hialeahzbg

i just bought a 93 vx last week. the motor was replaced by previous owner since it was blown. I believe an automatic dx longblock was put on with the manual vx tranny and stock vx ecu... car runs fine minus the IACV which i will replace... i bought this car so i didnt have to daily my 05 type s and this car is worse in gas than the rsx... i fill it with about $28 and it barely gets to 200 miles on a full tank...i read online that this car does 45 mpg...can anyone please tell me what can cause this problem? thanks!

S_F

Impossible to give you an answer since no one knows what engine is in there and how it was installed.

fv8s

A dx engine would mean its the d15b8 i believe, and my Integra Gs-R gets 325-340 miles per tank. I would start by checking for fuel leaks and what the actual ECU code is. I am pretty sure a PO8 should be running that engine. Do you have any CEL codes and are you sure the ECU is stock? Do you see any blackish smoke coming out of the exhaust during acceleration?

hialeahzbg

it had a CEL when i first turned it on but it was due to no map sensor which i put one on and it went away... ill make sure what ecu is on the car but im pretty sure its still the stock one... havent seen black smoke coming out of the exhaust, but ill double check as well...

kaiba

Here's your problem. DX engine with VX ECU.

hialeahzbg

that will cause it to run so bad? so what ecu do i need? is it a p06?

PSU

iTrader: (2)

While we're on the subject:

- Change your fuel filter.

- Change your spark plugs.

- Change your plug wires.

- Tire pressure to 35psi or so.

- Profit!

slogfilet

iTrader: (1)

Someone more knowledgeable than me can step in, but the VX ECU is probably looking for the 5-wire wideband O2 sensor. It seems reasonable to me that the wrong combination can seriously affect mileage.

Definitely go with the standard tune up. Especially tire inflation; if your ride quality and handling can take it, the higher the pressure the better for fuel economoy (staying under the sidewall max pressure.)

deschlong

iTrader: (8)

Find yourself the correct ECU to improve the mileage - but you'll never get the advertised 45+ MPG if you DON'T HAVE THE VX MOTOR! (D15Z1)

qweakers

iTrader: (1)

-the d15b8 is the motor out of a cx and is a 8valve
-d15b7 is what came out of a dx
-P06 is the ecu you need for the dx motor
-you can get close to the mileage you where getting but it's going to take a lot of tuning with the ecu

hialeahzbg

in fact it is a d15b7 and i believe it still has the vx intake manifold and the vx header with the o2 on the upper header part... i really hope me swapping to a dx ecu will make it run more economic...

so besides the ecu i should change
- Change your fuel filter.

- Change your spark plugs.

- Change your plug wires.

- Tire pressure to 35psi or so

as mentioned?

slogfilet

iTrader: (1)

Would the difference in location of the catalytic converter in the B7 vs the Z1 interfere with the readings of the O2 sensor?

hialeahzbg

i dont know?

deschlong

iTrader: (8)

Figure out what parts that make up your Frankenmotor are from what engine, and get back to us. Until then, people are just guessing. We don't like to guess, we like to troubleshoot. It's a better use of time.

S_F

No. This is a common change people make to the VX since the cat is so close to the head, in the event of a bad head gasket the cat gets so hot it contributes to burnt out valves.