Engine hesitation/sputtering

NATHANIEL FIELDS

MEMBER
1999 DODGE RAM
3.9L
V6
2WD
AUTOMATIC
108,000 MILES

Typically from a stop the engine will hesitate to go and or sputter and then go real fast. I have a brand new rebuilt engine with only 500 miles. I checked the compression on it and it is well. It has new spark plugs, spark plug wires, coil pack, fuel injectors, and all brand new throttle body sensors and which I checked on a data stream to make sure they were working properly.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

Can I ask which rebuilder did the engine? also does the engine seem to have the same power as the old engine? It sounds like you may have a bad MAP sensor. this guide can help us fix it with the MAP sensor location in the diagrams below:

https://www.2carpros.com/articles/engine-hesitates

We should check the fuel pressure as well and check the fuel filter.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

and

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

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Tuesday, May 25th, 2021 AT 10:30 AM

NATHANIEL FIELDS

MEMBER
3 POSTS

The rebuilder was AutoZone this is my 2nd one the first one had low compression on 2 4 and 6. So I made sure to check compression on this Ken and it is good. The fuel pressure is good.I recently put a new MAP sensor on it I tried to tell if it was good with a OB2 reader but couldn’t tell.I’ll leave that video below.

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Tuesday, May 25th, 2021 AT 10:47 AM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

With those reading it seems like we may have a bad cylinder. let's remove the spark plugs and take note of the color. We are looking for the plug that is different from the rest. Then let's do a compression test. this guide can help:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please let us know what you find. We are interested to see what it is.

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Wednesday, May 26th, 2021 AT 10:41 AM

NATHANIEL FIELDS

MEMBER
3 POSTS

I checked the spark plugs and compression already it’s all good.

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Wednesday, May 26th, 2021 AT 11:30 AM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

How did the spark plugs look was one dark or black? This can mean a bad injector. Also does it have a new MAP sensor? let's check for vacuum leaks.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know.