alternator delete problem (CRX 1.3 engine idles too high while belt removed) - Fuel Economy, Hypermiling, EcoModding News and Forum

mikehallbackhoe · 04-27-2012, 10:01 PM

I tried my crx with the 1300 engine without the alternator today. I installed an optima deep cycle battery, removed the alternator belt, and carried the stock battery and belt with me just in case. first thing I noticed was more power. I could climb hills in 4th, at 1500 rpm that I would have used 3rd at 2000 rpm before. I traveled 2 hours on mountain roads, but I noticed that when I pushed in the clutch, the rpm would stay at 3,000 rpm. when I got to work, I put the stock battery back in, and put the alternator belt back on. driving home, I had no trouble. what could be the problem?

California98Civic · 04-27-2012, 11:09 PM

I can't see the battery being an issue. The alt seems to put significant load on your little engine. With the belt removed the pulley is freewheeling and allowing the engine to rev up. Without the ECU systems most of us are accustomed to, the engine seems to have no way to adjust the idle. That's my guess. Maybe someone with experience with these older engines will have a solution. Good luck.

EDIT: it has to be a fuel thing, right? That's why you see more power in gear too. Your opportunity without the alt belt would be to adjust the fuel flow downward, no? Power-up your battery by plugging in. That would consolidate and expand the FE gain from eliminating the alt. Does that sound plausible?

ecomodded · 04-27-2012, 11:55 PM

Could be one of the unused alternator wires on the wire harness needs to see battery voltage. Check to see what each alternator wire is used for.
Most if not all North American sold passenger cars including trucks and Japanese imports started using a computer in their cars since 1980 - 81
You would know its your car but i would be amazed if it
did not have a computer.

t vago · 04-28-2012, 12:01 AM

I dunno... The simplest explanation may be the best one. If the OP's carburetor has no electronic controls of any kind (which is likely but not certain to me), then it could simply be a matter of loading (or the lack thereof).

mikehallbackhoe · 04-28-2012, 12:19 AM

the crx is an 84. no computers. I noticed the fuse box has an alternator/carb fuse. removing the alternator belt should not effect any electrical on the carb, unless a certain voltage is needed. I wonder if the choke, and high speed idle were effected?

Christ · 04-28-2012, 12:37 AM

Turn the idle down on the carb. There's a dashpot valve that expects a certain vacuum to operate correctly (unless it's the electronic version, can't remember) and is set to basically keep an idle speed under an expected load. You've removed a huge load from the engine, so it's bound to spin faster now.

Welcome to the joys of ecomodding.

There is also a chance that the electric choke isn't opening properly due to lack of proper voltage. You can check this by removing the filter pan and pinning the choke open with the engine warm. If the choke valve is already open, there's no problem there.

Check all the 200 feet of vacuum lines by shooting ether (starting fluid) or carb cleaner at them. Ether will make the engine race, carb cleaner will make it stumble. Watch as you soak the lines, any vacuum leaks will dry up quickly right around the leak, and this can also be a partial cause of your problem.

A few rudimentary checks, then report back and we can go from there.

Christ · 04-28-2012, 01:06 AM

There is also a wealth of information for your car on redpepperracing.com, including a walkthrough on deleting most of that vacuum crap and tuning your car to run properly. It's a performance oriented site, but some of the information is still applicable.

mikehallbackhoe · 04-28-2012, 01:40 AM

everything I have read about removing all the vacuum hoses usually ends up with a bad running engine. I believe you are right about the idle adjustment, and possibly the electric choke. putting the alternator belt on solved the problems, but I sure enjoyed the extra power with it off.

mikehallbackhoe · 04-28-2012, 02:56 PM

now that I realize the choke is opened when the voltage heats the spring, which opens the choke, I wonder if coasting allows the spring to cool off, also causing the choke to come on? up here in the mountains I can coast for miles. would I be better off getting a manuel choke?

California98Civic · 04-28-2012, 04:06 PM

Quote:

Originally Posted by mikehallbackhoe

now that I realize the choke is opened when the voltage heats the spring, which opens the choke, I wonder if coasting allows the spring to cool off, also causing the choke to come on? up here in the mountains I can coast for miles. would I be better off getting a manuel choke?

So you tried adjusting the idle? You're certain its the electric choke? Then I think you have a good idea. Remember though, part of your FE gain will be lost if the added power is used for faster speeds or for less than ideal acceleration conditions. I forget, do you have a vacuum gauge?