OMG ...... the dreaded Harmonic Balancer

 

Certainly not what I hoped, but I'm glad I saw it. No chirping yet.

Now to decide if I feel like swapping in an ATI unit myself or paying the astronomical labor. If it wasn't so hot at the moment I'd do it myself for sure.

 

You did say the magic words re intake, vararam. You also said you got the car with it on. So, what I'd say is the prior owner got it right as to making sure it was all sealed up well, but something you may have done (stress on word "may") has loosened it. Gasket flop over (lack of better term) and pinching is pretty well known for that intake. Check carefully. That may be the source of your air leak. Also, if you ask them, vararam has been known to give (I believe that is correct) a newer version that is supposedly better. Apparently, you do have to speak to someone there-can't recall his name. Hope the second tune is the answer.

 

How come your tuner has no suggestions for you? Did they review any of your datalogs?

If you are using a tuner device and you're hoping to use "pre loaded" tunes, you're NEVER going to get the car to run right.

The best solution is our AutoCal device which records your driving and you e-mail the results for me to review

so that we can make intelligent changes to your tune.

Having all the mods you have and NOT using a custom tune does not pay. You'd be better off removing the mods and using a stock

tune FWIW. If you keep the mods on the car then I would suggest you have a look at the following....


This is the best solution for any GM or LS based vehicle or Duramax Truck.

Call an time if you have questions.
Chuck CoW

 

I have been fighting the same battle as you with the surge. I have a Diablo tune, but I do not feel that is the issue. I removed the tune and reinstalled the stock tune. No difference at the idle - surge RPM range. I even pulled the intake looking for a leaking gasket and hoses. No codes are set. The car surges especially just above idle when the car slowly starts to move. Really noticeable in heavy traffic. I don't want to install headers until I get this straightened out, but it looks like this issue is not uncommon in the LS3.

 

It's funny you just posted this. I literally just got done uninstalling the tune to satiate my curiosity. It did not fix the surge in idle. Definitely not the fault of the tune in any way.

Mine sounds similar but it's worst when I'm slowing down, not starting out.

It's going back on the lift this weekend to reinspect everything. I'll let you know what I find.

 

Both of you Please list your mods.....

If you give me the details I can probably tell you what's wrong... Maybe some pics of the sir intake installs too.

Chuck CoW

 

I'm no expert but the same thing happened to mine. The simple fix was installing high flow cats and putting the EGT's back. Now I didn't actually do the work but if I am remembering correctly.... that's what he told me he did. Hope that helps. Good luck. Ps. I'm glad it worked out that way as I was tired of paying off a guy to pass my Vette for the smog. Take care. Rob

 

Sorry guys, I just saw this. I appreciate the help. At the time of posting this thread the car had:

• Vararam CAI
• Billy Boat long tube headers w/ deleted cats and no downstream 02 sensors
• Borla Stinger exhaust

Since I have:

• Replaced the spark plugs and wires
• Installed a Vmax ported throttle body
• Checked the air intake through intake manifolds for any evidence of leaks
• Checked all of the vacuum connections that I can find, etc.

I do have some concern of a small leak on the right side header at the manifold, but there's no actual indication of that. It looks like there may be gaps, but I can't find any air escaping.

I did notice something curious today that was able to pinpoint when the issue occurs most often. I've always noticed the surge occurs when I'm coasting in neutral but the vehicle is in motion. Tonight I noticed the idle flattens out when the clutch is not depressed, then raises when I depress the clutch. Every time.



Sorry for my ignorance, what is an EGT? I've been on the fence about putting high flow cats on, and if this can help I'm certainly not against it.

I've also noticed that there is very little engine braking now (for example I can go 15 in first then let off the gas while still in gear and it pretty much coasts) and I wonder if it's due to lack of cats.

 

From what I see, the first thing I would eliminate is the ported throttle body.

Change it back to stock and see what happens.

Exhaust leaks won't really do that.

EGT means Exhaust Gas Temperature.

Chuck CoW

 

The problem was present before the throttle body was added. I drove it for probably 1500 miles with the surging issue before putting on the throttle body. And unfortunately the core has been sent back, so I'm unable to swap it back at this point.

I didn't really think an exhaust leak would do that, but I wasn't sure.

 

What plugs and wires did you use? Did you use a power duct with the Vararam?

Chuck CoW

 

Thanks again for your time, Chuck. I replaced the factory plug wires with OEM and went with NKG Iridium plugs. It did not change the idle characteristics at all unfortunately.

The Vararam was on the car when I bought it. But, I did a bit of googling and it does appear to have the power duct.

 

This is a really good thread.... I'm sure others will get some use out of this...

 

GOT IT! While the Power Duct is a great piece that gives you some extra power.....

IT ABSOLUTELY must be custom tuned and by that I don't mean the "one shot mini tunes" that come pre-loaded in some

of the popular handhelds. They ABSOLUTELY will not work with the Power Duct.

You will have to have a custom tune from someone like myself with our autocal device to make that car drive right.

Chuck CoW

 

This is good info. I'm curious on your thoughts regarding why the issue just showed itself now. I've owned the car for almost two years and the Vararam came with it. Do you think the headers exaggerated the existing issue?

I did do an email tune, but maybe it wasn't to the level necessary with the Power Duct. I am installing a cam next week so it will be getting a local dyno tune. I think I've read that your solution can be run on top of a custom tune, is that the case? If so I'll be giving you a call over the next couple of weeks.

 

Sorry it took so long to come back to this thread. I replaced the oil pan gasket 2 weeks ago. I didn't feel like messing with the car but it was time to replace the pan gasket. It was not going to stop leaking no matter many times I jacked it up cleaned it.

Chuck Cow; Back to the surging issue. I have Borla attack exhaust and polished throttle body (for looks), that's it. (Diablo 93 tune) It was surging prior to that. I only polished the throttle body because it was off the engine and I had everything on the work bench to do it. I have replaced the plugs and wires twice in the last year. Stock NGK iridium. I replaced what looked like a lazy O2 sensor, maf sensor, intake gaskets (checking everything for vacuum leaks). A little extra history; the ECM failed about a year ago. It has not run right since dealer replaced the ECM. It was able to remove the tune before towing it to the shop. I don't want to get a custom tune on a basically stock motor, but I also don't want to mask an issue with a custom tune, however I had the battery disconnected for a weekend replacing the pan gasket. It ran better until I put a few miles on the car and it began to go back to it's old surge during a slow stop and idle. I know, makes you think it's in the tune, but even putting the stock tune back in it goes back to the same drivability issues within a few days.

 

While I agree with Chuck to a certain extent that a tune might cure the problem , the LS3 is very sensitive to airflow which is what is causing the surging , this is the reason that GM installed a Helmholtz resonator in the factory air duct system .

Remove this resonator and you might get surging especially if you have a stick car as the torque converter in an A6 hides some of this surging well.

I have not heard of the VARARAM ever causing this issue but then again I have never heard of a power duct ....

What I have heard is many of the other so called cold air systems HAVE induced surging ....

Dave

 

You actually need a good custom tune with proper datalogging like what we do with out autocal remotely.

The reason the car eventually goes back to running poorly is that the car's fuel trim system is compensating and

disconnecting the fuel trims resets all the trims to zero.

Please post 2 pics of your intake on the car. I'd like to see what's on there.

Call me to discuss futher. 914-332-0049

Thanks
Chuck CoW

 

Sounds exactly like what my car is doing. Purchased it a month ago. Has a Breathless Air Vortex ram air intake. Has a horrible surge especially when driving slow in first thru fourth. I bought a Jet Performance MAF that is suppose to work better with a CAI . I'm hoping this helps out. I'll know tomorrow. If not I guess I'll start looking for a tuner.