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Engine idle problem 5.9

3K views 20 replies 6 participants last post by  Jmw132001 
#1 · (Edited)
Well here I am back again with another engine idle problem. But this time around, it has to be something else causing it. My truck engine had 244,300 original miles on it and the heads cracked, so I got another used engine (100k miles).

Now, for the long story. Prior to this "new" engine, i had idle issues with my truck. If I try to let it idle, it may idle for a while and then all of a sudden it would start dumping fuel into the engine and bog it down to where sometimes it may catch itself, other times it may die. So, here is what all I had done.

New tps
New IAC motor
New tune up on it
New 02 sensor
finally cut the cat off because thought it may be a back pressure issue, still did not work.

Now, the only thing they used off my original engine when putting this "new" engine into my truck was the fan, alternator, power steering pump, and top breather housing with the filter. otherwise it is all new injectors, iac, tps, you name it and it is still doing it. Anybody have a clue what in the world this is?



1998 dodge ram 1500 qc sport 360 4x4



Here is the youtube video of the live frame data from the sensors. Sorry it is long, but thought it may help. I believe it is around the 8-9 minute mark somewhere in their is when it starts bogging down and doing the rough idle and the smell of fuel.

https://www.youtube.com/watch?v=nuCVQhPWA8Q&feature=youtu.be
 
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#2 ·
Can't see video, What is the temp reading? If it's not reading correctly the pcm will give it more fuel than it needs at operating temp. Are you saying that the "new" items where put on the new motor? Even at 100K you should have cleaned the ports on the throttle body. Are you getting any codes either with the old motor or this one?
 
#3 ·
No codes on either of the engines. Throttle body was cleaned and all that good stuff.

Highest temp it was at while it started doing it was 203F

Minimum was 105.8F (somewhat of a cold start. had run it earlier in the day.)

average was 176F

Max 203F Highest temp was when it was acting up from what I can tell


and yes all the "new" items were put onto the "new" motor. So, it is not the same sensors I had on my old engine, completely different ones, yet same issue.
 
#4 ·
As usual for 2G, batt and charging system needs to be almost perfect or it can have strange running issues.
..Thinking a rich condition may be a bad MAP sensor or if it's short elbow/hose is leaking (common for elbow to rot/crack/leak).
..Being both engines had the problem, would test fuel pressure to rule out possible issues.
 
#5 ·
Alternator tested out fine. Battery also tested fine. Had checked fuel pressure and it showed even when it was doing the rough idle that pressure was steady. :giveup:
 
#8 ·
They done a voltage check and supposedly a load test on it and it all checked out. Battery is probably 5 years old. Not too sure. as for the live data, you can see the different changes but what they really mean I do not know. If I rev the engine up it will eventually come out of it once it gets all the excess fuel out of the engine. But not long and it will return. I also noticed today when I started it and went to take off (not even warmed up) I went about 1500ft and stopped at mailbox. Went to take off and it was like the engine was not getting any power. I had my foot on the pedal half way and she would just barely do 1500rpm and then all of a sudden, BAM it kicked in and hauled butt. Not making sense to me.

I believe the 02 sensor was a bosch. But I have slept since then
 
#9 ·
I just got done doing a battery load test. The battery is a 930CCA. Results come out at 815CCA
 
#10 ·
5 years is usually the lifespan of a battery. Not sure what kind of load test you did but what i was talking about it a hand held one that you put the leads on the terminals and press on the load button for a few seconds. Then the meter will drop to what condition it's in.




I don't think the battery is the issue. What is the fuel pressure reading? You need to keep it hooked up while it acts up.
I had my foot on the pedal half way and she would just barely do 1500rpm and then all of a sudden, BAM it kicked in and hauled butt.
This seems to be from a pressure loss then it goes back up. Watch the pressure gauge i think it will confirm my suspicion. If you got 244K on the original fuel pump you are lucky. I did mine a 168K and the motor commutator was down to nothing.

 
#11 ·
5 years is usually the lifespan of a battery. Not sure what kind of load test you did but what i was talking about it a hand held one that you put the leads on the terminals and press on the load button for a few seconds. Then the meter will drop to what condition it's in.




I don't think the battery is the issue. What is the fuel pressure reading? You need to keep it hooked up while it acts up.


This seems to be from a pressure loss then it goes back up. Watch the pressure gauge i think it will confirm my suspicion. If you got 244K on the original fuel pump you are lucky. I did mine a 168K and the motor commutator was down to nothing.



Yeah, that is the tester we used and she still showed good. Also tried a different load tester and same results, so I am fairly sure battery is not a problem. (took battery out of car and tried it as well, same thing).

So now, I am sadly leaning toward fuel pump or the pressure regulator, because now that I think about it, when we had the gauge hooked up it was showing in the 50's, but it was bouncing. Which if memory serves me right, if the gauge is bouncing then it means your regulator is going bad. I could be wrong on that one. Might be why my MPG has been total cr4p for a while now.
 
#14 ·
you may already know the fuel pump job for all i know . if you dont this guys vid showed me how to releasse the wire harness and fuel line fittings on top of the pump which are a pain if you dont know exact way

many guys say its best to lift bed off to replace pump , could be i dont know

but i do know from doing it from underneath hardest part is releasing the fittings on top of pump so you can lower tank because you can only lower tank like 8'' before fuel line and wiring gets tight , then you must reach up from drivers side between frame and tank getting hand up on top of tank to release fittings . im average size person and it was a pita contorting arm up into there , a bigger person probably couldnt do it . but reason im writing this is after doing it i thought it woulda been easier if i removed the heat sheild on passenger side of fuel tank which is only like 3 plastic ribbed fittings that the sheilf slides right off of then get at top of pump from passenger side .
its a easy job if can get the fittings on pump disconnectedquickly

vid -

https://www.youtube.com/watch?v=LKZTItRyVzc
 
#15 ·
I mean I hope it is not the pump/regulator, but it seems to be coming down to that. I just wish their was a way to make sure 100% before I dump money into it that I do not have. Also, I can get the whole assembly cheaper from rockauto.
 
#18 ·
is it just me or has this site went downhill? Seems like a ton of ad's on the pages and the pages want to keep skipping up and down. Can't even read anything and don't matter what browser I use....
 
#20 ·
ok, so I am just now able to see everyone's responses. The only responses I was able to see were via email. I had to switch to the "classic" skin for the forum in order for it to work........... Anyway, I am leaning toward the fuel regulator/pump, but like i said just wanted to rule anything else out for the fact of money issues. Also, what was the easiest ways for you all to remove your pump? I have seen jacking bed up, dropping tank, pulling bed back so far. So many different ways.
 
#21 ·
Figured I would give an update on this. I never did get around to changing the fuel pump, but I did get ticked off enough that I unplugged both of the 02 sensors and the problem went away. I have a check engine light of course, but I don't have any problems with it idling now.
 
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