Honda VX engine not performing, why???

[briogio]

I've just done an engine swap in my '95 Civic and put in a VX (VTEC-E) engine and I'm missing something because I'm not getting any better gas mileage than my 450,000kms, old, stock, 16V, single overhead cam that I swapped out???
I've put in new spark plugs, distributor cap, air filter, oil change. What am I missing?

[GasSavers_Erik]

Are you using the FED VX ECU? It will put the engine into lean burn under certain conditions. The CAL VX ECU does not have lean burn capabilities.

[briogio]

Honestly I'm not sure, I bought it at TorontoJDM and the engine is from Japan, it's single stage that kicks in at 5,000rpm, I think it's a D15B1, it says VTEC-E on the head.

[imzjustplayin]

do you have the transmission that came with the car or do you have the VX transmission? The 2001-2005 Civics with Vtec (EX) only see a marginal improvement (2mpg avg increase) over the older vtec (96-00 EX) and no increase over the non vtec (DX/LX). Yes I am aware the EX has a slightly closer transmission than the DX/LX but when you compare the EX from '96 and the EX from '02 (best years), there you can see the mileage improvement. I would suppose if you coupled the newer vtec version with a DX/LX transmission, you'd see a marginal improvement in fuel economy but no VX territory. The VTEC in the 2001-2005 Civic EX is very similar to the VTEC in the 92-'95 VX and '96-'00 HX (12 valves low, 16 valves high). The primary reason to go with the vtec in the VX is because it adds low end torque which goes nicely with the "tall" CX/VX transmission and therefore adds fuel economy.

[briogio]

I have the stock '95 CX 5 speed transmission, it turns at 2,500 rpm at 55-60 miles an hour which I mostly travel at on my commute.

[briogio]

I've found that I should have a 5 wire oxygen sensor and I have a 4 wire. Also they put a non-stock 4 into 2 exhaust manifold. It sounds like it makes a big difference so I'm going to try and find the stock manifold and 5 wire O2 sensor.

[imzjustplayin]

Originally Posted by briogio

I have the stock '95 CX 5 speed transmission, it turns at 2,500 rpm at 55-60 miles an hour which I mostly travel at on my commute.

lulz... A CX transmission does NOT turn at 2500 rpm at 55-60mph.. THATS THE DX/LX/(1996-2000 CX)TRANSMISSION! If you really had a '92-'95 CX/VX transmission, you'd be going around 74mph at 2500rpm vs the current 59mph..

http://www.fatboyraceworks.com/gears...raph&Compare=1

[imzjustplayin]

Originally Posted by briogio

I've found that I should have a 5 wire oxygen sensor and I have a 4 wire. Also they put a non-stock 4 into 2 exhaust manifold. It sounds like it makes a big difference so I'm going to try and find the stock manifold and 5 wire O2 sensor.

you don't need a 5 wire for a D15B1.. You need to reconfirm again what exactly you have. I can't believe you knew enough to install an engine but not enough to actually know what the hell you installed.

[briogio]

Ok I have Montegi MR7 16" wheels with 205/45 tires. About knowing "what the hell" I installed, it says VTEC-E on the valve cover and yes I'm trusting it is, how can I tell if if really is VTEC-E?

[1993CivicVX]

Prolly is a VTEC-E but the VTEC-E is not a D15B1, it's a D15Z1.

Correct wheel size and transmission should help you with the mpg numbers, along with the correct expensive 5 wire o2 sensor. No surprised you are not getting better numbers with the current setup you have (high revving tranny and big wheels). If you can, get yourself a set of the original VX wheels on craigslist and put Vredestein Quatrac 2 tires on them 165/70/13. http://www.vredestein.com/

VX wheels