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Discussion Starter #1
Hi Everyone,
I'm a nub so bare with me. Here is the problem I have. I have a 2012 Shelby Cobra GT500. It has a 5.4 with the Super Charger,
I have owned it for about 2 months, It has a cold air intake, smaller Pully, and the cats removed all done by previous owner.
I got the mis-fire on cylinder 2, I replaced the plugs, cleared code, it came back, i replaced all 8 coil packs,
The cleared code it came back, I then ran a can of Sea-Foam through it with a quarter tank, code came back.
From the research I have done its pointing to a clogged Fuel injector on Cylinder 2 .
Here's my questions
1) Can i replace just 1 injector?
2) should i replace the 4 injectors on the passenger side
3) Should i replace all 8 injectors( if i replace all 8 injectors does the Super Charger have to come off?)
4) should i remove all 8 and send them out to be cleaned ?
 

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Moderator Dude!
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28,248 Posts
Hi Everyone,
I'm a nub so bare with me. Here is the problem I have. I have a 2012 Shelby Cobra GT500. It has a 5.4 with the Super Charger,
I have owned it for about 2 months, It has a cold air intake, smaller Pully, and the cats removed all done by previous owner.
I got the mis-fire on cylinder 2, I replaced the plugs, cleared code, it came back, i replaced all 8 coil packs,
The cleared code it came back, I then ran a can of Sea-Foam through it with a quarter tank, code came back.
From the research I have done its pointing to a clogged Fuel injector on Cylinder 2 .
Here's my questions
1) Can i replace just 1 injector?
2) should i replace the 4 injectors on the passenger side
3) Should i replace all 8 injectors( if i replace all 8 injectors does the Super Charger have to come off?)
4) should i remove all 8 and send them out to be cleaned ?
Welcome to the forum!

Sorry for your trouble. Hopefully it is something simple. Do you keep an eye on your air/fuel ratio? Since your car has been modded/tuned, I’d make sure your tune is good and not running lean. A lean condition can lead to engine damage that could first pop up as a misfire.

You can definitely pull individual injectors. You might even swap a couple to see if the problem follows the injector or stays with the cylinder. That would give you vital info on the problem.

Also, you’ll find our new member area here:

 

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Discussion Starter #4
Thank you for the suggestions. I am going to swap the injectors from 1 & 2 clear the code and see what happens,
As for the tune, I am totally new to that aspect and have no clue how to check it . If there are any members in central mass that could help out that would be great. I just ordered a new MGW short throw shifter and will be replacing the tranny fluid as well ( I have 1st to 2nd grind and hope it helps)
 

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Moderator Dude!
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Thank you for the suggestions. I am going to swap the injectors from 1 & 2 clear the code and see what happens,
As for the tune, I am totally new to that aspect and have no clue how to check it . If there are any members in central mass that could help out that would be great. I just ordered a new MGW short throw shifter and will be replacing the tranny fluid as well ( I have 1st to 2nd grind and hope it helps)
There are a few ways to check your tune John. Your 2012 has onboard wideband sensors to monitor the air/fuel ratio. You just need a gauge to see the number. I have an Aeroforce Interceptor gauge that plugs into the OBDII port for easy viewing of a host of parameters. You can also buy a standalone air/fuel gauge. If you have a gauge, you can either watch the ratio while you do some spirited runs or you can even record parameters for runs on gauges like the Interceptor. This would be a self-diagnosis. Other options would be to take your car to a local speed shop that has a dyno and is familiar with our GT500s. You could run it on their dyno and check things like boost and air/fuel. Lastly, you could work with a reputable tuner to datalog and tune your car to get it to a known quantity.

As for your shift grind, don’t shift while your rear tires are free spinning (lost traction). If they are free spinning, press in the clutch and pause until they grab before jamming the next gear.
 

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Discussion Starter #6
I have had it on a Dyno a few weeks back , in NH about 2 hours drive, I thought it was a little expensive ($550) but they also got the car to pass mass state inspection with out CATS, so I really didn,t have a choice, what is a good price for the dyno and tune check, I do have the UScan tool that’s bluetooth and I will see if it will capture a scan while I’m driving and will post the result . Thanks for all the help I really appreciate it
 

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Moderator Dude!
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I have had it on a Dyno a few weeks back , in NH about 2 hours drive, I thought it was a little expensive ($550) but they also got the car to pass mass state inspection with out CATS, so I really didn,t have a choice, what is a good price for the dyno and tune check, I do have the UScan tool that’s bluetooth and I will see if it will capture a scan while I’m driving and will post the result . Thanks for all the help I really appreciate it
I haven’t gotten a dyno tune so I’ll defer to others on that price estimate.

When you were on the dyno recently, did you monitor air/fuel? Got the graph or numbers?

Was the misfire there before the dyno run? When did it start?
 

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Discussion Starter #8
Hi Goose,
I have attached the Graph, and I have a video of the Dyno run, I put the link to the video below as well.
Like I said I am new to this so not sure if the Air flow was on the screen, maybe you can tell me.
As for the mis-fire it didn't show up until after to the Dyno run. Strange thing this morning the light went out on its own,

here is the link to the Video of the Dyno run
Having an issue post the links, so put the HTTPS at the beginning of the link ok
://share.icloud.com/photos/0A5_U7mk7a_QPLJ8wquVnQwUA
Here is the link to the Pic of the Graph
://share.icloud.com/photos/02jxmcoK4515xe8kVxpMwotaQ
 

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Moderator Dude!
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Hi Goose,
I have attached the Graph, and I have a video of the Dyno run, I put the link to the video below as well.
Like I said I am new to this so not sure if the Air flow was on the screen, maybe you can tell me.
As for the mis-fire it didn't show up until after to the Dyno run. Strange thing this morning the light went out on its own,

here is the link to the Video of the Dyno run
Having an issue post the links, so put the HTTPS at the beginning of the link ok
://share.icloud.com/photos/0A5_U7mk7a_QPLJ8wquVnQwUA
Here is the link to the Pic of the Graph
://share.icloud.com/photos/02jxmcoK4515xe8kVxpMwotaQ
No workie... upload the video to YouTube and simply paste the link here.
 

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Moderator Dude!
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I’m watching on my phone (small screen), but it looks like the blue bar is your air/fuel and it goes down to the high 10s at WOT, so the good news is it didn’t go lean and hurt the motor.
190206
 

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Discussion Starter #13
ok that's good news, so its looking more like the Fuel injectors then? I have a place that is local ( about 30 minutes away) they charge $16.95 an injector, 4 for $97.50 and 8 for $130, But I am not sure if the Drivers side injectors will come out with out pulling the Super charger. So i'm thinking about getting the 4 from the passenger side done,
What are your thoughts?
 

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Moderator Dude!
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ok that's good news, so its looking more like the Fuel injectors then? I have a place that is local ( about 30 minutes away) they charge $16.95 an injector, 4 for $97.50 and 8 for $130, But I am not sure if the Drivers side injectors will come out with out pulling the Super charger. So i'm thinking about getting the 4 from the passenger side done,
What are your thoughts?
I pulled my fuel rails twice. Once when installing my Whipple and the second time was to paint them. I was able to remove them with my Whipple elbow covering the driver’s side. It was a hard fought battle, but I won. Yours would be much easier to remove.

If your misfire started after the dyno, I can’t imagine the injector getting plugged at that moment. Did you check all of your connections on everything to make sure nothing came loose during the run? I’m talking all intake, vacuum and wires.
 

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Discussion Starter #15
Hi Goose,
I am going to check all the conections today when i get home, Matter of fact, i think i will remove the connector and re seat it and see if that will resolve the issue. Thanks for all the help and I will get back to you later tonight .
He is a picture of my car ...

190217
 

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Discussion Starter #18
Well i have an update, I checked the connections, all seem tight, The light came back on. I am going to pull the injectors off cylinder 1 - 4 and get them cleaned to see if that fixes the issue. If not what could it be?
Also the new MGW Short throw shifter came in i will be installing that in about a week or so. Hopefully it will stop the 2nd gear grind. Its happening only when i shift at high RPM,s ( tire are not spinning)
 

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Discussion Starter #20
thanks, I really don't want to think its a head gasket If it was wouldn't it smoke like hell? it only seems to happen about every 100-200 miles stays on for about 20 - 50 miles, then it goes out
 
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