Dope

iTrader: (2)

All right guys, here's the deal.

I am not new to the LS1 world. My previous car was a 2000 SS A4 and my current cars are a 98 SS M6 and a 99 FRC vette M6.

The 98 SS is my daily driver, and is mostly stock with bolt-ons.

The 99 FRC has heads/cam/longtubes/blah blah blah.

I'm new to the 'cam' world. The FRC has a T1 cam - 221/221 on a 112lsa, locally ported heads, cartek tuning. I don't know what they really 'tuned', but I suspect it was just dyno tuning as the car idles at stock speed. Car puts down 409rwhp through the stock cats.

Now, with my SS car, I can drive at VERY low rpms. I have a super cramped driveway and an even worse parking garage at work. It is very common for me to be navigating the car around very slowly, letting the clutch out from a stop at idle, idling in 1st up a garage ramp, backing up my inclined driveway from idle, hitting stop+go traffic once a week, etc, stuff like that.

Now, the FRC, which I just got, will not have ANY of that. I stalled it 3 times trying to switch positions in the driveway with my SS. It's got a cartek clutch, and it seems quite a bit grabbier (and heavier) than my stock SS clutch. It's got a pretty choppy idle, and once you go below that (start letting out the clutch) it sputters and bucks and dies 2 seconds later.

Now, my question is, what can I do to alleviate this?

I have ls1edit, autotap, etc. Can I raise the idle 100-150rpm in the FRC so that it will act better? Maybe more? Or will it not change a thing? I'd also like to raise the idle a bit because once you idle for a minute you can smell unburned gas (despite stock cats). It ain't gonna pass MA emissions, that's for sure! I'll probably pull up and they'll just laugh at me (has Corsa Indys too so it's not exactly quiet with the cam).

Another idea I had was to upgrade to shorter gearing. 3.90-4.10s. This should help too won't it? Less effort to get the car moving from a stop at idle right?

And finally, if it came down to it, I could swap out the cam. Maybe a 220/220-224/224 range on a 114 (TR220 or 224 likely). I kinda want to put a better oil pump, timing chain, underdrive pully, and springs on it anyway, so a cam would be easy to swap at the same time. The car has stock oil pump/chain/pully and 918 springs (want double springs in case I ever break one) so that's why I wanted to upgrade those pieces. Will the 114 LSA, even with higher duration (224/224) improve the very low speed/rpm characteristics or is it really not that much different?

Like I said, I was mostly planning all of these things eventually, but I am REALLY wondering how drastic an effect these changes will have. If I can get away with just raising the idle then I will do it immediately. Whereas the cam swap could be next spring.

Let me know what you guys think.

Thanks,
Dope

Ragtop 99

iTrader: (7)

No reasonn for a choppy idle with that size cam if you have decent tuning. I doubt raising the idle will help unless you are letting the clutch out without giving it any gas. However, it is an easy change and will help with the unburned fuel issue so you still might want to try it. You can also reduce the VE below in the 400, 800 & 1200 columns to 80% and see if that helps with drivability.

You might also see what your idle IAC counts are. If they are above 60, try opening the TB blade set screw by half a turn or so and see if that helps.

For more on tuning, look in the PCM section for a lot more help on this topic. There are similar questions posted frequently.

Gears will make it make easier to do parking lot manuevers at very slow speed because you'll be able to get the car rolling easier and can let the clutch all the way out at lower speed.

MyLS1Hauls

iTrader: (2)

The lower gears help a lot. You just need to ride the clutch more...Keep the rpms above 1000 when you're taking off. You can't idle around a parking lot with a cam like that. You have to slip the clutch and accelerate and the press it in a coast. Thats how I always do it. Clutch out, move, clutch in...repeat. Also, a TR220 will idle much much smoother than the T1. I had the TR220 and a buddy had a B1 and it was a huge difference...both on stock tuning.

Dope

iTrader: (2)

That's exactly what I'm doing. It is really super cramped, especially in my parking garage at work. Lots of cars moving through too and the lanes are tiny. I know keeping the revs up and slipping the clutch works but it is not practical for my situation sometimes.

I will try raising the idle a bit and see how it does for now. I wonder if a TR224 will idle better than a T1? Higher duration but higher LSA at the same time. I also think the TR cams have XE-R lobes vs XE for the older style MTI cams, that should help a bit too.

Dope

The Dragon

iTrader: (6)

No reason why you shouldn't have a near stock idle at as low as 900 rpm's. Mine is at stock rpm.

IAC Park Position
Idle Air in Gear
Main VE tables (already mentioned)
High Octane Table

All of the above tables can be modified to effect idle quality.

Definitely get a reading on your idle IAC's (also mentioned above).

If you need any more help feel free to pm me

hondakiller

iTrader: (3)

not really worth the swap but in your situation, you could try a b1 cam. same cam as a t1 except on a 114lsa.

MyLS1Hauls

iTrader: (2)

The TR224 has 6-9 deg less valve overlap at .006" than the T1 depending on if its a Lunati or Comp T1, given the same LSA. The TR220 has 10-13 deg less at .006". The less overlap, the better the idle. The T1 and B1 arent even on XE lobes...they are a little slower. The C1 (Hammer cam) was one of the first popular cams on an XE lobe. I've heard a TR224 114 in an A4 w/out tuning and it idled very nicely. If you have a Lunati grind, there is a lot of idle quality to be gained by going with a newer cam.

Dope

iTrader: (2)

Brad, are your figures using a TR220/224 on a 114 or a 112?

I don't have any idea if it's a Lunati or Comp, I bought the car like this. If I had to guess, I'd say Comp, it has all Comp valvetrain stuff.

I like the idea of going with a TR224 114 if I can gain idle quality/drivability, as well as power! I shouldn't have to shift any higher either, according to the dyno report, 6500-6600 is the ideal shift point for the T1 in the car (looks like it peaks at 6200).

Thanks for the info.

Dragon, thanks for the offer. I will let you know once I get my updated ls1edit cable in the mail (sent it out Next Day at lunch today).

One thing to remember guys, is that this is a vette, are idle issues different with a vette vs fbody? I've heard that a vette is harder to get to idle than an fbod, mainly due to the fly by wire TB.

Dope

Ragtop 99

iTrader: (7)

DOH; :o Forgot it was a vette, so the TB set screw may not exist; but other tuning tables are there.

Dope

iTrader: (2)

Just a little update, I think part of my problem is that it has a super grabby clutch. Doesn't really want to slip. So as soon as I start letting it out, it just kinda grabs and sputters and stalls. I played around with it last night and the car is nearly impossible to start off smoothly even with giving it plenty of gas. It's a cartek clutch with cartek hydraulics.

Dope

Cal

iTrader: (1)

I have the TR224 114, and after tuning it has a very smooth idle; almost so smooth many people wouldn't even know it has a cam (should be usefull around emissions time.) I can creep around at 1000 rpm, and even carefully let out the clutch at idle. I have my idle speed set to 950, and still have the stock clutch, though.

The Dragon

iTrader: (6)

Dang Cal, why so high an idle speed? I got a h/c full bolt-on '02 WS6 with a MASSIVE cam to idle at 850 easily Are you trying to avoid the lope?


TB screw is bad. Wouldn't suggest that for any F-body owners.


Yes 'Vette's are a tad more difficult but quite a few tables can be adjusted. This is a mild cam we're talkin' about here