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Growing up is an option
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Discussion Starter #1
just got my FTI cam installed last nite (228/232, .612/.600, 111 lsa). man does it sound bad ass :D. i heat cycled the springs on idle and took it out for a short easy spin. the car surges a lot at low rpm and it wouldn't idle after it warmed up if i didn't give it gas. i logged part of that run and my fueling was very rich, in the 12s AFR. i think it's because my MAP is high from back flowing due to the high duration cam. i also got some popping on acceleration. my questions are

1. i have a HPT speed density enhancement and it has the "multi" table as an addition to the VE table. it uses throttle position as a modifier for the VE table i think to help compensate for cam MAP problems like i have. how does it work and which way, up or down, should i adjust it?

2. with the high MAP and rich AFR should i be just adjusting my VEs to recalibrate my AFR?

3. is the low RPM surging a result of the screwed up AFRs and if i correct that will it go away or do i need to use the "multi" table?

4. i adjusted my target idle speed up to 900 rpm but it isn't getting there. would it be better or easier to just adjust the idle screw on the TB to get it close?

i'm asking because tonight i'll try to get some of the issues looked at and want to know where to start. i've got 3 days before the big M11 event at Mid Michigan Motor Plex in Stanton, MI this saturday and would like it to at least be close to running well... like low 12s :D
 

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You could put it in speed density mode to see if the MAF is causing the issue.

This came from an LS1 tuning guide, haven't done it since I am not cammed yet but these suggestions may help.

In addition to the Idle Airflow routines the PCM also has an RPM based idle spark correction "closed loop" operation that it uses to control the idle RPM. Since the spark advance can move much faster than the IAC, it can provide very fine control of idle speed. When logging you will see this as a jagged spark advance chart, most noticeable with cams at lower idle RPM’s where the spark advance generally oscillates between its min/max allowed values as the engine lopes at idle.

Idle Tuning
To set idle speed go to VCM Editor>Edit>Engine>Idle>Idle RPM>Target Idle RPM vs. ECT table and change cell values to desired idle RPM. If idle RPM is modified up or down, the VCM Editor>Edit>Engine>Idle>Base Running Airflow>Idle Airflow vs. ECT table must be adjusted up or down also.
If a lean idle condition is present modifying VCM Editor>Edit>Engine>Fuel Control>Open & Closed Loop>Idle Proportional Fuel Tables = Off will most likely eliminate it and any low RPM surging.
A Basic Idle Tuning Strategy
1. Set idle speed to desired RPM. 900-950 is good for cars with aftermarket cams.
2. Go to all your spark tables and set the park and drive idle values to about 22 degrees.
3. Now switch to a scanner that lets you see IAC counts and TPS voltage. This is where we will spend some time.
4. We want IAC counts to be 40-60 for cars with aftermarket cams. The stock cam runs about 60-80 counts. A car with an aftermarket cam will want less IAC counts.
5. To reduce IAC counts turn off the car. Turn the idle set screw clockwise to open the throttle blade a LITTLE. Unplug the TPS, turn the key to the on position, DO NOT start the car, for 30 seconds. Turn the key off and plug TPS back in.
6. Start the car and begin scanning. Monitor the IAC counts and repeat step 5 until the IAC counts come into line. It will take about 4-6 times to get the IAC counts correct.
Note: Keep in mind that TPS voltage must be in the .4 to .6 range. If above or below this voltage, the PCM will fall into the wrong cell at idle. Check the TPS voltage each time the set screw is adjusted and adjust as necessary.
Another adjustment that will help start-up and idle is to go to the cranking VE table and multiply the whole table by about 80% to lower it. Now go to the primary or secondary, if the PCM has it, VE table and drop about 3-6 counts off the idle area.

Open Loop Idle Fueling
The VCM Editor>Edit>Engine>Idle>Base Running Airflow>Idle Airflow vs. ECT table is like a software choke that is used to control the mixture at idle when the engine is in open loop. It controls AFR by opening or closing the throttle blade slightly to meet the values in the cells at a given coolant temperature.
Closed Loop Idle Fueling
For closed loop idle fueling the 400, 800, and 1200 rpm cells at the lowest MAP value’s in the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP table has control over idle fueling.
 

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Goatless
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walterd said:
You could put it in speed density mode to see if the MAF is causing the issue.

I don't know anything about tuning, but I'm doubting that his MAF is causing the problem...
 

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My cam is very close to yours. Mine wouldn't idle at all when started. I brought a Tech 2 home and adjusted the idle screw. It idled good after. A couple things to keep in mind though. I drilled the TP sensor to make it adjustable. Then monitored the IAC Counts, TP voltage, and TP angle along with idle speed. I got it to idle at 650 without a problem. One thing that was annoying was if you adjust the TP voltage to high is will raise TP angle above 0%. You can get around this by turning the car off for approx 15 sec then restarting. Once this was done, I was able to drive it for a solid week(with the a/c on) until I got it tuned.
 

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Growing up is an option
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Discussion Starter #5
well i physically adjusted the throttle screw to crack open the plate a bit, did the TP reset thingy noted above by unplugging it, turning on the key for 30 sec and then plugging it back in. i got it to idle and it slowly seemed to "learn" what to do. i also raised the target idle speed in HPT to 950 RPM. i then went out logging and my VEs were off in the low RPM and low MAPs by -20%. i just started flashing in "multiply by O2 error percents" to the VE table and now it's starting to run pretty good. i have a long way to go tho. one thing i do notice is that when i'm deaccelerating to a stop, when i push in the clutch the idle doesn't come down to target speed until after i stop and then it's a little slow getting there. great lumpity-lump cam :D. i can't wait to get to the track and finish tuning and see what she'll do.
 

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Growing up is an option
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Discussion Starter #7
thanks, i'll take a read at it. any help is appreciated
 
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