Poor Fuel economy and Idle Speed at 1100rpms and will not go lower

[87ccord]

After searching (search feature included) for about 2 or 3 nights in the carb tech section, I've found no answers to my predicament and hope that it's safe to post my own issues in search of an answer. After completing my engine swap, and getting the car back on the road, it was relatively problem free the day I got it running. But it still idles at 1100rpms, and I can't get it to come down.


Today I adjusted the valves and sprayed carb cleaner down the throat of the carb. Both of which helped smooth the idle and other functions of the car out. But the idle remains at 1100. The throttle stop screw is as loose as is effective (doesn't lower the idle anymore when you turn it out, so I stopped loosening it)

I was watching the carb go through it's warm up cycle today before adjusting the valves, I observed the choke plate, and after I initially started the car the plate was mostly closed, (2/3-3/4 of the way closed) and the engine was shaking pretty badly so I opened the choke plate all the way and the car revved up to high idle speed (2500rpms) and smoothed out (Overly rich choke condition?)

Last, the car is getting 17mpg in town. This is much lower than I've heard it should be, even under racing style driving conditions. ;)

Any suggestions would be greatly appreciated, and as I said before, I was afraid to jump the gun and post a question about something that was already answered, but after a few nights of dedicated searches, I feel now that my post is justified. If it has been answered, a simple link to the thread would be much appreciated! =)
Thanks for all the help and encouragement everyone
-Derek

[A20A1]

Fix the choke for sure... but you can still adjust idle by physically holding the choke open when the car is fully warmed up if you want.

The throttle stop screw is not the only idle screw, and will not lower the idle any more if the other Throttle Controller screw on the carb is not also loose.

The T.C. is on the same side as the throttle cable, it's mounted on the throttle cable bracket and controls idle speed. Turn the TC screw all the way out first before adjusting the Throttle Stop Screw.

If the idle still doesn't drop then there could be a vacuum leak, but not as likely especially if the TC screw isn't hitting the carb linkage.

Something could be physically holding the carb throttle plates open, like dirt.

The float level could be too high

Or in some instances the distributor is rotated changing ignition timing and slightly raises the idle.

[g.frost]

17 mpg says there is something wrong. (either fuel delivery or your brakes are stuck...)
When my choke opener failed I got 22 mpg and it ran terrible when cold. I would think at 17mpg it is running really rough, black smoke and smell of raw gas might be on the symptom list...

The usual suspects would be carb and choke heater and opener.
Download the manual and 'addendum' for your year. (link on this site) follow procedures to check the choke function. It sounds like you have already observed a problem here.

For fully warmed up idle, check to be sure the high idle unloader is working and then adjust the idle (knob on back of carb) only after all other issues have been resolved.

I get 26-27 mpg short trips around town in the winter.

[87ccord]

17 mpg says there is something wrong. (either fuel delivery or your brakes are stuck...)


When my choke opener failed I got 22 mpg and it ran terrible when cold. I would think at 17mpg it is running really rough, black smoke and smell of raw gas might be on the symptom list...

All 4 tires spin freely but it doesn't run too rough, and the only time i get an odd smell is for the first maybe 2 or 3 seconds after i start the car, and I'm sure that's what's left of the seafoam I ran through, and probably a little bit of engine oil because the smoke it blue not black. I'm going to print out the carb section of the repair manual for my car and borrow the vacuum pump/gauge from school and start tracing everything out and leave nothing to question. I'm also wondering how accurate my gauge of mileage was as I didn't run the car till it ran out of fuel nor did the fuel light come on (gonna follow the manual's instructions and test to see if the low fuel light works tomorrow), and my friend says that he could drive for 2-3 days after the gauge read "E" before it'd start sputtering and coughing



The usual suspects would be carb and choke heater and opener.
Download the manual and 'addendum' for your year. (link on this site) follow procedures to check the choke function. It sounds like you have already observed a problem here.

For fully warmed up idle, check to be sure the high idle unloader is working and then adjust the idle (knob on back of carb) only after all other issues have been resolved.

I get 26-27 mpg short trips around town in the winter.

I'm excited to start actually getting good mileage out of my "mileage" rig ;P

[A20A1]

Did you get your idle to drop?

[87ccord]

Did you get your idle to drop?

I haven't had much time to work on it yet, but I want to be sure, it's the screw directly underneath the end of the throttle cable?

Also, the choke housing has been riveted on, so does that mean this carb has had some ill equipped grease monkey of a mechanic playing around with it? or were these set at the factory and riveted in place to prevent someone from making adjustments to it? I ask not because my choke acts funny, but as a clue to why I might be getting such poor mileage.


Maybe I'm not getting poor mileage at all, maybe my fuel gauge is off and I had another 3-4 gallons in there? I decided to intentionally run it out of gas this time and see how far below E she goes. It's been 3 days of driving around town with friends, to and from school and work. She's still going.. so we'll see!

I still need to fill the tank again, and run it empty after that to see how a correct timing setting and the valve adjustment I did will affect my mileage. Paydays coming =)

In the mean time, I'm gonna see why the clutch isn't engaging on the air compressor, my rear defrost doesn't work, finish swapping the doors, the air recirculation button doesn't work, and maybe wash and detail it for kicks =P

Thanks for your Help A20A1, I look forward to hearing from you soon!
-Derek

[g.frost]

You don't have to run out of gas to get accurate estimate of your gas mileage.

*fill your tank(until fuel nozzle shuts off), and reset trip odometer.
* next time you fill up, record odo, and how much gas to fill the tank.
*miles driven / gallons to fill the tank = mpg.
* repeat a few times to get a good average; not all gas pumps will fill the tank to shut off exactly the same.

[A20A1]

I haven't had much time to work on it yet, but I want to be sure, it's the screw directly underneath the end of the throttle cable?

Yes :)

[87ccord]

Yes :)

Okay, Today I ran out of gas warming my car up to go to school, although I can't be sure as to how much gas was in the tank on my first fill up, as opposed to how much gas was in the tank 4 days ago when I decided the gauge read "E", but I resisted putting gas in the tank and drove almost another 50 miles. I've decided that no matter how I do the math on my first tank fill, my math includes to much guess work. So I'm going to throw it out, fill the tank again, and run it empty and see what happens.

Very true G.frost, I appreciate the advice, and will use that next time I wanna put gas in but don't necessarily have the money.

A20A1, I also pulled the plugs, glass beaded them, cleaned them with brake clean, blew them off with air, and reinstalled them, so I can tell if I'm getting a rich or lean condition. Tomorrow I'll pull them and see what they tell me, but before I cleaned them they weren't showing any signs of rich or lean, just that I had put a fuel additive in.


The sputtering sound emitted from the tail pipe at idle, and the fact that the exhaust system was connected to an engine with a severely blown head gasket for almost a month, I'm wondering if the catalytic converter is plugged. I don't live in an area where emissions testing is required, and I was thinking about just busting the catalyst out and bolting the section of pipe back on.


That would cause my poor mileage, low power, and would make most of my other minor problems worse wouldn't it? Correct me if I'm wrong, but the increased flow might also give me a "slight" performance gain even if it turned out not to alleviate any of my problems.


Any feedback on this would be greatly appreciated!
Thanks everyone =)
-Derek

[Oldblueaccord]

Valves are adjusted dead cold on Honda's not hot.

I would drive 100 miles and refill the gas tank and do the math from there. Just move the decimal point to the right one for the gallons you put in the tank thats you mileage. So 2.7 gallons 27 mpg. See no math needed. Just let it fill on slow speed till it clicks off. Dont top it off and really never top off and newer emmisons car.


wp

[kentwat]

^^Excellent tip!!

[87ccord]

Yes :)

Okay, Idle went down and is now at 750! Vibration increased as idle decreased, first thing I thought was vacuum leak, Sprayed starting fluid all over, and not once did it change anything.
What's my next step?

Today I'm going to replace the 278,000mile used steering column with broken headlight switch and almost broken wiper switch and an annoying squeal when you turn, with a 187,000 lightly used, in perfect condition steering column =)

Also, now that the idle has dropped, my previous timing seems out, so I'm gonna re-time it. I also gutted the cat yesterday, and it seems to have a little more punch to it now =)

I'm still concerned about the low mileage, but I will have to wait to find out how the adjustments have affected it.

My car was not hot when I got around to adjusting the valves, but they weren't dead cold either, so I may need to re adjust those I guess, my chiltons gives a WIDE range of gap for both the intake and exhaust, what do you guys adjust them to?
Thanks Everyone!
-Derek

[A20A1]

Actually now that I think about it... no.

The one closest to the end of the throttle cable on the inside of the linkage is the fast idle screw... the throttle controller screw is outside the linkage, they are on the same linkage and since I had my fast idle removed, I forgot about that screw.

[87ccord]

Actually now that I think about it... no.

The one closest to the end of the throttle cable on the inside of the linkage is the fast idle screw... the throttle controller screw is outside the linkage, they are on the same linkage and since I had my fast idle removed, I forgot about that screw.

ohh? So what did I do? lol The idle did drop soo? I'm half considering doing the vacuum removal stuff. So now that the cat is gutted it DEFINITELY smells like it's not burning all the fuel. Smells like noxious fumes. =S I will check the plugs tomorrow, in my experience, the cap and rotor don't look too bad, and neither do the plug wires, buttt, if I remove a plug wire, the engine vibrations don't increase by much, which leads me to wonder if maybe they're not setting off the mixture quite as well as they're supposed to?

I have the carburetor off the other engine laying around, if I decide not to do the vacuum removal (which sounds good right now, but I may very well opt out of it tomorrow) I will probably rebuild that carb and swap them out because I feel like this may be the source of my problems although I'd absolutely love it not to be.

[87ccord]

Update: Today I was making some adjustments because my idle was getting to be too low, (500 rpms) And while I was digging around I found 2 destroyed vacuum lines, #17, and #7, so I replaced them both, which didn't seem to make any difference. Vibration seems to have decreased slightly I suppose, but it still just doesn't seem to have much in the power department, it kinda surges while cruising, it vibrates at idle, and the exhaust still makes a sputtering noise.
I'm actually looking at selling this car in hopes of buying a 1992 lx 5 speed accord I found in good shape, or a 2nd gen DA9 LS Integra which I would do a 5 speed swap on. I love this 3gee, but I guess I just don't have the patience for the carburetion setup, and want better mileage. Having basically lost my job, I can't even afford to do this car justice, and hope that I can find it a good home.

[A20A1]

Whats the condition of the plugs and the gap on the plugs?

NGK's are usually preferred.

Plugs like BOSCH +4's will foul when they are not running hot enough, which is mostly at idle and cruise. I think the plug they give us may be okay on EFI but for carb motors it would have been nice if they gave us a different heat range which may or may not help the plug stay cleaner.


Off the top of my head... You could try hooking up the
- brake booster
- #2
- #14
- I think #6

Plug the line to the EGR and the AS valve and everything else not listed above. Hold the choke open once the car is warm then test the carb out. No real need to remove everything permanently, just plug them and test.

oh and Keep A, B, and C from the Air Jet Controller hooked up.

[87ccord]

Whats the condition of the plugs and the gap on the plugs?

NGK's are usually preferred.

Plugs like BOSCH +4's will foul when they are not running hot enough, which is mostly at idle and cruise. I think the plug they give us may be okay on EFI but for carb motors it would have been nice if they gave us a different heat range which may or may not help the plug stay cleaner.


Off the top of my head... You could try hooking up the
- brake booster
- #2
- #14
- I think #6

Plug the line to the EGR and the AS valve and everything else not listed above. Hold the choke open once the car is warm then test the carb out. No real need to remove everything permanently, just plug them and test.

oh and Keep A, B, and C from the Air Jet Controller hooked up.



Plugged the EGR, and the AS valves. Much more power, much smoother Idle. I'm assuming mileage is also seeing improvement, still need to replace the two lower motor mounts, and give the ignition a tune up, but as far as I'm concerned, Problem Solved!

I have a new addiction though. And my father is NOT happy :D
I drove a 1994 Acura Integra today. It was pretty riced out and I was pretty skeptical, but I took it for a spin, that car had more power from 650-1200 than my 3gee at 5500. With a redline of 7250 and dohc, I couldn't believe hitting 75 in 3rd gear before shifting, and the sound.... Ricer Heaven ;) but I was definitely impressed, for a car with mild tuning, and a gsr transmission, no header, no turbo, but boy o' boy was that go pedal sure doing it's job =P


Thanks for all your help everyone, I'll post my current mileage as soon as I can quit driving my accord like that integra, and do some math.
-Derek