Question Limp Mode

[Too Little Too Late]

Stopped at a red light, and while idling for 20 ~ 30 seconds the check engine light came on. The light changes, the go pedal is to the floor, and we're crawling for about a block and a half. Then the check engine light go's off and power is restored . . . until we get to the next light. Because there was a stored code, "low fuel pressure during start up," we replaced fuel filters. No change. The next day we are SB 5 going to LA and came upon an upside down SUV. Traffic stopped and MH went into limp mode. A minute later after passing the accident and the go pedal is to the floor, count to 30, the check engine light went off, and we didn't have another problem all the way to LA and back home. Weeks later we went to Tahoe without incident, but on the return trip we were stopped at the traffic light on hwy 88 in Jackson and the check engine light came on. Limped across the intersection and another half a block when it recovered and was fine again. Any ideas out there?

 

[Trav_lr]

I had something similar. Cat C7 Fuel Pump: Essential Guide to Function, Failure, and Replacemen

Mine turned out to be two failing injectors and the huei (high pressure fuel pump). I replaced the fuel pressure sensor at the same time since everything was open. If yours turns out to be the same, you can get reman parts with warranty from a Caterpillar dealer for half the price of new. This helps too CAT ET 2025A – Caterpillar Diagnostic Software - Autotech Diesel.

 

[Too Little Too Late]

I had something similar. Cat C7 Fuel Pump: Essential Guide to Function, Failure, and Replacemen

Mine turned out to be two failing injectors and the huei (high pressure fuel pump). I replaced the fuel pressure sensor at the same time since everything was open. If yours turns out to be the same, you can get reman parts with warranty from a Caterpillar dealer for half the price of new. This helps too CAT ET 2025A – Caterpillar Diagnostic Software - Autotech Diesel.

Wow great information. I have since taken it to the Cat place, and their software said low fuel pressure, and low fuel pressure at start up. They had no idea where to look. We replaced a fuel filter, and my neighbor has a can opener to open it up and check the contents. Boy was I the big hit at the Cat place. All of the mechanics were in the office going over that filter material like a road map. A little more history - I have already replaced two injectors, and I wonder if contamination was the contributing factor.
Cat software? And licensed for five years, for a hundred bucks? I thought that software was proprietary, and not available to the general public. And if I got the software, how would I connect the Dell to the coach? Gosh, and then I'd have to get the Dell too. Everything here is Apple.
Wait till my wife hears that we're gonna take the bedroom floor up and throw more money down there. We've put thousands into this already. The previous owner did nothing good for this coach. When we got it, the transmission was a gallon low, and the crankcase was a gallon over. A pinched crankcase breather hose didn't help. Returning from our first trip, the back of the coach was covered with oil. While trying to get the coach to travel in a straight line I discovered that both front wheel bearings were loose. Four revolutions on the bearing nuts to get rid of the clunking wobbling front wheels. Anyway, it's all good . . .good conversation.

 

[Trav_lr]

I feel your pain….. since getting our Expedition, we’ve discovered the same thing. The PO seems to have done nothing to maintain the driveline. I had to replace the water pump, alternator, turbo flex pipe, idler pulley bearings, two injectors, the huei and multiple sensors. On the plus side, it runs like a champ now. Next on my list to do is the transmission and air brakes.

If you’ve got a good Caterpillar, Frieghtliner or other qualified shop, they will already have the PC only software. No iOS version that I’m aware of. You’d only want the software and cable for DIY. The proprietary USB/J1939 (?) cable plugs into a port near top center of radiator. I’ve since found two good shops in Wa & Or who have been really good to me. Not cheap, but very professional work ethic. The last time I was at the Oregon shop, they worked until 7:30 pm New Year’s Eve to finish my coach so we could continue our trip south.