Mileage dropping like a Bonanza full of doctors
 

Hey guys, heres a run-down:

for the past month and a half I have been using the same BP gas station for gas (only one in town that doesnt have E10) and I've been getting 16mpg if i drive like an ass in town. Very recently I noticed shes burning rich. I mean, 65 mph on the highway and I'm getting 13mpg, and 9 mpg city.

I cleaned the MAF, IAT, IAC, filter, and throttle body. Nothing. Returned my 87 street tune to stock. Nothing. Tire pressure is good, and I have a dual-core radiator, 180* thermo, and electric fans keeping my water temp at 180*. Oil changed with Motorcraft 5W-20 Synthetic blend 800 miles ago, and no CEL. Plugs are Motorcraft 504s gapped appropriately about 10,000 miles ago. Coil pack has never been changed and wires have never been changed. The fuel filter is over 8K miles old, so I am about to go change that for kicks and giggles.

I'm thinking the pre-o2s are out. Is there a way to check this? I appreciate help as I drive this beast as delivery @ 100 miles a night. It really hurts to see that needle drop

BUUUUMP.

I've got an appointment with a dyno this saturday and I don't want to waste my 3 pulls if I'm burning rich!

I'm betting that you put that 180 stat in when you recently changed the radiator...........and this is about the time your gas mileage tanked.

Bad move. Put a stock stat back in (192 or 195?) and set your fans to turn on at about 210.

The 180* thermo has been in for months and the radiator is over 3 weeks old now. A tank of gas lasts me about 5 days and it was the last two tanks that my mileage crapped. Two tanks ago, however, I did put some Gumout fuel injector cleaner in my tank. Possible clogged cat?

The temp will contribute to the poor mileage. It needs to run at 200 to 210 degrees. I don't know if it decreases it that much, but you do need to change that thermostat.

I know a Doctor that crashed a Bonanza. Why is that their favorite one?

Maybe your old crappy radiator was partially plugged and it was in reality running 200+ on the water temp?

That's quite possible on the clogged cats - take it to a muffler shop that has an infrared tester.

The V-35 Bonanza was a radical design when it was first introduced, and therefore very expensive. Only doctors could afford it. But combining the elevator and rudder together was a very tricky design. Not to mention the early ones had metal fatigue in the eppenage (part that connects the tail to the fuselage) and led to a lot of tails flying off before Bonanza issued a AD to get it fixed.

My old crappy radiator was running 240*F idling and left me stranded should I decide to turn on the A/C.

I just hooked up my SCT and ran some datalogging. It read 1000*F for the cat temp. I dunno which one the temp sensor is on though. My B1 front and B2 front O2 sensors were doing their thing so I think those are okay. My B1 rear wasnt doing squat. Needle sat motionless. B2 rear was active as well.

What do the rear O2s do?

Monitor the cats.

The rear cats don't affect the way it runs at all - they only monitor cat efficiency for emissions tests. If a cat fails efficiency tests, they trip a P0420 or P0430.

Here's an article that might interest you:

http://www.aa1car.com/library/converter.htm

You might want to replace the front O2's and move the current fronts to the rear.

Okay, I just bought new front O2s and going to replace them once the engine cools off. I'm also going to pull my spark plugs for kicks and giggles and see if there is any discoloration.

glc, are the front and rear O2s the same when you say move the old front sensors to the back? I saw different part numbers and different prices between front and backs leaving me to believe they are two different things

id go back to 192 thermostat, the 180 is forcing your truck to stay in open loop, and warm up cycle at all times. dumping gas to try to get the truck to warm up to operating temp

truck is closed loop. already checked

The only difference between the front and rear O2's is the pigtail length. They are interchangeable. I hope you bought Motorcraft or Bosch sensors - other aftermarket brands don't work right.

I still say the temp is a big part of the problem. You probably do have the O2 problem. I'm not trying to say you don't. But it will not run efficiently at 180.


I never did like the Bonanza because of the low decent speed. Those intakes freeze up faster than you can notice it happening. I've always heard of the Vtail version of the Bonanza and its problems. But have never been in one.
I have flown a vtail before, and I've been trying to remember the type ever since you mentioned it. It was an aluminum production plane built from surplus WWII parts. It was a two side by side seater with a bubble canopy, and a flat four. There were a bunch of them built, and they were famous for their stall problem because the ailerons, elevator and rudder were all tied together. Do you know the airplane I'm talking about?