C.E.L. after carb swap on 307 Boxie Motor

So as many might already know, I replaced my rochester q-junk with an edlebrock. Wasn't going to bother rebuilding the q-jet. Posted it on the parts for sale part of the forum so if you want it for your own bad self head on over there.

More importantly, now I have a Check engine light on and off and on again in the car. Probably because the EGR is disabled now, but I'm not sure. Any ideas?

What year is the engine? Did the original carb have electrical connections? It's likely the ECM cannot find the carb anymore to adjust the mixture and is throwing codes for that. You can remove the ECM and check engine light since you already changed out the carb, install a straight vacuum advance distributor and call it good.

So that's all the ecm does is the carb and dizzy? No anti knock sensors or anything like that? Huh.

It's a 1987 engine. What distributor should I get for it?

I don't know much about the Olds 307, but I would think there is also a knock sensor in the mix. I would think any distributor to fit a later Oldsmobile engine would work. But just do your homework before ordering parts.

Strange: after a few drive cycles and one good long drive, the CEL went away and has stayed away for good? Maybe the computer 'learned'?

sometimes fixing a problem like the cel when you have removed or added parts,. involves modification to the dash display,...

You mean taking out the light bulb, right?

lakeffect wrote:

You mean taking out the light bulb, right?

Yes captain...

Maybe, those C3 systems were pretty primitive. If the car is running and driving fine then leave it. I seem to recall driving my 83 malibu with the ECM removed removed around the yard....didn't run great but that 229 V6 never did.

74-78 Olds 350 HEI...... Pre-ECM distributors completely self-contain the timing and spark function and operate off of the single pink ignition wire..... Later ECM- controlled distributors have no advance functions on board....They still are powered by the pink wire, but are controlled by the ECM by completing the negative side of circuits that are simply grounded on an HEI....

If you replace the distributor with a 74-78 HEI and have a completely mechanical carb, your engine is effectively no longer under the influence of the ECM..... Now would be a good time to disable the light, EGR, AIR, and anything else that doesn't help the car run.....You will probably lose fuel mileage, mostly to the carb, but you will have simplified your rig.... The penalty is buying more gas....

P.S.-- Another thing that often happens on 80's cars is that the catalyst honeycomb in the cat breaks up and clogs the tailpipe..... This can literally bring a vehicle to it's knees, barely running and overheating after the first half hour..... The fix is to cut a hole in the top of the cat, empty it out, and weld the piece back, so it's hollow.
Use a four inch hole saw tipped so as to leave the tab attached on one side for easy rewelding and do it on top so it won't be visible in an inspection