Need some help with a base tune changing intake LS1 VCM710

Hey All,

I've got an LS1 with cnc ported 241 heads, a VCM710 cam and 4L60E with a 3000 stall in my 85 TransAM knight rider replica (of sorts).

I had one of the sheet metal ebay intakes on it with a 102mm throttle body, but got the advice to dump it in favour of the LS6 intake they used on all the Holden VY commodores here in Australia and use the stock throttle body that came with it.

I've installed the intake and I'm having some troubles with the idle, and also having trouble with the revs delaying when letting off the throttle. Instead of dropping down quick it holds for a second and then takes a few seconds to come all the way down.

I've upped the idle to 850 across the board and it'll idle ok there but the timing seems a bit unstable jumping around a lot.
It will cold start around 12.7 AFR and then creep to 14.7 as it warms, the o2 sensors don't seem to as sensitive but it may be from some oil going through the intake when the vacuum lines were on wrong (since been removed and cleaned)

I plan to pull the o2 sensors and give them a good clean with some fuel then a butane torch, same as the wideband, but just wanted to see if someone can take a quick look at the tune and the log and see if they can suggest changes to get it a bit more stable.

The tune was a mail order one and ran good enough to get around in, and planned to take it to the tuning shop down the road but after the intake change and the oil dump from the vacuum lines, it got delayed and I still have some wiring to tidy up before they'll put it on the dyno, so any help is appreciated in the mean time.

Also is my OS set up for real time tuning, as I have the button but then nothing shows up to modify any values or tables.

Its rich in the short log you posted. Most idle issues are really fueling issues. A rich car will struggle to idle.

Quote:

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Originally Posted by evilstuie

planned to take it to the tuning shop down the road I still have some wiring to tidy up before they'll put it on the dyno

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fix the wiring and then take it the dyno.
then after they are done, start your street tuning to finish dialing in what they cant on the dyno.

Quote:

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Originally Posted by Alvin

Its rich in the short log you posted. Most idle issues are really fueling issues. A rich car will struggle to idle.

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Thanks for that. So should I pull fuel from the Primary VE table or is there another table for idle I should adjust instead?
Also what is the acceptable difference in fuel trims from bank to bank.
I was seeing about -7-10% difference in left bank to right bank, so wondering if I need to chase a faulty injector or if it's maybe just the narrowband o2 sensors playing up.

Quote:

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Originally Posted by bk2life

fix the wiring and then take it the dyno.
then after they are done, start your street tuning to finish dialing in what they cant on the dyno.

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The main problem with that is I don't want to do a rush job on the wiring. The car has gone through several iterations of body and engine wiring, as I had to transplant the whole 2004 holden commodore body loom, BCM and assorting wiring into the car to get the dash gauges working (also had the commodre dash) and now that I've made a custom dahs I can do away with a lot of the excess that came with it.

I'll have to take the whole interior apart stripp all the wiring and then start from scratch, so it's a big job to do.
I also have a 4 day car event I want to take the car to in 1st week or September so I don't want to start a job I won't get finished by then.
It's the usual 'have my cake and eat it too' scenario, but just looking to tweak the tune to get it running as it was with the old intake and then try and get some power out of it with the tuners later on.
It's more of a for show car than performance at this point.

Edit:
Found the setting for to enable Real Time tuning in the software so that's all sorted now.
Just need to know:
1) Which table to edit to lean out the idle a bit
2) Should timing be stable or jumping around a lot on idle?
3)Acceptable trim variation from bank to bank
4) what could cause revs to hold/come down slowly from blipping the throttle?
@4:40 on the log, it takes about 2 seconds for the revs to come down from 5,000 to 1200.

Quote:

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Originally Posted by evilstuie

The main problem with that is I don't want to do a rush job on the wiring. The car has gone through several iterations of body and engine wiring, as I had to transplant the whole 2004 holden commodore body loom, BCM and assorting wiring into the car to get the dash gauges working (also had the commodre dash) and now that I've made a custom dahs I can do away with a lot of the excess that came with it.

I'll have to take the whole interior apart stripp all the wiring and then start from scratch, so it's a big job to do.
I also have a 4 day car event I want to take the car to in 1st week or September so I don't want to start a job I won't get finished by then.
It's the usual 'have my cake and eat it too' scenario, but just looking to tweak the tune to get it running as it was with the old intake and then try and get some power out of it with the tuners later on.
It's more of a for show car than performance at this point.

Edit:
Found the setting for to enable Real Time tuning in the software so that's all sorted now.
Just need to know:
1) Which table to edit to lean out the idle a bit
2) Should timing be stable or jumping around a lot on idle?
3)Acceptable trim variation from bank to bank
4) what could cause revs to hold/come down slowly from blipping the throttle?
@4:40 on the log, it takes about 2 seconds for the revs to come down from 5,000 to 1200.

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1. VE table and/or MAF

2. yes, it moves around to compensate for idle changes

3. Ideally theyre the same, but a couple of percent is fine.

4. Try changing the throttle cracker decay delay.

Quote:

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Originally Posted by horsepowerguru427

1. VE table and/or MAF

2. yes, it moves around to compensate for idle changes

3. Ideally theyre the same, but a couple of percent is fine.

4. Try changing the throttle cracker decay delay.

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Thanks for that.
1) Speed Density so that should be ok, I'll trim the values in the VE table.

4) I checked that and there's no delay , but it looks like that only applies at speed <1km/hr.

All log data at the moment is just from idle in Park.

I noticed the log always says current gear is 1 whether in park neutral or drive, so not sure if that could be causing something as well.

Quote:

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Originally Posted by evilstuie

Thanks for that.
1) Speed Density so that should be ok, I'll trim the values in the VE table.

4) I checked that and there's no delay , but it looks like that only applies at speed <1km/hr.

All log data at the moment is just from idle in Park.

I noticed the log always says current gear is 1 whether in park neutral or drive, so not sure if that could be causing something as well.

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If youre just in park revving it and not moving then you need to look at throttle FOLLOWER. Try cutting the delay down, if it is zero'd out then increase the decay in small amounts to get the effect you want. Ideally you want to log idle airflow PIDs and actually see what you need to do based on what follower and cracker are doing.

Thanks.
Throttle follower has 1 second on it so I'll try removing that and see if it improves.

With 13 degrees overlap cam what MAP value should I be aiming for ar idle?
Cam is 232/234 110LSA
Currently it's sitting around 60-70kpa

Quote:

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Originally Posted by evilstuie

Thanks.
Throttle follower has 1 second on it so I'll try removing that and see if it improves.

With 13 degrees overlap cam what MAP value should I be aiming for ar idle?
Cam is 232/234 110LSA
Currently it's sitting around 60-70kpa

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Try adjusting the delay and note the difference. Then put it back and change the decay, note the difference. make adjustments as necessary.

With a larger cam youre going to be idling higher in the MAP range. 60-70 is probly fine, however, you can play with timing and see if adding or subtracting a few degrees helps lower MAP values. Get it to its lowest value that you can and then leave it. Then adjust the BRAF to be accurate with current changes.

Quote:

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Originally Posted by horsepowerguru427

Try adjusting the delay and note the difference. Then put it back and change the decay, note the difference. make adjustments as necessary.

With a larger cam youre going to be idling higher in the MAP range. 60-70 is probly fine, however, you can play with timing and see if adding or subtracting a few degrees helps lower MAP values. Get it to its lowest value that you can and then leave it. Then adjust the BRAF to be accurate with current changes.

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Thanks horsepowerguru427. Idle is much more stable now and the revs are dropping off faster.
I still need to trim the fuel a bit and still want to clean the o2 sensors so I'll do that after I fix up the exhaust gasket leak and then do a full log with the LTFT and PE turned off.