Sherlock

I HOPE SOME ONE CAN HELP ON THIS. THE CAR IS AT A SHOP THAT SPECIALIZES IN MUSTANGS BUT THEY ARE NOT THAT FAMILIAR WITH THE SPEED DENSITY SET UP. THE CAR IS A STOCK 5.0 AUTOMATIC, NEW CATS AND EXAUST, NEW TUNEUP, INJECTORS REMOVED AND CLEANED, THROTTLEBODY CLEANED, COMPUTER REPLACED, IT RUNS GOOD ABOVE IDLE AND THE DYNOMETER SHOWS THE OXYGEN SENSORS WORKING ABOVE IDLE VARYING THE VOLTAGE BACK AND FORTH, BUT AT IDLE THEY ARE READING .9 VOLTS STEADY, NOT CHANGING BACK AND FORTH FROM .1 TO .9 . THE CAR IS RUNNING TOO RICH AT IDLE, AND RPMS KEEP CHANGING, RUNS VERY ROUGH AND WILL STALL. I WILL TRY TO GIVE INTELLIGENT REPONSES BUT I AM NOT THE MECHANIC JUST THE OWNER OF THE CAR. THANKS.

TENGRAM

check the orange wire coming out of the wiring harness behind the intake manifold. this wire is the o2 sensor ground and should be connected to either the back of the intake or the back of the driver side cylinder head. also check all of your other grounds. if these all are ok, Check for Codes

capnacee

Almost sounds like the MAF..just a guess though

dryvingnut

You brought your car to a "mustang" shop that is unfamiliar with speed density, sounds like you need to find a new shop... also cannot be the MAF, since its speed density

Sherlock

THERE IS NO CHECK ENGINE LIGHT ON, AND I ASSUME NO CODES, THE MECHANIC DID SAY HE CLEANED ALL THE GROUND WIRES RELATED TO THE (ECM OR TCM?) I BELIEVE HE SAID THERE
WERE FIVE OR SIX CONNECTIONS, NOT SURE IF THE ORANGE WIRE IS ONE OF THEM. HE ALSO
CHECKED ALL THE VACUUM CONNECTIONS WITH CARB. SPRAY TO NO AVAIL, ALTHOUGH HE SAID IF THERE WAS A VACUUM LEAK THE CAR WOULD RUN BAD ON ACCELERATION AND IT RUNS GOOD ACCEPT AT IDLE. I THINK THIS PROBLEM IS MORE OF A BRAIN TEASER THAN A TYPICAL MALFUNCTION AS THE SHOP IS WELL EQUIPPED ALTHOUGH AS I SAID THEY ARE NOT
THAT FAMILIAR WITH THE SPEED DENSITY SYSTEM, THEY ARE USE TO THE MASS AIR FLOW SYSTEM WHERE THEY CAN ADJUST THE FUEL/AIR AT IDLE WITH OUT AFFECTING AIR/FUEL DURING ACCELERATION. THANKS. ROBBIE

Sherlock

THIS SHOP IS THE BEST IN A THREE STATE AREA FOR MUSTANGS, HIGHLY RECOMMENED BY THE AREA MUSTANG CLUB. THEY MOSTLY SEE MAF SYSTEMS AS THEY BUILD HIGH PERFORMANCE ENGINES, THEY ALSO DO COMPLETE MUSTANG RESTORATIONS WITH A WAITING LIST OF ABOUT 2 YEARS. I THINK IT WOULD BE TOUGH TO FIND A LOCAL SHOP THAT SPECIALIZES IN SPEED DENSITY SYSTEMS THATS WHY I AM POSTING THIS ON THE INTERNET. RR

TENGRAM

the CEL will not illuminate for many "less important" codes. it is a mustang so really, i would assume that there are some codes.good luck, let us know.

Sherlock

GOOD POINT, I WILL HAVE THEM LOOK FOR CODES. THANKS. RR