Code 41: No distributor signals

I have not had any luck figuring this out and spent hours looking for an answer. Not sure if it is electrical or mechanical.

I have a stock 305 L69 vin G running an E4ME carb. The E4ME is not stock to the car. It is from an 85 Caprice 305 vin H. It was a junkyard find for $25. The car had an edelbrock on it, but I had to go back to stock due to emissions. The car starts and runs great down the road. The only problem, I get is when idling at a stoplight. After five minutes engine idle will fall around 200 rpms and it will trigger a check engine light giving me code 41.

The car does idle a little rougher and the vacuum does fall from 18 to 15 hg. I have a fulltime vacuum gauge mounted in the car. If I restart the car, the light is gone and I do not see it again unless I stop and idle for 5 minutes.

If I run the A/C, the idle kickup solenoid engages and the idle is stable enough not to trigger a code 41. It might fall a little bit, but not enough to trigger the code. Feels very stable.

I tried adjusting the idling screw up a little bit, but idle still likes to drop triggering the code.

One small problem, I have with carb is the occasional seepage of very tiny amount of fuel out of the throttle body linkage. I am talking a few drops of fuel. I have taken it to several people about re-bushing it, but all said it fine and if the carb is starting and running down the road well, don’t mess with it. Of course, I do not know how bad the seepage is due to evaporation of fuel due to engine heat. The other day I ran the car and did not find anything. Also, the fuel mileage is still really good.

Any help would be appreciated…..

 

What kind of distributor is on the car?

 

The factory HEI distributor that is controlled by the ECM. It does have a factory EST system that works with the HEI distributor. As far as I can tell the distributor is original to the car.

 

It turns out the problem was an intermittent vacuum leak at the T-fitting that goes to the EFE. I have marked the spot with a red dot in the attached picture. When the car was cold the vacuum hose was sealed, but as the car got hot at idle it started to leak, falling idle and code 41. I have an aftermarket hood with air vents in the front, which I believe would allow cool air to blow on this hose sealing it back up until the car would idle making it hot once again causing the hose to leak. Anyway, I found it one day by accident when I was under the hood. I changed it with a new vacuum hose, which got rid of the code 41, but also changed how the whole car idled and ran emissions. When, I first got the car, I hooked up led lights to each emission device to see when the computer would operate the devices. The only time the computer ever operated these emission devices was at start up during the first couple of minutes and nothing after, which did not follow what the factory manual said would happen. Now after replacing the hose the computer operates these devices all the time just like the factory manual says. The emission devices go on and off during acceleration and deceleration. Replacing the small vacuum hose completely change how the car ran for the better.

 

im having this same issue, idle though is around 500rpm.

 

I was told by an old-school mechanic that the idle for these electronic carbs have always been somewhat erratic. My car idles much better now, but the idle does move up and down on occasion. Sometimes it is 500 rpms, others it is 700-800 rpms. The only time it is absolutely stable is when I run the a/c and the solenoid on the car kicks the idle up. Then it is rock solid.

If you have not already, I would recommend buying a vacuum gauge. Running a full time vacuum gauge has helped me figure out a lot of problems.

 

thanks, i seem to have a broken line in that part too, didnt think that would be a problem though. ill mess with it later, so did your check engine light go away after fixing it now?

 

Yes, it went away.