93 Honda Civic VX horrible fuel economy

[benfrogg]

Imjustplayin-
Bad wiring, maybe? No codes. Bad grounds are not likely, but possible. I added 4 grounds with 8 or 6 gauge wire to various points on the motor including the thermostat housing.
Do you mean EGR ports? I have cleaned those by drilling and tapping the IM and cleaned the EGR valve itself. What's this about a control box? Do I need to clean the vacuum pump that operates it?

Well, anything is possible on the tranny front. I posted a data collection thread to try and see if there is any correlation.

I should say that my FE isn't horrible now. I need to update the gaslog to reflect the two 40mpg tanks I recently got this winter. That's the lowest it has been. That is including all of my aero mods, driving changes, LRR tires, synthetic oil on all fronts, a fair amount of EOC, and a host of other FE type things. It just seems like I'm still reaching really hard to achieve the FE that other users seem to get with less effort. (no offense intended)
An example is a user named Rancho VX. He hasn't been on in a while. Take a look at his gaslog here:
http://www.gassavers.org/garage/view/1112

Now he lives in the plains states. But he used tons of A/C and had really no mods other than driving technique. He also never EOC's.

Anyway, thanks again.
B

[imzjustplayin]

Originally Posted by benfrogg

Imjustplayin-
Bad wiring, maybe? No codes. Bad grounds are not likely, but possible. I added 4 grounds with 8 or 6 gauge wire to various points on the motor including the thermostat housing.
Do you mean EGR ports? I have cleaned those by drilling and tapping the IM and cleaned the EGR valve itself. What's this about a control box? Do I need to clean the vacuum pump that operates it

Just follow the lines the EGR goes through and you should end up at a black box. While you may have cleaned the egr valves, the lines going to the box and the box itself which is really just more lines may not have been cleaned. The car does idle at stock speeds and seems to run smoothly though, correct? Can you post your smog report of this car? Are you using the manufacturer specified ignition wires and spark plugs? Have you ever adjusted the valve lash? I know one member who adjusted their valve lash and they noticed a bit of an improvement in fuel economy.


Well, anything is possible on the tranny front. I posted a data collection thread to try and see if there is any correlation.

Originally Posted by benfrogg

I should say that my FE isn't horrible now. I need to update the gaslog to reflect the two 40mpg tanks I recently got this winter. That's the lowest it has been. That is including all of my aero mods, driving changes, LRR tires, synthetic oil on all fronts, a fair amount of EOC, and a host of other FE type things. It just seems like I'm still reaching really hard to achieve the FE that other users seem to get with less effort. (no offense intended)
An example is a user named Rancho VX. He hasn't been on in a while. Take a look at his gaslog here:
http://www.gassavers.org/garage/view/1112

Now he lives in the plains states. But he used tons of A/C and had really no mods other than driving technique. He also never EOC's.

Anyway, thanks again.
B

What are the temperatures in your area? A warm air intake may help but I'd just look at every little thing like wheel bearings, dragging brakes, engine compression, etc. Also, why did you remove the exhaust heatshield? That is suppose to help with warmup times as it reflects the heat back onto the exhaust..

[benfrogg]

I'll try cleaning the lines to the EGR control box. I suspect throttle body cleaner would do the trick.
The car does run smoothly and idles at stock speed, (lowest line on the tach, before the 0 line right?) although it has the slightest very slow heartbeat at idle; I'm guessing on the numbers but it seems like it increases and then decreases by 50-75 rpm every 20 seconds or so. Hardly noticeable but I notice it. Idle is not as smooth as the rest of the driving range but it is set at the lowest line on the tach.
Maine does not test for Smog so it hasn't been smogged.
Plugs are stock. (zfr4-11)
Wires are last on my list to not be aftermarket. I bought new aftermarket ones about 6 months ago and will replace them soon with a set from the dealer/majestic honda.
Temp today is 27. It's been warmer lately, above freezing most days. It's been a mild winter. I have a WAI that runs at about 100-110 degrees Fahrenheit at the air box. It's intention was to make the car warm up faster, but it seemed like it was harder to hold lean burn on the highway. It definitely kept my numbers up a little higher if I'm using a lot of throttle (like when accelerating to get on the highway) but made it harder to maintain lean burn on slight grades on the highway. I'm still experimenting with which is the best way as of now.
I just installed a block heater yesterday so I'm thinking I'll see some improvements with that too. Look at my write up in the how to section!

Brakes have all been gone through and do not drag.

Bearings all appear good; no heat at the hub after a long trip, no play, no extra loud noises (well, as quiet as a honda can be with no seats in the back anyway!). I have not taken any apart and inspected for wear, however. How much of a job is it to check the rears without actually replacing them? It's probably just easier to replace them. Who knows when they were last done.

Thanks again
B

[imzjustplayin]

Originally Posted by benfrogg

I'll try cleaning the lines to the EGR control box. I suspect throttle body cleaner would do the trick.
The car does run smoothly and idles at stock speed, (lowest line on the tach, before the 0 line right?) although it has the slightest very slow heartbeat at idle; I'm guessing on the numbers but it seems like it increases and then decreases by 50-75 rpm every 20 seconds or so. Hardly noticeable but I notice it. Idle is not as smooth as the rest of the driving range but it is set at the lowest line on the tach.

You need to clean out your IAC valve and everything going in there... Not in horrible shape but that's why you don't have a steady idle.

[benfrogg]

I've cleaned the IAC valve, throttle body, and intake manifold all about a month ago. This was the third or fourth time I pulled the IAC to clean it. I have a spare one that is clean too that doesn't hold the idle as well as this one does. It may be time for a new one, but how much effect can a weak/slightly poor functioning IAC have on FE?

Is there any other way to check rear bearings than to see if they are warm and wether or not they have play?
Thanks
B

[imzjustplayin]

Originally Posted by benfrogg

I've cleaned the IAC valve, throttle body, and intake manifold all about a month ago. This was the third or fourth time I pulled the IAC to clean it. I have a spare one that is clean too that doesn't hold the idle as well as this one does. It may be time for a new one, but how much effect can a weak/slightly poor functioning IAC have on FE?

Is there any other way to check rear bearings than to see if they are warm and wether or not they have play?
Thanks
B

I mean it's possible you have a small vacuum leak but when you cleaned the IAC, did you remove the solenoid in order to get inside? Did you clean the FITV?
http://www.honda-tech.com/showthread.php?t=1564019
http://www.honda-tech.com/showthread.php?t=2579760

Are you able to do a leakdown or at the very least compression test?

[benfrogg]

Are you certain the VX has a FITV? All data I have seen (and the car itself) says it does not have one. It was the only one that did not.

I did not remove the solenoid from the IACV. How is that done?

I have a compression tester and did a compression test. All cylinders are within 3psi of one another. I don't recall the exact numbers, but I believe they were all + or - 195psi. (could have been 185, lost my data sheet)

No on the leakdown test.

B

[pgfpro]

I can't remember but did you have the injectors clean and flowed?

Also you could do a simple individual cylinder power test. Loosen all the plug wires so they will pop off easy. Then have one person watch the rpm while you pull up on each spark plug one at a time (then put the plug wire back before going to the next one). Have the person check to see what the rpm drop is for each cylinder. They should be pretty close to each other.

Make sure you use a well insulated rubber glove or pliers to do this.

[benfrogg]

Yes, I cleaned the injectors myself. I posted a youtube video about it a while ago. I did not have them flow tested, but I'm confident they are cleaner than before.
I'll try the plug wire test next time I have an assistant over.
Thanks
B

[pgfpro]

Originally Posted by benfrogg

Yes, I cleaned the injectors myself. I posted a youtube video about it a while ago. I did not have them flow tested, but I'm confident they are cleaner than before.
I'll try the plug wire test next time I have an assistant over.
Thanks
B

Sorry. I have been following to many forums lately.

After looking at your log your car seems to be doing great! I think the drop in MPG recently is all to do with the dreaded winter months.

My wife's Honda and Sons Honda are both put away for the winter to protect the new paint jobs, but I do know when we used to drive them during the winter months the mileage sucked.