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Chevrolet Repair/1991 Olds Cutlass Supreme Base 3.1L V6

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Question
QUESTION: 112,000 miles. This car sat for a year or two. It dies when I come to a stop sometimes. It surges (RPMs up and down) when it does idle and the headlights get brighter/dimmer with the surges. It's hard to start sometimes. Seems worse in cold. I ran B12 through the gas 3 times. It helped the first two times but now it's worse. It dies more now and is harder to start. I drive it 5 to 10 miles, turn it off a few minutes and it won't start. When it does it lets out a big black exhaust cloud but just one and back to normal after it tries to idle. I gun it at that point and get it home. New fuel filter, air filter, spark plugs, fuel pump relay, fan relays. New coolant temp sensor but didn't replace pigtail wires so I leave it unplugged and the fans stay on. Plug it in they never come on. While it idles, I give it a good punch on the gas and can hear a high pitch whistle or sucking noise.

ANSWER: HI POCKETKNIFE,I WOULD REPAIR THE WIRING TO THE COOLANT TEMP SENSOR..THIS MAY ALSO CONTROL THE MAPPING TO AND FROM THE PCM LETTING THE COMPUTER KNOW THE ENG TEMP..THIS WOULD EXPLAIN THE BLACK SMOKE. RICH CONDITION..I WOULD NEED TO LOOK AT A WIRING DIAGRAM FIRST TO BE SURE..THE OTHER PROBLEM COULD BE A STICKY EGR VALVE,REMOVE THE VACUUM TO THIS VALVE AND DRIVE IT LIKE THIS TO SEE IF IT IDLES BETTER.IF SO THE EGR VALVE IS STICKING OPEN WHEN IT SHOULD BE CLOSED AT IDLE.THIS WILL ALSO CAUSE YOUR PROBLEM..THE LAST 2 THINGS I CAN THICK OF IS A BAD IDLE CONTROL MOTOR [IAC]THIS WILL CAUSE A BAD OR NO IDLE PROBLEM AND POSS MASS AIR FLOW SENSOR..UNPLUG THE MAS AIR FLOW SENSOR AND SEE IF IT RUNS BETTER LIKE THIS,IT WILL NOT BE PERFECT[ BUT] BETTER.IF SO THE MASS AIR FLOW IS BAD.. ALONG WITH THE RICH CONDITION OF THE COOOANT TEMP SENSOR...THE WHISTLE OR SUCKING NOISE COULD BE FROM A PARTIALLY PLUGGED EXH SYSTEM. REMOVE THE OXYGEN SENSOR BEFORE THE CONVERTOR AND SEE IF THIS RUN BETTER THIS WAY..THIS SHOULD KEEP YOU BUSY FOR A WHILE GET BACK TO ME WHEN YOU KNOW MORE..GOOD LUCK ,,,,TOM..

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QUESTION: I repaired the wiring to the coolant temp sensor and it starts right up and the Service Engine light went off. Hesitates when I first give it gas but it runs/idles better than before. It isn't stalling like it was. I also sprayed carb/throttle body cleaner into throttle body. The cooling fans still don't work. They kick on as soon as you unplug the coolant temp sensor. There's a fan switch that can go out but I can't find the part in the car or in the store. The EGR valve has no vacuum. It's digital so only has an electrical plug. I didn't know whether to unplug it or not? Haven't checked the IAC yet but plan on it soon. Gotta check the MAF as well. Still whistles when you punch the gas at idle. Gotta look into that. The cooling fans are my main concern at this point. The last thing I need is for it to overheat.

ANSWER: HI POCKETKNIFE,DID YOU SPRAY THE CLEANER BEHIND THE THROTTLE PLATE ?? ,NOT IN FRONT OF IT..OPEN THE THROTTLE AND CLEAN THE BACK SIDE OF IT...ARE YOU SURE THIS EGR VALVE HAS NO VACUUM GOING TO IT,,1991 ??? I THINK THIS YEAR SHOULD. DOES THIS EGR VALVE GET IT SOURCE OF VACUUM OFF THE THROTTLE BODY ??  THE WHISTLE SOUNDS AGAIN TO ME LIKE A PARTIALLY PLUGGED EXHAUST SYSTEM OR A SLIGHT CRACK IN THE EXH MANIFOLD..THE COOLANT FAN SWITCH SHOULD BE IN FRONT OF THE INTAKE MANIFOLD AND HAS TWO WIRES GOING TO IT. YOUR GM STORE SHOULD HAVE THIS AND THEY WILL ALSO BE ABLE TO GIVE YOU THE CORRECT LOCATION OF THIS SWITCH..TRY THIS FIRST, YOU DO NOT WANT THIS TO OVERHEAT. IN THE MEAN TIME JUST LEAVE THE PLUG UNPLUGGED AT THE COOLANT SWITCH SO THE FANS RUN ALL THE TIME..THIS WILL NOT HURT ANYTHING SHORT TERM..THE FANS WITCHED SOUNDS LIKE IT IS OPENED...LET ME KNOW WHRE THIS LEADS YOU..GOOD LUCK TOM...

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QUESTION: I found and replaced the fan switch. Still no cooling fans. When it got hot I noticed it sprayed just a little antifreeze from the front of the engine, the belt slung it forward. The only other place that had antifreeze on it was the bracket that's right above the water pump. Both temp sensors/senders or switches, whatever you call them, have been replaced. It has new relays and the fan motors work. They still come on when I unplug the bigger 2 wire sensor that's under the thermostat housing. The fan switch/sensor only had one wire and was smaller and very difficult to replace. I noticed the coolant level sensor on the side of the radiator was unplugged. It's full of coolant but the LOW COOLANT light flashes so I unplugged it. No fans with it plugged in or not.

Answer
HI POCKET KNIFE, YOU KNOW THESE FANS WILL ONLY TURN ON WHEN THE ENG TEMP HITS 196 DEGREES OR SO..IT IS POSSIBLE THAT YOU HAVE A BAD WIRE FROM THE COOLANT TEMP SWITCH TO THE PCM WHICH SIGNALS THE RELAY TO TURN ON THE FANS. I WOULD REMOVE THE FAN MOTOR RELAY AND JUMP AT THE FUSE BOX AREA AND SEE IF YOU CAN GET THE FANS TO TURN ON LIKE THIS POWER AND GROUND,IF NOT THE WIRING HARNESS FROM THE FUSE BOX OUT TO THE FANS ARE BAD SOMEWHERE..IF THE FANS WORK LIKE THIS THEN I WOULD SUSPECT A FAULTY PCM OR BAD WIRING HARNESS FROM FUSE BOX TO PCM...THIS ENGINE ALSO SOUNDS LIKE THE WATERPUMP IS STARTING TO LEAK FROM THE VENT HOLE ON THE BOTTOM SIDE OF THE PUMP....GET A MIRROR AND FLASHLIGHT AND CK THE BOTTOM SIDE OF THE PUMP UNDER THE BELT PULLY. IF IT IS WET OR SHOWS A STAIN MARK,MORE THEN LIKELY IT IS BAD..LET ME KNOW HOW YOU MAKE OUT,GOOD LUCK,,,TOM

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TOM SHEETS

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PLEASE READ ALL OF THIS BEFORE ASKING ANY QUESTIONS. IF THIS CHEVY SECTION IS MAXED OUT.YOU CAN REACH ME IN THE OLDS/BUICK SECTION. Will answer questions from 6:00am to 10:00pm all days [EST][[[ NO DIESEL OR PAINT QUESTIONS]]] will answer all 1965 to present QUESTIONS ON ALL GM'S on mechanics of these cars. Keep in mind i am not there in person i am going on what you are telling me !! PLEASE IF ASKING A QUESTION GIVE ME AS MUCH INFO AS POSSIBLE. THE MORE THE BETTER. SUCH AS YEAR,MAKE,MODEL,ENGINE SIZE. THIS WILL HELP ME HELP YOU. I will not be able to answer all questions because of some situations that i would really need to be there and see things for myself,such as electrical issues. In many cases i would need wiring diagrams. I can also give you an estimate on what the cost would be at our repair shop as an idea to help you. Keep in mind that my answer is ONLY MY ADVICE,ck with your mechanic as well.. >> THANK YOU, TOM..

Experience

I have been a ASE certified master mechanic for over 30 years and certified IN ALL 8 CATEGORIES,[engine repair,engine performance,auto trans,manual trans,clutches,steering and suspension,brakes,electrical systems,heating and air/cond. I am also a state CERTIFIED inspector for over 30 years. I do computer work [pcm]fault codes,pcm flashing,state inspection monitor readiness,repairs on exhaust,fuel service,[injection and carburetor,] charging system problems, running issues,alignments,frame problems,tire balance,struts and of course standard and anti-lock brakes.

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nys state auto repair industry and ase group.

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high school,4 years of tech school,and many many hours of auto training with many gm classes and aftermarket training classes..

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ASE MASTER TECH CERTIFIED IN ALL 8 CATEGORIES.NYS INSP LICENSE AND A/C CERTIFIED

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MANY CUSTOMERS IN OUR BUSY SHOP.

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