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Engine stumbles

mossyoak71
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mossyoak71

mossyoak71

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The info in my signature is up to date, with that in mind, I have an issue with the engine stumbling. No matter if I'm in the 0 setting or 3 setting it will stumble on acceleration from around 55 mph. When if you slam the throttle. In the stock setting it doesn't do it as bad. Feels like a miss. Now if I place the quad in 4 or 5, it will stumble until it kicks the wire tap in and then you can feel the miss ever so slightly. There are no codes, I have changed out the injector lines all 6 and torqued them down 28lbft. I was thinking it was the old lines, maybe they were just over torqued, no luck. This issue is really prevalent when towing. Now with no codes, could it still be the VP? Also I have noticed that my pressure gauge that I have hooked to the fass is bouncing. Still holding 20psi at the fuel pump, but pulsing. Just confused on where to go. Don't want to start throwing money at it. The VP is 14 months old and has 45k miles on it now. Any advice appreciated, thanks in advance.

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mossyoak71

mossyoak71

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2 hours ago, Dieselfuture said:

I had exact same issue with mine about 4,5 years ago. A set of new injectors made it a lot better, and then rebuilding my alternator did the rest. 

Do you have a needle valve on your pressure gauge

No needle valve. The injectors are DAP and only have 25k miles on them. The gauge never bounced until this issue started. 

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Mopar1973Man

Mopar1973Man

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13 hours ago, mossyoak71 said:

The injectors are DAP and only have 25k miles on them.

 

You might want to talk to @pepsi71ocean he only had 31k miles on his DAP injectors and went from 300 bar pop pressure down to 280 bar pop pressure. Now sent them back and had the re-popped and set a bit higher and problems are gone for him. 

 

I'm closing in on close to 100k miles on my injectors I'm going to send my old stocker injectors in for new nozzles nad set the pop tad higher from stock 310 bar. When they settle in they should be close the 310 bar mark. 

 

Pop pressure make a huge difference in the quality of the spray quality and droplet size of the fuel. The finer the droplets the easier it heats and goes BANG quicker. If your pop pressure is off or low then the droplets get bigger and harder to heat quick enough to make them go BANG. Some of that fuel will sizzle and create smoke when the pop pressure is too low. 

 

I would just have those injectors checked and re-popped if too low.

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mossyoak71

mossyoak71

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1 minute ago, Mopar1973Man said:

 

You might want to talk to @pepsi71ocean he only had 31k miles on his DAP injectors and went from 300 bar pop pressure down to 280 bar pop pressure. Now sent them back and had the re-popped and set a bit higher and problems are gone for him. 

 

I'm closing in on close to 100k miles on my injectors I'm going to send my old stocker injectors in for new nozzles nad set the pop tad higher from stock 310 bar. When they settle in they should be close the 310 bar mark. 

 

Pop pressure make a huge difference in the quality of the spray quality and droplet size of the fuel. The finer the droplets the easier it heats and goes BANG quicker. If your pop pressure is off or low then the droplets get bigger and harder to heat quick enough to make them go BANG. Some of that fuel will sizzle and create smoke when the pop pressure is too low. 

 

I would just have those injectors checked and re-popped if too low.

Thanks and guess I'll put the other ones I have in and send them off. I'll let you know

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pepsi71ocean

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On 10/30/2018 at 8:05 PM, mossyoak71 said:

No needle valve. The injectors are DAP and only have 25k miles on them. The gauge never bounced until this issue started. 


being you have 250HP injectors I would look into the pop pressure. Being your Injectors are so high i would consider popping them into the 330bar range. For me the black smoke and hesitation i had was complete gone. I popped mine to 322bar from a mean avg of 280 bar. that's a 42 bar increase.

I would at the least get them popped.

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mossyoak71

mossyoak71

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7 hours ago, pepsi71ocean said:


being you have 250HP injectors I would look into the pop pressure. Being your Injectors are so high i would consider popping them into the 330bar range. For me the black smoke and hesitation i had was complete gone. I popped mine to 322bar from a mean avg of 280 bar. that's a 42 bar increase.

I would at the least get them popped.

Thanks, I'm putting in my other injectors tomorrow and sending these off to be checked and reset.

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pepsi71ocean

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6 hours ago, Mopar1973Man said:

293 bar (4,250 PSI) is the bottom end of the stock pop pressure. 310 bar (4,500 PSI) is stock injector pop pressure. 

 

 

...or 602 PSI increase on spray at idle.

 

Which is why they are clean as ever, and this truck idles so smoooooooooooooth.

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mossyoak71

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On 10/31/2018 at 9:38 AM, Mopar1973Man said:

 

Let me know if the problem continues with the other injectors. If so this the injectors are not the cause. 

Installed the DDP125's I had laying around and they are running ok. Although they are very Smokey and laggy. Sending the others off today.

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Mopar1973Man

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On 11/7/2018 at 5:00 AM, Marcus2000monster said:

Any reason I couldn’t bump my pressures up to get this smooth idle and reduced smoke? 

 

1 hour ago, pepsi71ocean said:

Because you need to pop them mechanically to a higher pop pressure.

 

 

Bingo. The Injection pump automatically raises pressure as you throttle up. Now if the injector pop pressure is too low then the fuel mist is much larger droplets and then it tends to smoke more than burn because there isn't enough time to heat the large fuel droplets to go BANG! So when you raise the pop pressure back up the 310 to 320 bar realm the droplets are much smaller and all the fuel is burnt like its meant too and the smoke is minimized.

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Marcus2000monster

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On 11/10/2018 at 9:20 AM, pepsi71ocean said:


Because you need to pop them mechanically to a higher pop pressure.

 

On 11/10/2018 at 10:56 AM, Mopar1973Man said:

 

 

Bingo. The Injection pump automatically raises pressure as you throttle up. Now if the injector pop pressure is too low then the fuel mist is much larger droplets and then it tends to smoke more than burn because there isn't enough time to heat the large fuel droplets to go BANG! So when you raise the pop pressure back up the 310 to 320 bar realm the droplets are much smaller and all the fuel is burnt like its meant too and the smoke is minimized.

I realize I have to send them in to dap to get repopped I’m just wondering if they’re is any reason I couldn’t do it being I have different mods than Pepsi? 

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Marcus2000monster

Marcus2000monster

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Mike I think we’re off track. @pepsi71ocean mentioned that he raised his pop pressures to 322 and had a smoother idle and less smoke. I was just wondering if they’re was any reason I couldn’t do the same thing and set mine at 320 or so being mine are 75s and his were 100s. I would love decreased smoke and smoother idle. 

 

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