What is happening in mornings when my truck has no power?
Asked by
rojo (
24179)
May 16th, 2016
Some mornings when I start up the truck and immediately begin driving the engine races when I step on the gas but there is no accompanying acceleration or power to go along with it. If I continue driving it will recover and become its normal cantankerous self eventually with power/speed/acceleration leveling out with the applied pressure on the gas pedal and all is fine.
What is happening when this occurs?
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22 Answers
I’m almost certain this is a transmission issue.
I assume the truck is equipped with an automatic transmission.
To oversimplify the transmission is slipping until it reaches normal operating temperature.
This will continue to worsen to the point that it will not properly engage at all.
It would be helpful to know more details such as model year, make, noises, smells, etc.
I agree with @SecondHandStoke sounds like transmission.
Check the tranny fluid ?
Not transmission. Fuel pump. It’s failing or it’s not getting enough oomph to pump the gas to the engine. Until the fuel pump kicks in you’re just getting drips and drabs of gas.
Depending on the model, it could be wet spark plugs that dry out, or bad injectors… as @SecondHandStoke said, knowing the make and model and year would be helpful.
My money is on the fuel system having a problem.
@elbanditoroso
” the engine races when I step on the gas but there is no accompanying acceleration or power to go along with it.”
Not fuel system related. This really only leaves the tranny.
1997, F150, Auto, 4.6L Triton motor.
It is also idling rapidly at the time almost like the choke is stuck in open or something.
Wait, so is the idle smooth, rough etc?
If you notice it while driving at speed and then it isn’t constant speed, I’d say fuel pump.
If it’s happening as you start moving, especially as you make slow turns and also just in the morning, my guess is something with the spark plugs. Have they been changed recently?
If you mean the transmission doesn’t seem to change into gear, I don’t think you are saying that, then transmission.
All guesses, I’m no expert.
@ARE_you_kidding_me smooth idle just higher than normal rpms almost “racing” until it warms up. And, if I let it sit in the drive until the idle returns to normal, it runs fine.
@JLeslie not at speed, one it warms up, less than a mile, it runs fine.
Does sound like transmission to me, too. Slipping, maybe low on fluid. Proper level on dipstick is halfway between “low” and “full” on dipstick when trans is hot, driven more than 10 miles. (Engine may be warmed up but that doesn’t mean transmission is.) Engine will idle faster in the mornings when cold; this is normal.
Have you ever serviced the transmission, changed oil & filter? Debris in pan could tell you something, if there is a lot. There will always be some due to normal wear of clutches.
Pull trans dipstick and look at color of fluid, as well as the smell. Does it smell burnt? Is it dark?
How does the transmission shift otherwise? Any problems with reverse?
No, there are no transmission problems that I am aware of. It goes into gear without noise or difficulty.
I will look at the dipstick (and smell it) this evening.
Thanks
Let us know what cures it.
Sounds like there is a clutch slipping. Is this engine racing but no acceleration thing happening in low only, second only, or third only, or all forward speeds. Is everything OK in reverse?
For proper trouble-shooting we need very exact problem descriptions.
I’m with @kritiper on this. Unless there are additional details to present about other symptoms, as described so far this is a “slipping clutch” issue. It may require either adjustment or replacement of the clutch. I don’t see any type of engine or generalized transmission problem in the description.
Maybe you need a tune up. My car was hesitating at driving speed a few years ago, felt like it was decelerating/cutting out at higher ( freeway ) speeds when I gave it gas. It needed a full tune up.
A long time ago, my aunt’s automatic transmission slipped when she went around a corner. Turns out the transmission fluid was low, so the torque converter was slipping when the fluid sloshed to the side during a turn. Filling up the AT fluid helped a lot.
Not an expert, but I’ve driven many vehicles with automatic transmission over the years. Sounds like tranny fluid to me. Either you’re running low, or flow is impeded by a clog, probably in the filter.
@ RocketGuy All torque converters “slip” unless they are of a locking type. When your aunt’s car rounded a corner, the pump quit pumping fluid due to it’s being low and a clutch slip was the result.
@rojo Back in the old days before engines were computerized, the choke would set on a cold engine and raise the idle until the engine reached operating temperature. The computer manages it now. It’s to help the engine run adequately while cold since engines aren’t designed to operate at low/cold temperatures. (Fuel isn’t being atomized very well when cold so the engine doesn’t run well and could stall at low RPM.)
Ok, checked the transmission fluid and it is fine. It is in the range, translucent and does not smell burnt or burning. I have also not had a repeat performance of that morning. This is not unusual, it is only an occasional happening.
A couple of things that may or may not have some bearing:
It only occurs occasionally
It only occurs in the morning
If the truck is started up and the idle immediately drops to the correct RPM (just under 1000) then it doesn’t occur.
If I drive while the engine is racing the idle increases as I step on the accelerator and drops off when I take my foot off but does not drop to normal.
If I continue stepping on the gas and letting off then eventually the idle WILL drop to normal and once it does I no longer have the issue.
Have a reputable transmission technician check the transmission linkage adjustment for proper detent positioning. (To make certain the steering column selector lever/shift lever is positively in “D” and the transmission linkage underneath on the side of the transmission is positively in “D.”)
I suspect your torque converter is the culprit. ( A one-way bearing like clutch.) Keep driving it and if it does get worse after time, see a transmission specialist.
Check your rear wheel seals for leakage and/or brake pad/lining contamination. This can be done with a flashlight by examining the wheels and tires from the back side of tires and wheels.
If you’re driving the vehicle and it is cold, the engine shouldn’t return to normal idle speed until it’s warm, so that is normal.
Check the vacuum line/hose from the intake manifold to the vacuum modulator (vacuum can) on the transmission. Look for breaks, splits, cuts, burnt spots from exhaust pipe/manifold that might cause a vacuum leak. The vacuum line should dip down below the level of the modulator so that any condensation will not enter the modulator. Remove vacuum line from modulator and check for moisture, gas in modulator. There shouldn’t be any.
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