I just bought a 1989 BII XL, 2wd w/ manual 5 spd trans. I got from a shadetree mechanic that replaced both the heads after the 1st owner cracked one of them by overheating. It seems to be in good shape and runs OK but I just checked the gas mileage and it's a terrible 12.5 mpg mostly hwy miles. he did tell me it could use some new spark plugs. But can new plugs make that much difference. He also had the catalytic converter removed and exhaust modified because the cc was clogged. I also get a black **** coming out the exhaust when it first cranks.

Does the computer affect gas mileage? The oil pressure stays around 20 also.
Also, do all of these models have the 33 gal gas tank?

Sorry for all the questions. I did search for these questions to see if they've been asked.

Thanks in advance.
blhudge

 

I forgot the most important part. It's a 2.9L.

apologies

 

23 gallon tank on the 4x4 '88. I guess on the 2x4 '89 also.

It sounds as though you need to do a tune up and check the codes. Black emissions on warm-up might be a bad O2 sensor.

 

I have a 88 and I'm positive the tank is a lot less than 23 gallons. I fill up when on Empty nad it only takes 11 gallons. See the thread I just posted called TPS.

 

FYI, The O2 is not used until the engine is warm, it runs in open loop until warm. Bad mileage could be due to a bad O2, bad fuel pressure regulator, clogged fuel return line, bad ECT, exhaust leaks. Run the codes and test the fuel pressure.

The oil pressure is OK for idle but low if you get that at 2000-2500rpms, low OP might be due to bad bearing from when the head cracked and coolant was in the oil.

 

b2's stock come with a 23 gallon tank if your reading full at 10-17 gallons
your floater or sending unit is bad or have a bad wiring connection.
86-90 b2's have a 23 gallon tank.

 

i have the same question. i know what to do to get better milage: new air filter exhaust blah blah blah. but i was wondering what a new coil and plugs would get me gas milage-wise. also, i was on summit's website and i see that accel makes a high output TFI control module and an ignition system, (300+ ignition ford,eec-iv 1984-98). anyone know if these will get me any gas milage and/or performance gains? is it worth it to sink that kind of money into my daily driver?

 

an msd ignition coil part number 8227 can give you the performance you need and gain
you can go with accel which is also known as mallory. just remember you will need to use 89 or higher

accel tfi module and ignition system will cost you about 351 dollars tops with all included. if you think it's worth it go for it.

 

questions are, monty, what kind of gains can i expect? and are they worth the money?

 

anywhere between 5 to 25hp and 10-30lbs of torque
on gas better gas flow throughout the engine this is with my msd install of part number 8227 i gained 15hp and about 20lbs of torque i also put in bosch platinum 4 plugs and 8.8mm wires . i only paid about 40.00 bucks for my msd ignition coil 2bucks per plug and 30 for wires. i think it was worth it depends on how you use your b2
monty

 

monty, its my daily driver, city and highway. those gains sound pretty good to me. any ideas about the TFI control module or ignition module? thanks for the input!

 

go with an accel tfi module or get yourself ,if you have the money a aftermarket module like jet chip or hypertech. even better

 

one more monty, i was on ebay and i saw that theres a wiring harnedd to go from the MAD to the Ford TFI. did you need this?

 

not if you just get 8227, the wiring harness is for the 6al or 6a ignition control box
then you would need the wiring harness

i have the coil the control box and the wiring setup on my b2. doesn't help to add what i had on my previous post .

 

Thanks for all the suggestions. I had the codes ran and a long list came up so my mechanic scrapped them and ran it again and only the Map Sensor(?) came up. He also set the timing which was 10 deg off. I'm up to almost 15 mpg but I want to get it a little better if possible. I already have the Map sensor and I'll be installing it tomorrow. anyone know what a map sensor is. It screws to the firewall and has a wiring harness and an air(?) line running to it. filled with epoxy.

I'll be changing the plugs, wires & dist cap soon then I'll get the codes ran again. Unfortunately I have to sacrifice performance for gas mileage but it's tempting. I drive 30 miles to and from work.

Would bad O2 senor show in codes?