Tune vs. Spark Plug Question
Thread Starter
5th Gear
Joined: Aug 2016
Posts: 5
Likes: 0
From: Forest VA
Tune vs. Spark Plug Question
Wanted a Vette for 20 years and finally have an '06. Purchased with 28K miles with mild mods - headers, x-pipe, Borla's, dyno tuned.
If the car was tuned with NGK TR55 plugs gapped at ~.058", can I switch back to OEM plugs without retuning?
I get the dreaded "service charging system" message at idle and the GM Tech said there was a TSB regarding aftermarket plugs. I asked him to go back to OEM plugs but he wouldn't touch it because of the tune. He indicated that doing so would cause the engine to run too rich or lean.
In my opinion, new plugs would have no impact on the air/fuel ratio but I wanted to consult with the masters on this forum before changing plugs myself.
This is my 1st post so if I posted in the wrong forum, you can publicly flog me after my car is fixed
If the car was tuned with NGK TR55 plugs gapped at ~.058", can I switch back to OEM plugs without retuning?
I get the dreaded "service charging system" message at idle and the GM Tech said there was a TSB regarding aftermarket plugs. I asked him to go back to OEM plugs but he wouldn't touch it because of the tune. He indicated that doing so would cause the engine to run too rich or lean.
In my opinion, new plugs would have no impact on the air/fuel ratio but I wanted to consult with the masters on this forum before changing plugs myself.
This is my 1st post so if I posted in the wrong forum, you can publicly flog me after my car is fixed
Le Mans Master
Joined: May 2016
Posts: 7,227
Likes: 1,546
From: Florida
Wanted a Vette for 20 years and finally have an '06. Purchased with 28K miles with mild mods - headers, x-pipe, Borla's, dyno tuned.
If the car was tuned with NGK TR55 plugs gapped at ~.058", can I switch back to OEM plugs without retuning?
I get the dreaded "service charging system" message at idle and the GM Tech said there was a TSB regarding aftermarket plugs. I asked him to go back to OEM plugs but he wouldn't touch it because of the tune. He indicated that doing so would cause the engine to run too rich or lean.
In my opinion, new plugs would have no impact on the air/fuel ratio but I wanted to consult with the masters on this forum before changing plugs myself.
This is my 1st post so if I posted in the wrong forum, you can publicly flog me after my car is fixed
If the car was tuned with NGK TR55 plugs gapped at ~.058", can I switch back to OEM plugs without retuning?
I get the dreaded "service charging system" message at idle and the GM Tech said there was a TSB regarding aftermarket plugs. I asked him to go back to OEM plugs but he wouldn't touch it because of the tune. He indicated that doing so would cause the engine to run too rich or lean.
In my opinion, new plugs would have no impact on the air/fuel ratio but I wanted to consult with the masters on this forum before changing plugs myself.
This is my 1st post so if I posted in the wrong forum, you can publicly flog me after my car is fixed
I tried TR55s in my LS3 for 3K miles. After which, I checked gaps and they had opened significantly from install, so I removed them and replaced with NGK iridiums. TR55s are copper/copper plugs, so very soft and not expected to be high mileage plugs. Where did the 058" come from? Did you measure? BC that's pretty wide to have set them that way.
Last edited by BlindSpot; Aug 28, 2016 at 01:09 PM.
Le Mans Master
Joined: May 2016
Posts: 7,227
Likes: 1,546
From: Florida
If it were my car, based on what I know, I wouldn't hesitate to put factory iridiums back in. Dealer techs are in business with liabilities so are cautious. There is nothing that would indicate the plugs are related to the CEL, except some have had spark plug wires back off causing a miss and it does crazy things like set unrelated CELs. Try a little dielectric grease ON THE RUBBER PART OF THE WIRE ENDS ONLY, not the metal connection ends and you can burp the coil connection ends to relieve any air trapped in the connector with a small screw driver. Reset the CEL and go from there.
Last edited by BlindSpot; Aug 28, 2016 at 02:15 PM.
Le Mans Master
Joined: Oct 2014
Posts: 8,674
Likes: 2,728
From: Atlanta GA
Not to overreact and buy something just to data collect. I was more just asking the Q if you had one. Net, net, you're not modded enough that a tuner could have gone very far with a tune, and you're still using factory specced heat range plugs, albeit the TR55s are a popular aftermarket.
If it were my car, based on what I know, I wouldn't hesitate to put factory iridiums back in. Dealer techs are in business with liabilities so are cautious. There is nothing that would indicate the plugs are related to the CEL, except some have had spark plug wires back off causing a miss and it does crazy things like set unrelated CELs. Try a little dielectric grease ON THE RUBBER PART OF THE WIRE ENDS ONLY, not the metal connection ends and you can burp the coil connection ends to relieve any air trapped in the connector with a small screw driver. Reset the CEL and go from there.
If it were my car, based on what I know, I wouldn't hesitate to put factory iridiums back in. Dealer techs are in business with liabilities so are cautious. There is nothing that would indicate the plugs are related to the CEL, except some have had spark plug wires back off causing a miss and it does crazy things like set unrelated CELs. Try a little dielectric grease ON THE RUBBER PART OF THE WIRE ENDS ONLY, not the metal connection ends and you can burp the coil connection ends to relieve any air trapped in the connector with a small screw driver. Reset the CEL and go from there.
Just change the plugs back to the factory plugs
the ECM will vary fuel trims will up or down 20% and with the mild tune yuo have for headers there should be absolutely no problem at all
Dave
Last edited by Dcasole; Aug 28, 2016 at 02:35 PM.
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Le Mans Master
Joined: May 2016
Posts: 7,227
Likes: 1,546
From: Florida
Good to hear! Did you use dielectric grease and release air pockets at the coil end connections? If not, and the CEL comes back, check each boot at the coil and make sure one hasn't popped off from air pressure trapped in the boot.
Last edited by BlindSpot; Aug 30, 2016 at 09:49 AM.
Le Mans Master
Joined: Oct 2014
Posts: 8,674
Likes: 2,728
From: Atlanta GA
Thread Starter
5th Gear
Joined: Aug 2016
Posts: 5
Likes: 0
From: Forest VA
I bought the car 2nd hand with the mods and tune completed by the previous owner. Pretty sure it was a garage queen. 10 years old, original tires, 28K miles, and not one paint scratch, chip, or ding on the whole body. The Borlas had a moderate coating of carbon on the outlet. Was worried that it was running rich, so I scrubbed them clean and the discoloration hasn't reappeared.
I've always wanted a vette but wasn't looking. Had to get tags for a new F-350 and popped into the local Ford store to pick the plates up. There she was, a perfect Corvette, in a Ford showroom. The rest is history.
Thanks to everyone for their support in helping me fix the issue.
I've always wanted a vette but wasn't looking. Had to get tags for a new F-350 and popped into the local Ford store to pick the plates up. There she was, a perfect Corvette, in a Ford showroom. The rest is history.
Thanks to everyone for their support in helping me fix the issue.
Safety Car
Joined: Mar 2004
Posts: 4,048
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From: South Florida
Example: If your fuel trims learned 7% more fuel in the cell right before the MAF cutoff threshold, then 7% more fuel will be added to the base commanded fuel value when you go full throttle.
Le Mans Master
Joined: May 2016
Posts: 7,227
Likes: 1,546
From: Florida
Not exactly true. The ECU does the fuel adjustments at part throttle below a certain MAF value. However, the values (+ or - ) of learned fuel trims is carried over into the Power Enrichment calculation at WOT.
Example: If your fuel trims learned 7% more fuel in the cell right before the MAF cutoff threshold, then 7% more fuel will be added to the base commanded fuel value when you go full throttle.
Example: If your fuel trims learned 7% more fuel in the cell right before the MAF cutoff threshold, then 7% more fuel will be added to the base commanded fuel value when you go full throttle.
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,342
From: Gilbert AZ
Yes, if you have LTFT enabled, positive ones can be applied to PE, but depending on the car to adjust is beyond stupid. You should't expect the car to adjust for WOT tuning based of fuel trims.
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,342
From: Gilbert AZ
I see time and time again on FB, and locally where people are constantly saying "Stock ECU can adjust for up to 20%, so don't worry about tuning for that mod". Just throw headers, or a new CAI, or bump the boost up, or whatever. Only reason I posted was because I wanted to make sure people understood what that meant. Hell I wouldn't want my FTs to be +15% at part throttle, let alone WOT.