PCM Diagnostics & Tuning - FI tuning - timing and afr




View Full Version : FI tuning - timing and afr


273sunsetZ
04-08-2012, 10:17 PM
I've been tuning on my car all weekend and just noticed today that its seeing 2* of kr at part throttle acceleration of no more than 145kpa. It will go up to 2* at first and then works its way to 0.

My question, is there a general rule as to what afr and timing needs to be, at part throttle? I'm thinking this might have something to do with it since I've botched the timing table up so many times in the past when I was running nitrous. I've thought about just starting with a stock timing & Ve table and going from there but i've put a lot of time into the drive ability tune of this car, and have never seen kr before unless it was @ wot. Any advice?


273sunsetZ
04-08-2012, 10:20 PM
More info:

Front mount pte 76
346 ci
Total commanded WOT timing 14*

gectek
04-08-2012, 10:37 PM
The better info would be the log and tune. I have stressed this in quite a few other threads, but are you sure its actual knock? It could be burst knock since you said it goes away so fast. You can log that and see what is going on.


273sunsetZ
04-09-2012, 02:11 AM
i've attached the files. let me know if you find anything. Part throttle and driving around it's fine but when I stab the peddal there is hesitation, afr skyrockets and so on... so this is the log where I kept trying to create the issues so i could see what kpa, rpm, afr, and timing were at when it happened, i think it shows a total of 1.7* KR during part throttle acceleration and i never get over 50% tp, i believe timing ended up going down to 10* but to be honest i have no idea what this number should be during part throttle??? I'm waiting for a new IAT sensor to come in so set everything in the table to 0, but never had any issues before with the iat pulling timing. Generally, i know how to tune for WOT by BE, VE, and timing tables and have never seen any knock at wot, it always shows what it commanded, which is 14* and afr in the mid 11's but this part throttle issue is a first, i've been driving this car for about 7 months and never noticed it.

I recently changed the fuel setup from factory lines, regulator, 80lb's to -8 feed, fast rails, brfpr, and return.

gectek
04-09-2012, 02:39 AM
So you have the maf turned off in the diag tables, but adding fuel? Are you speed density? Open loop speed density? Since your long terms are off, your short terms are off all the codes are erased.

Is there a reason you are doing it this way? How high does the car really idle at?

Honestly your VE table has some bad transitions in it. And your spark table as well. I think your PE is not coming on soon enough with boost and you are running into a problem of an overlean followed by overly rich condition. Esp if you look at the eq ratio. Your pulse width skyrockets out of nowhere with your normal transition. I am not seeing any MPH so its hard to tell. Both are zero. You still running the 4L60?

273sunsetZ
04-09-2012, 05:39 PM
So you have the maf turned off in the diag tables, but adding fuel? Are you speed density? Open loop speed density? Since your long terms are off, your short terms are off all the codes are erased.

Is there a reason you are doing it this way? How high does the car really idle at?

Honestly your VE table has some bad transitions in it. And your spark table as well. I think your PE is not coming on soon enough with boost and you are running into a problem of an overlean followed by overly rich condition. Esp if you look at the eq ratio. Your pulse width skyrockets out of nowhere with your normal transition. I am not seeing any MPH so its hard to tell. Both are zero. You still running the 4L60?

I had a partial tune put on it last year. i'm not sure what all he changed and to be honest i have no idea how it should be. I am only running a wideband out of the downpipe which dumps at the front passenger tire, I really need to get a bung welded into each side of the crossover pipe for the 02's but just havnt had time. The car idles right at 1k, it has a pretty healthy cam and much lower than that will cut off when i put it in gear. I'm running a th350