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Guys I am at a loss as to what is manifesting itself in the way of a noticeable but quite miss at idle. A little while back I noticed my car having a slight "miss" sound in the exhaust note and chalked it up to nothing more than the stock cam after annoying everyone I could about the sound. 2 weeks ago I was taking a person for a ride and began to notice a slight hesitation and rough idle. The can ran great up top but it was bugging me. The next day I dyno'd the car and it put down 337.25 HP and around 350 lb-ft of torque. The car is basically bone stock which made me think I was imagining issues.
The next day after my wife and I were out riding around and I began to notice a very defined rough idle and extreme hesitation/ dead miss sounds when leaving from a dead stop or when putting the car into a high gear at low speed.. It did it with the AC on and off but is noticeably worse with the AC on. On the way to dealership the other day to pick up a part I noticed some severe detonation beyond 5K RPM. and decided to baby the car until after I did the deep clean.
NO CODES... nadda, zero. I had Autozone check and their reader said nothing.
I asked if the dealership would check and they said if the Autozone computer showed no codes or anything in the history their Tech 2 wouldn't either. I argued that their tech 2 should be able to help me find a weak or bad coil or injector. They insisted that unless my car through a CEL it wouldn't show anything.
This past weekend I embarked on a full fuel and induction system cleaning regiment to which I have received no improvement. We pulled and cleaned the following: Intake mani, MAF, injectors, fuel filter, fuel rail, plugs, ran a can of BG44K through the tank. Individually activated each injector and ran cleaner through them, and then painstaking cleaned the inside of the intake runners.
Also pulled the valve covers to check for loose rocker arms and broken springs. No broken springs, no bent pushrods. Mechanincally the car seems to run fine with no obvious knocks or tells that you might expect from a broken component.
The particulars of the car are as follows:
04 V1 (LS6)- 78,3XX miles on the clock.
Mods...Stock.
New Stock Plugs 2K ago
Oil Changed 1500 miles ago and is clean and at the correct level.
New Rad and fluid 5k miles ago.
Fuel module recall performed 2k miles ago.
Battery is new
Clutch is original
Water pump is original.
Exhaust and 02 Sensors are original as far as I can tell.
Shows 13.5V- 14.0V on DIC all the time.
Temps are typical 205-210 Water and 220 for oil.
Oil Pressure at temp is 35 PSI at idle and 60 60 PSI +/- at WOT.
Compression checks out within tolerance across on all cylinders.
No visible signs of any melted wires anywhere under the hood.
The only variable here that makes the situation worse is when you are running the AC. AC makes the hesitation or stutter much more pronounced.
Did you check fuel pressure? Live scan displaying where the misfires coming from?
To answer your question on fuel pressure no I have not. I may try to do that today. I asked the dealership if they could put the tech 2 on it to check for misfires and the well meaning but uninformed service advisor told me that they can't see anything without a code being thrown which I know to be untrue.
Dealerships are a joke. Let me ask you a question.. How long ago has this been happening? Did it start before or after the dealer did the fuel pump recall?
If the person working on your car can not read live data or refuses to when they have ome of the best diag systems, then you really dont wanna take your car there.. 2cents
Dealerships are a joke. Let me ask you a question.. How long ago has this been happening? Did it start before or after the dealer did the fuel pump recall?
If the person working on your car can not read live data or refuses to when they have ome of the best diag systems, then you really dont wanna take your car there.. 2cents
I noticed a very minor skip in the exhaust note about a year ago...I say minor because literally every single person I let listen to it including some very reputable tuners in my area said that the LS6 cam was more aggressive than the LS2 and thus even with stock exhaust it had a noted slight lope to it. I had 3 seperate LS specific techs ride along in the car to listen to what I thought sounded funny and all of them said..."Because LS Power". The dealership that I frequent performed the fuel module service back in April or May and the car has run fine with the same little skip as before until 2 weeks ago as I mentioned above. Hell in bone stock trim it put down nearly 340hp...so who was I to complain.
Yesterday I decided I was done trying to diagnose blind and took it up to the dealership. I checked in and asked to take the lead tech for a ride so that I could let him hear and see the issue. I was not about to drop it off and get a "could not duplicate" response. I was able to duplicate it in the parking lot and the lead tech told me "ok no problem at all, I'll slap the tech 2 on it and see where exactly the problem coil is"... I knew they could and I had my suspicions as to what was wrong. The issues with the dealerships aren't usually the tech's it is usually the proper conveyance of the problem to the proper service adviser.
Frankly I think they are so used to clueless people coming in and dumping their issues, that they are not used to someone who knows their car and knows their procedures.
Got a call today. The lead tech discovered a bad coil on #2 which had fouled the plug. This would be consistent with my own thoughts as intentionally moved coil brackets from side to side to put that coil up front for easier access assuming we were able to pinpoint that it was a bad coil. He also discovered a failed coolant temp sensor and after installing both discovered that the tune was causing the car to run really poorly so he re-flashed. I am on the way up to pick it up now and will verify what if any change was made and report back.
And we have a Wiener... Just got the car back and sure enough the skip is gone and so is the hesitation and bucking. 100% coil had gone bad and taken the plug with it. Amazing how much more power the car seems to have at part throttle. Before it would barely break the tires loose unless you matted the peddle now it it will do it easily at part throttle.
Damn it NAF....at the exact moment you posted this morning, my car decided to get embarrassed of yours and **** the bed.
In all seriousness I went out and cranked the car up this morning only to be greeted by a it running so rough it felt like there had been an impromptu cam swap over night.
Because it felt so choppy I let it warm up longer than usual. I went to get into the car after it idled for 10 minutes and when I opened the door I noticed that the door chime was crackling like some kind of RF feed back you might get with a cell phone held too close to a speaker. Listening more intently I noticed that the crackling coincided with the noticeable misses in the exhaust note and could also be detected in the audio of a CD I had playing in the car. I decided that I wanted to limp it around a little to see if it would behave like before and smooth out with RPM's and it did sort of.
I got brave and put my foot into it a little after driving around and noticed that the fuel trims must have been way out of whack because I was getting a bad miss in low RPM part throttle. With high RPM with near WOT it felt like an absolute raped ape. Hell it broke the tires loose at 4K RPM in 3rd which it had never done before.
I think most folks would have been happy with that but I was worried it was running too lean and thus burning a hole in my Pistons. Lucky for me it did finally throw a Check Engine Light.
I dropped it off at the same service center as last week and the lead tech that had worked on it the last time took it in. My service guy said that the lead tech thought the changing of the #2 coil might have set off a chain reaction but was going to go through the whole car to make sure it wasn't something simple like a wire arching in the harness. Apparently his Tech 2 was showing something like 862 misfires from #8, 430 misfires from #6, and 450 misfires from #3.
Thank the Lord I have this aftermarket warranty because this fix would have been stupid expensive without it. Especially if the alternate issue of a damaged PCM is the cause.
Tobhave that many misfires probably means you need new wires.
Its not my fault you open your chat near your car...
Today i have a nice one, takin my friends truck to the shop, rad fans are inop, the ac doesnt work, and its already 100f so i will be cruising to work with the windows open and the heater on to help bleed off some of the heat from the rad
... Frankly I think they are so used to clueless people coming in and dumping their issues, that they are not used to someone who knows their car and knows their procedures ...
Dealers get a bad rap too often when you realize that 99% of their customers are indeed clueless, and the dealers can't trust anything those 99% say when describing issues related to their cars.
Your problem is interesting because it was gone after the coil replacement but returned on steroids the next day. Hope you and that tech get to the bottom of this.
Check the ground on the back of the head and over at the the hood lift. My guess is that you have the typical ground issues on these cars. It will definitely cause the ignition noises in the radio you mentioned (but they can also just show up because of bad plug wires). The reason I think it is more likely a ground issue is the intermittent nature of the problems. Lots of bad plug wires won't all get better all of a sudden. One bad head ground can cause lots of misses and then all of a sudden they all work...
Dealers get a bad rap too often when you realize that 99% of their customers are indeed clueless, and the dealers can't trust anything those 99% say when describing issues related to their cars.
True BUT they should still do quality work even if the customer is an idiot. I have had multiple problems at multiple dealerships with things as minor as oil changes and 50k mi service visits. At this point I do everything except the balance and alignment.
I would just like to chime in that when my car had a similar issue, it was the battery cable shorting out against the header. Every time it would arc the car would spit and sputter and sometimes fall on its face for a second.
So I could imagine a poor battery connection, alternator connection, fuse panel connection or a short could cause this. Also, a loose or bad ground.
Alright guys some time has passed since I updated. Since my last the following has occurred:
4 more coils were replaced by the dealership. According to the dealership my coils were failing because the double insulated extremely robust plug wires I had on the car sans the factory aluminum heat shields, were getting too hot near the plug and causing the coil to ground out on the end near the coil...
So the replaced coil count is now cylinders #8, #7, #1, #2, & #4.
I took it home and considered my options for how best to combat this issue of heat and a rapidly diminishing spare plug wire supply. A quick message over to David and Ron over at Vengeance Racing and the issue of overheating plugs was better than resolved with a set of their plug wire sleeves.
Next step was purchasing another new set of wires, this time back to factory stock wires. I installed the heat shields onto the existing wires and reserved the stock wires for once I had completed my up coming install of my new OBX long tube headers.
Well, that was all for not because a week after getting the car back for the second time I started hearing a sound at WOT from 5000rpm up 6500rpm that sounded like detonation or a series of loud pops. I later discovered that the sound was most likely the sound of arcing occurring between the coils and the bracket on the passenger side #8 cylinder.
No the plug does not have the heat shield on in the picture and that is because I took it off to inspect the wire and then put the wire back on to reference where the issue occurred.
Arcing from coil to manifold and heat shield.
Damaged Coil bracket where arcing to bracket and the harness are seem to have occurred.
Pics of plugs from cylinders 7 (Left) &8 (Right)
So, now all new plug wires are installed with the heat shields and verified to be properly seated on the plugs and coil packs.
The car idles rough, has the same knocking or popping sound in the upper RPM's and the car seems to have a bit of a surge.
Tonight while checking once more to ensure that all the plugs were snugged up and that I wasn't having a stupid moment I had my wife and little girl with me keeping me company. Once I got everything all buttoned up I cranked the car and let it idle for a bit. My wife, who knows very little about my car other than I work on it too much, asked what the rattling noise was she was hearing. I videoed the sound and so I submit to you the latest in a string of **** with this car that absolutely baffles me. :40-52 and 1:09 I hear it the best but now having heard it, I am able to hear it through out the video below.
A missing cyl will give the same noise. You need to hook it up to a tech 2 and find which cyl is causing the issue. Hopefully its just electric and not a lifter.
I went through three sets of ctsvr gmpp lifters and they are not cheap...
I dropped it off again this morning and talked with the lead tech about what it has been doing and showed him the video if tick sound. As of right now they are going to run the tech 2 on it again and then call GM tech support to see what if any history there has been for this on my year model. He asked if I had the recall's performed and I told him "yes at this dealership" and then the service advisor told him that that car was in better than awesome shape and that they had performed all the recalls and or warranty fixes.
I got a call today from the tech advisor who seemed a bit frustrated because he and the tech in the back had been on the phone for an hour with GM trying to determine what could possibly be causing these issues on an stock car.
The advisor asked me if I still had the factory heat shields because GM was hanging their hat on the fact that all of the issues regardless of symptom were originating from me not having their damn heat shields on the car. I reminded him that what was installed was way better and extremely overkill considering the car was stock. Obviously irritated at my answer because he knew it would illicit bureaucrat BS from GM, he told me that GM was suggesting that anything aftermarket was the cause of the issue. Essentially they are trying to say that the heat that is rising up past the plug wires is dissipated by the shields (true) but that the shields prevent heat from getting to the coils.
I told him that if that was GM's stance then they needed to forget getting anything useful from them because they had obviously lost their minds.
08-17-2015, 07:47 PM
Stutters & Hesitations on an 04 V1 
