Miss not throwing codes.

[the sandman]

I have a 07 GT that has a definite miss at Cruise speeds and below. No codes are showing up. What should I look for? Thanks

 

[Juice]

Why is the misfire monitoring disabled in the first place?

 

[JC SSP]

Is this a new issue? Could be bad gasoline?

Connect a scanner with datalog capabilities and drive it to record the event.

 

[StockishS197]

You would need to scan for misfires to identify it if you want to target the specific cylinder.

To trigger a CEL, it has to trigger enough misfires per 1000 revolutions so it may be under threshold.

If you cannot use a datalogging software, start with the basics - pull coils, plugs and look for any inconsistent cylinders and replace any worn parts.

 

[the sandman]

Brother Juice; I didnt know they could be turned off. Brother JC; yes its new but doubt its gas as its a intermittant miss. Like one cylinder. Brother Stockish; Can I data log with my SCT x4? Is there instructions? Planning on keeping car as long as I can drive. Plugs have less than 5k but coils are unknown age.

 

[JC SSP]

SCT X4 does have datalog capabilities but as I recently found out… mine needed updating and 5,000+ files prevented me from doing it over WiFi. Last time I used it was over 5 years ago when I uploaded the tune. SCT was no help and doesn’t have live assistance or even a phone number to call and speak with a representative.

 

[Juice]

Yes, it can be turned off. Some tuners do it for cams.
If you actually have a miss, pull sparkplugs. One (or more) will look different from the others if there is a miss.

 

[the sandman]

Thanks for all the help. I dont think monitors are turned off as it has thrown codes in past. If it is a coil it will get worse. I will see if I can check header temps for a cooler cylinder. Im learning but the computer side will always be a stumbling block. I do need to learn to data log. Any suggestions? I too am disappointed with SCT,s lack of customer service.

 

[whitmanink]

so i had a stumble i couldnt figure out,,
ended up being the cop.

no codes nothing,,
and my misfire detection was on.

spark plugs and cop, all known to fail or go bad without notice

 

[MrBhp]

A word of advice. If you have to replace a coil, use OEM.

 

[86GT351]

Is this a new issue? Could be bad gasoline?

Connect a scanner with datalog capabilities and drive it to record the event.

Actually a scanner with Mode 6 capabilities should show these events if it is truley a misfire. Is the car in question an Auto or Manual?

 

[the sandman]

Manual and its not a dead cylinder, its annoying to hear. Im replacing A arms and tierod ends. So might get to miss soon.

 

[whitmanink]

if i were you id get it fixed by replacing all the cop with ford ones , (unless you have a good coil tester. but they are prolly starting to go out )
and replace all the spark plugs,

that will give you the best choice for success ,and if it still does it (which im pretty sure it will),
you will be alot better off trouble shooting

 

[MasterofDisaster]

A couple years ago, I thought I had a small occasional, intermittent miss. No CEL and no codes. Changed the plugs, but still had this vague unsettling problem. No CEL/codes. Tried fuel injector cleaner. Even changed the coils, but still not change and no codes. About a week later the CEL came on with a code for a misfire. The fuel injectors were clearly working normally, so I took it to a shop. Their analyzer said it was my PCM. Took almost two weeks to get a new computer, but it definitely fixed the problem. No problems since.

I still think I did the right thing by trying the simple, cheap things first.

 

[whitmanink]

if i were you id get it fixed by replacing all the cop with ford ones , (unless you have a good coil tester. but they are prolly starting to go out )
and replace all the spark plugs,

that will give you the best choice for success ,and if it still does it (which im pretty sure it will),
you will be alot better off trouble shooting

i wanted to say, im pretty sure it will fix it.

 

[whitmanink]

A couple years ago, I thought I had a small occasional, intermittent miss. No CEL and no codes. Changed the plugs, but still had this vague unsettling problem. No CEL/codes. Tried fuel injector cleaner. Even changed the coils, but still not change and no codes. About a week later the CEL came on with a code for a misfire. The fuel injectors were clearly working normally, so I took it to a shop. Their analyzer said it was my PCM. Took almost two weeks to get a new computer, but it definitely fixed the problem. No problems since.

I still think I did the right thing by trying the simple, cheap things first.

yea ive heard people changing the ecu and still having problems,
but then again , im pretty sure the mechanics were just throwing parts at it,

i had the same thing as you had ,, only new cop and plugs fixed it.

i think ecu go bad on these cars when you live in cold climate , or its in bad weather all the time,

i dont think they just go bad just because ,, its due to corrosion in the breadboards and shorting out the little capacitors and such

 

[MasterofDisaster]

***

i think ecu go bad on these cars when you live in cold climate , or its in bad weather all the time,

i dont think they just go bad just because ,, its due to corrosion in the breadboards and shorting out the little capacitors and such

Michigan definitely gets cold in the winter. Very humid here too b/c it's just two peninsulas.

 

[the sandman]

Got one A arm and tierod end on, doing otherside today. I drove car yesterday and it threw 4 codes p0132 o2 sensor circuit high voltage bank 1 sensor 1, po153 o2 sensor circuit slow response bank 2 sensor 1, po420 catalyst system efficiency below threshold bank1, po430 catalyst system efficiency below threshold bank 2. So what do they mean? Car has Accel coils. Probably put in when cams were installed. Unknown age.

 

[Juice]

Got one A arm and tierod end on, doing otherside today. I drove car yesterday and it threw 4 codes p0132 o2 sensor circuit high voltage bank 1 sensor 1, po153 o2 sensor circuit slow response bank 2 sensor 1, po420 catalyst system efficiency below threshold bank1, po430 catalyst system efficiency below threshold bank 2. So what do they mean? Car has Accel coils. Probably put in when cams were installed. Unknown age.

The plot thickens.
O2 codes could make it feel like a miss, but its actually just running rough.
Cat codes are saying the cats failed the tests, so worn out cats or removed cats.