Backround:
I recently put my car back to stock about 2 weeks ago. When I put it back to stock I noticed that my car has been idling rough.
I did a few test on the dyno.
Before my car was idling rough I was making the following numbers :
(These numbers were all on a mustang dyno, these are weather correction numbers)
The bolt ons I had was FMIC, exhaust, and DP's
Before rough idle
-Stock boost, bolt ons, no piggy back, 96 octane.
305 rwhp / 315 wtq
After rough idle
-Stock boost, bolt ons, no piggy back, 91 octane.
267 rwhp/287 wtq
I also got a miss fire from cylinder 4. Which lead me to think that it was a spark plug, or an injector failure. I only had this CEL 1 time.
I know theres no way that a 5 octane difference would yield 38 rwhp difference on the stock DME.
Ive been talking to alot of people that have had the same symptoms as my car. They said it was their fuel pump.
I went to the dealership and had the car tested.
I did the following test :
-Leak down
-Check spark plugs
-Check injectors
-Check fault codes
-Replace fuel pump
-change oil (to check if there was any coolant or metal shavings in it)
Every test that was done came back 100% normal. I even replaced the fuel pump to make sure, and the car is still rough idling...
Now Ive been reading around seeing other people been having this problem and some people think this is normal.
My question is how many people have this problem?
My car was running perfect with the mods on the car. With no mods it started rough idling.
Starting to think that I have a vacuum leak or my coil packs are messed up.
Heres what it sounds like. Notice that the rpms dont fluctuate. I think they probably move about 50 rpms if that. Sounds like it has a mild cam... Inside the cabin it drones a bit harder sometimes also (only at certain times)
Heres the engine bay clips. All the noise is coming from the DP's back.
All revs are from 0-3k rpm.
Also note I have HFC DP's which is why you can hear the turbos a little better
