Turbo6.0L

Sorry for the long post in advance.
Stock 2010 ZR1 with 3400 miles on it except headers. Air cleaner and air intake also stock. No check engine light or pending codes.

Car is 2010 that is stock other than 1 7/8" ARH catted headers. First noticed the surge on the highway when the cruise was set about 50 miles after header install. It felt like I kept getting hit with a gust of wind but there was none. Found exhaust leak on both headers on the cylinder heads so replaced the stock gaskets with the ones from ARH. No more leak but surge was still there. Replaced spark plugs, wires and upstream 02 sensors(Bank 2 was acting a little lazy and when pulled was soot covered). Surge is much better but still can be pretty annoying at times.

Almost any off idle light acceleration up to about 2000 RPM's or steady cruising will cause the issue. Logging data with EFI live at steady speed it usually will affect RPM's by about 50 and sometimes you can see a 1/2 MPH drop. Long term fuel trims seem pretty stable at aroud 2. Short term trims are centered around 0 but can take some pretty big swings at times as high as -14 to +9. Both banks look almost identical.
Also with stock exhaust the car was never perfect. Mostly noticed the issue when going down hill with light throttle. More like cam surge.

I have read that some ZR1 owners have noticed this and was wondering if any fix was every found? I also read that this might have been addressed in the new cars with a different calibration. I even found a post from 2009 that the car was bought back by GM.

Any help would be appreciated.

Bigjsn250

Was the car tuned after header install?

ZR1Gerhardt

You likely need a dyno tune. You may also have an air leak up front in the air box and its connections.

I also have a 2010 ZR1, and when I put an air filter on, I had tremendous surging. Even with the filter, the car was pig rich. I had to take the car to get it dyno tuned, and it made a tremendous difference. No surging, no exhaust popping, etc.

Scott

Turbo6.0L

No. Still factory tune from 2010. Like I mentioned the car was never perfect even from day 1.

Turbo6.0L

Thanks for the reply. I still have the stock filter box and element. I also pulled it off and inspected it with no issues found. The MAF signal didn't show any oscillation as you would expect if air flow is disrupted.
Good to hear the tune fixed your issue. We're all the improvements made by redoing the MAF table? Or were there other tweaks as well? I talked to our local tuner and he said he has not seen headers cause this issue but honestly how many ZR1's do most shops see.

Turbo6.0L

Anyone else have any experience with this?

Turbo6.0L

Bump

ZR1Gerhardt

Unfortunately I don't remember all the adjustments made as it has been several years.

Turbo6.0L

I have been working with one of the tuners on the forum and we have only found a couple things that have helped with the surge. Turning off low volatility fuel option and adding 2ms to spark dwell. Also separately adding 5 to 6 deg of timing to problem areas also helped. Running in open loop vs closed loop makes no difference. Car will still surge if tuning tweaks are not implemented.

Makes me wonder if I might have something ignition related going on such as a weak coil or bad trigger signal or bad ecm? Still no codes.

Any thoughts would be appreciated.

Gary '09 C6

^ you could be onto something...

my 2010 ZR1 is also stock...I have not experienced the surge condition you are reporting.

Turbo6.0L

Well after swapping in known good coils issue was still the same. Have been working with a tuner all summer and have not gotten anywhere from the tune side. Had the injectors flow tested and they found one that was a little leaner than the other 7 so it got replaced. Still same issue.
Currently the only consistent thing that seems to help is running the car in open loop mode or adding a bunch of timing in the problem area. Discovered this while dialing in the MAF.

SIK02SS

It really sounds like it needs a good tune. You can't do much to these cars without having to tune it. I would call Ryne @ CMS or Greg at Kong Performance. Even if it's not tune related, either one should be able to figure it out with you

Also, what fuel are you using? if not already, switch to Shell or BP and see if problem continues.

Turbo6.0L

I was sticking exclusively to shell but did put a few tanks of chevron through it with no changes. I am waiting for a call back from Kong.

Texasthunder

Greg is the MAN!!!!

Nick Martorano

I also installed ARH and a K&N on my 2010. No surging but it does pop when shifting gears. It was dyno tuned after the mods were done.

Turbo6.0L

So if you are doing 30 mph in second gear with light throttle and are just barely holding it there is it perfectly smooth?

Any chance you have a copy of the tune I can compare?

Turbo6.0L

Finally fixed this issue. It was a bad crank sensor. The connector was full of oil. It must have separated internally and let engine oil leak through it into the connector causing signal\connection issues. I tested it off the vehicle and was able to draw water through the sensor base into the connector with a small amount of vacuum.
What led me down this path was that while logging data finally saw the timing drop out during light acceleration. It seemed to be going back to the idle spark table values so it was a huge change you would definitely feel. In some cases it was changing by as much as 20 deg. Before replacing the sensor I used a tech 2 to run the CPK to CMP sensor correlation test per the factory service manual and did not see anything obvious. I was also never able to catch the sensor dropping out using the tech 2 either. Now that the car is running better I might look at the correlation to see if anything changed.

So in summary a $38 crank sensor fixed my issues. All the tuning in the world would not have fixed this but I will likely go back and make sure we are optimized.

SweetZO6

So you did not get a CEL or DTC with a failed crank sensor? I would think the ECM would pick that fault up.

Ed

Turbo6.0L

Nope. Not a single check engine light or pending code was ever seen over probably a 1000 miles. According to the service manual to set the DTC for crank sensor performance code P0336 it would have had to:

-Receive less than 53 or more than 63 crank sensor pulses, during each engine revolution, for 8 of 10 engine revolutions.

-The ECM detects that the engine is running, but more than 25 crankshaft resyncs have occurred within 20 seconds.

-The ECM detects that the engine has been running but the crankshaft does not sync for .4 seconds.

Pretty much the way I read it is that you are not going to throw a code unless something has seriously gone wrong.

joshp14

The crank sensor is in the same location on every LS motor produced from 97 up to even the brand new LT engines...on the lower passenger side rear of the block. And yes, the starter must be removed. Can't help you on the part number but I'm sure a GM parts department could.