Erratic miss at idle

[Rollin’ stock]

Hello, at the risk of being redundant on the forum, I drive a 98.5 24v with a 5 speed manual.

 

About a year ago I started having a slight stutter at idle. It’s not hard, just enough to to feel and hear and it’s very erratic and only when the engine is at operating temp. At the time I was seeing some metal shavings in my fuel filter housing every time I would change it so I attributed it to the lift pump. 
 

Within the last month I changed my lift pump to a FASS 165, afterward my truck developed a hard start issue. Due to the fact my VP was original to the truck and I figured my old lift pump had warm enough to have low fuel pressure, I replaced it with a reman from Thoroughbred Diesel and the hard start went away but I still had the miss.

 

I pulled my injectors and cleaned them, still have the miss. I replaced my injectors because they were the original Bosch and I thought the pop pressures were off. Still have the miss. 
 

I have a puff of black smoke on startup but it doesn’t smoke any other time. And it runs like a top. Plenty of power, good acceleration, and average fuel economy. 
 

At this point I’m leaning towards a sensor but I don’t have any codes either. 

 

[Me78569]

I'd say you are best leaving it be until you get symptoms that point to something.    throwing $ at parts is a pricey way to find the issue. 

 

Cam and Crank Sensors are however cheap and would be my first guess.,

[Rollin’ stock]

Will those sensors go bad without throwing a code? Is there a way I can test them. 

[Me78569]

they can get marginally bad and not throw a code.

[Haggar]

You didn't mention if you had checked your valve lash lately.  If you have not, you might be surprised.  re-adjusting mine made a huge difference.  (they were wayyyy out)

 

GL

Hag

[Mopar1973Man]

On 6/5/2020 at 1:25 PM, Rollin’ stock said:

About a year ago I started having a slight stutter at idle. It’s not hard, just enough to to feel and hear and it’s very erratic and only when the engine is at operating temp.

Missing at idle only warm is typically a sign of injectors failing. You can pull the injectors and clean them up using my article. 

 

If this buys you time then you injectors are nearly wore out and the pop pressure might be low too. You can check that with a live data tool like OBDLink LX or Quadzilla tuner.

 

 

[TheGreatWhite]

1 hour ago, Mopar1973Man said:

Missing at idle only warm is typically a sign of injectors failing. You can pull the injectors and clean them up using my article. 

 

If this buys you time then you injectors are nearly wore out and the pop pressure might be low too. You can check that with a live data tool like OBDLink LX or Quadzilla tuner.

 

 

I've been having the same problem as OP but my injectors are only 2 years old, and my quad reads 6-9% load at idle. If they were bad it would explain the high engine loads I've had problems with recently...