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Auto's are for pansies
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Discussion Starter #1
My truck has two things it does that I think is slightly odd, and I was wondering if all manuals do it, or if it's the tunes, or what.

1) With the 250 tune, in first gear, I run the RPM's up to about 2500 on a side road to help warm the engine on cold mornings. Sometimes, I push the gas above 2500, say around 2700, and no matter how much I let off the gas from that point, the RPM's keep going up, until I take my foot all the way off, resulting in a jolting deceleration. It's like the truck really wants to go above 2700. I have feathered the gas at that threshold RPM before, and it still climbs at a pretty fast pace. It does it in second too, but not near as bad.

2) The trucks are resistant to stall. If you idle in first gear, the truck will stay at 750 RPM's no matter what. I've tested it on hills without hitting the gas. I've tested it with a 3k trailer without hitting the gas. Now, I learned a trick the other day, if you hold the brakes to keep the RPM's between 500-600, the engine will fight back (trying to get back to 750 again), and with my 250 tune, it dumps smoke like a train in this phase. It works in all gears, but best in second gear, so you're going about 4 mph just flooding the road with smoke, like an insect repellent truck. If you let off the brakes and let it get back to 750, it acts fine when you hit the clutch. But if you just hit the clutch when you're below 750, the RPM's jump to over 1200 and waits a few seconds before coming down. I assume that's the engine's reaction to going from one second trying to boost speed and the next not having any resistance. I know the smoke is tune related, but the jump when the clutch is hit is what I'm wondering about.
 

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.

2) The trucks are resistant to stall. If you idle in first gear, the truck will stay at 750 RPM's no matter what. I've tested it on hills without hitting the gas. I've tested it with a 3k trailer without hitting the gas. Now, I learned a trick the other day, if you hold the brakes to keep the RPM's between 500-600, the engine will fight back (trying to get back to 750 again), and with my 250 tune, it dumps smoke like a train in this phase. It works in all gears, but best in second gear, so you're going about 4 mph just flooding the road with smoke, like an insect repellent truck. If you let off the brakes and let it get back to 750, it acts fine when you hit the clutch. But if you just hit the clutch when you're below 750, the RPM's jump to over 1200 and waits a few seconds before coming down. I assume that's the engine's reaction to going from one second trying to boost speed and the next not having any resistance. I know the smoke is tune related, but the jump when the clutch is hit is what I'm wondering about.
video please :thumbsup
 

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Whipersnapper
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681 Posts
I noticed the same thing when I was running the RPMs up al of a sudden it would just take off and had to almost completely let off. I am running the 210 but from what I can remember it did it stock too.

Yes I haven't been able to stall the truck. A weird thing is that the clutch sounds so bad I can't help but push in the clutch.
 

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I like beer.
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...It works in all gears, but best in second gear, so you're going about 4 mph just flooding the road with smoke, like an insect repellent truck....
insect repellant truck? i wanna see vids :thumbsup :haha
 

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Yep my 6spd does the same thing. I only run the 210 as well because I can get that to slip my clutch with out trying that hard. If I want to floor it all the time I have to run the 150??

It is a very weird to drive this 6spd unlike any other diesel I have owned. I love it tuned though very easy to drive no lag etc!! Mine doesn't smoke a ton but again I only run up to the 210.

Yours sounds normal willie!
 

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* * * * *
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246 Posts
Yep, mine does it too.

p.s. Thread Hi-jack:

Since SW has got some 6-speeder gathered up,
I can't pass up this opportunity ... :happymugs

Can someone please tell me where the clutch master
cylinder is? It's not anywhere near my brake master
cylinder, or anywhere else I can see, for that matter.
A picture of the darn thing would be great :)
 

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Auto's are for pansies
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2,117 Posts
Discussion Starter #7
Dang it Rod, you always gotta hi-jack. We were really getting somewhere!

Y'all don't have those trucks drive down your street and spray for mosquitos? They look like this:


I took a video this morning, but it wasn't that good, so I'll try again tonight.
 

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Dang it Rod, you always gotta hi-jack. We were really getting somewhere!

Y'all don't have those trucks drive down your street and spray for mosquitos? They look like this:


I took a video this morning, but it wasn't that good, so I'll try again tonight.
That looks kinda scary to me ... I don't think I'd want to be breathing
that stuff ... if the west nile doesn't get us, that spray surely will :0
( That guy on the bike on the right is probably coughing up blood
about now ... :throwup

Sorry about the high jack ... couldn't resist ... you know this clutch
master cylinder thing is driving me batty ... while looking for it some
more last night from underneath the truck, I noticed that I'm leaking
brake fluid from my brake master cylinder ... and I have a very small
seep of oil coming from the back of the engine above the oil pan :( And,
appearently I'm missing a clutch master cylinder ... but the good
thing is that I can't stall my engine :)
 

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my 7.3 does this and it's an auto, if i'm cruising in 3rd and i have the TC locked (manual lockup) and slow down to under ~15mph it goes below it's normal idle and bucks like crazy and pours smoke, i learned this by accident when i forgot to unlock the TC one day
 

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Mine does both of the things you described willie, but the only time ive noticed it is on the 250.
 

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my 7.3 does this and it's an auto, if i'm cruising in 3rd and i have the TC locked (manual lockup) and slow down to under ~15mph it goes below it's normal idle and bucks like crazy and pours smoke, i learned this by accident when i forgot to unlock the TC one day
This is becuase you have locked the thing solid just like a clutch with the lockup switch, basically the same as coming to a stop without pushing in the clutch on a manual,I dont think what willie decribed would be the same scenerio.
 

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My Stick shift is stock but I have never noticed any wierdness like that at all.... It is consistent like a stick should be.... Good topic! Maybe there will be a fix for this before I am ready to buy.... Thanks.
 

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This is becuase you have locked the thing solid just like a clutch with the lockup switch, basically the same as coming to a stop without pushing in the clutch on a manual,I dont think what willie decribed would be the same scenerio.
yup that's exactly what my lockup switch is doing
and that's what i thought he was describing, being in a certain gear and getting down to a speed below idle and having the truck try to stay at idle
 

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Auto's are for pansies
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Discussion Starter #14
This is becuase you have locked the thing solid just like a clutch with the lockup switch, basically the same as coming to a stop without pushing in the clutch on a manual,I dont think what willie decribed would be the same scenerio.
No, that's how you do it. It's like coming to a stop without the clutch in, but instead of stalling/stopping, keep moving under idle RPM's. That's what I do with the brakes - make it creep with the brakes on under 600 RPM's. The lower the RPM's, the more it smokes.

My Stick shift is stock but I have never noticed any wierdness like that at all.... It is consistent like a stick should be.... Good topic! Maybe there will be a fix for this before I am ready to buy.... Thanks.
Since you're still stock, can you do me a favor?
1) Move the truck idling in second gear, clutch let out, and start applying the brakes until the RPM's get below 600, then just hit the clutch. Tell me if the RPM's jump over 1200 or so, and how long it stays high like that.
2) Drive in first gear, get the RPM's above 2600 or so, and keep climbing slowly. Tell me if the truck tries to take off faster on its own or if it just does what your foot tells you to do.

I sure would appreciate it! :happymugs

PS, video still to come. :D
 
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