Civic VX Problems

[Jonny]

Hello! I guess I haven't ever posted on here, so I'm not sure this is in the right place, but I've experienced an MPG drop down to an average of 28-34 mpg, consistently. I've also noticed power loss on the lower end, and even VTEC just isn't what it used to be — even in this car.

I have a D15B (rare VTEC-E variant), and suspect a bad MAP, though I'm getting no codes.
Any ideas? EGR was replaced just a couple of years ago and car is maintained with fully synthetic oil, DOT3, etc. Replaced O2 sensor & fuel pump already.

Trying to take a road trip this weekend for my birthday, and I'd rather get the record 63-68.9 MPG I got pure highway a few years back.

Thanks for any help!

P.S. My brother actually found my VX on this forum back in 2011.

[California98Civic]

The VX came with the D15Z1. Which D15B do you have? I don't think there were any 15b engines with v-tec.

[Jonny]

Originally Posted by California98Civic

The VX came with the D15Z1. Which D15B do you have? I don't think there were any 15b engines with v-tec.

There were two VTEC implementations: Economy, and 3-stage. This one is essentially identical to the D15Z1, but obviously a different head code, etc, being JDM. I know it's not anything else because of the mileage I've been able to achieve in the past. Not much on that E variant, though, as the 3-stage went into production not long after — which I should have bought when I found one on eBay (mind you he knew what he had, and the price reflected that).

I guess at the time the previous owner bought it, the Z1 was toast and it ended up being cheaper to get the JDM equivalent. Weird, huh?

[California98Civic]

Originally Posted by Jonny

There were two VTEC implementations: Economy, and 3-stage. This one is essentially identical to the D15Z1, but obviously a different head code, etc, being JDM. I know it's not anything else because of the mileage I've been able to achieve in the past. Not much on that E variant, though, as the 3-stage went into production not long after — which I should have bought when I found one on eBay (mind you he knew what he had, and the price reflected that).

I guess at the time the previous owner bought it, the Z1 was toast and it ended up being cheaper to get the JDM equivalent. Weird, huh?

Oh, yeah! I have heard of that before, and maybe I remember the car you bought here at EM... this one or a different one?



It is a sweet ride that got a lot of love on this site as I recall:
http://ecomodder.com/forum/showthrea...tml#post154573

So have you tried replacing the O2 sensor? And have to done compression tests (wet and dry).

[California98Civic]

...and one more question: why do you suspect the MAP sensor? (I had a problem I interpreted as the Map once, and it turned out to be the ignition coil.) So what's the source of the suspicion?

[Jonny]

Originally Posted by California98Civic

...and one more question: why do you suspect the MAP sensor? (I had a problem I interpreted as the Map once, and it turned out to be the ignition coil.) So what's the source of the suspicion?

Well I've replaced the "slightly" expensive wideband O2, and I can't think of anything else.

[California98Civic]

I'd get the FSM and start testing stuff. Fuel pressure, Map, ignition, ... the old mantra "test, don't guess."

[Jonny]

Originally Posted by California98Civic

I'd get the FSM and start testing stuff. Fuel pressure, Map, ignition, ... the old mantra "test, don't guess."

Initially suspected fuel pressure, which wasn't holding, so replaced pump. Still...

[Jared]

Routine maintinance is always something to keep in mind. Cap, rotor, plugs, wires, throttle body cleaning, injector cleaning. Air filter, tranny fluid (low?), coolant level.

Also is there any other numbers or letters after the d15? If not then you might have a jspec motor swap.

[Jonny]

Originally Posted by Jared

Routine maintinance is always something to keep in mind. Cap, rotor, plugs, wires, throttle body cleaning, injector cleaning. Air filter, tranny fluid (low?), coolant level.

Also is there any other numbers or letters after the d15? If not then you might have a jspec motor swap.

I know this is quite a delayed reply, but yes, it's a JDM motor. Dude who owned it before me put it in for some reason (at the time, I believe it was MUCH cheaper). From what I can tell, there is absolutely no difference between the D15B and D15Z1 aside from the head code, which obviously doesn't matter aside from the obvious things (ECU, etc). I perform all regular maintenance.

Car is a KL variant, so passed smog just fine for years with both engines apparently.

Now I'm burning oil. Worried about compression, but hoping it's something simple like PCV valve.