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
backfire at 3000 rpm n up
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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.
Re: backfire at 3000 rpm n up
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!
Its finaly on the road! Self Custom Made 440 Road Runner efi. http://www.youtube.com/watch?v=974YsInWxhQ ms2extra release2.1.0p code