Extreme misfire and then won't start

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Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
26
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1
Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
Alrighty. So I got it started with the foot to the floor method (thank you btw, started up pretty gnarly) Then I unplugged the MAF sensor and it kinda "stalled" for about a second then went back to what seemed like an idle. I didn't pay attention to whether the idles were different.
 
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1
Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
You are correct... Some cars work differently than others.
Alrighty so while the engine was running I disconnected the MAF sensor and it stalled for like a half second but then proceeded to idle again. Any advice for a next step?
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94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
[QUOTE="LARRY70GS, post: 272675, member: 726"my ]Yes, will it idle indefinitely? You really should have disconnected the MAF with the engine off, THEN started it. Have you driven the car?[/QUOTE]
Not yet I will do so later on today and update you. IF it's the MAF sensor, when I unplug it and then attempt to start it; it should start without it. BUT if the MAF sensor was in functioning order the car won't start? Or is there something i'm missing there?
 

LARRY70GS

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Oakland Gardens, N.Y.
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98 Riviera, 70 GS455 Stg1
When you start the car cold, the engine is in open loop, basically, the engine runs on preset sensor values. Once the engine and catalytic converter and O2 sensors warm a bit, the computer takes over and the engine runs in closed loop. When my MAF went bad, the engine would start and run for about 10 minutes. As soon as it went closed loop, the engine would chugg, cough, spit, and what have you, and it would stall. It would not re start and run. When I unplugged the MAF, it would start and idle indefinitely, and I could drive the car. It didn't run at it's best, but the car was drive able and I drove it back and forth to work while I waited for the new MAF from rock auto. When I replaced the MAF, the car ran great and my gas mileage jumped up from what it had been.

I'm not sure why you are making this more difficult then it has to be. It's a simple test and costs nothing. Unplug the MAF first. Then start the engine and let it idle. If it continues to idle for 15-20 minutes, then drive it around the block. If you get no further symptoms, try cleaning the MAF. There is a special spray cleaner for MAF's. It didn't work for me, so I replaced it.
 
26
0
1
Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
When you start the car cold, the engine is in open loop, basically, the engine runs on preset sensor values. Once the engine and catalytic converter and O2 sensors warm a bit, the computer takes over and the engine runs in closed loop. When my MAF went bad, the engine would start and run for about 10 minutes. As soon as it went closed loop, the engine would chugg, cough, spit, and what have you, and it would stall. It would not re start and run. When I unplugged the MAF, it would start and idle indefinitely, and I could drive the car. It didn't run at it's best, but the car was drive able and I drove it back and forth to work while I waited for the new MAF from rock auto. When I replaced the MAF, the car ran great and my gas mileage jumped up from what it had been.

I'm not sure why you are making this more difficult then it has to be. It's a simple test and costs nothing. Unplug the MAF first. Then start the engine and let it idle. If it continues to idle for 15-20 minutes, then drive it around the block. If you get no further symptoms, try cleaning the MAF. There is a special spray cleaner for MAF's. It didn't work for me, so I replaced it.
Alrighty So I did what you advised here and WOW was there a difference. I timed it and at about the 8 minute mark the engine changed idle dramatically ( this must be the closed loop you guys have been talking about), and yes it does run like a pickup from the 70's but it can idle all day and night and drive around just fine as long as I baby it. That being said, it's safe to assume that my MAF sensor has gone bad because I cleaned it too and nothing changed. She's got 253K so it's probably just finally broke that heating wire inside the assembly. Any suggested brands for the replacement?
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Zeroboostbuick

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2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT

LARRY70GS

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48
Oakland Gardens, N.Y.
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98 Riviera, 70 GS455 Stg1
When I drove my car around with the MAF disconnected, it would start cold instantly. It would hesitate briefly, and then it would smooth out. The throttle response was off, and it would have some flat spots when on and off the gas, but it drove just fine.

If you had OBD2, you could actually look at the sensor value and the fuel trim. The MAF sensor reads out as grams per second. At idle, you would see a large value, and the fuel trims would be extremely negative. The negative fuel trims reflect the engine running rich because of the incorrect MAF sensor value, and the PCM's trying to lean the motor out.
 
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Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
So I replaced the MAF sensor with a brand new duralast one. I popped it in and it chugged for about 10 minutes and then died again. Now I also didn't clean the spark plugs because from the checking , they are sooted and the threads are covered in oil/gas. should I expect then that without cleaning these plugs that I will expect the same shitty result?
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874
185
43
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
Ok, will do because I really don't want to start thinking about the opti
It's obvious the MAF is/was the problem. But now you put a new one and still the same thing. Unplug the new one and see if car runs the same when you unplugged the old one. This might tell us weather the plugs are good or not and possibly hint towards the new MAF being bad or something with the wiring / connection.
 
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Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
So it wouldn't start unless the MAF was plugged in. And when it did run it ran like absolute shit. next on the list then would be spark wires?
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26
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1
Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
Is there any way to correctly do diagnostics. I tried the paperclip thing and it only triggered my radiator fans for some reason.
 

LARRY70GS

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Oakland Gardens, N.Y.
Buick Ownership
98 Riviera, 70 GS455 Stg1
Yes, there is a way. If you want to work on ANY car, you buy the Factory Chassis Manual. There is NO substitute for that Manual. In it are trouble trees and charts that enable you to narrow down a problem to an individual part or circuit. Without it, you become a guessing parts changer. End result, you spend way too much money and time trying to fix something without the proper diagnostics. Fortunately, E Bay usually has great deals on FSMs.

1994 BUICK ROADMASTER CHEVY CAPRICE Service Repair Shop Manual SET WITH SUPPLEME | eBay
 
26
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1
Buick Ownership
94,96 Roadmaster, 69 Wildcat, 95 lesabre , 97 park avenue
ok here's an update

1: I checked the EGR and PCV they're both good
2: MAF sensor is brand new and shouldn't be the problem
3: Car still idles rough and SMELLS LIKE FIREWORKS. why is this? could it be O2 sensors that are causing this whole calamity?
 

LARRY70GS

Full Member
1,907
50
48
Oakland Gardens, N.Y.
Buick Ownership
98 Riviera, 70 GS455 Stg1
ok here's an update

1: I checked the EGR and PCV they're both good
2: MAF sensor is brand new and shouldn't be the problem
3: Car still idles rough and SMELLS LIKE FIREWORKS. why is this? could it be O2 sensors that are causing this whole calamity?
Smells like fireworks? Sulphur smell? That is an indication of an overly rich mixture. That will overheat the catalytic converter and damage it. If the MAF was bad and you drove it for awhile like that, you may have damaged the cat. If you have a vacuum gauge, hook it to manifold vacuum and fully warm, note the reading. Increase the engine RPM to 1500-2000 RPM in Park, and hold it steady. The vacuum level should remain steady up around 20". If it starts to drop off, that is an indication of a plugged exhaust. Most likely the cat or collapsed pipe/muffler.
 
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