Surging while idling

[Blakers]

Hello Folks, I've made some searches on this and found similar symptoms, but not exact.

Recently my truck began having slight rpm surging or fluctuations while idling - only a couple hundred rpm for the most part. When I let the clutch out with no throttle, it sometimes lurches again like I just tromped the throttle. And trying to just idle along in 2nd gear it surges up and down. It doesn't do this all the time. Could it be the FCA on its way out?

My truck is an 03 6 speed that I bought new. I replaced the lift pump at probably 125,000 miles ago and I always carry a new one with me.

Thanks,
Blake

 

[p-Bar]

Try some 2 stroke oil in the fuel tank to lubricate the FCA if it smooths out that's the problem. Or maybe a leaky injector want to be careful of that one. Good luck

 

[Blakers]

Thanks! How much 2 stroke oil do you use? Hope it's not a leaky injector - a friend had one that burned a piston and ruined a cylinder on his 5500 Ram.

 

[p-Bar]

I would throw a quart in. it wont hurt anything. Ya that's what I was thinking too.

 

[Blakers]

No smoke when surging while idling, so hopefully that's a sign that an injector is not leaking. I have an appointment with our local VoTech diesel shop to check everything out.

 

[SDrake]

The FCA is plug and play, 3 screws, and an electrical connector to unplug. When mine started doing what yours is doing, I purchased new one, changed it out creating no disturbance to the rest of the system. Plan was to eliminate FCA as a cause and go from there but that was it and easy to take care of.

Mine was most noticeable on cool mornings as I eased off just above idle before making turn onto street where I would spend up. The slight pulsation at idle became very pronounced as I would be driving off at about 1100 rpm and with cold engine it would cause a bit of pulsating clatter.

 

[Blakers]

Well I just got back from the VoTech diesel class where they hooked my truck up to their $$$ thousand dollar analyzer machine. For the most part, no problem. I filled up with fuel last night from a different station and the surging at idle seems to have stopped. Who knows? Anyway, he said the FCA has some fluctuations, but is within range of where it should be. He said that might be causing the problem, but he said if it is the cause, it will get worse over time. Injectors are good and it starts quickly. I know with my mileage, injectors are something to look at down the road.

They did find that my ABS warning lights and alarm is caused by a bad rear sensor.

If the surging comes back, I will pick up an FCA.

Thanks guys.

 

[SDrake]

My ABS warning light turned out to not be a bad wheel sensor as diagnostics indicated. There are some relays in the abs control board that go bad, driversside under hood back of battery. Needed anew board one but I sent mine off to be rebuilt.

 

[Blakers]

I replaced the rear axle ABS sensor and the ABS has worked fine ever since. I did have some difficulties getting the old sensor out as it broke off and I had to dig it out with a screwdriver. Fortunately, its shell was plastic and came out in pieces.

My ABS warning light turned out to not be a bad wheel sensor as diagnostics indicated. There are some relays in the abs control board that go bad, driversside under hood back of battery. Needed anew board one but I sent mine off to be rebuilt.

 

[Prairie Dog]

Replace the FCA. You wont believe the difference it will make.

 

[Blakers]

Update on Surging Issue: Since I have been buying fuel oil from a different station, the surging issue has stopped. No problem. I will keep an eye on this.

Today another issue sprung up: my driver's window would not go up. I messed with the switch for 15 miles, then stopped on a dirt road on my way to work and listened to it. I could hear the motor running intermittently, but no movement. After a little praying and actuating the switch some more, it came up. Tonight I will pull the cover off the door and investigate.