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Douggy
New Member
2 Posts |
 Posted - 08/16/2018 : 9:28:10 PM
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Hi all, looking to get some expert opinions....
I have a 2000 3800 international, 8 row bus, DT466e, attached to a AT545. 137K on engine, just recently serviced by a shop. Bus sat for one year unused. Only driven it about ten miles so far because the shifting is far from smooth%
The bus shifts somewhat hard into gear, going up and down, but feels very jerky, like she is never happy in one gear or another. As soon as I let of the gas, she downshifts, lurching me forward, and probably scaring the willies out of any driver behind.Nothing is remotely smooth about driving her.
Since the bus is new to me, I am still trying to work out if the jerky up and down shifting is me getting used to driving this bus, OR, if there is an issue with the transmission.
A few possible issues I see pop up when researching what could cause the effect I am feeling are (1) stuck governor, (2) modulator and modulator wires to the AT545, and (3) valve body issue.
I did a bit of digging and experimenting…..
What I did was hook up a 12V light bulb to the modulator input wiring, and played with the accelerator pedal.
I get no 12v signal when the accelerator pedal is not touched – which is what I expected.
But I notice I get a 12V signal once the accelerator pedal is just barely touched – I’d say way less than 10% pressed down.....just off idle, basically.
Everything I read mentioned that a 12v signal to the modulator should not occur until around 40-60% travel on the accelerator pedal – yet I am getting mine at waaay less than 10% pedal travel.
So, with the 12V signal going on early, is this a faulty relay,
(If there is one in this circuit) or a faulty switch on the accelerator pedal mechanism??......
any input from anyone is greatly appreciated!
cheers, Douggy |
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kummins
Active Member
41 Posts |
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Black Smoke Customs
New Member
USA
4 Posts |
Posted - 08/22/2018 : 7:18:40 PM
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| If you have access to a scanner, you should be able to see the % of acceleration, watch for any jumps or breaks as you accelerate slowly from 0 to full throttle, to verify the TPS is bad. Personally, I suspect that you have a sticking spool valve in the Valve Body. I would recommend 2 cans of Seafoam Hydratune and drive it about 5 miles,Seafoam products are the only "Mechanic in a Can" that I have actually seen work more times than not. |
Yes I am looking for a job, PM me for a copy of my resume. 20 plus years bus and 34 years as a Mechanic. Currently the Lead in a Federal shop. |
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AT545 shifting jerky..... gas pedal Issue?
