8V92 DDEC I Low Power...

[steve940]

History is as follows:

Owner has owned bus (Bluebird Wanderlodge motorhome) since 1999 and notes it was never particularly well-powered. Motorhome weighs ~42,000lbs and would tow ~9,000lbs car and go up Interstate 80 and 81 hills at ~20mph – but this has since worsened…

Bus was stored for approximately 5 years without being driven. Work began approximately two years ago when bus was noted by mechanics as more severely underpowered.

Fuel tank and lines were replaced, as were injectors. Turbo and blower were reported as changed. Road acceleration remains extremely poor.
At this time:

1- Fuel Pressure checks – good.
2- No diag codes noted.
3- Battery voltage – checked / corrected.
4- Exhaust system: leaks addressed correctly, changed the muffler to a
resonator, turbo pipe and exhaust manifold replaced.
5- Exhaust temperature = erratic / cold. Injectors rechecked and they were
rechecked as ok.
6- Stall test (holding brake) only pulling 900 rpms at full throttle.
7- Throttle up in Neutral (no load) is good.
8- Free run on dyno: (no load) limited to 53 mph!
9- Transmission function appears correct.
10- No excessive white, grey or blue or black smoke.
11- Compression tests normal

Many different avenues have been dead ends in solving the low power issue and the shop is considering ordering a replacement EDU (cost > $2000 plus labor) with the guess that that may be responsible for incorrect firing of injectors.

Any ideas on other possible causes before replacing the EDU?

Also, does anyone have any leads on obtaining DDEC 1 EDU PN# R1227328 (Needed for 8V92 08vf120945)

Thanks for ideas – and leads!

Steve

[Arcticdude]

Since it's not noted it's been done- have the fuel filter(s) been changed? I know you noted no abnormal exhaust colors, but the symptoms sure sound like it.

Was the fuel pressure checked on a pull or just at idle?

[steve940]

Yes on fuel filters...

Any other ideas?

[Arcticdude]

Since all the various abnormal test results are pointing towards a fuel issue, you're going to have to go back through the entire fuel system to see where the problem is.

[patticake]

Since the bus sat for years, possible algae in the tank. Check or change the filter again, and look for a clogged or collapsed fuel line.
This is based on your statement about the cold and erratic exhaust temps.

[Arcticdude]

He indicated the tank, lines and injectors have already been replaced. Is there a hard point someplace in the fuel system that would not have normally been replaced? It's definitely a fuel issue. The chance of an ecu causing the problem has to be only a very minute chance. I've never heard of an ecu failing. I guess this could be the first, but I'd be looking at everything again to verify before I replaced the ecu.