Rough Idle tuning noob
 

Hi all,

I had my car tuned around 4 months ago and everything was great until recently. Now when the car is cold I sometimes get a rough idle or the car will instantly drop to 0 rpms and stall. If it doesnt stall the car will go from 500-800 rpms back and forth and slowly close the gap until at operating temps. I have never done any tuning myself so I am very confused and was hoping i can find some help here.

I took a datalog of the issue so if anyone can help there that would be great. Also its possible that this started sometime after I did a coolant reroute, could that have anything to do with it? Any help is appreciated.

Thanks

I attached the .msl datalog

I didn't look at your log, I drive an NB so we don't do coolant reroutes, BUT, there is a CLT/MAT correction factor.

Pretty much, it says that since coolant runs to the TB, that at idle, the air coming into the motor (MAT) should be equal to the Coolant Temp (CLT). Truthfully, on my car, I haven't messed with it, as I haven't seen a need to, but since you mentioned coolant reroute, that maybe a possibility.

Try adjusting your warmup enrichment. A wideband O2 sensor will be helpful here.

When I first installed my ms it was warm outside. Car ran fine, everything was good. I finished up my turbo install a few months later when it was 30* outside. The car would barely start and would idle rough and kill like you describe. I called begi and steph helped me tune the warm up enrichment. If the temp is cooler than usual that might be what it is

?

it's actually warmer than it was when it was originally tuned. Could be the same issue though.

On the 01+ NB's, Mazda changed the head gasket design, so we're not supposed to do reroutes, unless we change head gaskets.

I was implying that there may be an issue with the MAT/CLT correction factor.

Best thing to do OP, is add a gauge on TS for MAT Correction, and check the percentage.