I'm just wondering, why is the timing all over the place on this log, the car sounds a little odd warming up, like a misfire almost, but smooths right out when its warm.

The timing on this hits lower than the map has, my lowest advance in the load columns for these loads and rpm is 7... why do I see 6 on here, and I think 3 once!?


Mods are mbc, flash, comp280s, 3"tbe, o2 housing

 

Possible exhaust leak at the O2 housing jacking up the O2 sensor readings. Or maybe the O2 sensor is jacked (I didn't look at the log). You are running some pretty big cams which generally makes it a little tougher to idle.

 

Definitely the cams are the cause. I have 272's and have been messing with numerous different setting to smooth the idle. It will idle smooth to the ear, but the timing jumps on the logger.

 

i run some of our cars at 11 degrees static at idle, seems to help

cb

 

Ok, Thanks for the input... I was wondering why the timing was less than what I have in the map when it "dips" but the octane on the logs is still 100

 

If the dip bugs you, paste your 1250 rpm row value into the 1000rpm, then vertically interpolate 1000 rpm row to 500 rpm to transition.

 

Would this help smooth out warm up "idle" do you think? I could give it a try

 

likely not, hopefully someone would chime in on how they smoothed their 280 cam idle.

Search "Timing 280 Idle"

Or compare ROM to someone with 280 and decent idle

 

a majority of the idle problems are actually engine vacuum and MAF related. If you can keep the airflow up through the MAF, the idle will be much smoother.

Another key point is to spend time making minor adjustments, your DV Opening and closing at idle depending on its seat/spring pressure will alter the airflow and cause dips, your Idle speed needs to be a minimum of 1000rpm and your fuel trims at idle needs to be very close to optimum so it never has to reset trims.

I never needed to touch my idle timing with 280 cams in my car. I have a stable MAF reading at ~37hz using my blowthrough setup.

 

Ok, so being that this is during warm up, 1000+rpm, it is possible the DV is opening and closing causing the idle to jump from 1000 to 1200 ?

I am still running the stock DV, I hadn't seen any trouble with it that I could tell, so I just left it alone and figured if it failed I could replace it then.

I also am possibly interested in a blowthrough maf setup... maybe I'll have to do that sooner than I thought.

 

There is a table for Idle speed based on coolant temp, you may have to raise the idle when the car has low coolant temp.