Idle fluctuation

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Feb 29, 2024 | 09:08 AM

DanielT28

Thread Starter

Laughing Gas

Joined: Sep 2012

Posts: 1,239

Likes: 104

From: idaho

Idle fluctuation

As the title states my truck is fluctuating RPM at idle (like 50-100 rpm) it also lopes when cold started and ever so often when it’s warm it will lope on startup . It will also seem to misfire after coming off higher RPM like off the freeway coming down the exit ramp. Get to the stop light and the engine is shaking somewhat. Get on the accelerator pedal and it clears out. Im thinking ICP or IPR but I wanted to get an opinion first. The ICP & IPR readings were “normal” on my ForScan app according to the information I could find online

new parts in the last year include
Riffraff diesel
brand new OEM glow plugs
Bitterroot injectors
Oem fuel pump
uvch harness
upgraded glow plug relay
2 year old batteries
some other parts

Mar 1, 2024 | 08:33 AM

z31freakify

Hotshot

Joined: Dec 2012

Posts: 11,278

Likes: 1,658

From: Las Cruces New Mexico

Isn't your engine low on compression?

Mar 1, 2024 | 11:21 AM

Hit Man X

Lead Driver

Joined: Sep 2002

Posts: 9,555

Likes: 2,035

From: North Texas

A/C compressor cycling?

Mar 12, 2024 | 03:28 PM

Pat.510Marra

1st Gear

Joined: Mar 2024

Posts: 1

Likes: 0

Quote:

Originally Posted by Hit Man X

A/C compressor cycling?

Yes mine is.

Mar 12, 2024 | 03:50 PM

DanielT28

Thread Starter

Laughing Gas

Joined: Sep 2012

Posts: 1,239

Likes: 104

From: idaho

Quote:

Originally Posted by z31freakify

Isn't your engine low on compression?

Probably. But this wasn’t happening before

Mar 12, 2024 | 08:18 PM

Hit Man X

Lead Driver

Joined: Sep 2002

Posts: 9,555

Likes: 2,035

From: North Texas

Quote:

Originally Posted by Pat.510Marra

Yes mine is.

Okay, good for you.

Mar 17, 2024 | 10:47 AM

Warpman89

5th Wheeling

Joined: Jan 2017

Posts: 47

Likes: 0

Quote:

Originally Posted by DanielT28

My 94.5 has been doing the same thing, 50-100 rpm up and down while at idle. Also when coming off of a hard run the idle will cause a jerking/twitching feeling, while cold start idle is very smooth. Recently I unplugged my ICP sensor and the rpm stabilized, however new MC ICP sensor from Clay did not help. I’ve been trying to work this one out for years, reman injectors, ICP, IPR, different CPS’s, IDM. I’m leaning towards the engine just being tired, so I’m going to live with it until it leaves me stranded or starts using oil. Mine will start down to 0 degrees on glowplugs only.

On the tuning side, I’ve had a 6 position chip for 10 years now. I pulled it out in Feb to have Jody give me some new tunes. For the week it was out and my truck was back to all stock tuning, I had a cold start lope/stumble that wasn’t there with the chip. With the chip back in cold starts are very smooth and truck fires right off.