2010 Base - Issues
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
2010 Base - Issues
Hey all!
Newer to the forums. Bought the car back in June, with 62k miles on it.
Replaced spark plugs (AC Delco), and wires (Taylor)
Mods:
-Vette-Air scoop
-CAI - which I removed, and put stock back on due to surging
-Catch Can
-Magnaflow Axle back mufflers
Issues that have developed over the past month:
-Rough Idle at 500rpm, with rare shudder, like it's about to die, but doesn't.
-low popping sound in exhaust
-Fuel consumption is up
-Some hesitation when hitting it hard, with rare stall.
-Exhaust had the sulfur smell for it brief time
I checked all the basic stuff for peace of mind. No smoke from exhaust. No milk in the coolant. No milk in the oil, totally clean. No huffing from the oil fill (very slight suction actually).
I have taken it to a shop that specializes in Vettes. Had random misfire codes. They did a resistance check on the injectors...all good. They had a set of coil packs, and swapped them out to test. No change. They ran some scope, and said all the cylinders were firing. Replaced the upstream o2 sensors for grins, no change.
Frustrated. Never get a CEL, except for the occasional tire pressure monitor, which needs to be replaced.
Throttle body issue?
ECM?
Newer to the forums. Bought the car back in June, with 62k miles on it.
Replaced spark plugs (AC Delco), and wires (Taylor)
Mods:
-Vette-Air scoop
-CAI - which I removed, and put stock back on due to surging
-Catch Can
-Magnaflow Axle back mufflers
Issues that have developed over the past month:
-Rough Idle at 500rpm, with rare shudder, like it's about to die, but doesn't.
-low popping sound in exhaust
-Fuel consumption is up
-Some hesitation when hitting it hard, with rare stall.
-Exhaust had the sulfur smell for it brief time
I checked all the basic stuff for peace of mind. No smoke from exhaust. No milk in the coolant. No milk in the oil, totally clean. No huffing from the oil fill (very slight suction actually).
I have taken it to a shop that specializes in Vettes. Had random misfire codes. They did a resistance check on the injectors...all good. They had a set of coil packs, and swapped them out to test. No change. They ran some scope, and said all the cylinders were firing. Replaced the upstream o2 sensors for grins, no change.
Frustrated. Never get a CEL, except for the occasional tire pressure monitor, which needs to be replaced.
Throttle body issue?
ECM?
Race Director
Joined: Sep 2009
Posts: 11,338
Likes: 2,437
From: Eastern
It is strange that you get no CEL, or DTC codes on the scanner except for misfire codes.
Was the car running OK before changing plugs and wires? Without a DTC code, it is very difficult to diagnose what could be causing the misfire.
If the car was running OK before the spark plug/wire change, that is where I would start. Assure that all the spark plug wires are seated and not arching at the boot.
How is your battery? Has it been run down?
Good Luck
Was the car running OK before changing plugs and wires? Without a DTC code, it is very difficult to diagnose what could be causing the misfire.
If the car was running OK before the spark plug/wire change, that is where I would start. Assure that all the spark plug wires are seated and not arching at the boot.
How is your battery? Has it been run down?
Good Luck
Instructor
Joined: Sep 2015
Posts: 167
Likes: 33
From: TN
Like the previous post said, hard to tell without any DTC.
maybe you accidentally cracked a spark plug while installing it? Maybe they’re not the right spark plugs?
maybe the car was tuned for the other Cold air intake so now it’s not quite right with the stock air box? Check fuel trims ? Yeah... I’m just guessing.
maybe you accidentally cracked a spark plug while installing it? Maybe they’re not the right spark plugs?
maybe the car was tuned for the other Cold air intake so now it’s not quite right with the stock air box? Check fuel trims ? Yeah... I’m just guessing.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
Thanks for the input. When I took it to the corvette shop (does work for the dealership as well), they apparently locked out the ECM. I took it to a local mechanic closer to me, and he discovered that he could not adjust anything. Now he's talking about wiping the ECM by uploading a 2015 update or something like that to get it unlocked, and reset everything. Then he can adjust fuel trims etc. Confusing.
Instructor
Joined: Sep 2015
Posts: 167
Likes: 33
From: TN
OR ... go back to the "corvette shop" and ask them to unlock it. By the way, you can record data, and monitor fuel trims even if the ECM is "locked". Locking it just stops you from changing the tune. If the fuel trims are bad why dont you just take it to the corvette shop and ask them to adjust it.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
OR ... go back to the "corvette shop" and ask them to unlock it. By the way, you can record data, and monitor fuel trims even if the ECM is "locked". Locking it just stops you from changing the tune. If the fuel trims are bad why dont you just take it to the corvette shop and ask them to adjust it.
Burning Brakes
Joined: Sep 2018
Posts: 1,023
Likes: 171
From: Auburn Al
more air in-more air out = tune, first question you ask a tuner "do you lock the ECM/" if they say yes you walk. Your paying them, they work for you. go back tell them to unlock it or your taking them to court, with the cost of a new one and programing it won't be small claims. as soon as they unlock it walk and find a tuner who works for you.
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Burning Brakes
Joined: Dec 1999
Posts: 765
Likes: 11
Cruise-In I Veteran
I would like to see what the fuel trim and O2 sensor values are.
A popping noise from the tail pipe, to me sounds like a busted valve spring.
Some things to check... Good luck and keep us posted.
A popping noise from the tail pipe, to me sounds like a busted valve spring.
Some things to check... Good luck and keep us posted.
Safety Car
Joined: May 2016
Posts: 4,633
Likes: 1,818
From: Erlanger, Kentucky
I would check some more basic things. Check the sparkplugs and their gap. Maybe put in the old set and see if there is any difference. Same thing with the plug wires; put the old ones back on or put a new set of factory AC delco wires. New parts can be bad at the get go. Also, lots of problems are caused on cars by going with "upgraded" plugwires, coil packs, etc. when the best is what came on the car new.
I would also have the battery tested and check all your grounds.
Check for any vacuum leaks at all the intake connections, check for any cracked hoses or plastics on the PVC system. Vacuum leaks can make a car run very bad and cause increased fuel consumption. Check to make sure the catch can is installed correctly and the hoses are routed properly. Check for hose leaks; with a catch can, its more connections where a vacuum leak can happen.
Lots of times these very basic things are the problem.
I would also have the battery tested and check all your grounds.
Check for any vacuum leaks at all the intake connections, check for any cracked hoses or plastics on the PVC system. Vacuum leaks can make a car run very bad and cause increased fuel consumption. Check to make sure the catch can is installed correctly and the hoses are routed properly. Check for hose leaks; with a catch can, its more connections where a vacuum leak can happen.
Lots of times these very basic things are the problem.
Last edited by Spaceme1117; Dec 6, 2019 at 03:32 PM.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,150
From: SW Florida
2021 C6 of the Year Finalist - Modified
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
I had another shop look at it, and they think they found the issue. The pigtail/extension wire connecting to the crankshaft position sensor is crimped/damaged. They asked me to order the part online. I went to the dealer, and all they have is a pigtail wire (connector on one end to the CPS) that you have to splice in. I found the camshaft sensor wire with connectors on both ends, (https://www.summitracing.com/parts/n...27501/overview) but can't find one for the crankshaft sensor. The shop prefers not to use the splice method, to avoid any potential electrical interference in the radio (whine etc.)
Anyone know where I can get one, or am I sol?
Last edited by slam69; Dec 7, 2019 at 12:24 PM.
Race Director
Joined: Sep 2009
Posts: 11,338
Likes: 2,437
From: Eastern
I did a search and could only find the spliced connectors, and not the extension wiring for the Gen 6. I did find some for the Gen 4 Corvettes.
I can't see any issue with splicing in a new connector if one solders the wires, then uses 2 layers of electric heat shrink tubing on top of the soldered connections.
It is no different than having the wire covered in the rubber sheathing.
Good luck in whatever you decide to do.
I can't see any issue with splicing in a new connector if one solders the wires, then uses 2 layers of electric heat shrink tubing on top of the soldered connections.
It is no different than having the wire covered in the rubber sheathing.
Good luck in whatever you decide to do.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
I did a search and could only find the spliced connectors, and not the extension wiring for the Gen 6. I did find some for the Gen 4 Corvettes.
I can't see any issue with splicing in a new connector if one solders the wires, then uses 2 layers of electric heat shrink tubing on top of the soldered connections.
It is no different than having the wire covered in the rubber sheathing.
Good luck in whatever you decide to do.
I can't see any issue with splicing in a new connector if one solders the wires, then uses 2 layers of electric heat shrink tubing on top of the soldered connections.
It is no different than having the wire covered in the rubber sheathing.
Good luck in whatever you decide to do.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 9
From: TX
Well, still having the issue. Being that I bought it used, I went ahead and changed out the injectors, and coil packs as well. It seems to smooth out after resetting the ECM, but then after a day or two of driving it around, hammering on it a bit, it starts running a little rough again.
Here is a video of the popping sound in the exhaust at idle.
Here is a video of the popping sound in the exhaust at idle.
Last edited by slam69; Dec 22, 2019 at 03:27 PM.
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Need to data log to see what is happening, fuel trims, spark, injectors, O2 sensor readings, etc. I would do the following in order:
1. I would remove the catch can and bring to stock just to eliminate the possibility of a vacuum leak from the can, it actually happened to me.
2. Check each ignition wire with ohm meter (I know they are new), wiggling the wire as your read them to make sure the reading does not fluctuate.
3. Buy a decent code reader that will allow you to data log parameters I mentioned above. Data log while driving can capture the issue in real time making it easier to diagnose.
4. Find someone with Hptuners and data log, download Hptuners software onto your computer or laptop (it's free) and upload the data log file to read. You can email the file to a competent tuner to view for suggestions. You do not need to buy credits, unless you tune it.
1. I would remove the catch can and bring to stock just to eliminate the possibility of a vacuum leak from the can, it actually happened to me.
2. Check each ignition wire with ohm meter (I know they are new), wiggling the wire as your read them to make sure the reading does not fluctuate.
3. Buy a decent code reader that will allow you to data log parameters I mentioned above. Data log while driving can capture the issue in real time making it easier to diagnose.
4. Find someone with Hptuners and data log, download Hptuners software onto your computer or laptop (it's free) and upload the data log file to read. You can email the file to a competent tuner to view for suggestions. You do not need to buy credits, unless you tune it.
Last edited by Mike's LS3; Dec 23, 2019 at 12:37 PM.
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
-Fuel consumption is up
-Some hesitation when hitting it hard, with rare stall.
-Exhaust had the sulfur smell for it brief time
ust a though:
These symptoms could be the possibility the car is running rich. If a vacuum leak is present, the ECM will add fuel and this fuel (positive fuel trims) will carry over to WOT creating a richer air/fuel ratio. Also, the sulfur smell could be a rich condition or COT, catalytic overtempt protection when the ECM adds fuel to cool the catalytic converters.. Again data log is the best diagnostic tool rather than guess work.
-Some hesitation when hitting it hard, with rare stall.
-Exhaust had the sulfur smell for it brief time
ust a though:
These symptoms could be the possibility the car is running rich. If a vacuum leak is present, the ECM will add fuel and this fuel (positive fuel trims) will carry over to WOT creating a richer air/fuel ratio. Also, the sulfur smell could be a rich condition or COT, catalytic overtempt protection when the ECM adds fuel to cool the catalytic converters.. Again data log is the best diagnostic tool rather than guess work.