Skip the auto shop - Our mechanics make house calls

Q: cracked exhaust manifold pipes/headercar will not go fast revs high but No speed ?Cause?

asked by on

car will not go past 30 miles an hour engine revs high with no speed increase No power on acceleration while taking off it takes a long time to get up to 20 mph like the engine is struggling. help please 2003 hyundai elantra gls auto 4cl 2.0l

My car has 151000 miles.
My car has an automatic transmission.

A: In order of priority, if you have a cracked...

In order of priority, if you have a cracked exhaust manifold (leaking carbon monoxide), that actually has to be fixed first or at least coincident with the repair(s) to the engine/transmission. The principal danger from exhaust leaks (carbon monoxide) is NOT death from acute exposure but rather long term tissue damage from chronic low level exposure. Way more people die from chronic, day to day CO exposure than from the kind of acute exposure you read about in the newspaper. So, basically, so as not to damage your health be sure to get the exhaust leak fixed at the same time the acceleration is resolved.

If your vehicle won’t go over 30 miles per hour, it is possible the PCM has forced the transmission to operate in limp mode. Forced limp mode operation can occur if, as an example, there is a fault with the input and output speed sensors on the transmission, or the kickdown switch. There are probably downloadable OBD-II trouble codes that will help the Mechanic hone in on the trouble area. You might try checking the transmission fluid level and condition. If the fluid level is low and/or burnt, that might be related to the problem. To rule limp mode in or out (without a code scanner) sometimes you can disconnect the negative battery cable for a 1 minute to reset the PCM and then see if the transmission shifts normally until it enters limp mode again. There are other possibilities for what you are describing though including faults in the fuel, ignition, air induction systems, and even the possibility of a severely restricted exhaust system. What I would suggest is diagnose the engine/transmission issue first, but again, once that is restored, the car is unsafe (unhealthy) to drive unless and until the exhaust leak is also repaired. Please let us know how we can best assist you.

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・Fair and transparent pricing

Get a quote

What others are asking

Q: What does the tail light indicator mean?

The tail light indicator is located on the instrument panel. This light illuminates when the tail lights are turned on.

Q: Pinging during acceleration

Hi There, Pinging is a result of pre-ignition which means the fuel/air mixture in the cylinder spontaneously explodes, slightly before the spark plug ignites it. There are several things that can cause this to happen. Installing the wrong spark plug...

Q: Exhaust leak from engine gasket right after catalytic converter keeps blowing out. What needs changing O2 sensor or converter ? 2000 Chevrolet S10

Hello - I suspect that either the flange joint after the converter has a defect that continues to leak, despite new gaskets, or the muffler is stopped up, increasing exhaust pressure on that joint. I recommend an exhaust system inspection...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...