VX shift light question

[dogncatboy]

I searched for a post on this but didn't find a good match. When I got by VX about 1700 miles ago I got FE in the low to mid 30s. Since then I've put the correct plugs in, installed and calibrated the TPS, new O2 sensor and cleaned the eavc (leaking air internally) and will replace it this week. So far I've cured the engine lag and I suspect that the new eavc will bring the idle under control. To date the best tank I've gotten is 43mpg and yesterday it came to 37mpg. Not bad for a Civic but crappy for a VX.

I've noticed since I got the vehicle that sometimes the shift light works and at times it doesn't. I use my car for running the same 120 mile RT route 4 times a week and I've noticed that on the trips where the light isn't working my gas mileage really stinks and I can watch that gas needle drop. On trips with the light working the needle barely moves and if in a given tank the light works a lot, I can count on decent mileage. When the light doesn't work so much the car consumes a lot of gas. Maybe I'm crazy, but its starting to bug me a bunch. I drive the same route the same way and FE is sometimes great and sometimes it stinks. I am aware that the gas gauge isn't exact and that the first part of the tank goes farther than the last. Trust me that is not the issue here, I've had plenty of vehicles with these kind of gauges and this is not causing the variance in distance travelled per gallon. So can the light issue be indicative of an underlying problem, maybe a bad ECU? Does this sound familiar to anyone? I hate to spend more money on a car that is supposed to save me money, but if that what it takes to get the most from this thing then I'll try it. Thanks.

[dogncatboy]

Oh yeah, one more thing.... when the light is working the engine actively hunts for a good idle speed (it goes up and down) when in neutral. When the light isn't working the engine idle remains high and doesn't hunt.

[Danronian]

Maybe the light being on or off has to do with ecu having a code? I'm not sure really, but assume your CEL light on the cluster is burnt out, and try jumping the service connnector to see if there is a code stored in the ECU.

On my VX the shift light has never worked, hopefully I'll have success removing the dash bezel to fix it soon.

[1993CivicVX]

my shift light is pretty wonky too. I don't need it tho, do you? Shift by your speedo, not your tach, for best FE. On flat it should go something like this if you have the '92-'93 civic VX (I believe higher mph shift points on the '94 '95 VXes)

shift into 2nd gear at 12mph
shift into 3rd gear at 20mph
shift into 4th gear at 25mph
shift into 5th gear at 31mph

Seems rather unlikely your shift light alone is affecting your FE. You say you are not changing at what speed you are shifting gears when the light is not working?

I am going to replace my ECU on my car in a few weeks. I will let you know how it goes! My idle is still high and I think it's the ECU.

[dogncatboy]

Originally Posted by Danronian

Maybe the light being on or off has to do with ecu having a code? I'm not sure really, but assume your CEL light on the cluster is burnt out, and try jumping the service connnector to see if there is a code stored in the ECU.

On my VX the shift light has never worked, hopefully I'll have success removing the dash bezel to fix it soon.

CEL light works, brand new 74 bulb a few weeks back. there was no code after resetting after the new O2 sensor, but I'll check it out. Thanks.

Originally Posted by 1993CivicVX

my shift light is pretty wonky too. I don't need it tho, do you? Shift by your speedo, not your tach, for best FE. On flat it should go something like this if you have the '92-'93 civic VX (I believe higher mph shift points on the '94 '95 VXes)

shift into 2nd gear at 12mph
shift into 3rd gear at 20mph
shift into 4th gear at 25mph
shift into 5th gear at 31mph

Seems rather unlikely your shift light alone is affecting your FE. You say you are not changing at what speed you are shifting gears when the light is not working?

I am going to replace my ECU on my car in a few weeks. I will let you know how it goes! My idle is still high and I think it's the ECU.

There is now way I could possibly shift into 4th at 25, 3rd is dodgey at that speed and 5th at 31???? Surely you jest!!! Hmmm... if those ARE supposed to be my shift points, me thinks something else is wrong. I saw a TomO post talking about the effects of being off a tooth on the timing belt, I think he said it would still be drivable but underpowered. Maybe this could account for some of the FE problems. The previous owner got new timing belt installed by his Honda dealer... maybe they got it on wrong. I'll try to ferret out the post.... something about a 16mm socket and cylinder 1....

[thisisntjared]

the shift light works on vacuum pressure. if the vacuum is low and you are not in top gear, the light will come on.

a vacuum leak would stop it from working. when you replace the eavc then i suspect your fuel economy should get right back to where it is supposed to be in the mid to upper 40s.

good to see that you turned that vx around!! also, what are the tires you have on there? a cx, vx, or hx with a tire with that would belong on any other civic or integra will cost you at least 1-2 mpg, even if both are the same brand and model.

[dogncatboy]

Originally Posted by thisisntjared

the shift light works on vacuum pressure. if the vacuum is low and you are not in top gear, the light will come on.

a vacuum leak would stop it from working. when you replace the eavc then i suspect your fuel economy should get right back to where it is supposed to be in the mid to upper 40s.

good to see that you turned that vx around!! also, what are the tires you have on there? a cx, vx, or hx with a tire with that would belong on any other civic or integra will cost you at least 1-2 mpg, even if both are the same brand and model.

Thanks, I hope you're right! The tires are 175s not165s, but my FE numbers are adjusted for the difference. I also have steel rims. I just got 2 vxrims and am looking at a set on ebay as too. I plan to swap when I get a set of 4. I would just dump the tires, but the previous owner had just put them on and they still had their whiskers when I bought the car. I figured that replacing them was prolly a false economy, but I havent crunched the numbers.

[thisisntjared]

175 isnt that bad at all, i meant something like 185-205. i should have specified newer civic wheels

you will be ok with the 175s and they will get a lot better as they age, not to mention they are safer. keep new tires properly inflated though so they wear even. dont inflate them rediculously so the center wears faster than the edges.

[1993CivicVX]

Originally Posted by dogncatboy

CEL light works, brand new 74 bulb a few weeks back. there was no code after resetting after the new O2 sensor, but I'll check it out. Thanks.




There is now way I could possibly shift into 4th at 25, 3rd is dodgey at that speed and 5th at 31???? Surely you jest!!! Hmmm... if those ARE supposed to be my shift points, me thinks something else is wrong. I saw a TomO post talking about the effects of being off a tooth on the timing belt, I think he said it would still be drivable but underpowered. Maybe this could account for some of the FE problems. The previous owner got new timing belt installed by his Honda dealer... maybe they got it on wrong. I'll try to ferret out the post.... something about a 16mm socket and cylinder 1....

I remember the post, I'll try to dig it up. I am intensely curious how other VXers drive their VXes. I also wonder if my gearing might somehow be different than other VXes? Not sure how this could be but I'm already at 2000rpm at 60mph. It would be great if we posted videos of ourselves driving! haha. So what RPM/speed are you shifting at?

I believe my RPM translation of those speeds are as follows:

shift into 2nd gear at 1800 rpm
shift into 3rd at 1600 rpm
shift into 4th at 1500rpm
shift into 5th at 1500rpm

what RPM are you at at 60mph?

[1993CivicVX]

here's the timing belt thread you requested

http://www.gassavers.org/showthread....timing+belt+vx