately my TJ is starting very bad, sometimes I have to cycle the key again so that it starts, if the engine starts, it runs very rough for the first 20-30 seconds, as if it's not lighting the fuel. Since two weeks the idle is getting worse and worse, I can push down the throttle but the rpm stays the same and the engine cuts out almost. Also there is a loud clonking sound, maybe the engine is backfireing ? And it sounds a bit like a lawnmower.

Best regards from Austria, maybe you have a clue
 

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Watching, as Im having intermittent first start rough idle at times too. Probably 1 of every 6. Even get a hesitation in lower gears randomly after long drives when shifting through lower gears. Very sporatic.
 
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@Feralkid not sure if you meant that for all of us but I did that about 1,000 miles ago, sometime in 2019. Though it's the original OE IAC and my TJ is close to 200k. Could be time to go new. Would hate to drop $80 bucks on a guess. No CEL makes it just that, a guess.
 
fourpointzero said:
Watching, as Im having intermittent first start rough idle at times too. Probably 1 of every 6. Even get a hesitation in lower gears randomly after long drives when shifting through lower gears. Very sporatic.
Click to expand...

My 99 did this and then completely cut power on me while driving down the road after leaving the shop. The shop said that they caused the problem by installing the CPK sensor wire too close to the exhaust manifold causing it to overheat and fail (after they replaced the cracked manifold).

My 05 briefly cutt out on me while driving down the road and then wouldn't start. Though, that time I had a P0344 code for those issues (and the CPS sensor fixed it).

Could it also be a timing issue? How are your grounds?

Just spit balling here
 
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JeepLj06 said:
I have an 06 Lj doing the same exact thing, replaced entire exhaust thinking it was the cats, new 02 sensors, new plugs, no vacuum leaks, new MAP sensor, new TPS sensor, still doing it.
Click to expand...

With that year model, I’d be talking to Mark @Wranglerfix, he will have some good input.
 
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Mikee024 said:
Could it also be a timing issue? How are your grounds?

Just spit balling here
Click to expand...

I surely have a grounding issue with my starter. When its 90 degrees plus outside and, after a ride, after shutting it off, when I come back to start it, I find that my starter wont engage. I'll have to pull my ignotion switch back and try once (sometimes twice) and it'll fire right up. Im guessing I have to clean my ground wire or replace it. Been happening for two summers. Starter is new and it used to happen with my old starter. Which didn't need replacing. A very novice mistake: changing it prematurely without testing it. 🤯
 
fourpointzero said:
I surely have a grounding issue with my starter. When its 90 degrees plus outside and, after a ride, after shutting it off, when I come back to start it, I find that my starter wont engage. I'll have to pull my ignotion switch back and try once (sometimes twice) and it'll fire right up. Im guessing I have to clean my ground wire or replace it. Been happening for two summers. Starter is new and it used to happen with my old starter. Which didn't need replacing. A very novice mistake: changing it prematurely without testing it. 🤯
Click to expand...

Fwiw, I had an intermittent hard-start/no-start on my Jeep a few months back.

I first realized that the starter wire was missing its insulation. I spliced in a good wire and spade connector.

I also noticed that the larger plug on the back of my multi-purpose (turn signal) switch was pretty burnt up so I spliced in a new connector.

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All’s been fine since then.
 
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I've been cleaning my IAC for years to remedy a slightly rough idle (no starting issues). This new part smoothed out the idle immensely and seems to have also fixed a studder 1st to 2nd shift my 42rle Jeep has had for 30k miles.
I found the part on this forum:

Edit: The one I linked has bad reviews. The one fourpointzero linked below is better.
Mopar 4874373AB Fuel Injection Idle Air Control Valve https://a.co/d/dRSA6IA
 
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Frankred said:
I've been cleaning my IAC for years to remedy a slightly rough idle (no starting issues). This new part smoothed out the idle immensely and seems to have also fixed a studder 1st to 2nd shift my 42rle Jeep has had for 30k miles.
I found the part on this forum:

Mopar 4874373AB Fuel Injection Idle Air Control Valve https://a.co/d/dRSA6IA
Click to expand...

This is the one Ive got on my 'list' for Amazon:
Mopar 53030657AC Fuel Injection Idle Air Control Valve , Black https://a.co/d/bsgv7k7

Those misfires in lower gears is exactly what I get now and again too.
 
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