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Car jerks off when cold.


Buick666

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So i've noticed this while getting right on the highway 2 minutes after starting the car.

 

When it shifted between 3rd and overdrive i gave it some throttle to get on the highway faster... the car started jerking off and when it shifted onto overdrive it stopped jerking off.

 

When the cars temp got to 'normal' i slowed down to 50MPH put the shifter into 3rd and shifted back into OD position... it didint shaked nor jerked off whatsoever.

 

So i was getting worried that the tranny is starting to break... but my friend who was with me while this happend told straight up: Your lucky is you blow up one of theses trannies... They are really tough. He told me that most definitly the spark plugs and wires would need to be changed and that's probably what causes the jerking when it's cold.

 

Any thoughts???

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sounds like some kind of misfire, i had the same thing happen on the monte around 70MPH, happened with such force that it caused the lower engine mount to tear open.

 

also, these transmissions are not in any way what i would call strong. if a 2.8 can kill one without being neglected or abused, it isn't a strong design. strong enough to go 300K miles without tearing itself apart if used gently? usually.

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How about letting that 15+ year old engine warm up a bit before hitting the highway? In addition to what has already been mentioned I bet its about time for a oil and filter change too. Upkeep and preventative maintenance beat repair work any day. Also inspect your coils, on a 3800 they`re right there in your face.

Edited by rich_e777
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Please my english isint perfect so i'm trying the best so please be indulgent.

 

Not sure if i should change the oil in my transmition or not... it's over 255 000km's.

But the oil is clean and doesint smell burnt or anything.

Engine oil has been changend 2500km ago so that's not the problem.

 

I've been doing mostly city driving with this car and the transmition shift perfect in 1-2-3 gears.

I've talked to a friend that he's being driving GM's all his life and thinks also that it might have missfired a bit since this problem didint cam back when the warmed up because it happend to him on a couple of occasions.

 

I've checked the coils,wires... and they seem to be the original ones that were on the car since new.

Any other ideas??

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I've checked the coils,wires... and they seem to be the original ones that were on the car since new.

Any other ideas??

Since the car was new? A tune up routine DOES include changing of the plugs and plug wires you know. Get this done and then if the problem persists then you might have other issues.
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Okay that's good.

What kind of spark plugs do you recommend me?? NGK Platinum's seeemed to be a good choice for my old 2200SFI.

I'll probably pick-up some NGK wires also at the same time.

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Okay that's good.

What kind of spark plugs do you recommend me?? NGK Platinum's seeemed to be a good choice for my old 2200SFI.

I'll probably pick-up some NGK wires also at the same time.

I, Personally have never used anything but AC Delco(plugs) and Duralast(wires) and haven`t had a problem. I am thinking about getting some larger diameter wires(ive only got a 3100) going to 8mm or 9mm. Been curious about the E3 diamond fire but from what I have heard they are just a sales pitch or gimmick. I would also clean up all of your battery, alternator, starter, coil, and ground connections as well. If a bad insulator at the coil exists it can cause all kinds of problems.
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I hav e3s theyre ok lil better performance but they spark knock a lil bit id go delco

I, Personally have never used anything but AC Delco(plugs) and Duralast(wires) and haven`t had a problem. I am thinking about getting some larger diameter wires(ive only got a 3100) going to 8mm or 9mm. Been curious about the E3 diamond fire but from what I have heard they are just a sales pitch or gimmick. I would also clean up all of your battery, alternator, starter, coil, and ground connections as well. If a bad insulator at the coil exists it can cause all kinds of problems.
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larger diameter wires are worth nothing.... i made and ran a custom set of 8 or 8.5mm Talor Spiro-Pros on the monte since ~2006. resistance was somewhere along the lines of 75 ohms/foot(compared to the ~1500 of stockers). never caused an issue with the PCM, but they don't make any more power over a set of fresh stock replacement wires.

 

they look neat, but that is about it.

 

if you get down to the science of it, they deliver the same amount of spark energy, but how they deliver is where the difference lies. with low resistance, you have a very short but powerful spark event. with high resistance, less powerful burst, but it lasts longer. the short duration spark is more susceptible to a misfire, especially as the AFR leans out. i ran them up to ~16.2:1 without much issue, but beyond that, problems. with the 3.1 with high resistance wires, i got all the way up to 17:1 before lean misfires occured.

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I wonder if the clutches in your converter are failing, I didn't think of it as "Jerking off" when mine went but I guess I can see it. Easy enough to test by just resting your other foot on the brake pedal enough to open the switch and see if it stops.

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I wonder if the clutches in your converter are failing, I didn't think of it as "Jerking off" when mine went but I guess I can see it. Easy enough to test by just resting your other foot on the brake pedal enough to open the switch and see if it stops.

 

I did another test when i got out of work tonight.

But this time i slowly accelerated until overdrive kick in... and still between 3rd and overdrive i felt a slight 'shake'.

Did the test again when tranny was a normal temp and it hasint done it again.

 

Weird....

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Tranny filter you know ur supposed to change it every 30k miles (or 50k kilometers)

I did another test when i got out of work tonight.

But this time i slowly accelerated until overdrive kick in... and still between 3rd and overdrive i felt a slight 'shake'.

Did the test again when tranny was a normal temp and it hasint done it again.

 

Weird....

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