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Engine/Transmission Shudder


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My 90 with 117000 miles (all mine) has been intermittently "shuddering". It does not happen all the time, but when it does its very consistent and repeatable - @42 mph on flat terrain with light acceleration to maintain speed I will feel a shudder whtough the drivetrain.<P>As part of my regular (some would say anal) maintenance, I just had it tuned up and the transmission fluid changed, hoping this may alleviate the problem, but no luck.<P>I'm hoping this is something reasonable as she's a third car and between the other cars and the 17 month old daughter I may not be able to justify a big investment.

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You may want to look at your engine temp. If it's running cool then your thermostat is bad. Engine needs to be atleast 170 deg. for the ECM to go into closed loop condition and control air/fuel mix,torque converter lockup etc,etc... This happened to my Olds Touring Sedan. Good luck hope this helps<BR> Ken<BR>

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  • 2 weeks later...

I suppose that this question will betray my limited automotive repair abilities, but here goes anyways... How do I check the engine temp (obvoiously I have the "idiot" guage on my dash - but I don't believe that it'll tell me +/- 170.

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CEK - I've also got a 1990 Reatta with the same problem, though it tends to shudder at ~82mph. Anyhow, there are a number of things that can cause it. Best to check the codes. I'd almost bet that the system has a code stored that indicates either the EGR Valve or the ECM needs replacing. Mine is the ECM (which I just haven't gotten around to replacing for 2 years), though I've been told a bad EGR Valve will cause the same problem.<BR>BTW - I have 185k on mine (with the engine replaced 9k ago). Both have done the same thing. Have no reason to believe it would ne a trans problem, esp not when the ECM codes keep coming back.<P>... just my 2 cents.<BR>~Brenda

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Guest jadesdrift90

Oh Dear...<P>That just happened to me last Friday trying to get on the freeway. At 41 mph it started shuddering. The whole dang car just rummbled everytime I applied the gas. After a couple of miles something finally kicked in and I was ok, except my hair has a greyer tinge to it now...lol! Might this be the same thing?<P>TIA,<P>Jade<P>P.S. My first impulse was to have the transmission serviced? The folks I bought it from had no records of doing this at all...they had the car about two years. shocked.gif" border="0<P>P.S.S. The Drift only has 88,000 miles on it.<p>[ 04-26-2001: Message edited by: jadesdrift90 ]

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A ignition problem is not the only cause but it is the most common for this shuttering. Plugs, wires, maybe a coil. When it's in 3rd or 4th gear at a slower speed for that gear just giving enough gas to maintain the speed. The engine is not making enough power or missing under a hard load. If it's been some time sence a tune-up just do that first because it probibly needed it anyway. Don't forget your fuel filter, air filter, and PCV valve.<P>Tom

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Guest Greg Ross

As discussed here recently (3.8 with 170 K miles) once I'd eliminated all the tune-up/ Trans. service possibilities my shudder turned out to be a burnt exhaust valve. A compression test revealed 5 cylinders in the 160-170 psi range and #6 at 55 psi. After the heads were done over driveability and "Power" was restored.<p>[ 04-27-2001: Message edited by: GM Ross ]

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Guest jadesdrift90

So I was dropping another lady from work off to pick up her car from being repaired and mine died in the drive way...a shudder at 42...got to the light and put it neutral til the light changed and then had to start it four times to get to the driveway (app 50 feet)! shocked.gif" border="0 <P>I asked the mechanic if he had ever worked on a Reatta and his reply was..."it's a Buick ain't it"...is this where I get worried???<P>I have printed out everything in that thread and have manual in hand for in the morning... grin.gif" border="0<P>Jade

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Guest jadesdrift90

My shudder problem turns out to be the catalytic converter. When the engine gets to a certain temp it becomes blocked. As I usually only drive to work and back (5 miles)the problem rarely occurred.<P>The mechanic did also find out what was causing the weird noise I was hearing...wheel bearing on it's last leg. Didn't sound like any wheel bearing I had heard before. He explained and showed me why. No wonder the part cost $174.00!!! And by the way I "had" locking lugnuts. Folks I bought it from never mentioned it nor did they hand over a key.<P>I have to bring the car tomorrow to a muffler place to get the catalytic fixed. I've read the threads here on that part and imagine I will be looking at another big chunk of change...lol! rolleyes.gif" border="0<P>Jade<P>P.S. My tape is now stuck in the cassette player...geesh...go read another thread!<p>[ 05-03-2001: Message edited by: jadesdrift90 ]

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I had the same exact problem you describe at 45-55 mph when I was test driving the car before I purchased it from a Buick Dealership. They replaced the wires and the problem was gone. A cheap fix. Give it a try.

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Guest jadesdrift90

New wires and plugs put on 6 months ago. But thanks for the heads up. <P>The reading from the history codes all showed exhaust. And the exhaust smells rotten (sinuses from all the pollen prevented me from smelling it...lol). The mechanic comes highly recommended by several different folks I know and the shop has been there forever. The son now runs it and he loves what he does. How bad can that be?<P>Jade cool.gif" border="0<P>P.S. He also does work on two other Reattas. Cripes...I didn't know there were two others in Forsyth County!!! shocked.gif" border="0

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  • 1 month later...
Guest jadesdrift90

Ok...the never ending "shudder" finally got fixed today...<P>To make a very lengthy story short...<P>Ignition Coil $ 147<BR>Ignition Control Module $ 194<BR>Scan (that showed ZERO codes) $ 54<BR>Labor (he spent 3 days) $ 96<P>Jade rolleyes.gif" border="0<P>PS Think I will put the whole story up on the Drift's homepage...it is kinda funny! grin.gif" border="0

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Guest jadesdrift90

Ok...it is NOT the end of the story. <P>She shuddered and stalled pulling into my driveway today. So far we have replaced the catalytic converter, ignition module, ignition coil, plugs & wires 6 months ago, and the computer is not showing any codes...any ideas??? Please... shocked.gif" border="0 <P>Jade

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Guest Stan Leslie

Could be the locking cluth in the torque converter acting up. Could be a plugged EGR valve from all the slow driving. Both could cause shudder and stall.

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Have seen a marginal ignition do that, in one case the shudder was most apparent at light throttle or moderate incline just after the TCC lockup occurred. In that case the coil pack was bad. In another, bad plug wires caused an occasional but severe vibration at idle. Agree that you should check the trouble codes first but ignition problems rarely set trouble codes.<P>Re 176ish degree closed loop: had an experience with that on the interstate on time. In evening when temperature dropped to 38 degrees suddenly the TCC would unlock. Stopped and looked, eveything was fine. Stared up and lockup was normal but within five miles would unlock. Hooked up scan tool and saw open loop/low coolant temp - thermostat was stuck open. When I'd stop the "hot soak" would raise the coolant to 180 but would drop right back down at 70 mph.<BR>Have learned over the years to check ignition first when things happen "like a switch was thrown" because it probably was..

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Shuddering when coming to a stop may be a stuck TCC as several have mentioned - if you have ever stopped a manual transmission car without depressing the clutch, this is what it feels like because is the same thing. One way to check is to unplug the TCC and see if the shuddering problem goes away - will not lock up then but should not hurt anything except MPG. I drove a Fiero for several years that did not lock up. YMMV, Notary Sojac & all them legal disclaimers.

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  • 2 weeks later...
Guest jadesdrift90

Ok...just maybe this is the fix!<P>Crank sensor $ 47.00<P>Labor for 3 days $ 0<P>Keeping fingers crossed.<P>Jade wink.gif" border="0

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