Throttle control failure (split from Re: Break down on I-10 )

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Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #50 – January 31, 2015, 10:48:32 am

Miz,

Cummins has manufacturing facilities in Warez and San Luis Potosi with shops in many cities. DINA worked with Cummins to design and produce heavy and medium duty engines in Mexico. Mexico is the world's sixth largest truck manufacturer (number seven for cars). Many Detroits that can't pass smog have found their way to Mexico and Canada where they join their brothers. Always being curious, I have looked in several bus engine compartments in the past and have seen the the Detroit 6V-92TA with the DDEC (electronic engine). Mercedes now owns Detroit Diesel and Freightliner trucks among others so has a huge presence all the way to the tip of South America. All the thousands of Mercedes buses in Latin America have Detroits in them as they all share the DD (Detroit) or OM (Mercedes) designation depending on the vehicle they are installed in.

Anytime you see a MCI (Grayhound, etc) bus, the Mexican company DINA purchased them quite a few years ago, moved the headquarters from Phoenix to Chicago but are Mexican controlled. Ford, Navistar, Nissan, VW already have plants in Mexico.

One Foretravel member had their Allison transmission expire south of the border. They were towed to an Allison facility where the transmission was rebuilt at half the cost quoted here.

Times have changed from the rusted out vehicles of the 1950's. Here is a quote from last year:

"Gone are the days when Mexico produced only compact sedans and pickup trucks. Later this decade, new plants will be producing premium vehicles, BMWs and Mercedes, Infinitis and Audis. Many Nissan vehicles that roll out of the existing plants in Aguascalientes are bound not for domestic showrooms or to auto dealers in the United States but for Brazil, Colombia, the United Arab Emirates and dozens of other markets.

The huge growth comes not just because of Mexico's good highways and railways, its healthy steel industry and its cheap wages. It's also because of plentiful engineers and the skill of global automakers at keeping quality high, wherever their cars are built."

We spent a week in Detroit, MI this last December. From a city of 2.5 million to just 700,000 today, it's pretty easy to see where the jobs and auto/truck factories have gone.

Pierce

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #51 – January 31, 2015, 10:58:29 am

I agree totally with what Pierce has said and have full confidence in Mex mechanics. They do things different sometimes but have great knowledge and try to fix things on the spot, yes roadside. The road down so far is amazingly smooth and we did not see one rusted broken down style car of previous trips, but newer ones just as above Border. Except for Hermosillo we ran at 70mph being passed by Buses sounding so sweet it was amazing. in the 17 yrs I have been coming down mainland it has changed a great deal and some of the toll roads make hwys north of the Border look like junk. Things have changed a lot and the people are ever so friendly still.
The tow situation is not quite the same but I am sure that will improve. Due to the fact that money is generally not as free flowing as in US etc they tend to look at simple things first and as I am fairly confident our problem is this, maybe it would all be fixed right now--who knows.
@Don-- the PID is 91 so check that out on Silverleaf and what it does is give you a percentage of throttle action with a sliding coloured scale in bar form. I like it a lot--so again thanks dave K.
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #52 – January 31, 2015, 11:34:40 am

John,

Have been putting together parts from your puzzle as they keep coming in. Trying to put my best guess forward, I think it may have something to do with the fly by wire throttle. Since the engine went to full throttle and back to idle by itself, I would think it could have to do with the wiring close to the engine where abrasion, rodents or something else has compromised the wiring. Changes in temperature and or vibration may be causing the intermittent problem. The other possibility could be in the wiring between the ECU and the injectors. This would also be close to the engine where the above causes would be relevant but putting more $$ to my first guess.

This would also explain why there are no active or stored fault codes.

Rigging a temporary wiring loom from the engine ECU up to the foot throttle could be used to check this. Since the ECU has been changed out, it would seem to be eliminated as a possible cause. A temporary foot throttle and short wiring to the ECU could also be used on a chassis dyno to simulate operating temperature, shifting , vibration, etc.

Pierce

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #53 – January 31, 2015, 02:13:56 pm

How does the fly by wire throttle system work? Is there a follow up or position sensor behind the throttle peddle? If so could you disconnect it and use an ohm meter to check if the output signal is smooth through out the entire range of travel?
Bad signals (loss of throttle and full throttle ) could be caused by erratic signal output from the throttle position sending unit.

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #54 – January 31, 2015, 02:32:39 pm

Quote from: John Duld – January 31, 2015, 02:13:56 pm

Is there a follow up or position sensor behind the throttle peddle?
If so could you disconnect it and use an ohm meter to check if the output signal is smooth through out the entire range of travel?

John,

The short answer is Yes to both questions.

Pamela & Mike

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #55 – January 31, 2015, 04:50:32 pm

The root cause of these problems is usually quite simple in the end. It's probably a broken/cut wire or bad connector or bad foot throttle.

The ECM is just box that takes a bunch of inputs uses some logic, and makes some outputs. If those inputs are BAD or erroneous, but it thinks they are good, the ECM is just going to continue doing it's thing.

It helps to be able to see what the ECM is seeing using the proper scan tool, but even VMSPC would help you diagnose.

Using known good components and isoaltion is the only way to solve the problem. Start buy wiring a different foot throttle directly to the ECU

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #56 – January 31, 2015, 05:07:15 pm

It is and has been for a while that my thought too is a wire problem by ecu (abrasion etc etc) and that is what I have told them to check first and remove filter to give better access and sight.
They did mention that if no plain answer they would run a wire from one to another so hope by Monday there is some info coming this way.
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #57 – January 31, 2015, 07:05:49 pm

Quote from: John Haygarth – January 31, 2015, 05:07:15 pm

They did mention that if no plain answer they would run a wire from one to another so hope by Monday there is some info coming this way.
JohnH

Whoo, fly by wire buddy bus!

Anybody know what the signal is, pwm perhaps? Is the throttle servo actuated? My money is also on the pedal assembly.

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #58 – January 31, 2015, 07:23:08 pm

Pedal sensor was replaced and ohms checked and good. Road test-failure, proved not to be sensor. ECM replaced and I drove for 45 mins with tech sitting in Passenger seat and computer hooked up and all showed well in every parameter. Hooked up car to drive to Mexico and 3 hrs later it all happened again and worse. Everything that has been mentioned has been done and still no go.As I said before I believe it is bad wire by ECM that makes contact for a while then changes position and all hell breaks loose by shorting out or?? One thing that is common is after 5 hrs + sitting all returns normal, but, for how long??
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #59 – January 31, 2015, 07:27:47 pm

John, does the stinger module control the fuel on your engine.

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #60 – January 31, 2015, 09:38:59 pm

Did they check grounds?

I've been bit quite a few times by bad grounds. Whenever something strange or intermittent happens, I always start with grounds---I learned the hard way!

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #61 – January 31, 2015, 11:09:09 pm

Bill W, actually not sure but am certain someone on Forum knows the answer. I did the By Pass of stinger and it made no difference to problem at the time.
On the ground issue I will ask them by email if that could be an issue, as I am sure the tech that was working on it would know. He has been there 14 yrs as their problem solver so sure he would know. He has a 40ft DP too.
Thanks all for input again.
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #62 – February 01, 2015, 12:04:03 am

John, you are on the right track with wiring most likely. That's only a five volt max signal from pedal to ecu and needs to be near perfect connection to work. Wiring is supposed to be twisted pair and not run in a bundle in bundle with other harnesses. Did you see the pedal recalibrated with three slow presses key on? Supposed to do it whenever pedal is disconnected .

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #63 – February 01, 2015, 10:34:11 am

Chuck, you are correct about the voltage being 5v, and mine tested out at 4.2 going to senser and 4.8v coming back which is not good as the out volts should not exceed the in ones (to make it simple) I have been having some much higher that cause the cut out of throttle but faults recorded do not show what that voltage had been at the shut down time.
The 3 slow passes on peddle to reprogramme it I did a couple of times and so did tech and it did not work, but as we are having other issues as well maybe that was reason?
Hopefully tomorrow they have some answers so I can forget this whole thing and start to enjoy our time down here.
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #64 – February 02, 2015, 11:28:57 am

Just had an email from Cummins on coach. They are putting it in shop for checking tomorrow and install of new lift pump as I asked them too. Mind you if coach will not go anywere I do not need a new lift pump do I?

Let you know what happens.
JohnH

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #65 – February 02, 2015, 11:44:50 am

John, What possible connection can there be between the lift pump and runaway or stuck throttle.
Man I hope you get some real answers soon, you have been thru hell on this issue.
Gary B

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #66 – February 02, 2015, 12:02:38 pm

John, This thing has me bugged, I am no mechanic but my BIL ran a fleet of over a hundred tractors and recently retired.
In my conversation with him and reading these posts to him he agrees that Cummins is chasing a fuel problem of some kind.
In his fleet he found some odd things such as rags in the fuel tank, the float off the fuel level gauge in the tank and once even a plastic ball that got sucked into the fuel pickup in the tank.
His take on it is that since Cummins has eliminated everything else it is time to inspect the fuel pick in the tank for foreign objects that restrict fuel.
Don't know if any of this is valid but it does make sense.
Good luck with it.
Gary B

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #67 – February 02, 2015, 12:04:52 pm

Quote from: Gary Bouland – February 02, 2015, 12:02:38 pm

His take on it is that since Cummins has eliminated everything else it is time to inspect the fuel pick in the tank for foreign objects that restrict fuel.

Gary - would fuel restriction be applicable in the most recent instance of a runaway throttle?

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #68 – February 02, 2015, 12:08:40 pm

Michelle, If pump lacks fuel the governor will be telling the pump to supply more and since there is no more fuel engine will run faster and faster til it hits stops on Governor. Not a very technical explanation but that's what I understand. Also a blocked or crimped fuel return line would have the same effect.
Has John had any recent repairs done on fuel tank, gauges, return lines ?
Gary B

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #69 – February 02, 2015, 12:10:48 pm

Quote from: Gary Bouland – February 02, 2015, 12:08:40 pm

Michelle, If pump lacks fuel the governor will be telling the pump to supply more and since there is no more fuel engine will run faster and faster til it hits stops on Governor. Not a very technical explanation but that's what I understand.

Thanks Gary - I get the picture now (sometimes you have to draw them with crayons for me

)

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #70 – February 02, 2015, 12:36:21 pm

Gary, no fuel line problems worked on and mine are in good shape as I had checked them from tank to engine, no cracks etc.
This is definitly an electrical issue as Silverleaf also said that as well as their diagnotic stuff.
The lift pump I am having changed is only because I have a new one and the one on is original and of course there have been many leaks etc on others due to ULSD damage of gaskets etc, so I just wanted it done while it is in their shop as I cannot get in their myself.
My tank is clean as a yr ago I drained it to see if any algea and it was spotless and only I have done anything to coach in last 3 yrs.
Will wait for update tomorrow.
Johnh
edit, one thing they have not eliminated yet is my thought that a broken wire next to engine block is causing it all. hope that is it.

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #71 – February 02, 2015, 01:20:54 pm

John, I wish we had it over your pit. Alligator clips, jumpers, a good fluke meter and someone wiggling the harness would answer some questions quick. Hopefully your Cummins guys have a test harness to ring out the wiring and connectors.

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #72 – February 02, 2015, 01:43:26 pm

OK John, Just a thought, as you know sometimes the least obvious fact can hold an answer while the most obvious means nothing. Good luck with this mess.
Gary B

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #73 – February 02, 2015, 02:42:12 pm

Gary, appreciate all ideas totally and have just written JT to see if he has any too, we will see if he answers with any.
JohnH ( in sunny blue sky San carlos mexico)

Re: Throttle control failure (split from Re: Break down on I-10 )

Reply #74 – February 02, 2015, 06:35:06 pm

Just had a reply from JT and he has sent me trouble shooting checklist so sent it to shop and hope it helps.
JohnH

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