Cant get it to not run in the rich mode after closed loop is made , check engine light comes on while driving for about a minute then goes off for a few minutes , I rebuilt the carb, new egr, new o2 sensor , all sensors read correct motor gets to 180 degrees .... engine runs great but every so often it will stall at a red light when you hit the gas but starts right up.
Any ideas will be great. Thanks ahead

 

The dreaded code 45... funny (well not really) but I was talking to my daughter tonight about my wife's old car that had the same issue... it's almost like... "Hey, lets set a code that you can't figure out"... it's a crap shoot for sure and as bad as I hate to say it, you like me... will chase this for a long time.

So many things can cause this.. normally code 45 is set when the o2 sensor signal voltage remains above .7 volts for 30 seconds or more and in the closed loop mode. If the car was a 1982 I'd say go to the injector and see if it's leaking, on a 81 it is very hard to diagnoses.

So.. I'm going by my notes on my office computer (I'm at home)
Code 45 can be caused by rich exhaust, too much fuel pressure, and believe it or not... lack of HEI shielding (HEI noise in the system). an open ground can result result in induced electrical noise. The ECM looks at this noise as reference pulses. The additional pulses result in a higher than actual engine speed signal. The ECM then delivers too much fuel, causing the system to go rich. The engine tachometer will, also, show higher than actual engine speed, which can help in figuring out the issue.

Next.. I'd take a look at the 02 sensor... make sure it's clean and the wires are not melted...make sure the sensor is clean looking.. possibly replace it.

The issue is so wide out........ 45 is a hard code to determine... I've got a page at my office on this if you'd like, email me at Service@Willcoxcorvette.com and I'll forward you a copy tomorrow... Normally... I'd stay away from code questions, (cam issues, engine build questions, and other stuff... because everyone has an opinion)...

But no one responded so felt compelled to offer my opinion... I don't like getting involved in code questions and mainly because they are difficult to figure out.. the dreaded 45 to me is a crap shoot... and as bad as I hate to say it, you'll chase this for a long time until you figure it out.... Email me and I'll send you a page tomorrow... hopefully this will help.

Willcox

 

I would take that carb and ecm and throw them in the river. GM had to try something in 81 to get emissions better. This setup is the end product. Buy a wideband kit since you have an oxygen sensor mount hole. And just about ANY carb will be an upgrade. Trying to meter fuel with an ecm while using atmospheric pressure to suck it in instead of fuel pressure to inject it was a stupid idea. Trying to continue using that stupid idea with 37 year old components is not gonna end well

 

thank you , the o2 was reading correctly making full sweeps when I opened vacuum hose or closed choke but I changed it anyway no wire issues, mc dwell seems to be working around 30ish in open loop but when it goes closed goes up to 54ish as the o2 goes rich reading , timing right on 6 degrees .... I read that about the sheilding I do have the distrbutor cover I might try to put that on but dont think thats it a high 50's reading means the mc is trying to lean it out right? , a couple of things I noticed in carb when open the secondary tubes were off laying inside , and the float looked wet still after sitting on the bench I thought it would be dry , it is set and wasnt sinking sitting ... the tubes were put back. One other thing the primary rods one had a much firmer spring than the other not that that would make it run rich. The evap vent hose at the carb is dry as is the other vacuum hose conections.
I dont give up easy lol I will mess with this till its fixed. I will email you

 

Derek I could not agree more the system blows but I want to fix it its really not that complicated something is wrong. I will give it a try .