The problem - during part throttle cruising (such as using cruise control on the highway) my car feels like has a slight miss to it. At about 3-4 second intervals you can ‘feel’ it in the seat coming from the car. And the frequency is consistent…it’s always there. At highway speeds it’s barely noticeable and at lower speeds it’s very noticeable; you can clearly hear & feel it. I don’t notice anything at higher RPMs or on acceleration/deceleration. Ambient temp and if the engine is warmed up or not don’t seem to matter either. It’s still there - although before the engine warms up or its above 1200rpms the driveability sucks. But that might just be the nature of cams.

I installed cams/LT headers/O/R X/pulleys/new plugs/updated 93P tune/and added hi-flow cats all less than a month ago. I didn’t notice anything at first, but over the past 2 weeks or so it seems to be getting worse. Or maybe I’m just fixating on it now.

So far I have – pulled & re-gapped plugs (.045), cleaned MAF, removed & cleaned TB, sprayed electric cleaner on all of the coil pack, injector, MAF, & TB connectors and spammed Bama tunes to death with about 20 datalogs. And yes, for what it’s worth I used the correct type of cleaner for each of those. Bama says the datalogs are spot on and to check for mechanical issues.

Other than ‘feeling’ the miss the car runs perfect with no leaks/CELs/noises/vibrations/etc or anything else that would cause me to think there’s a problem. I’ll have the car up on a lift tomorrow re-torqueing perpetually loose header bolts and installing jam nuts on the studs. While I’ve got the car apart what else should I look at??

Hope this makes sense and sorry for the novel.

 

If it's truly a cylinder miss you should be able to plug in a scan tool (Snap On, etc) & identify which cylinder it is to at least narrow down the search to a specific cylinder, then move on to identify whether it's fuel or ignition.

 

Have you tried keeping the octane in your tank the same and using a lower octane tune to see if the problem persists?

Have you tried pulling the negative battery cable and reconnecting to reset the computer and see if it goes away. 05+ Stangs learn your drivign habits and makes adjustments (learn) your habits over time. Don't know why it would have 'learned' a miss but you never know.

You could also do a data log of your car while its running and have someone mark the time when it happens so when you look at the log later on you can see what the sensors are seeing. That would help you narrow things down.

 

Unless it's consistent and constant, it won't throw a code or even store a pending code.

I've pulled a coil wire on mine before just so I can see how the car idles with a miss (long story). It took a few seconds for the Check Engine light to kick on. If I plugged the wire back the light would turn off after a trip around the block and no code would be stored.

 

Replying w/ my phone so no quotes. Anyhow, I only run 93 and I've sent >10 datalogs to bama. Haven't pulled a coil wire w/ it running or disco'd neg cable. It's very constant & consistent, but no codes. So would a scan tool dO anything my SCT won't?

 

I would run a cylinder check and if everything turns out ok you may need a tune adjustment. Those cams can cause some funny things to happen.

RPM hunting, during idle and cruise, surges in RPMs, all sorts of oddities.
You need to find a tuner that is AWARE of these kinds of issues and KNOWS he can fix them if that is the case.

If you Private Message me I can refer you to a great tuner that fixed problems with my car after the cam and tune install after going to two different online tuners and three dyno tuners with no luck.

Great guy and KNOWS what he is doing.
If you had a way to do some data logging odds are he could fix you right up without even having to make a trip there. If you are in Texas he is in the DFW area and it's always fun going to his place. He will fix your problem in ten minutes or less and THEN take a test drive with you and he will not stop tweaking it until you have the car running EXACTLY the way you want. With your power curve and all.

In my opinion he is one of the best tuners in the United States hands down.

 

A Snap On Solus would show live misfire as it happens even if its not enough to set a code or turn on the Ck Engine light on.

 

Could it be this? https://mustangforums.com/mustang-ts...NG-CRUISE.html

 

If its the fuel pump that would suck. Everyonce in a while out on the highway I let off the gas to slow down and when I step back on the gas it'll buck once or twice. A couple other members have mentioned the fuel pump IRT to that as well. Might need to change it anyway.

I've got 15 datalogs I pulled with LiveLink & my SCT. The .csv files look like the Matrix to me...I'm sure someone could probably decode them better than I. Any takers? I can make sense of them in playback on my laptop but I'm not seeing anything jump out.

I inspected the COPs, injectors, wiring, and everything else I could get my hands on under the hood and saw no defects. I didn't use a spark plug scan tool yet but I did pull the COP wires one at time with the engine running. At idle w/ cams you cant even tell when one is disconnected.