MSefi.com read only forum (Jan.15,2018)

i have a 87 crx si road racer that i have been working on since may it has a megasquirt 2 version 3.0 (preassembled), running megatune 2.25 and narrow band o2 sensor (which just recently went out) and stock ignition with the exception of a high output coil. i really dont understand alot of this stuff but i find that the more i read the more i do learn and understand. i am at the point where the car will start up great and have gotten the warmup enrichments set great. being the car is a race car i cannot just take it out on the street and "drive tune it" so i am just going through the rpm band while in neutral setting up the VE table. i have been doing good untill i got to 3000 rpms. i get heavy backfiring from there up. i have tired both leaning out and richening out heavily and i still get it. this was happening before the o2 sensor went out also. i am going to go back and check my wiring because i have had issues with that on my part in the past since installing it. i have a feeling it is something really simple that i need to adjust or change but has not hit me.

the other thing is how do you check a 02 sensor does it have resistance that can be checked. i have a oe manual for the car but it is for the stock ecu and it basically checks that and says replace the o2 sensor if the ecu is in specs.
thanks in advance to any help

i found the problem. thanks for the help

monzster wrote:i found the problem. thanks for the help

what was it?

it turned out that i had to change the dwell to a low number. i changed it to 1.0 and it solved the problem. unless i am reading the manual wrong this is backwards. im not sure if this has anything to do with it but the car does have an adjustable cam gear and it is retarded from TDC. the car seems to be doing great at a idle and when given gas through the whole acceleration band. i have yet been able to actually have the car driven. this will happen next weekend.

I have the same problem and at about 3000 rpm At light throtle and up my car pops I found lowering the max_dwel helps I havent tried 1 because tha seems weird I am running a msd to a coil and a 8cl with a distrubitior. I will try 1ms tomorow o my 1400 km trip home!