ComancheGurl Posted November 8, 2010 Share Posted November 8, 2010 Its a 4.0 FI automatic tranny recent tune-up Starts fine when hot or cold. Hesitates,backfires,and sputters when accelerating in all gears. Any thoughts? Link to comment Share on other sites More sharing options...
Geonovast Posted November 8, 2010 Share Posted November 8, 2010 Sounds similar to when my fuel pump was going out in my 2.5. First thing I would do is check fuel pressure. Link to comment Share on other sites More sharing options...
Darren Posted November 9, 2010 Share Posted November 9, 2010 Wouldn't hurt to replace the fuel filter either, it's only like $5. Why did this get edited?! Link to comment Share on other sites More sharing options...
fiatslug87 Posted November 9, 2010 Share Posted November 9, 2010 Check the EGR valve. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted November 10, 2010 Share Posted November 10, 2010 O2 sensor could cause this too if its bad. My 2.5 would act like that sometimes while accelerating. I tried several things with the fuel system hoping to get it to go away, finally put a new O2 sensor in it just because, and as soon as I took it out on the street, it smoothed out and has been running great ever since. But like the other posters said, check the EGR valve for proper operation and closing ( it would cause a vacuum leak if it didnt close all the way), Vacuum lines, fuel pressure, fuel filter, check that the intake manifold bolts are tight... My 258 I had in My Grand Wagoneer would do this, tightening them regularly would keep things working properly. But I don't think the 4.0's had much of a problem with this. Good luck! Link to comment Share on other sites More sharing options...
carnuck Posted November 10, 2010 Share Posted November 10, 2010 Vacuum leak, clogged injector, water in the gas, slightly bent pushrod, bad dist cap (or incorrectly installed) Link to comment Share on other sites More sharing options...
ComancheGurl Posted November 28, 2010 Author Share Posted November 28, 2010 Took apart head and replaced a bent pushrod. Brand new gaskets on the thing. All vaccuum hoses have been replaced within the last 3 months. All injectors are firing. After installing new pushrod it still acts the same. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now