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Throttle Cut-Out


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The last few days, I've been experiencing an odd momentary cut-out of the throttle...usually as I'm accelerating up to speed, the truck will act as though I lifted off the throttle, then stepped on it again. Ordinarily, it isn't a problem...unless I'm in the low split gear and have pre-selected the high split...when the throttle cuts out, the transmission tries to split, but the throttle comes back before the RPM's drop enough to catch the next gear and it revs up pretty high if I don't catch it quick enough and lift my foot off the throttle. The other day, it happened on my way up the coal pile...stayed in gear (split selector was in low & so was the transmission...so it wasn't trying to shift on me), but it jerked pretty hard on the drive line. It only lasts a split second...but it's enough to bug me...can't afford to tear anything up right now.

It's an '01 CH613, E-7 460 :wacko:

When approaching a 4-way stop, the vehicle with the biggest tires has the right of way!
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Check the flux-capacitor...which can lead to a bad muffler bearing and cause your 5th wheel to go flat...making for hard often times 'jerky' acceleration.

Ever wonder how a blind person knows when to stop wiping?

gallery_1977_876_21691.jpg

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The last few days, I've been experiencing an odd momentary cut-out of the throttle...usually as I'm accelerating up to speed, the truck will act as though I lifted off the throttle, then stepped on it again. Ordinarily, it isn't a problem...unless I'm in the low split gear and have pre-selected the high split...when the throttle cuts out, the transmission tries to split, but the throttle comes back before the RPM's drop enough to catch the next gear and it revs up pretty high if I don't catch it quick enough and lift my foot off the throttle. The other day, it happened on my way up the coal pile...stayed in gear (split selector was in low & so was the transmission...so it wasn't trying to shift on me), but it jerked pretty hard on the drive line. It only lasts a split second...but it's enough to bug me...can't afford to tear anything up right now.

It's an '01 CH613, E-7 460 :wacko:

another guy is having same problem, i think it is in electrical forum, just last week, fjh showed some stuff i never heard of.

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The last few days, I've been experiencing an odd momentary cut-out of the throttle...usually as I'm accelerating up to speed, the truck will act as though I lifted off the throttle, then stepped on it again. Ordinarily, it isn't a problem...unless I'm in the low split gear and have pre-selected the high split...when the throttle cuts out, the transmission tries to split, but the throttle comes back before the RPM's drop enough to catch the next gear and it revs up pretty high if I don't catch it quick enough and lift my foot off the throttle. The other day, it happened on my way up the coal pile...stayed in gear (split selector was in low & so was the transmission...so it wasn't trying to shift on me), but it jerked pretty hard on the drive line. It only lasts a split second...but it's enough to bug me...can't afford to tear anything up right now.

It's an '01 CH613, E-7 460 :wacko:

are you f@#kin with me.

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another guy is having same problem, i think it is in electrical forum, just last week, fjh showed some stuff i never heard of.

I read his post...mine ain't 'zactly like that. I get throttle response when I step on it...it's just that sometimes it cuts out momentarily. Most of the time it isn't really an issue, but every once in a while it'll happen at an inopportune time and I'd hate for it to wind up tearing something up when it happens.

I seem to remember when I bought the truck, there was something about some sort of throttle recall. I'm not sure if it was ever taken care of or not...it was such an old recall by the time I got the truck that nobody had the parts on hand to do it and they weren't sure if it would still be covered...or something like that. I'll probably have to take it in and have the shop look at it. :pat:

When approaching a 4-way stop, the vehicle with the biggest tires has the right of way!
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I wish I was....but I'm not. The problem is real. :wacko:

if you use a blow gun to clean the cab its worth checking, if you take out throttle assy. remove servo, you can turn it with a small screw driver, if there is a grit of sand in it you can hear it, most time brake cleaner will wash it out.

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The last few days, I've been experiencing an odd momentary cut-out of the throttle...usually as I'm accelerating up to speed, the truck will act as though I lifted off the throttle, then stepped on it again. Ordinarily, it isn't a problem...unless I'm in the low split gear and have pre-selected the high split...when the throttle cuts out, the transmission tries to split, but the throttle comes back before the RPM's drop enough to catch the next gear and it revs up pretty high if I don't catch it quick enough and lift my foot off the throttle. The other day, it happened on my way up the coal pile...stayed in gear (split selector was in low & so was the transmission...so it wasn't trying to shift on me), but it jerked pretty hard on the drive line. It only lasts a split second...but it's enough to bug me...can't afford to tear anything up right now.

It's an '01 CH613, E-7 460 :wacko:

There are a couple service bulletin's on stuff like that, one has to due with the engine position sensor on the timing cover and the other one has to do with the starter solinoid(on the starter). I'll see what I can find.

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There are a couple service bulletin's on stuff like that, one has to due with the engine position sensor on the timing cover and the other one has to do with the starter solinoid(on the starter). I'll see what I can find.

This is part of the service bulletin on the engine position sensor, we have see this happen without setting a code but only between the listed rpm's. The real fix is reshiming the sensor and installing a larger vibration damper. If it happens outside of the listed rpm's it could be something else. SB221037

Date: 05/24/06

Model: E-Tech™, ASET™

(Also applies to Mack Trucks Australia)

(Supersedes bulletin SB221037 dated 2/13/04)

Troubleshooting an Intermittent 3-4 (Engine Position Sensor) Fault Code

The electronic malfunction lamp can illuminate briefly, and a 3-4 fault code (engine position sensor) can be logged intermittently under the following conditions:

When the engine is accelerated progressively to high idle while the vehicle is in neutral

Under a hard pull (engine load greater than 75%) with an engine speed between 1,490–1625 rpm

The 3-4 fault code can be reproduced consistently when either of the above conditions are met. When the code is active, engine load and speed will drop suddenly, causing a brief but pronounced engine stumble.

Outside of the above mentioned operational conditions, engine load and speed ranges, the engine functions correctly with no active codes.

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This is part of the service bulletin on the engine position sensor, we have see this happen without setting a code but only between the listed rpm's. The real fix is reshiming the sensor and installing a larger vibration damper. If it happens outside of the listed rpm's it could be something else. SB221037

Date: 05/24/06

Model: E-Tech™, ASET™

(Also applies to Mack Trucks Australia)

(Supersedes bulletin SB221037 dated 2/13/04)

Troubleshooting an Intermittent 3-4 (Engine Position Sensor) Fault Code

The electronic malfunction lamp can illuminate briefly, and a 3-4 fault code (engine position sensor) can be logged intermittently under the following conditions:

When the engine is accelerated progressively to high idle while the vehicle is in neutral

Under a hard pull (engine load greater than 75%) with an engine speed between 1,490–1625 rpm

The 3-4 fault code can be reproduced consistently when either of the above conditions are met. When the code is active, engine load and speed will drop suddenly, causing a brief but pronounced engine stumble.

Outside of the above mentioned operational conditions, engine load and speed ranges, the engine functions correctly with no active codes.

I'll have to look at the print-out the Mack dealer gave me when I was there a week or so ago...they cleared the codes after printing everything off. I seem to remember something about a position sensor, and the 3-4 sounds downright familiar. They cleared 'em to see if any would come back (all were non-active) the next time I was in...definitely going to have 'em take a look.

The problem is, it is not a "consistent" stumble. Sometimes it happens, most of the time it does not. Might occur 3 to 5 times throughout the course of a day....sometimes more, sometimes less.

When approaching a 4-way stop, the vehicle with the biggest tires has the right of way!
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I'll have to look at the print-out the Mack dealer gave me when I was there a week or so ago...they cleared the codes after printing everything off. I seem to remember something about a position sensor, and the 3-4 sounds downright familiar. They cleared 'em to see if any would come back (all were non-active) the next time I was in...definitely going to have 'em take a look.

The problem is, it is not a "consistent" stumble. Sometimes it happens, most of the time it does not. Might occur 3 to 5 times throughout the course of a day....sometimes more, sometimes less.

Also see if you had a 9-2 code, that could be your starter solinoid.

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  • 3 months later...

Also see if you had a 9-2 code, that could be your starter solinoid.

had the same thing on a rb688s bad engine position sensor at the bell housing wire was rubbing on the clutch arm and causing a dead short and no accelleration,replaced the sensor and no problem since.

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I had one of my Fliner's with A series 60 Detroit do the exact same thing your 460 Mack is doing. The T.P.S under the accelerate pedal was bad, it seems my driver would wash the cab floor out with a water hose an thats a no no. Just a shot in the dark BULLHUSK

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well usually when its a sensor you'll throw a check engine light. and thats good because then its something you can have checked. but if i had to guess at it, id say either MAF (mass airflow) sensor or TPS (throttle position sensor). MAF detects air load entering the engine and therefore how much fuel to send, at wide open throttle youve got HUGE amounts of air entering and with a bad MAF your pump may not be getting the signal to keep up. TPS detects how far your throttle plate is open also to assist in measuring engine load. sometimes a certain spot burns out on the sensor put only a specific spot (its a potentiometer so it isnt necessarily "good" or "bad" it can have bad spots) burns out so when your throttle hits that section, your fuel may hiccup for a second while you race past it or just change throttle position. hard to tell without getting my hands on it. hope this helps.

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