Low car power and low acceleration

not enough details for an answer
is it automatic or manual transmission
does the rpm counter rise rapidly with out a corresponding increase in speedo reading
are the back wheels spinning on acceleration
post again with make , model ,year , transmission type , hydraulis or cable etc

GAS
3s-fse-d4-engine???? 3s-GE OR GE WITH RED BEAM? "VVT"
M./T OR A/T (STICK OR AUTO)
the key factor is engine RPM
if it rises, but not speed, that is trans./clutch slip
if no rpm rise that is weak engine , BUT IS THE RED BEAM.?

LOW POWER, 101
1: NEVER TUNED UP. BAD SPARK CLOGGED FILTES X2
2: ENGINE ecu stuck in limphome, scan it, see errors, BINGO
3: engine misfiring, cause by low compression, weak spark or bad fueling (too rich or too lean) many tests, ask.
4: low fuel pressure or regulator not regulation per FsM PAGE
5:STUCK OPEN egr main valve (missing in some countries)
6: melted cat converter , vacuum gage reads real bad,
7: and more, i charge more for more, LOL vvt?

ask or tell?
i want wild guessing
or I want to do the tests. to find it.

Gue$$ or Test.
toss coin.?

Is the car equipped with the Automatic Transmission?
If so, read on.
Otherwise skip to the end and answer some questions.

POSSIBLE SCENARIO:
I have observed a condition where my car surges slightly when the torque-converter clutch (TCC) cycles between lock and unlock when driving on an uphill grade.
First some basics and history that will explain why the TCC is used.

Engine, Torque Converter, TCC, and Transmission relationship--
The TCC allows for a solid connection between the engine and transmission which allows the input to the transmission to rotate at the same speed as the engine.
Without a TCC, there is slippage between the engine and automatic transmission. The slippage is greatest at low engine RPM. That is what allows the engine to run with the automatic transmission in gear, like when you first shift into gear or stop at a stop sign. When the throttle pedal is depressed, the engine RPM begins to increase and the torque converter begins to slip less and less the more the engine RPM increases. The car moves. But even at cruising speeds the torque converter slips slightly. Engine RPM is greater than transmission input RPM, which is realized as slight decrease in fuel efficiency.
When acceleration is complete and a constant speed is being maintained, the engine power output is reduced to the point where the TCC can engage and eliminate any slippage between the engine and transmission. If the car has a tachometer the engagement of the TCC can be verified when a slight reduction in engine RPM observed without a corresponding change in vehicle speed.
One method used to test the operation of the TCC is as follows:
Find a flat section of road where it is safe to perform the test.
Reach a steady speed and keep the gas pedal depressed with one foot. While observing the tachometer (or listening for an increase in engine RPM), with the other foot depress the brake pedal enough to activate the break light switch but not enough to engage the brakes. When the brake light switch activates, the TCC receives a signal to disengage. With the gas pedal being held steady, release the brake pedal and the engine RPM should decrease when the TCC engages.
Old cars with Automatic Transmissions did not use a TCC. I believe the TCC was put in use in an attempt to increase fuel economy.

MY EXPERIENCE WITH SIMILAR SYMPTOMS
The condition that causes that issue on my car is this:
- A slight uphill grade increases the load on the engine.
The car tends to gradually slow and it is necessary to depress the gas pedal to maintain speed.
- Depressing the throttle pedal (manually, or automatically with cruise control engaged) signals the torque converter clutch to unlock when the load increases slightly. (A more drastic load increase would signal the Transmission to downshift to a lower gear.) The corresponding increase in engine RPM and output is enough to compensate for the reduction in speed. When the vehicle speed, engine RPM, and throttle position stabilize to the point that the TCC will engage and the engine RPM will reduce in correspondence with TCC engagement. Now, if the road conditions have not changed, power output is not enough to maintain vehicle speed. With the increased load caused by full engagement between engine and transmission, and the cycle (surging) repeats itself until the road conditions change.

Does that help?
If not:

QUESTIONS
Please define the symptoms.
What are the road conditions when the surge occurs? (A slight uphill grade?)
What is the frequency of the surge?
Does the engine power output have a noticeable surge?
Is there a speed change related to the surge?
Does the tachometer move up and down with little or no change in vehicle speed?
Are all instrument indication in the normal range?
What else has changed?

Good luck!

1. Locate the automatic level control height sensor under the rear of the vehicle on the rear suspension support. If the back of the car is too low and will not pump up, ground pin B Yellow wire and see if the compressor will come on and the car will raise.

2. If the car does raise when pin B is grounded, check the powers and grounds to the height sensor.
3. If the powers and grounds are OK and the pump does come on and the car raises when pin B is grounded, the height sensor will need to be replaced.

4. If the car is too high and will not come down, ground pin E White wire at the height sensor to see if the car will lower.

5. If the car lowers when the White wire in pin E is grounded, check the powers and grounds to the height sensor.

6. If powers and grounds are OK and the car does lower when pin E is grounded, the height sensor will need to be replaced. Tech Tips: There are two different automatic level control systems for this car; one is without RPO F45 and one is with RPO F45. The system without F45 has an automatic level control height sensor and with F45 the automatic level control compressor is controlled by the continuously variable road sensing suspension module. Tests/Procedures: 1. Using a head lamp as a load, test the ELC height sensor power/grounds.

2. The power feeds are: Orange wire, pin C and a Brown wire, pin D.

3. The ground is pin A, Black wire.

4. Ground the White wire at the height sensor, check that the vent solenoid in the ELC compressor clicks and vents the air from the system. Author: Bill Siegmann

Engine speed increasing w/o acceleration suggests a problem w/ torque converter slipping or drive clutches slipping. I assume this is an automatic. Make sure you have adequate fluid in the transmission. I would also check for any OBD2 transmission codes that might be presented.

Code P0420 for catalyst system efficiency below threshold will not affect engine performance. It only means the catalytic converter is not performing as designed.

good luck


Parts Of BMW

Your problem would be in the power valve/accelerator pump circuit. This is the circuit that feeds gas to the engine when the changeover from idle to driving occurs.At idle the vacuum in the carb draws gas so no mechanical means of delivering fuel is needed. The same is true when you reach a consistant driving speed.During the changeover you need a way to increase fuel to the engine by mechanical means. Some carbs have an accelerator pump some call it a power valve. The changes in your intake and cam are enough so the stock circuit is unable to compensate properly. The dealer for the carb should be able to help you out with parts to increase the flow and rate of flow. Hope this helps.

this could be one of many problems or even a combination, most common are: clogged air filter, clogged catalytic converter, malfunctioning ECM, faulty mass airflow sensor, plugs/wires. take the vehicle in to have it diagnosed professionally. hope this helps.

try a fuel cleaner u add to the fuel sounds like u have a blocked fuel jet this will sort it out

Mine did the same. It was a bad idler pulley

Have someone handy to press the gas pedal for you after the engine has warmed up well; best if driven.

While you listen at the exhaust pipe, have your helper increase the revs slowly and note whether the exhaust note changes to a hiss, instead of the sound of an engine firing.

You may have a decayed catalytic convertor and when they come apart inside, they can clog mufflers and resonators (the second, smaller muffler).

I've had this happen on more than one car and when it happened on a Fiat Strada years ago, since the routing of the system was fairly straight and made of heavier gauge stainless steel, I fired two shots with a .357 magnum into the tailpipe.
Never had another problem with it.