Engine failing to run

DEJONG.MUSTARD

MEMBER
2001 DODGE RAM
5.9L
V8
4WD
AUTOMATIC
190,000 MILES

I just rebuilt my transmission and I went to start up my truck and it started up perfectly after a little messing around with the starter. While it was running there was a weird sound and I found out it was the brake power booster vacuum line that was hissing because it was unhooked. I then put it back in and the engine quit. When the vacuum line is in I can still start my truck but has a very low idle and if I give it gas it stalls. But if the hose is unhooked (which I know is incorrect) then engine runs perfectly normal besides the hissing of the vacuum hose.

5 Replies

CARADIODOC

MECHANIC
33,871 POSTS

Most likely you had the battery disconnected to remove the transmission. As a result, the Engine Computer lost its memory. All the fuel trim data and sensor values will be relearned without you even noticing, except for "minimum throttle". That requires a specific set of conditions to be met for that relearn to take place. Until then, idle speed will be too low, the engine may not start unless you hold the accelerator pedal down 1/4", and it will tend to stall at stop signs.

To meet the conditions needed for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

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Friday, October 9th, 2020 AT 7:57 PM

DEJONG.MUSTARD

MEMBER
2 POSTS

Yes, the battery was disconnected. But I am not able to press the gas at all without the engine shutting off. Here is a video of what happens when I start my truck and press the gas:

Video (Click to make bigger)

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Saturday, October 10th, 2020 AT 12:27 PM

CARADIODOC

MECHANIC
33,871 POSTS

I hear the engine revving up. It sounds like it stalled when you released the accelerator pedal. What happens if you hold the pedal down 1/4" steady?

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Saturday, October 10th, 2020 AT 6:05 PM

DEJONG.MUSTARD

MEMBER
2 POSTS

If I hold it down steady it runs and revs up and when I release it’s really close to shutting off but keeps running. As soon as I put it in reverse and press the gas then it shuts off.

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Sunday, October 11th, 2020 AT 1:46 PM

CARADIODOC

MECHANIC
33,871 POSTS

Go out and drive it. Use two feet if necessary. At the dealership we either took customers' cars for a short test drive to relearn minimum throttle, or we explained the need to do so.