2004 Ram 1500 5.7 Hemi drive ability issue

[Nelsen2004]

Hello,
I am new to the forum but need some help with a 2004 Dodge Ram 1500 5.7 Hemi only 66,000 miles on it. The issue is this, the vehicle starts and runs fine, great power on acceleration everything is fine. Once the vehicle warms up fully lets say 45 minutes of driving. If i try to pass someone or accelerate for a hill it falls flat on its face. If you give it a lot of gas pedal it will start to buck. Interestingly if I slip it into neutral, shut it off and restart while rolling the problem goes away for a bit. I have replaced the plugs, coils, wires, cleaned mass airflow sensor and throttle body. The truck has a new fuel pump which i put in when i replaced the fuel tank because the 7lugs rusted off the hold down ring. With a Scan tool the O2 sensors are within range as are the crank sensor, TPS and purge valve. There are no trouble codes stored and i logged a couple driving sessions but nothing seemed out of the ordinary. Any help would be appreciated !!!

 

[Redfisher1974]

Does tranny downshift?

 

[Nelsen2004]

Yes it will down shift then starts to buck. if i force a down shift it is worse, revs then stops then revs etc.

 

[04fxdwgi]

Check the fuel rail pressure to see if the new pump is up to the task.

 

[Nelsen2004]

Thanks that was my next step! the only odd thing is if i turn the vehicle off while rolling and restart it works fine for a time. its like something is resetting. Ill let you know what i find with the fuel pressure testing.

 

[Nelsen2004]

Tested warm engine fuel rail pressure . Found it to hold at 60psi under load or unloaded. Static pressure after shut off held 56psi for ten minutes. This is well within factory specs. I’d love to try a driving test hooked up to meter but hoses are not long enough. Might try to make longer hoses.

Any other thoughts are welcome, this one is puzzling!

 

[Nelsen2004]

I have another question, i am working on testing for an exhaust restriction as a possible cause. I have a scan tool and it gives me good data but it is not actual Vacuum values. It gives absolute values that range from 0 to 30, 30 being the barometric pressure engine off. running i am getting a reading of 10 and cruising i am getting between 19 and 23 as a value. on heavy acceleration it goes to 30. What i want to do is convert these values into vacuum numbers. Any thoughts? where can i find a formula? Im going to see if i can find my old school vacuum gauge this weekend.

 

[Nelsen2004]

So no exhaust restriction found so onto more testing. Could my new fuel pump be bad?

 

[Nelsen2004]

Just thought I would close out this post thread with the solution to the issue. The new fuel pump i installed was the issue. It had a crack in the internal line. Replaced pump and it is running awesome. Never trust a new part is guess.

 

[jacoblane216]

I’ve been having some weird problems too that I can’t figure out and haven’t gotten any replies on previous posts I’ve made so gonna try here. It’s a 2004 Ram 5.7 rwd, I’ve been having surging issues since I got this thing years ago after totaling my pristine white one, it’s weird it’ll surge for like the first 10 minutes of driving and if I’m going slower sometimes it’ll just completely die, after the 10 or so minutes mark it’s absolutely perfect with no problems. I’ve already tried 2 reman pcm’s reprogrammed for my truck, cam and crank sensors, o2 sensors, map and iat sensors, trans speed sensors input and output, trans pressure transducer sensor, and 2 different throttle bodies. All the named sensors except o2 sensors are new from ngk, the o2 sensors came off a 08-12 charger(they’re the exact same sensors) for similar reasons but didn’t change anything so theres nothing wrong with the o2 sensors, 1 pcm was from flagship1 and the other was from all computer resources or whatever their name is(it fixed my white truck). I remember having the scanner hooked up while trying to check tps as well as trying to see if it was missing at all a while ago and it wasn’t missing a lick and tps was functioning fine. That tells me that surely it has to be electrical since it seems to figure it out and run perfect after about 10 minutes, and if you simply cut the truck off and back on it’s running like garbage again restarting the learning process of whatever the hell is wrong. Hopefully someone has unfortunately had the same issue or has the answer cause I can’t take it anymore. The engine itself actually came out of my white truck so that also makes me believe that it has something to do with the bee truck as a roller like I bought it instead of engine related. The things I know for a fact it needs is a cluster and maybe a bcm, is there any random possibility that either of those could be the problem even though unlikely? Also what about the TIPM and FCM, my mothers 12 ram was fried from a lightning, I know because I was less then 50 feet away when it happened, I jumped higher than Willie Nelson gets daily it scared the hell out of me, anyway insurance ended up paying over 5k to have it fixed and among the problems was a TIPM that is said to cause similar issues. Once again sorry for my novel I just wrote but I'm sick of this never ending problem Thanks in advance for any help whatsoever PLEASE.

 

[NCRaineman]

Have you considered the possibility of a vacuum leak somewhere? Some small gap that leaks when cold, causing the engine to lean out and run like garbage, but once she warms up and things expand with the heat it seals and *magic* works just fine.

If you can get the truck to idle when cold have someone spritz starter fluid or parts cleaner around the top of the engine. If it revs up you know you've got a leak and that combustible fluid is getting pulled into the engine.

 

[jacoblane216]

I ruled out that possibility because it will finally run good then if you stop and cut the key off and crank it right back it does it all over again not giving anything time to shrink or expand from temperatures. It’s gotta be electrical but just don’t know what it could be at this point