Skip the auto shop - Our mechanics make house calls

Q: Long crank time, low idle, and poor to no acceleration.

asked by on

Just replaced the engine due to being run low on oil. Although the previous engine was starting to knock, it accelerated and ran ok to the shop. After installing a used engine in the car, the car has a very long crank time before firing (but turns over well) and then has a very low idle (500-750 RPM) and throttle response is poor at best. Acceleration is so lacking that the vehicle can not be driven. In park I can get it to rev up (no odd noises). If I hold it at part throttle for about 2-3 seconds and then it will catch up but feels bogged down. I have changed out the electronic throttle body, spark plugs twice with two different gaps, fuel rail and all injectors, crank sensor, cam sensor, (all parts came on the used engine, and I have swapped them out for the ones original to the car with no change. Only part that is on it now that is not original to the car is the intake manifold itself) and checked all harness connections including MAF. There is no Service Engine Light on.

My car has 125000 miles.
My car has an automatic transmission.

A: Hi there, thanks for writing in. I'd be...

Hi there, thanks for writing in. I'd be happy to offer my insight. I would suggest checking the idle air control module. If the motor is starving for air (similar to an engine being choked at normal operating temp), this may cause it to bog down as you describe including the very low idle. As you may already know, if it were a leaner fuel condition such as a vacuum leak, the tendency is for the idle to naturally be higher.

If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make any repairs as needed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Car starts in On position

The most likely cause of this issue is a faulty ignition switch or lock cylinder. One of the tumblers may have fallen out of place causing a connection to the starter when there should not be. My best recommendation would...

Q: Car shudder, tire noise, engine clicking - 2006 Lincoln Zephyr

It sounds like there are worn suspension bushings in the front suspension. When braking, the front suspension is subject to large stresses which accentuates a worn or damaged bushing. The "jerking" sensation you observe when braking sounds like a severely...

Q: Noise inside the B pillar when the weather is cooler.

Hello. A good body technician may be able to use a stethoscope to get as close to the noise as possible then dismantle the trim in the area to find what is causing the rattling. Seasoned mechanics equipped with a...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.