# Nissan Frontier Vibrates Going Uphill P0400 **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [July 22, 2013, 6:06am UTC](https://community.cartalk.com/t/nissan-frontier-vibrates-going-uphill-p0400/80474 "2013-07-22T06:06:48Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![nw2012](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@nw2012](https://community.cartalk.com/u/nw2012)\ **Post date:** [July 22, 2013, 6:06am UTC](https://community.cartalk.com/t/nissan-frontier-vibrates-going-uphill-p0400/80474/1 "2013-07-22T06:06:48Z")
2003 Nissan Frontier with a 4cyl engine, just over 300k. It vibrates and starts chugging anytime it’s under a small load, like going up a hill. Cruises nice and smooth on level ground or going downhill. Feels like a misfire, but idles perfectly and had new plugs/wires installed a few month ago with no problems. So there’s no service engine light, and no codes set, but when I plug my scanner into it the code P0400 appears and disappears randomly on the screen but never sets itself in the computer. My question is, where is a good starting point? Any components known to go bad in the EGR system? And would a bad/stuck EGR valve cause these symptoms? Thanks! PS - there is also a code set for the catalytic converter, it was catalyst efficiency below threshold but I don’t remember the exact code. Any way this could be part of the problem, or related in any way? ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [July 22, 2013, 7:20am UTC](https://community.cartalk.com/t/nissan-frontier-vibrates-going-uphill-p0400/80474/2 "2013-07-22T07:20:56Z")
It could be that with an EGR fault the ECM is trying to retard the timing due to a looming pre-ignition rattle and that is the cause of the misfire or surge. Given the 300k miles on the truck, a compression test should be done to make absolutely certain that you’re dealing with a good engine. A dropping cylinder could cause a problem like this also. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [July 22, 2013, 7:40am UTC](https://community.cartalk.com/t/nissan-frontier-vibrates-going-uphill-p0400/80474/3 "2013-07-22T07:40:49Z")
@nw2012 If your cat is plugged, your engine can’t breathe properly and you’ll have lousy power Just something to consider ---
**Author:** ![nw2012](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@nw2012](https://community.cartalk.com/u/nw2012)\ **Post date:** [July 22, 2013, 11:55pm UTC](https://community.cartalk.com/t/nissan-frontier-vibrates-going-uphill-p0400/80474/4 "2013-07-22T23:55:22Z")
Thank you, I’ll keep both of those in mind as I’m working on the truck.