I HAVE A '93 BLAZER S-10 WITH THE "Z" (MFI) 4.3. IT IS A TRANSPLANT FROM A SALVAGE YARD AND HAS GIVEN ME MANY MILES OF QUALITY SERVICE.

HERE IN THE PAST WEEK IT HAS STARTED RUNNING "ROUGH" AT IDLE AND NOT ACCELERATING SMOOTHLY AS IN THE PAST. I NOTICED TODAY WHEN I "FLOOR" IT, IT GETS TO ABOUT 70 MPH , WANTS TO "KICKDOWN" AND STARTS BACKFIRING/CUTTING OUT.

I RAN A SELF-TEST AND GOT A DTC OF "23". ACCORDING TO MY CHILTON 28160 MANUAL, THERE IS NO "23" CODE FOR THE "93 PCM EQUIPED VEHICLES"-JUST A 22 (THROTTLE POSITION SENSOR...) AND A "24" (VEHICLE SPEED SENSOR). THE '88-92 ENGINES (EXCEPT MFI-TURBO) SECTION GIVES A "23" CODE="MAT-LOW TEMPERATURE INDICATION"

THE SECTION ON "THROTTLE POSITION" SENSOR AND RELATED DIAGNOSIS AND PROBLEMS SEEMS TO RELATE MORE TO MY PROBLEM THAN ANYTHING.

I DON'T HAVE THE MONEY OR PROPER TOOLS TO DO/HAVE DONE A COMPUTER SCAN OF THE PROBLEM. I AM UNEMPLOYED AND NO UNEMP. $$ COMING IN AT THE MOMENT.

I HAVE REPLACED THE ROTOR/DISTRIBUTOR CAP SINCE I HAD PROBLEMS LIKE THIS ON THE FIRST ENGINE AND THAT SOLVED THE "ROUGH" PERFORMANCE. THIS TIME, NO LUCK.

CAN ANYONE OUT THERE GIVE ME SOME ADVICE ON WHERE TO START, ON WHAT TO TROUBLESHOOT AND/OR WHAT TO "CHEAPLY" REPLACE TO SOLVE MY DILEMA.

THANX FOR LISTENING.

ED BASS
BOONE, IOWA

 

CODE 23 - Intake Air Temperature (IAT) Sensor Circuit (Low Temp.)(PCM & CMFI Only)

There is a question as to whether that code applies to your vehicle. I would check it again to make sure.




78 Corvette Pace Car For Sale-18k mi orig-Florida

THE ONBOARD SELF-DIAGNOSIS TEST (A+B), GIVES A 2-PULSE+3PULSE INDICATION FOLLOWED WITH THREE 1-2 PULSES, ENDING THE TEST.

ONCE AGAIN, MY CHILTON MANUAL DOESN'T LIST THIS CODE (23) FOR THE YR OF MY BLAZER ('93 4.3 MFI). THE ECM, AS FAR AS I KNOW IS THE ORIGINAL ECM. IF THIS WERE A '92 MFI TRANSPLANT, WOULD A '93 ECM RECOGNIZE A 23 PROBLEM AND DISPLAY IN A DIAGNOSIS?

PLEASE ADVIZE. WHAT SHOULD I DO TO CORRECT THE PROBLEM?

THANX FOR LISTENING.

ED BASS

Look and see if the engine has an IAT and check it out for obvious problems. It could be unplugged or a bad sensor.




78 Corvette Pace Car For Sale-18k mi orig-Florida

SORRY TO KEEP BOTHERING YOU.

ONE THING I NOTICED AFTER MAKING SOME CHECKS OF WIRING, HOSES, ETC.AND TAKING IT FOR A TEST RUN-I LOST POWER BRAKES.

I CHECKED THE LARGE HOSE GOING TO THE MASTER CYLINDER AND IT LOOKS IN GOOD SHAPE AND CONNECTED. THIS ACTS LIKE A MAJOR VACUMN PROBLEM-HIGH SPEED + POWER BRAKE FAILURE.

ANY SUGGESTIONS OTHER THAN THE IAT?

THANX

ED BASS

Just the obvious one.......look for a vacuum leak.
Take a vacuum reading with a gauge to determine if you have full vacuum or not




78 Corvette Pace Car For Sale-18k mi orig-Florida




(This post was edited by Hammer Time on Oct 17, 2009, 9:20 PM)

QUICK UPDATE:

WITH IGN ON, I RAN A VOLTAGE BACKPROBE ON THE TPS. ACCORDING TO CHILTON, VOLTAGE SHOULD BE 1.25 V OR LESS-THROTTLE CLOSED. SLOWLY OPENING THE THROTTLE, ACCORDING TO CHILTON, THE VOLTAGE SHOULD SLOWLY RISE TO ABOUT 4.5 V. CHILTON STATES TO REPLACE IF THESE READINGS AREN'T FOUND.

ACCORDING TO MY FINDINGS, USING A MULTIMETER WITH A 12.1 BATTERY VOLTAGE CHECK, THE READINGS I OBTAINED WERE 00.0 THROUGHOUT THE WHOLE TEST.

I WILL TRY A NEW TPS AND SEE IF THAT SOLVES THE PROBLEM.

DO YOU AGREE?

THANX AGAIN FOR YOUR TIME.

ED BASS

That would be correct if I'm assuming you had the key on, tested the right wire, used the circuit ground for testing and verified 5v coming in also.




78 Corvette Pace Car For Sale-18k mi orig-Florida