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DDEC I blues
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Bill, 5 or 6 turbochargers? Something is wrong with that picture.. That’s just poor luck or poor maintenance. In normal conditions, you could go thru one turbo per 250K miles..
You mentioned that you inspected your turbocharger. The shiny side is the compressor wheel (charge air side), I requested checking the hot side/turbine wheel. If you FOD 3/32″ of the blade tips you will notice the boost reduction and EGT issue.
Like Ken has mentioned, moving up to a new DDEC system will allow you to get parts and service for the next 10 years or more. You can have a digital dash, or LCD panel to report all your gauges including your fuel burn.
If the parts are getting so difficult to get with DDEC1, why spend the monies on it. Update it to allow more options in the future.. If we can get a parts list going for you, I bet we can get pricing soon after.. DDEC3 ECU’s are on Ebay or thru 2nd hand sources..
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First I have no experience with DD engines.
But I did have a turbo blowup on my Dodge ,Cummins 6.7 two yeaars ago, which dumped all
the oil in the CAC and exhaust system. Dodge dealer replaced all the CAC and exhaust compentents
because of oil contamination. Keeping in mind the truck was a 2011 and had a catalytic converter.
Jim Brown
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Bill I sincerely hope you don’t leave us hanging here, not knowing if you were able to find the fix or are still working/looking for the solution.
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This may seem too basic, but with all the time that has elapsed and all the money and effort spent in an attempt to fix a problem, have you ever put it on a dyno to measure your HP output so as you make changes or repairs you have a benchmark?
The absolute worst way to measure performance is “seat of the pants” especially when the test criteria is how fast you go up a hill. I go up hills slow. I suspect almost all of us go slow up hills. I go up faster when I don’t tow. I go up slower when I tow. In colder weather I presume the speed up the hill differs from warmer weather. There are so many variables my “seat of the pants” measuring device isn’t good enough to be sure or anything.
Then we have conditions none of us can control and which have a not very subtle impact on performance. Since this issue has been going on for a decade your loss of power can also be attributed to your fuel. I can prove by 24 years of data that my MPG has been hammered by changes in fuel. Within the last 10 years we have had the sulfur content and the content of ethanol impact our performance. I saw a change in mileage that could only be attributed to the change in sulfur content. Then as the percentage of ethanol increase I really saw an impact. Pure diesel fuel has a high BTU content. Each 10% of ethanol is going to drop the BTU content and performance will suffer by about 5%.
I don’t know about your bus, but when I am hill climbing 5% is a huge amount because it might make the difference between holding the speed and the higher gear, or being just enough loss of power to drop me to the next gear and the reduced speed associated with that.
So have you run the bus on a dyno and if so, have you measured the various changes on a dyno as well?
BTW I had my DDEC I 8V92 for 17 years. Over that period of time I had cracked manifolds, blown manifold gaskets, cracked turbo inlet pipes, and a completely failed turbo inlet pipe. These were spread over the 17 years so how many of those type of issues have you encountered in the 10 years? Some of those failures were almost impossible to find such as the rear manifold crack that cost turbo boost, but was hidden because there was no visible sooting.
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Bill,
A stock Series 60 515hp will climb the southside of the Grapevine at 40, pulling a heavy toad he would be down to 35.
You aren’t doing bad.Later
bv -
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So in all your years you still don’t know what the HP output is?
Suction gauges are not specific to a particular engine or coach. They measure vacuum. If you can put a gauge in the red by stepping on the gas pedal you have likely described your problem. Something is restricting the flow of air into the turbo. The suction gauge goes into the red when a filter gets dirty. As the dirt inhibits air flow the vacuum in the big air tube increases. My guess is if you disconnect the fresh air pipe from the turbo and go drive your power will be back. I wouldn’t recommend driving for a long distance with no air filter but a short drive up a hill should tell you if that is your problem. Or you could go find a shop with a dyno and do a HP measurement with the air intake as it exists now, and then with the intake tube disconnected from the filter housing.
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Have you checked into exactly how the dyno check at S&S was performed? In other words what exactly did S&S tap into when hooking up their dyno to your coach?
I assume you have a copy of the dyno report? Were there any excedences shown during the dyno pull?
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Bill, I could never pull the Grapevine at 40mph in my 40 foot ’90 xl with 8-v92 and DDECII set for 500hp and since I live in LA I tried many times. My engine was a factory rebuild with only about 50k miles on it and I’m confident it was performing as intended. (I also had a dyno confirmation.) I think 35 (true mph according to GPS) was the best I ever managed and I pulled that hill at 20MPH more than once if I had to brake at all on the climb. Also, above 7500 feet I experienced significant power loss. A frequent destination of ours is Mammoth Lakes at 7880 feet. Pulling from a stop there took FOREVER and sent up a plume of black smoke that probably still hovers over the Sierras even though it did not smoke at all at sea level. I never had my bus higher than about 8200 feet and I would not have wanted to try 9000. I understand you are saying yours used to perform better, but in my experience, your performance seems pretty normal for that engine.
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I guess you have it all covered Bill. Good luck.
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I understand! Been there. have found most of them but sometimes not. Bk found one several years ago that was a fuse holder (in line) on a ddec. That would screw things up on occasion. Low voltage –replaced it and all was good. this was after taking several sensors back to parts house. Another was using teflon tape on sensor and created a lost of ground.. go figure.. Haven’t the answer.. I did notice there was mention of a engine change in past. Lots of Hp choices for that basic engine and muffler sizes–should be 6 inch for example.. Do wish you all the best..You have tried about everything. there is a thread over on BNO about someone with simular problems going on now. It refrenced this thread. His is a 6-92 NJT bus. I think the 748 (correct?) is common to both of your units. The 89 XL I had with the 750 Allison was a great trouble free set up.DDEC II–though.
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Bill I understand what you are saying as to why you think your problem is associtaed to what a gauge on the intake side of your turbo is now and was showing in the past, it no longer ‘gets buried in the red’ as it did before your power loss accured.
For every one minute your engine is idleing at 750 RPM’s you are sucking 320 cubic FEET of air through your intake piping, not a great deal but a reasonable amount. The gauge that you have on there now as you have indicated was designed for probably a much smaller system so altho it is not the proper gauge it has been a good indicator for you. I got that much.
I am just wondering if that gauge could somehow be damaged by being placed in a system for which it was never designed (larger), have you thought about replacing it with a decent vacuum gauge? The one you have now could have a small hole in the diapragm which would give you a very different reading than what you were once used to. If it were to be a cheaper gauge it certainly could have been damaged.
Just a thought. I know it would by no means solve your problem but possible give you another more accurate means of trouble shooting.
I feel for you, been there and as everyone here would agree, no fun.
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