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Discussion Starter · #1 ·
Drove my car to work last Monday & Tuesday after sitting for about a month. The car ran great especially withe the upper 50's and low 60's. On the way home Tuesday a couple miles from my house the car bucked/hesitated a couple times, almost seemed like the trans was acting up. I got it home and it started doing it a lot on my street plus I heard a lot of racket under the hood. Pulled in my drive way and shut it off, opened the hood and found my belt had peeled off one or two of the ribs and was whipping the broken piece around. Once i cut off the bad loose and listened to the motor and trans all was quiet. I picked up a new belt Friday and installed it yesterday...started the car and all seemed good. This morning I took the car out to a Sunday morning Cruise hangout that is about 28 miles away. About half way there at around 55 mph it starts bucking again almost like it is slipping in and out of gear and then I hear a bunch of racket again. I pull over and pop the hood...my brand new belt peeled off a rib or two again. I cut off the loose piece, turned around and headed back home. It ran OK for a couple miles then started bucking again but this time if backfired through the exhaust a few times. I pulled over and shut it off for about 15 minutes then started it back up and headed home. It ran fine the rest of the way home...~20 miles or so? So what is going on to cause my belt to shred? The backfire makes me think the ignition cut out possibly by the coil pack failing or the battery is shorting out and going bad? But what would lock up and cause the belt to shread...or can the bucking of the engine misfiring and cutting out cause the belt to jerk and break? The belt before this one was about 5 or 6 years old with maybe 8-10K miles, the alternator and battery are both fairly new. Voltage is a steady 13-14 volts and the alternator is nice and quiet. I had a MAF go bad years ago and the car just cut in and out but never backfired...replaced MAF with LT1 and Translator. Any ideas?

Thanks,
Scott
 

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check the balancer for wobble , look for loose bolt on balancer or damage (cracked balancer)

it would account for the belt misalignment. and the backfire is when it looses crank signal and then finds it again and fires out of correct sync untill the cam sensor puts it back in sync
 

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Discussion Starter · #3 ·
check the balancer for wobble , look for loose bolt on balancer or damage (cracked balancer)

it would account for the belt misalignment. and the backfire is when it looses crank signal and then finds it again and fires out of correct sync untill the cam sensor puts it back in sync
Paul,

I'll check the balancer...Julio mentioned that as well on the other board. Looking at the pullies while running they all seem smooth and straight though. Also the AC compressor was mentioned as well...I did have the defroster on when the bucking started and shortly after it started I heard the belt slapping around before I could get off the highway. Doesn't the compressor come on with the defroster and if so if it is seizing up I'm guessing that could eat up the belt pretty fast but what would cause the bucking? Could the lose strip of belt interfere with the crank sensor while it is whipping around and cause it to get out of sync and backfire...only backfired 2 times. When I headed back home I turned off the defroster (didn't need it anymore) in case it was the compressor seizing up and the car ran perfect all the way home...almost 20 mile. I even got into to it a few short bursts once I was near enough to my house and again ran perfect. I suppose another thing to check would be the idler pulley but I would think it would be noisy if the bearing was failing?
 

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Discussion Starter · #4 ·
OK...so I finally had a chance tho check my car out yesterday. Just idling in my driveway the car was running excellent...very smooth then I turned on the defroster and immediately the compressor started cycling on and off. Every time it did the engine would baug way down and almost sputter then come back to normal with each cycle. I unplugged the compressor and let it run for 15 minutes or so and everything seemed fine...I didn't get a chance to drive the car though. I decided to drive it to work this morning and after about 20 minutes (20+ miles of driving) it started to surge/buck again some with a small backfire...no issues with the belt this time however it was not nearly as bad as it was before when the compressor was plugged in. All my pulleys look good, balancer looks fine...no wobble that I can see. Obviously something is failing and causing the motor to stumble ocassionaly backfire after it is running for a while. Last week when the surge was bad it literally felt like the car was shifting in and out of gear and was almost violent at times...again wasn't nearly as bad this morning but still there. How do I know if the crank sensor or cam sensor is bad or going bad...any way to test them?
 

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I would check some of the cheap stuff first. Inspect the crank sensor make sure nothing is loose but your car is starting so that might be ok. You can still check the gap clearance should be able to slide thin piece of cardboard through it. Another thing TPS sensor check with a voltmeter on the blue wire,use a good ground, should be between .36 and .45volts. Pull some of the plugs and check them. After you get this fixed I would definitley get some new plugs on the car. Finally check your grounds always check the grounds.

Stefan
 

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While you're down by the balancer, check the end-play on the crank. My old motor had way too much (thrust bearing was gone) and it would cause the crank sensor to come out of sync, like Paul said, casing a weird intermittent stumble. Never ate a belt though.
 

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Discussion Starter · #7 ·
Update to yesterdays post...
On my ride home from work the car started stumbling much sooner (only a couple miles or so). Now it appears to be cutting out and then coming back on...very similar to when my original MAF went bad. A few times after it cut out and came back on it did backfire through the exhaust. I also noticed every time it cut out my tach lost signal. The further I went the worse it got at times causing me to drive on the shoulder with flashers on...still occasionally taking off and running somewhat normal again. About 1 mile from my house the CEL came on briefly and it was so bad and cutting out that it eventually stalled. I waited a few minutes and it started right back up and I drove it the rest of the way home. The problem is definitely seems worse under a load...at idle it seems perfectly fine. While running in my driveway I tapped on the MAF and didn't notice any stumble...the MAF is relatively new (LT1 and Translator from Full Throttle a few years ago). I had an ignition module go bad on one of my other cars a few years ago and it acted similar. Not sure why but my Scanmaster did not record any malfunction codes?
 

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Discussion Starter · #8 ·
Here are a couple videos of the ignition cutting out, backfiring and the tach loosing RPM signal on my way home last night just before it finally stalled out. I have the Scanmaster set on RPM in one of the videos.

[ame=http://www.youtube.com/watch?v=CmHdHQVTqzk&feature=autoplay&list=UL3ehV9AIluQk&playnext=7]TTA ignition breaking down around 50 mph. - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=3ehV9AIluQk&feature=autoplay&list=ULCmHdHQVTqzk&playnext=8]Failing ignition on TTA - YouTube[/ame]



Scott
 

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I impacted my crank bolt tight on my last rebuild and it came loose. It acted exactly like your car is, in fact the bolt wasn't even finger tight when checked.

Chuck
 

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Discussion Starter · #10 ·
tach signal loss has to be the crank sensor or the ignition module that powers and interprets the crank sensor or the wiring from crank sensor to ign module

did you check to see if the balancer moves in or out ( dont want to hear it looks straight while running)
No I did not physicaly try and move it yet, haven't had time to get it up on the ramps and check it out...I will do ASAP. If it is moving should I be able to move it by hand? Just a FYI...the balancer has never been off as far as I know. The car had 44K when I purchsed it and has a little over 50K now 6 years later. Is there a test for the ignition module I can do?

-Scott
 

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Discussion Starter · #11 ·

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Discussion Starter · #12 ·
Update...I'm keeping my fingers crossed! I swapped out my coil-pack and ignition module with Doug's good ones and that seemed to do the trick. I need to to drive it more to make sure it's not time or heat related. I'm pretty sure at this point it was the ignition module failing as it heated up. I pulled the damaged belt off and while on the ramps checked the crank sensor, balancer and all the pulleys. Crank sensor was oil soaked from my leaky front main so I cleaned it off real good with brakekleen. I also checked the balancer with a pry bar and Paulie suggested for any movement or damage and possible thrust bearing wear while the belt was off and it was solid with not a bit of movement. So I think I can rule out the crank sensor going in and out of sync do to a bad balancer or movement from a worn thrust bearing. Thanks Doug for the loaner...now I need to order a new one!

I'm still not sure what caused the belt to shred off a a couple ribs though unless that was related to my AC compressor seizing or acting up? I plugged it back in and it definitely cycles constantly and causes the motor stumble when it does...unplugged for now. I did a half a$$ R134 conversion last Summer that didn't really work all to well and probably damaged the compressor from some posts I have read. Will probably rebuild the AC system next Spring and hopefully solve that problem.
 
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