Transmissions and DrivetrainNeed help with your trans? Problems with your axle?
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I seem to be having a torque converter or transmission problem. The car involved is 1992 Camaro RS with less than 100k miles. I noticed last summer that while driving on the highway (70 mph limit) between 75 to 80 mph that my rpm's would fluctuate between 2800 and 3000. Well now it's up to 3200 rpms at that same rate of speed. What is going on here and why does it seem to be getting worse? It goes into O/D fine and I feel no shudder or jerks while it goes into O/D. I have changed the fluid at least two times in the last 5 or 6 yrs with valvoline maxlife trans fluid and new a filter.
Please hlep me out here I am lost and losing mpg!
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First make sure your tach is accurate, its common for our cars factory tachs to go bad, and second make sure you know what gear ratio you have in your rear end, if you have something 3.42-4.10 your cruising rpms on the highway will be noticeably higher then you would normally think. My tach is off by a bunch also causing it to read right in the range of yours, i have 3.42's in my rear end also.
I have a 305 TBI with 700r4 trans, rear end is the terrible open differential of 2.73. I did have new tires put on it, size 245/50/R16 and a flowmaster exhaust was installed.
I still think my car is way too high in rpms. I remember my tach used to read around 1500 to 1700 rpms at 50 mph and now it reads 2000 rpms. At 60 it's at 2500 rpms and when I get to 70 its right at 3000 rpms. Last summer I remember having a problem where the rpms would keep fluctuating back and forth between 2800 rpms and 3000 rpm like it kept going into closed/open loop or something. I could even hear the rpms fluctuate while cruising at that speed. It doesnt even do that now.
definitely verify the tach first. They're notorious for taking a crap. If for some reason your computer is going in and out of closed loop it could effect converter lock-up, thus you need to figure out why it is doing so.
definitely verify the tach first. They're notorious for taking a crap. If for some reason your computer is going in and out of closed loop it could effect converter lock-up, thus you need to figure out why it is doing so.
i think my car may be going in and out of loop mode what can i do to fix this or check this?? im having the same problems
Its sounds like your tach could be way off. With 2.73s and an OD trans you should be under 2000 RPM. My car with 3.23s runs about 2100 RPM at 70MPh.
What condition does the tranny fluid look? If the converter is slipping enough to cause a 1000 RPM difference the ATF would be getting pretty HOT and burnt.
I have checked the fluid and fluid level and it doesnt smell burnt and still has a pink color with some varnish but not much. I heard a strange rattling noise when I came home from work this morning and I thought it was coming from the engine but it could have been from the converter. If it is from the converter what is wrong with it? I don' t understand how a converter could go bad especially with less than 100k miles.
I like shagwell's idea.
is the engine light on-that would cause open loop not allowing lockup?
you can watch with a scan tool if the car is going into closed loop while at cruising speed in fourth. you can also see if the computer is commanding tcc in fourth. don't get it twisted-even though the computer commands it doesn't mean the trans is accomplishing it. the newer cars use slip speed of the converter on the scan tool to check how much the converter is holding-example-40rpm slip-- while locked////// 100+ while unlocked.
the old cars didn't have this feature in the computer program. you will have to monitor it with the seat of your pants with a scan tool for the most accurate checkout.
Are you sure its going into OD and not just the converter locking up ?
If you pop it down into drive from OD @ 80, does the rpms go up about 1000?
The speeds your indicating. 80mph, im about 2800 rpms and i have 15 inch rims, "dont remember the size of my tire, its 12am, its cold im not going outside lol" But there nothing HUGE.
Tach is accurate
torque converters don't usually make any noise. unless your car doesn't move anywhere when hot, the converter will talk to you. hence-leaving you stranded. the noise might not be related. then again it might if it's coming from the trans... the converter not holding in tcc doesn't make noise it just doesn't lower the rpm's at cruising speed. no fourth not a noise maker either-the band slipping doesn't make any noise, it just doesn't stop the reverse input drum from turning.
I can feel, hear my car when the Torque convertor locks up, it almost sounds like OD, but the car does not drop the rpm's like you said.
One good way to find out, is to get a response from him and see if his Rpms are dropping when he thinks its going into od, That could eliminate what i said
Thank you for replying. The car is dropping the rpms once O/D engages but only after the car has been warmed up or driven 10 miles. Is this normal? Otherwise the car will not shift out of 3rd. But it still seems that the rpms are a bit high, like at 50 mph Im at 2000 rpms after it drops into O/D. I would say that 4th engages right around 40 to 45 mph and my rpms are at 1750 to 1800at that speed.
Oh one other thing that I have noticed is that as I am crusing down the road after the engine has warmed up the car keeps going in and out of O/D, most of the time it will stay out of O/D until it warms back up again. What does this mean? Do I have a stuck open thermostat causing the engine to cool off to soon thus disengaging the O/D? My gas mileage is about 17 to 18 mpg due to these high rpms problems whether i drive highway or city.
Something doesn't seem right. On my '84 T/A when its very cold out(around 20 degrees or less) it will bump up the shift in OD about 5mph and won't engage the converter lockup until the engine coolant begins to come up but this only lasts for about a minute. It shouldn't take 10 miles or until the engine is fully up to temp for the transmission to go to normal driving operation.
Being my car is an '84 it shifts into OD a little early around 35MPh and that drops the RPMs down to about 1100. Shifting into OD around 40MPh sounds about right for a '87-up trans but your RPMs seem awfully high with a 2.73 rear axle. Have you ever verified the rear axle ratio by turning the wheel one full rotation and counting how many times the driveshaft has turned?
What temp does your car run? It should go to around 200-220 and stay there. The needle shouldn't be swinging from cold to hot while you're driving.
Thank you for replying. The car is dropping the rpms once O/D engages but only after the car has been warmed up or driven 10 miles. Is this normal? Otherwise the car will not shift out of 3rd. But it still seems that the rpms are a bit high, like at 50 mph Im at 2000 rpms after it drops into O/D. I would say that 4th engages right around 40 to 45 mph and my rpms are at 1750 to 1800at that speed.
Oh one other thing that I have noticed is that as I am crusing down the road after the engine has warmed up the car keeps going in and out of O/D, most of the time it will stay out of O/D until it warms back up again. What does this mean? Do I have a stuck open thermostat causing the engine to cool off to soon thus disengaging the O/D? My gas mileage is about 17 to 18 mpg due to these high rpms problems whether i drive highway or city.
the transmission doesn't use any electrical to get 1st through 4th gears. in fact you could disconnect the square connector and still have all four gears-just not tcc. make sense? disconnect the square connector and take it for a test drive. you will be able to see if it is the tcc because it won't be kicking in and out like you described-just cruising in fourth light throttle not too fast not too slow.
