03 Ram 5.7 Hemi problems.

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Clelan

Clelan

Inferno Red Duster
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I'm not sure if this is the right place for this question, but here goes. I just replaced the head gaskets on my 03 5.7 hemi in a quad cab truck. Everything seemed to go very well until my first time going any distance with it. When warmed up to operating temp, it seems to have a misfire at around 1500 rpm and the Idle drops to about 500 rpm as well.

I went back through and checked all my wiring connections and everything is good. It shows no codes. When I first started it up in the shop it had P0113 - Intake air tempsensor circuit, voltage too high (It wasn't connected when I first fired it so that is why), and P0117 - Engine coolant temp sensor circuit, voltage too low. I cleared them and they never came back.

It always starts good, runs good at 2000 plus RPM but at warm idle and 1500 rpm cruise it seems to run rough and misfire.

I'm not too familiar with the newer stuff, so any guidance would be greatly appreciated.

Admins please move to a more appropriate board if necessary.

Cley
 
Correct me if I'm wrong, but that should have the dual plug heads with one plug having a coil pack and the other getting spark by a plug wire running from opposing cylinder? If a pair of wires are crossed, may do this and not throw a code. Also, the condition of the wires and the boots on the coil packs is something to look at. Had similar issue develop with my 05 Hemi Durango. Had a low rpm miss, but no codes. Threw plugs, wires, and boots on and we're good again.
 
It may have an O2 sensor that is sticking rich. The computer pulls fuel out trying to get to the O2 to read lean but it doesn't switch. You need a scan tool to look at the fuel trim and see what its doing.
 
.....................yup, I agree to read all the data, not just codes, and get someone that actually knows how to read and interipet the data not just someone that can look at it.......kim..
 
A38Valiant said:
Correct me if I'm wrong, but that should have the dual plug heads with one plug having a coil pack and the other getting spark by a plug wire running from opposing cylinder? If a pair of wires are crossed, may do this and not throw a code. Also, the condition of the wires and the boots on the coil packs is something to look at. Had similar issue develop with my 05 Hemi Durango. Had a low rpm miss, but no codes. Threw plugs, wires, and boots on and we're good again.
Click to expand...

Correct, the first few years they had that goofy cross plug wire sets, until they went to the dual coil on plug in 05 ish. The thinking being that if a coil fails...you don't have a complete cylinder failure, you only lose one plug, on two cylinders. Many prop airplane engines are like this.

anyways, alot of hemi swap guys that got stuck with the earlier coils just put these mini wires on them (see link below), to jump the coil to the cylinder it's actually mounted on. I also have seen truck guys use them. I'd say it's worth a shot for $45. If you do plugs, good luck on cylinder's 5 and 7. Complete pain. probably should have done them when you were doing the gaskets.

http://www.summitracing.com/parts/tay-72641/overview/make/dodge
They also have black and red, but they are 10 bucks more.
 
I just had the same problem with my 97 Ram with the 360. Almost identical to your story except mine shut off at every stop or when I left off the throttle to go around a turn. I ended up taking it to my buddies garage and this is what we eventually found. The coolant sensor was reading a different temp than the actual engine temp. It was saying overheat but engine heat was normal. Replaced the heat sensor and it is now back to normal and how it was running before the head gasket job.
 
Thanks for all the hints. If the snow and freezing rain screw off this weekend I'll hopefully get it sorted out.

Cley
 
If the spring breaks and the valve floats and lets a retainer go and drops the valve then it will barely run, but if the spring is just still broken but intact it might just intermittent misfire until it does let it go. If you catch it early it is a much less expensive fix.
Our 08 5.7 had a bad coil not firing one cylinder at all and you could hardly tell it was missing. By 2008 they don't cross the wires anymore so when a coil goes you don't get either plug firing in that cylinder. Luckily it did throw a code and $32 and 20 mins later it was fixed.
 
I agree with checking the coils and wires, if it runs poorly especially under load try this... Pop the hood at Nite when it's dark and spray the wires/coils down with a spray bottle full of water... If you see acrhing or sparking when it's wet, it's probably doing the same hot or under load. replace the bad stuff... It also may be a good plan to just swap a O2 sensor. I know guys have had cam and crank sensor problems, but I wouldn't expect a intermittent problem with that...

Why did you do head gaskets? Did it get really hot, if so any sensor could be suspect from heat...
 
Tech857 said:
It may have an O2 sensor that is sticking rich. The computer pulls fuel out trying to get to the O2 to read lean but it doesn't switch. You need a scan tool to look at the fuel trim and see what its doing.
Click to expand...

The cheap way to get a scan tool is to download the torque app (basic app is free, full blown app is $4.99) from the Google Play Store. then buy a $7 bluetooth dongle from Amazon, I believe number for the dongle is Elm 327. it does a lot of other things as well.
 
I did the head gaskets because I could not get it to blow hot through the heater in the winter time. I did fix up the heater box first and replaced the broken parts there (What a PITA that was) but it still would not blow hot. I changed the thermostat twice and still no difference. A buddy of mine who owns a shop near me suggested the head gaskets would be all that was left so I did that.

Not only did it not fix the problem, now it runs like ****. I am now going through the wiring connections hoping to find something loose but no luck. I just ohmed out all the plug wires and they seem fine. I guess plugs are the next thing ill check.

I should be putting my Duster together and I'm working on this damn truck. It's frustrating as hell.

Cley
 
I'm hesitant to spend money on O2 sensors since the ones in there aren't very old, and this all started when I did the head job.

Cley
 
I forgot to update this. The push rod for #5 cylinder was not in place. Fixed that and itv runs like a dream.

Cley
 
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