All tuners please help I got a problem...

**chieftransam** · 02-26-2008, 04:14 AM

I have a h/c package in my 01 TA m6. I got the stage 2 cnc ported ls6 heads (59cc) and a 224/224 .581/.581 112 lsa. I have noticed that a lot of times now when I go to stop at a redlight or stop sign my rpms will go up to like 1500 and stay up there for 3-4 seconds and then slowly and eventually drop back down by the time the light turns green. Is it common?? Is there something wrong with the tune I got? (I made around 410 rwhp and 395 rwtq on the dyno

.) Sometimes it may go a few days or a day or so without doing it and then sometimes it will do it all day long or everytime I stop. I let my car warm up before I jump in it and take off. I don't dog it, actually I baby her a little to save on gas. Can someone help me out with this rpm thing? Is there a problem with the cam or heads? Or no problem at all? Please help, its annoying and I'm wondering if I have a huge problem on my hands.

thanks
Billy

**Frost** · 02-26-2008, 05:12 AM

It's either an intermittent vacuum leak or the idle airflow iss too high in your tune.

**chieftransam** · 02-26-2008, 05:23 AM

Thanks Frost,

Excuse my ignorance, but how could I tell if I have a intermittent vacuum leak? Would they have to put my car back on the dyno to re-tune it to fix the idle issue if that's the problem? My car sounds like a darn sewing machine too. I hear this is normal with h/c/lt's setup.

**Frost** · 02-26-2008, 06:15 AM

Originally Posted by chieftransam

Thanks Frost,

Excuse my ignorance, but how could I tell if I have a intermittent vacuum leak? Would they have to put my car back on the dyno to re-tune it to fix the idle issue if that's the problem? My car sounds like a darn sewing machine too. I hear this is normal with h/c/lt's setup.

GO back over the places that have the potential to allow unmetered air in the car.

If all is well there, it may be in the tune. How long after your tune visit did it begin? If it was within the first few days, it's likely the tune.

Have you adjusted the set-screw on the TB at all since after tuning?

**chieftransam** · 02-26-2008, 08:15 AM

I can't really remember how long but its been doing it for like the past maybe 2-2 1/2 months. I got my tune around 3 months ago or so. No I haven't adjusted anything on the car since it was installed. I don't want to mess anything up...lol. Should I have them look at the set-screw and check the tune they did to it?

**chieftransam** · 02-28-2008, 09:53 AM

any other input?

**0rion** · 02-28-2008, 08:47 PM

check the backside of the pcv hose going into the intake. Those have known to crack or rub through on the backside.

**Jay Dee** · 03-03-2008, 03:41 PM

Without having some type of tune/scanner it's really difficult. I had the same problem after replacing my heads and cam (almost the same combo). I finally broke down and bought EFILive and it turned out to be a combination of the Idle air control steps, throttle cracker and desired air flow. None of which can be fixed without a program like EFILive, LS1edit, etc. You can try with the set screw by increasing it until 2-4% depending on what your IAC steps are at. Did you drill out the stock TB hole on the blade (not always good to do).

**chieftransam** · 03-03-2008, 04:29 PM

I didn't drill anything or mess with anything what so ever. I keep having people check everything in the tune and they say everything is fine, when obviously its f'n not! It's annoying and I want it fixed, but I don't know how and apparently neither does either of the shops I have taken it too!

**Jay Dee** · 03-03-2008, 04:54 PM

Do you have a tuner? Or know someone who does? It was abig investment, but well worth the money. Now any time I upgrade, just plug in and make the necessary adjustments.

**408WS6** · 03-03-2008, 05:44 PM

There is an adjustment that lets air in (via IAC) but lets assume thats not the problem. It does sound like you are getting some unmetered air in. Or maybe your throttle body is not quite closing when you let off. Get someone to push on the gas and let off with your lid and maf out of the way so you can see if maybe your throttle blade is sticking momentarily. Also check your blade to see if your tuner drilled any holes in the blade in attempt to get more air in at idle. I can't imagine you needing much of a hole with a cam that size.

I would tend to think that if it were a real vacuum leak that it would idle high and stay there. If all else fails take it back to your tuner and ask him to take a look at the IAC graph when letting off the gas.

**Frost** · 03-03-2008, 06:23 PM

Where are you at in North carolina?

**chieftransam** · 03-04-2008, 05:09 AM

Fayetteville NC. I do have a little diablo handheld tuner, but I'm not sure what all I can do with it. I've honestly only used it to read codes. I'm thinking of taking it back to the shop on thursday to let them look at this graph that your talking about.

**Jay Dee** · 03-04-2008, 05:47 AM

I agree, it's likely not a vacumm leak. With my experience it's rarely a sticky TB blade but certainly a possibility you should rule out. If you find out your IAC steps are correct, between 40-60, tell the tunner exactly what it's doing. Next time your just start the car and drive before the engines completely warm see if the RPM's fluctuate as it does with the engine warm. There are a number of possible causes for the rpm fluctuations:
DAF, IAC steps, VE’s, TC/TF and any combination of those.

**chieftransam** · 03-04-2008, 06:17 AM

The rpm's will still jump up like that when I drive it cold or warm. I checked for leaks yesterday after work and I didn't see or feel anything cracked or leaking or sucking air. I haven't messed with the tb at all, so maybe it should be looked at? I'll have to write all this stuff down and ask them to check this out. I've already had them check it before - along with another shop and they say everything is fine, but the problem still is not fixed. I'll make a list of the possibilities and see if they will check them.

**chieftransam** · 03-04-2008, 06:34 AM

Can the diablo do anything for this?

**408WS6** · 03-04-2008, 09:21 AM

Originally Posted by chieftransam

Can the diablo do anything for this?

No I don't think so.

**chieftransam** · 03-04-2008, 09:55 AM

well dang! I dunno why I waisted my money on that darn thing anyways. Any who I hope that the shop will find out what's wrong with it. I can't figure it out and I don't want to go buy some high dollar fancy computer program or anything like that to find out what it is.

I appreciate you guys chiming in to try and help me figure this out. Like I said earlier I'll make a list of possibilities and go from there. I might just have to find a new shop...lol.