idle a litle rough?

[CDeeZ]

Most of you already know that I swapped from the '747 to the 427 PCM recently. Thanks to the help of those who inhabit this forum, I was able to get up and running on the '427 PCM.

Now I made some logs and adjusted VE using dave's spreadsheet and things were starting to look decent, but I have decided to start over on tuning the VEs for the two reasons below.

First, I wanted to see if I could get away with a higher injector flowrate since I have always been pretty rich at idle after the '427 swap. And also, My VE tuning that I had done, I forgot to turn off DFCO and PE when recording BLMs, so I think my data was inevitably skewed.

I raised my injector flowrate (again) from 69 to 74 lbs/hr, and pasted the stock fuel tables back in and proceeded to collect BLM, this time with PE and DFCO OFF. After one run of logging BLMs, my highest BLM was 127 and lowest was 110.

Now after several rounds of using daves VE spreadsheet, this thing runs and pulls STRONG with the engine loaded.

My question for today pertains to idle: At idle, the BLMs are around 110-117. When idling, the engine is a little more choppy than I think it should be, especially given that the cam is just under .5" of lift. Also, on startup sometimes the idle will fluctuate pretty wildly, then settle down. During idle, my transmission seems to make what is known as "neutral rollover rattle" which is totally normal to a manual transmission, but, I wonder if my rich and therefore choppy idle is responsible for making this more noticeable? When I was running the 747 the idle was very smooth and you didn't hear the rollover rattle as much. I think the rough idle caused by the being rich is what is causing this exacerbated rollover rattle.

And BTW to determine if a noise is in fact neutral rollover rattle, you can "float" the noise out by revving up the engine a little bit, and this is my case.

How should I go about cleaning up the idle manners of this thing? Try an even higher injector flowrate? Or slew down then entire VE area responsible for idle?

I'm posting the datalog I made tonight, you can easily see the idle fluctuation I'm talking about at the beginning of the log. Would someone please take a look at this and tell me what they think??

[gregs78cam]

At the end of that log while at an idle you are still at right around 1.00ms PW and BLM says the VE table is rich. So you still have room to take fuel out of the VE table. You should easily be able to get down to around 0.60ms PW before things get unstable. What are your IDLE VE table values in the area that you idle in?

I would also say to flatten out the SA in the idle SA table right around idle, that should smooth out the idle by not making SA jump all around. Your SA is anywhere between 4 and 16 at idle and IAC steps are just as bad. Those two items should almost be rock steady.

[EagleMark]

The little bit of idle in beginning of log looks bad... most in open loop and RICH. Look at O2 data in .900 to .800 range = rich... First thing is temp at 100C is 212 F is high and could be adjusting for it in bin. Second is MAP, RPM and Spark are rocking back and forth so bad your entering AE, may need to raise idle some for cam, steady spark timing by leveling it out and even raise it some, lean out VE...

[CDeeZ]

At the end of that log while at an idle you are still at right around 1.00ms PW and BLM says the VE table is rich. So you still have room to take fuel out of the VE table. You should easily be able to get down to around 0.60ms PW before things get unstable. What are your IDLE VE table values in the area that you idle in?

I would also say to flatten out the SA in the idle SA table right around idle, that should smooth out the idle by not making SA jump all around. Your SA is anywhere between 4 and 16 at idle and IAC steps are just as bad. Those two items should almost be rock steady.

I'm not sure exactly what the PW is? Pulse width as in number of miliseconds injector is on? During my last log, I thought I enabled data tracing so I could see precisely what cells I idle @ on the IDLE VE table. But, when reviewing the log there is no data tracing for some reason..... I'll have to try again to log with data tracing enabled and get back with an answer for EXACTLY what RPM/MAP cells the idle is. In the meantime I've tried flattening out the low RPM/MAP area on both VE tables for what I THINK is the general idle area on the VE tables. Also made the changes to spark advance, flattening out idle area as suggested.

The little bit of idle in beginning of log looks bad... most in open loop and RICH. Look at O2 data in .900 to .800 range = rich... First thing is temp at 100C is 212 F is high and could be adjusting for it in bin. Second is MAP, RPM and Spark are rocking back and forth so bad your entering AE, may need to raise idle some for cam, steady spark timing by leveling it out and even raise it some, lean out VE...

Ahh I bet you're right about the high temp... See what I did was set my Fan ON temp to 10 degrees ABOVE what my T-stat is, which is a 195F stocker. I did this because it was what 93V8S10 did with his own fan settings with that '427 E-fan code, only he used 165F T-stat..... In the thread I started about the E-fan code I asked about this and I remember RobertI said this was to potentially avoid increased thermal cycling...
Anywho: I lowered my Fan ON temp to right @ when the T-stat opens up (195F).

I raised the Idle SPeed tables by 100 RPM so that my target idle when up to operating temp should be around 625-650-ish RPM. Come to think of it, I think the idle speed tables for this bin (BJLH) w/ a automatic are just going to be low in general for a vehicle running this bin, but with a manual trans.. I remember when I was messing with my '7747 I used a manual based bin and compared the idle speed table in a manual bin to a bin from an automatic and found the manual to be roughly 100-150-ish RPM higher than a comparably equipped truck with an automatic.




I know I've been able to get data tracing to work in TP before, but I can't remember, do you have to link the XDF to ADX on the laptop used for datalogging?

[EagleMark]

Your working on all the right things to get the idle dialed in!

Data tracing:
http://www.gearhead-efi.com/Fuel-Inj...unerPro-How-To

[CDeeZ]

Okay that's good to hear. Thanks for the help and words of encouragement.

I read the thread on data tracing and have now successfully setup data tracing on both VE tables... Success! Just need to setup data tracing for spark, idle speed tables and a few other things ....

BTW, did one of the $42 XDF/ADX combos we have laying around here already have data tracing setup? Seems like I remember connecting with the old '7747 and just clicking the data tracing button in TP and BAM! it worked without any manually changing of XDF.

[EagleMark]

All of the $42 files I have been working on since V4 have Data Tracing set up. They have to be used as a set.