Momentary jerk/miss/shudder at highway speed

[mgray]

Noticed this a couple times now in the last month, very brief tho. Cruising down the highway at 95kmh/60mph and there is a quick jerk/miss/shudder then all is back to normal. I almost think I'm taking my foot off the pedal then putting it back on quickly...but I'm pretty sure I'm not.

Just looking for ideas on where to start looking for a potential problem.

Thanks

 

[Brooklyn Tow]

Start with a fresh fuel filter....and a clean fuel filter manager.

Lift pump and fuel pressure should be checked also.

Check fuel quality from FFM.....Maybe you got a batch of bad fuel.

 

[MAGNUM SERVICES]

No lights, no codes, where is PMD or FSD mounted?

 

[Matt Bachand]

Does it happen w/ cruise control also?

 

[Dan Hunter]

Noticed this a couple times now in the last month, very brief tho. Cruising down the highway at 95kmh/60mph and there is a quick jerk/miss/shudder then all is back to normal. I almost think I'm taking my foot off the pedal then putting it back on quickly...but I'm pretty sure I'm not.

Flat ground or going up hill? You could be at the threshold where a inop lift pump - for whatever reason - is challenging the IP and it can't keep up.

 

[mgray]

Heath FSD on kickplate. Seems to only happen on flat ground, very little throttle. No check engine or any other indicators.

 

[ak diesel driver]

check to see if you have an Optic Sensor filter if so remove it. My 96 had one.

 

[mgray]

check to see if you have an Optic Sensor filter if so remove it. My 96 had one.

Thanks, but where would that be? And why would it have another filter after the main fuel filter?

 

[NVW]

It's a filter harness above the IP. It's before the Optic Sensor.You can unplug it and just plug the remaining leads together.This is the best I can do to show what it is: http://www.mamut.net/royh/newsdet9.htm

 

[ak diesel driver]

Thanks, but where would that be? And why would it have another filter after the main fuel filter?

It's an electronic filter that is known to cause problems

 

[buddy]

Check you lift pump pressure as suggested, and are you using any fuel additives? Did you add any particular additive in the last month, such as an injector cleaner or fuel system treatment? Some of the additives will cause bad things.

Also, get a code reader and check to see if there are any supressed transmission codes that dont always set off the SES light. This is quite common. You may have a TCC lockup problem.

 

[paintballrepins]

I had the same problem under, except mine happened in 4th gear under hard acceleration. I still to this day do not know what caused it, however it did not show the ses light, but it stored codes PO236 and PO238 which are for boost. The ecm was reading to much boost and cut vacuum or fuel for just a second. After a while I started to get stuck in limp mode. I plugged up my vacuum line and added a TM, when i set the TM to high it would do the same thing. The big thing is to check for codes.