• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

"Stutters" at 1/2 throttle/uphill/getting up to speed ['84 V6 2.8L]

firefight343

NAXJA Forum User
Short Version: '84 V6 carb'd 2.8; Tf904; NP207. Cuts out/stutters uphill/first start/getting up to speed/highway driving. Changed: Fuel & air filters, water pump, brand/grade of gas. Have not changed: wires, cap & rotor. Has gotten worse after timing change (coincidence?). Feels fuel related. TPS, fuel system, fuel pump???? I have no idea.

Detailed (TMI) Version: 1984 v6 2.8L, with a TF904 and NP207; 3.5-4" of lift; ~168K miles

I first started noticing the problem on the highway after longer drives (30+ mins), at half throttle...the XJ would stutter/cut in and out until i changed the pressure on my gas pedal. Unfortunately I dont have a tach (so i cant tell you if its RPM specific). The problem's kind of evolved, getting worse and happening more frequently. It has been cutting out when I put it in any of the following situations:

1) getting up to speed on the highway (or even small increments in speed i.e. passing someone)

2) going from a dead stop/slow speed up-hill (like on an over-pass)

3) when i frist start it up in the morning, it turns over fine, keeps a good idle in Park, Neutral, and Drive, but once i GIVE it gas in Drive it dies...but it doesnt repeat this....it only does it once, and on the second start it fires up, and drives...but stutters until it warms up

Recently I've put a lot of miles into the thing. I bought it off Craigslist a little over 2 months ago, and have since been attempting to maintain it religiously, however the Jeep overall, wasnt in bad shape at all when i bought it (and i dont mean "relatively" for the year). To give you an idea of how much ive been driving it: bought it at the beginning of Feb. 2007 with 164,800 miles, and at present have a little over 168K on it (mostly freeway miles).

I have changed the oil twice in that period (with Valvoline High Mileage), varied the brands/grades of gas I have put in it (dont know if it matters, but 76 doesnt work to well with it), and have changed the fuel and air filter. It over-heated due to a busted water pump in late Feb. but I have replaced that with a reman'd pump. I played with the timing to get it to pass smog (down 4, to 16+), and have not since put i back to its original timing (20+). The problem started getting worse after the timing change (coincidence?), and after I stupidly put in gas treatment for 3 consecutive tanks (I really wanted a clean system...and wasnt aware that I might loosen 'stuff' thats not supposed to be loosened). I have yet to change wires, cap & rotor.

My interpretation:
Im in no way a pro...but becuase of financial circumstances (18 year old, self-sustaining, college kid) I do ALL of the work on my jeep...hell if it werent for my Jeep I wouldnt know my ass from my elbow when it comes to cars. It doesnt feel engine related, i think it might be a fuel system issue because it almost feels as though fuel is being given in bursts (or drops in some cases... :( ). Ive talked to various buddies (all mechanically inclined) and have gotten everything from 'gas evaporating before reching the cumbustion chamber' to 'busted TPS.' Most of the posts regarding 'surging' or 'cutting out' on NAXJA are I6 4.0L related...I didnt know if the 'fixes' would be any different on my carbourated 2.8L

Any ideas? Sorry if there's too much info, Im just trying to help people help me, the Jeep till runs, but, it being my ONLY car, i need it to last at least through college! Thanks in advance, Ed
 
Last edited:
Back
Top