New cam, idle issue

**allpontiac** · 07-29-2010, 03:07 PM

Hey you'all.. I just got a cam a while back and they re-tuned etc. Can they get the car to idle consistently after a cam swap? At first it wa idling at 550 rpm which was good as it gave you a real good sound from the cam, but upon initial starting in the morning it was very cold blooded as they used to say about a carbed engine. After it warmed up it was fine, I sent it back to the tune guy and now when you start it the car runs at about 1000rpm sort and has a surge between 1000 and 800 rpm or so, then it settles down to a 750rpm idle, just sort of weird.. Never was that eratic before the cam. Cam is a 575 lift, 240 duration etc, nothing real radical. Any ideas?

**IH8EVRY1** · 07-29-2010, 03:17 PM

I'm not an expert at this but those who are seem to ask these questions:

Who tuned it and what kind of tune? Dyno or mail order?

What transmission?

What MAF?

If I were troubleshooting it myself, from what you are saying the first thing I'd do, if you haven't looked at it already, is to clean the MAF. If you have an after market one, was that a factor when the car was tuned?

Other than that, someone more knowledgeable will chime in soon and give you some feedback. Answering those questions will probably help them start helping you.

**allpontiac** · 07-29-2010, 04:19 PM

The car is an automatic, 2800 stall, etc, the tune was done on premise with the dyno, no mail order. The maf is brand new aftermarket as well as the throttle body is a new holley. The intake he put on was an ls2, that is why the new throttle body and maf.

**IH8EVRY1** · 07-31-2010, 04:40 AM

Assuming that the tune was done after ALL of the parts were installed and that the MAF is clean the tune may just need adjusting. I'm not sure and there's still some information missing. What other mods do you have? That size stall isn't really large enough for me to think you have a cam swap but intake swap make me curious too. So, what other mods and have you called the tuner?

**69LT1Bird** · 07-31-2010, 06:13 AM

A 240 duration cam hs no business idling below 850.

If the only tuning he did was on a dyno its time to find a new tuner. You can't do driveability on a dyno.

Cold start issues again are from a lazy tuner. Sorry but I would look for someone else to tune your car.

**PontiacFan** · 07-31-2010, 07:39 AM

550rpm idle might sound good, but I agree, it may not work for that cam with a good tune. The 1000-800 hunt is sometimes typical for some cold starts depending on the tune.
2800 on the stall might not be enough either. Does it wanna drive right thru it while stopped? With an 850+idle, it might.
Visit your tuner again & get more driveability answers.

**IH8EVRY1** · 07-31-2010, 01:36 PM

Originally Posted by IH8EVRY1

Assuming that the tune was done after ALL of the parts were installed and that the MAF is clean the tune may just need adjusting. I'm not sure and there's still some information missing. What other mods do you have? That size stall isn't really large enough for me to think you have a cam swap but intake swap make me curious too. So, what other mods and have you called the tuner?

I'm an idiot and was racking my brain. I forgot that your title said "new cam" in it. I was thinking about the size of the torque converter so hard I just forgot to look. Sorry

**LSXZ28** · 08-01-2010, 01:29 PM

You should not have driveability issues with it - sounds like it wasn't tuned properly... I would tell them your not happy and if they can't do it right, go elsewhere...

**ne0fiend** · 08-02-2010, 07:17 AM

Originally Posted by allpontiac

Hey you'all.. I just got a cam a while back and they re-tuned etc. Can they get the car to idle consistently after a cam swap? At first it wa idling at 550 rpm which was good as it gave you a real good sound from the cam, but upon initial starting in the morning it was very cold blooded as they used to say about a carbed engine. After it warmed up it was fine, I sent it back to the tune guy and now when you start it the car runs at about 1000rpm sort and has a surge between 1000 and 800 rpm or so, then it settles down to a 750rpm idle, just sort of weird.. Never was that eratic before the cam. Cam is a 575 lift, 240 duration etc, nothing real radical. Any ideas?

The main consideration in this case is whether or not your motor is running at its desired idle; fluctuations for better or worse are usually the result of incorrect perameters in the tune.
If I understand you right, you're saying when the car idles, and you give it a little throttle, the RPM climbs a bit, but lingers or hangs there for a period of time before relaxing back to idle.
If that's correct, and assuming the tune is not faulty - My preliminary diagnosis would start with a vaccume leake.
Check the following for leaks or hissing:
Fuel tank vent (near intake)
Brake Booster components (firewall area)
Crank vent valve (near intake)

There are additional items to check, but these three would constitute a massive leak and cause the following:
Irratic idle
lazy throttle response
loss of bottom end (torque)

There are a few intigers and perameters that rely on those items I mentioned to ascertain correct idle fuel/air idle mix; 'if XXX is <whatever then supply x amount of fuel/air at x RPM less xxx is >whatever' etc.
If you're interested in reading through the idle and its involved processes, you can do so HERE.

Hope that helps. If you don't find a leak, let us know and we'll dig some more.