Running rough

Antonio Lamar

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I have a 05 GT that recently started running kind of rough. I replaced sparkplugs, coil packs and now injectors. It runs decent when I get on it, it's just the idle that's really bad and the engine is shaking a lot. I pulled codes and it told me system 1 is too rich and system 2 is too lean. It's also popping at idle.. What can cause this issue? any help is appreciated.
 

stkjock

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Have u cleaned the MAF AND TB?
 

Dino Dino Bambino

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Have u cleaned the MAF AND TB?

Yup, start by carefully cleaning the MAF sensor wire and the inside of the throttle body. Make sure both are squeaky clean. If that doesn't fix the problem, try disconnecting the harness from the MAF sensor and see if the engine runs better. If it does, replace the sensor.

Edit: Beyond that, being rich on bank 1 and lean on bank 2 suggests you have a vacuum leak on bank 2 (driver's side). The most common sites are the intake and exhaust manifold gaskets. Hire a smoke machine to trace it.
 
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Juice

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When one bank is lean and the other is rich, it cannot be a maf issue.
Time to pull data and see where the misfire(s) are.
 

Speedracer67

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I am having the same problem but don't have a check engine light and no codes. My code ready might be to cheap to read any codes so I don't know if I need a better one.
 

Speedracer67

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So far I have been 30 days.
Only misses at idle. or part throttle with RPM change. Running down the road good. Road mileage still good.
 

Juice

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Forscan, Mode 6 data. It will tell you which cylinder(s) are not happy. No need to wait for a CEL and possibly damage the cat converter.
 

86GT351

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What plugs did you use? Have they been gapped? Or did you just take them out of the box and assume they are gapped properly. Gap should be between .040 and .050
 

Pentalab

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What plugs did you use? Have they been gapped? Or did you just take them out of the box and assume they are gapped properly. Gap should be between .040 and .050

On my 2010, the book sez to gap at .060". Since it has the small Roush M90 blower, and only 5.7 psi of boost, the brisk plugs were gapped to .035". With 9 psi, then the gap is reduced down to .032".
IF his gap was > .060" it could cause misfires. I can see the qty of misfires on my aeroforce gauge, plugged into obd port. It re-sets to zero when eng is off. With the new brisk plugs installed, and gapped to .032" the misfires dropped to zero.
 

86GT351

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On my 2010, the book sez to gap at .060". Since it has the small Roush M90 blower, and only 5.7 psi of boost, the brisk plugs were gapped to .035". With 9 psi, then the gap is reduced down to .032".
IF his gap was > .060" it could cause misfires. I can see the qty of misfires on my aeroforce gauge, plugged into obd port. It re-sets to zero when eng is off. With the new brisk plugs installed, and gapped to .032" the misfires dropped to zero.
A lot of people forget how critical plug gap can be. Obviously on a blower car the gap is reduced so it does not get blown out with the additional air flow
 

shadad

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Try from simple to hard,
remove the Battery positive plug, remove the MAF and clean it by using CRC MAF cleaner ( very careful ). clean the throttle body. clean the Air Filter.
this should fix. if not help, see if spark plugs are not faulty. twice this year, i bought set of 8 spark plugs and 2 of them were burned out of the box! twice not only once! how to test them? remove the plug one by one. if you notice change then its not the one and proceed to the next plug.
see if you have also a vacuum leak somewhere.

please share a screenshot or the CODE if you have. if not, drive it till its throw error.
sorry for my bad English :)
 

Speedracer67

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So all I need is an OBD adapter with a USB plug for my laptop and the software on the computer?
 

Juice

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Forscan uses an ELM327 adapter. Wifi, Bluetooth or wired. For PCM you do not need one with HS/MS can switch, but you might as well get one with the switch.
Forscan software will run without license for diagnostics. You only need the license if you want to make module configuration changes. Last time I checked, you can still get a 2 month trial license if you want to make some hacks to your module(s) Warning: This can be dangerous if you make the wrong change and could brick a module.
There is zero danger if you are just diagnosing, or looking at live data.

Wired adapter
https://www.amazon.com/Forscan-Scanner-ELMconfig-FoCCCus-Diagnostic/dp/B07MQ8GHG3
 

Antonio Lamar

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I disconnected the maf and the car continued to idle poorly and then died when reconnected..As for my LTFTS, LTFT1 was at -25% and LTFT2 was at 25%. SHRTFT1 was switching from -11.7 to -13.3 repeatedly. SHRTFT2 was mostly sitting at 14.8 but would sometimes go to 18. I didn’t do my spark plugs, I had a shop replaced all the things I’ve mentioned before, but now I am getting an ignition coil code for 5 different coils even though they are two weeks old.
 

Juice

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That is a huge spread between banks. Suggests a mechanical issue.
5 coil codes suggests its electrical.
Post all your exact codes.
 

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