I recently have had my check engine light coming on and going off whenever it wants when it does come on the car bogs down and does not pick up as quick as it usually would occasionally the light will go back off before i get a chance to try and read it but when i do have the chance to read it the light wont flash. the most recent incident i had with it was this evening was pretty cold out and started the car to let it warm up light came on and it had a little trouble cranking but once it started had no issues turning off and starting again. anyways i let the car warm up and when i came back outside to check it the light was off im completely stumped by this and im hoping someone can help me sorry for the long post and in advance thankyou for your help

 

Also shortly before the check engine light does come on the car will start to fluctuate idle between 1k-1.5k going up and down during the duration of the light being on however long it decides to stay one

 

Still have not been able to figure out this issue any help would be greatly appreciated

 

What model year?

After the CEL has come on while driving (even if it later goes out), put in the jumper with the engine still running-- do not turn the key off.

If you don't have "back up" power to the ECU it will forget any codes when the key is turned off. The back-up circuit is an always live wire fed from the battery via a fuse in the underhood fuse box. This also powers the AM/FM radio, so it is common to blow the fuse when trying to install an aftermarket radio.

 

It is a 1993 honda civic eg hatchback it is b18a1 swapped with only like 2100 miles on a freshly rebuilt motor this is the first issue i have had with this car since the rebuild and swap i have tried to jump it while leaving the car on the light will not flash the CEL only goes out when it wants to not just because the car is turned off and on all of my fuses are good when the light is not on car runs perfect no issues but like i said when the cel comes on it bogs down i have check the o2 sensor and all of its wiring no issues there i know the car is running pretty rich could that clog up the o2 sensor so bad in 2100 miles that it would start to malfunction? i have removed the o2 sensor the other day and it did not look too bad on the outside just looked pretty old but i have seen them get alot worse i suppose i could look into replacing that but im willing to bet that is not the issue