MikeInCape

1998 Mustang GT



Aftermarket MAF, Upper Intake, Intake Spacer, K&N, MSD Coils, MSD Wires, Bosche Platnium plugs, Hypertech powerprogramming, shorty headers and no rear cats.

Sock Fuel injectors, line, pump

Fuel Filter & all routine matenience done recently.

Symptoms:
Pings and pops down the road

Pings I believe are intake and pops are exhaust. Floor it and it backfires good (in park)

Idles low & rough

Has about 1/2 power as before

Can not locate a dead cylinder

Ran perfect when parked yesterday.

What is diag fee?

I know it could be MAF, or have jumped timing, or possibly something else... Can anyone tell me which it might be with the following pics of DigiMoto (sensor data):

At Idle:


at 2500RPM:


at 5000RPM:


I will post resolution if I find on my own... For anyone who might have the same symptoms.

Some help would be appreciated.

Also... Sorry for so many continous replies below. I just realized I can edit a post and will do that from now on.

-Mike

MikeInCape

I've taken it out several times trying to get it to throw an error code... Still none...

Backfiring really bad...

It ran 100% when I drove yesterday up to parking it...

I'm baffled and about to just start pulling parts and replacing, and that is never good.

Any ideas? Any recommendations for troubleshooting?

Thanks,Mike

MikeInCape

New information:

Vacuum: 24psi - Steady... So hasn't skipped timming right?

Running lean... (25% lean, actually??)

Definitely not a cylinder skip...

Cracked intake maybe?

Any ideas???

MikeInCape

As far as the sensor data goes... I have used the same program and interface on a friends mustang, and you can ignore the timing advance and missing throttle position sensor reading... His does that too..

But the fuel trim reads correctly near o% on his and 15% (not 25 like I said above, sorry) on mine (at 5000rpm). Why so lean?

MikeInCape

"Thanks for all of the help, guys!"

"You're welcome for the help Mike. It's not a problem at all. That is what this community is for! "

Or do we just answer what if?

If so Imagine... What if my car was running like crap? What could it be, then?

Come on guys! I need help, and I am doing my best to supply you with good information on the matter and not just say its not runnning right, help. Why answer some of these what ifs and not help someone fix their car?

I've seen several posts on here with people asking for help, and no answers. If I knew the answer to what color gear for buddy's transmission... I'd help.

"Loosing faith in the MustangForums.com community."
-Mike

MikeInCape

I will post my resolution, so it could possibly help someone in the future...

End Story:

My mass air flow meter died, which caused my fuel trim to be incorrect.

Changed the mass air flow and it was still skipping.

Checked plugs... Although BRAND NEW (less than 100 miles), the mass air flow sensor failing caused my BOSHCE IRRIDIUM (sp?) spark plugs to fail.

Replaced the spark plugs with my standard ford plugs, and runs great.

"Thanks" for all your "help" guys...

"Lost faith in the MustangForums.com community."
-Mike

Sxynerd

I'm sorry bud, I tried reponding to your thread twice and both times it said Database error. (After I typed a book, twice) If it's any conciliation my very first question t you back was, what kind of MAF is it and do you get an Erratic signal.

Before I hit send this time I'm copying what I typed.

MikeInCape

Lol... Thanks anyway... I was just frustrated because I had exhausted all of my ideas on the subject.

It is a C&L (brand) and it was reading a correct and steady flow (as far as grams per second), but it was reading an incorrect barameteric reading (which my software didnt do). I had to call a ford guy out with his comp to take a look and it was reading 3000ft (ft2 per square inch i think... let me know if I understood wrong)... I am in Florida at sea level. It should read 150ft or so.

I replaced the sensor part in my C&L housing... Car ran better but still backfired and sputtered. Restored about 75% of my power that was lost. After running through a few other test, I pulled all spark plugs and put my ones back in from before my last change (had very few miles on those also) and it runs perfect now...

#7 cylinder spark plug (only one I did not check because of that damn bracket) looked somewhat toasty... Rest looked fine.

Also for future reference... Anyone know if these MAFs are digital or analaog? Meaning can I read with a multimeter? Or do I need to get some new software to read my MAF?

Any recommendations on software for an ELM interface? Or recommendations on a better interface if this one is incapable?

Thanks,
Mike.

Modular_Madness96

For future reference bosch plugs are garbage!Stick with an autolite or motorcraft.

MikeInCape

I know this now... And I will never buy them again... $100 down the drain in spark plugs with very few miles. Motorcraft would not have died that easy I like to believe.

I need to write in a complaint.

-Mike