MTI Stealth Cam Idle Problems
Race Director
Joined: Mar 2001
Posts: 19,965
Likes: 6,769
From: Bonneville Salt Flats
Re: MTI Stealth Cam Idle Problems (X_03_Cobra_guy)
Well, now we're getting more info...
If it ever idles smoothly (intermittently or when cold), you know it's not the cam.
Keep at it and please, keep us informed.
If it ever idles smoothly (intermittently or when cold), you know it's not the cam.
Keep at it and please, keep us informed.
Thread Starter
Racer
Joined: Jul 2003
Posts: 398
Likes: 0
From: Calera AL
Re: MTI Stealth Cam Idle Problems (Avanti)
The car idles best before it goes into closed loop. Computerized cars are much more sensitive to overlap in a cam than a carbuerated motor is. I am sure it is the cam causing the lope..question is why mine lopes more than other stealth cam apparently do. Lou told me that the overlap in the cam is what causes the idle to be rough and such. I am getting to the point where I have checked and double checked everything on the car and am really just gonna say to heck with it and just drive it like it is assuming that is normal MO for this combination. Half the guys on LS1 tech say that is lopes like mine does the other half say it idles like stock. I am just guessing that there are other factors in the heads/exhaust that is causing the lope to be more pronounced in some cars than in others. The fact that the cam is ground 4 degrees advanced may also play a role in it as well. If I were to retartd it back 4 degrees I'd be willing to bet it would idle a lot better...but I would loose some top end power. I might try that some day. But am not anxious to take the timing cover off just yet
Resident moron
Joined: Jun 2003
Posts: 4,746
Likes: 20
From: Assachusetts
Re: MTI Stealth Cam Idle Problems (X_03_Cobra_guy)
It's been asked several times but not answered - have you verified the LSA? That will make all the different. A 220/.581/112lsa cam will idle lots different than a 220/.581/115lsa cam. LOTS different. I have a 221/221/.558/.558 on a 112lsa (old T1 cam) and it idles pretty well at 800rpm. At 900rpm it's smooth but it does have that camming sound (but not really a rough idle). Car has longtubes and Corsa Indys too.
Free flowing exhaust will not make a car lope more, it will however make it more NOTICABLE. That's because you can hear it more. Nothing else.
Do you have a lightweight underdrive pully btw? What about aluminum flywheel? I've found that either item can worsen idle quality too.
Dope
Free flowing exhaust will not make a car lope more, it will however make it more NOTICABLE. That's because you can hear it more. Nothing else.
Do you have a lightweight underdrive pully btw? What about aluminum flywheel? I've found that either item can worsen idle quality too.
Dope
Racer
Joined: Nov 2001
Posts: 274
Likes: 0
From: Houston Texas
Re: MTI Stealth Cam Idle Problems (Dope)
Well, I just got my car back with the stealth cam installed. It lopes. Not bad, just barely. Like you described at first start up when the idle is higher you can't tell, as the car warms up and the idle drops a definte lope is there. It is mild though. My wife even said it didn't bother her. But not stealthy. I could probably raise the idle and get rid of it. I do have headers and exhaust so it is free flowing. My car is an A4. The stealth cam I heard that was not noticeable was an m6 with Z06 exhaust so that it is line with your theory of quiet with factory exhaust. I will try and get some clips if some can host them for me. Have you talked to Jayson at MTI. They were great for me. I'm sure he will do everything he can to help you. His direct email is jaysonmti@aol.com.
Thread Starter
Racer
Joined: Jul 2003
Posts: 398
Likes: 0
From: Calera AL
Re: MTI Stealth Cam Idle Problems (Dope)
I have an underdrive pulley. Don't quite know how that would affect idle quality. The cam is ground on a 111 intake 119 exhaust lobe sep angle. In effect the cam is ground 4 degrees advanced. So if I were to retard it 4 degrees the intake would be 115 and the ex 115 lsa.
Racer
Joined: Nov 2001
Posts: 274
Likes: 0
From: Houston Texas
Re: MTI Stealth Cam Idle Problems (X_03_Cobra_guy)
Ever so slightly till it finds an idle then it really doesn't. It comes and goes. Of course that is is an objective comment. What I may consider rough, you may not or vice vesrsa. Not bad enough to shake liquid out of a cup as you mentioned.
Yes I do have an underdrive pulley. ASP
FLP headers with cats, B&B route 66 exhaust.
Yes I do have an underdrive pulley. ASP
FLP headers with cats, B&B route 66 exhaust.
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Thread Starter
Racer
Joined: Jul 2003
Posts: 398
Likes: 0
From: Calera AL
Re: MTI Stealth Cam Idle Problems (Boos2)
Thanks for the info. I think I will try changing out the MAP sensor. There has to be a sensor problem. Though Lou found nothing suspect at his shop. Maybe the MAP sensor is too sensitive. That is just a guess.
Thread Starter
Racer
Joined: Jul 2003
Posts: 398
Likes: 0
From: Calera AL
Re: MTI Stealth Cam Idle Problems (Boos2)
I have a de-screen MAF. But I meant to say I think the problem lies with the MAP sensor. The Manifold Absolute Pressure sensor I think it is called. It is behind the intake manifold and senses the intake vacuum. My theory which I will test is that the MAP sensor on some cars is more sensitive, and reacts quicker to changes in manifold vacuum. This is one sensor that is directly impacted by a cam change. Most larger cams will have more overlap and probably a more erratic or lower vacuum. So the MAP sensor would react to this by giving the computer mixed signals instead of a steady reading. Just a wild guess but I will try disconnecting it and see what happens. Or will try to remove it and rig up a steady vacuum for it somehow to see if it doesn't help.
Burning Brakes
Joined: Jun 2002
Posts: 996
Likes: 0
From: Frisco Texas
Re: MTI Stealth Cam Idle Problems (X_03_Cobra_guy)
I have the same problem, except I have a smaller cam. My guess is ported throttle body or lt exhaust.
I am very interested if you find out how to get a stable idle. Hell a friend has a 224 on a 114 that is smoother than my idle!
:lurk:
I am very interested if you find out how to get a stable idle. Hell a friend has a 224 on a 114 that is smoother than my idle!
:lurk:
Thread Starter
Racer
Joined: Jul 2003
Posts: 398
Likes: 0
From: Calera AL
Re: MTI Stealth Cam Idle Problems (cscollis)
I am going to experiment with the MAP sensor. The sensor in back of and under the intake. As soon as I get my computer back from Lou I will try warming the car up and then while it idles, I will disconnect the MAP sensor and see what happens. I have tried changing plugs and plug wires and the O2 sensors. That did no good. I am certain it is sensor or computer related and not mechanical. When it is cold, before going into closed loop mode, it idles smooth. It isn't until it warms up and goes into closed loop mode that is starts idling rough and shaking the car.
