Acceleration problems and jerks at highway speeds

JAREDR123

MEMBER
2003 CADILLAC DEVILLE
4.6L
V8
FWD
AUTOMATIC
118,000 MILES

I have an 03 cadillac Deville base sedan and I want to know what is causing two problems that I have with it. One of my problems is that the acceleration is a bit slow when I pin it and sometimes hesitant. It rides really good otherwise. It's only hesitsnt when I floor it after im alreadyt going around 40 mph. But for 275hps I feel like it should have a better and faster kick to it. Another problem is when I'm traveling down the highway around 65mph or higher it will jerk every once in awhile. It never jerks when I'm going 62mph or lower. Other than these few things it ride excellent. I also have po101 code and po410 code. I just replaced the mass air flow sensor for the po101 code and I'm having same problems. Not sure if it's the catalytic converter, vacuum leaks, etc. The idling and coasting are fine.

5 Replies

TY ANDERSON

MECHANIC
684 POSTS

For the code p0101. Did this code return after replacing the mass air flow. This sensor is one of the main sensor for the vehicle's computer to determine proper fuel injection. If all sensors are not working to design it could cause driveability issues such as acceleration.

Check the transmission fluid level for the jerking issue. If you can check to see if there is any codes stored for the transmission computer. If it isn't misfires your feeling it sounds more like the transmission specifically the torque converter clutch.

It doesn't seem like a vacuum issue because vacuum leaks are more prevailent at idle when vacuum is at its highest.

The other code P0410 is for the air injection pump not working. Its usually the pump itself or an issue with the wiring to the pump including the relay. I don't think this would cause any of the issues above it's just to reduce emissions on engine start up.

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Friday, January 16th, 2015 AT 6:00 PM

JAREDR123

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29 POSTS

When I repleaced the MAF sensor I did not reset the code. So I'm not sure if the code is still there. I haven't had it checked since I replaced it which was about two weeks ago. But I have still having the acceleration problem. I'm not sure if it's the wiring or maybe something else.
And I actually just checked my tranny fluid yesterday and it looked low. I checked it right after I got done driving for a little bit and with the engine off. How do I chrck the codes stored for the transmission computer? And how do I check for misfires? Hopefully it's not the transmission. I don't think it would be because it shifts great.

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Friday, January 16th, 2015 AT 6:13 PM

TY ANDERSON

MECHANIC
684 POSTS

The other code p0410 will still cause the check engine light to be on. You'll need to see if it is still there You'll need to clear those codes to be sure and then the vehicle will need to be driven for the cars computer to do it's self test (usually takes several days of normal driving for all the self test to complete).

When checking automatic transmission fluid in Cadillacs the transmission fluid must be warmed up from normal everyday driving with the engine running. The car must also be parked on a flat level surface to reflect the actual fluid level. With the engine off checking the transmission fluid level will be higher than actual.

Usually if a fault in the transmission is detected there would be a check engine light for that but not always. The reason I brought up the torque converter clutch is that is really the only part of the transmission that is switching (on off) at free way speed cruising. And not really involving shifting.

There is a lot parts that can cause misfires so I'll go more into that later because Mass air flow sensor and the transmission fluid level. If you'll like me to go more into misfires I can but I wanted to start with the basic and easier to check before jumping into something else.

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Saturday, January 17th, 2015 AT 10:38 AM

JAREDR123

MEMBER
29 POSTS

Ok I will clear the codes to see if po101 will come back. If it comes
Back what could it be? Like wiring or what else? And I'll check the transmission fluid again later tonight. If I need to add some, do I just dump the correct amount in when the engines off? I will see if it jerks still after I reset codes and add fluid.
I am traveling about 350 miles on Monday, do you think my car will be ok? I'm just worried about the jerking because I don't know what it's from.
And do you know what elae could be causing the acceleration problrms. The only time I notice the acceleration thibg is when I floor it. The rpms can reach above 5000 but it just takes a while.

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Saturday, January 17th, 2015 AT 10:49 AM

TY ANDERSON

MECHANIC
684 POSTS

If it comes back it could be wiring but usually it is just the sensor itself.

To add trans fluid you use a funnel and pour directly into the tube the dipstick is in. You'll need to wait a minute or two for the fluid to drain out of the this tube because is will get all over the dipstick when checking fluid level making it difficult to read the correct fluid level. I pour fluid in while it is running since you need to check fluid level with the engine running.

I'll list a few things that could cause like a hesitation at full throttle.

Low transmission fluid level ( enough fluid is required to propel the vehicle)
Fuel restriction or low fuel pressure could cause this but is usually more noticeable when accelerating (all acceleration) not just full throttle.
You could have some exhaust system restriction
The transmission fluid level seems the most logical at this time.
Because this only an issue when accelerating at full throttle I don't really see a significant issue not to drive the car.