Sluggish Acceleration & Little Power!

Hello Guys!

I have encountered a problem with my car engine. I noticed the car was not putting out enough power. When I press on the gas pedal aka accelerator the car drives real slow or sluggish; it seems like there's something clogged. I recently replaced the alternator which was draining the car battery. Since then the car starts up without any problem. I assumed its the EGR valve. The original EGR valve was quite carboned up but the used one from the junk yard didn't do much justice to the problem.

Additionally, the car is rough idling which I believe was due to bad gasoline. ANY ADVICES OR SUGGESTIONS WILL BE EXTREMELY HELPFUL!!

P.S. - Catalytic converter was struck by curb and heat shield was damage. Everything seems to be intact!

2000 Pontiac Grand Prix SE 136km+

Bad/faulty EGR wouldn't affect acceleration. The car can run without the EGR installed and blockoffs in its place.

If the cat was struck its possible chunks have broken free inside and are plugging your exhaust. This will cause rough idle and poor acceleration.

X2 on the cat.....

Basically, with vehicle at normal operating temp, from a dead stop, lay into the gas pedal......if car revs out at 3K, and bogs down and doesn't shift, stop.....now LIGHTLY accelerate...if it shifts and slowly gets up to speed, it's the cat.....

Can verify by creating an exhaust leak before the cat(remove O2 sensor or loosen exhaust pipe....it will be noisy....just take a quick short trip....if hard accel is there, it's the cat....

Or you can attach a back pressure tester...rev to 2k...should not exceed 1.25 psi.....

Disconnect the MAF sensor and test drive the car. If the problem goes away, then get a can of maf cleaner and clean the sensor.

Do you have a scanner that reads live data or a vacuum gauge? You could also test for a blocked exhaust with any of those.

Oscar.

Do you have a scanner that reads live data or a vacuum gauge? You could also test for a blocked exhaust with any of those.

Oscar.

I've got the inexpensive dongle that plugs into the OBDII and bluetooths to my phone. How could I confirm a blocked exhaust with that or a vacuum gauge?

Using a vacuum gauge:

Connect the gauge to a suitable vacuum port BEHIND the throttle body. Watch the needle and take note of the reading, now raise the rpms to 2500 and look at the gauge, it should be slightly higher than at idle. If it starts moving down to 0 there's a restriction in the exhaust.

Using OBD data:

Check the reading of the map sensor with key on/engine off (anything between 24 and 29.9 inHg depending on your elevation), start the engine and compare the reading, it should be a lot lower than before (around 9 inHg). Now raise the rpms to 2500 and watch the reading, it should be lower than at idle; if it starts going up to the reading at KOEO the exhaust is blocked.

Oscar.

Thanks everyone for sharing your feedback. So far today has been the second day of short-distance trips with the car since I posted this thread. The car rough idle extremely bad at stop signs, traffic lights, etc. After take off it accelerates slow but picks up. The car coast with no problems at 40-60mph. I made a quick trip to AutoZone and got these trouble codes:
A) P0449
B) P0300 - Possible bad engine coil CAUSING MISFIRE
C) P0102

(Exhibit A) - One thing I noticed is that the tube that is connected from the air intake tube to the rear of maniford is slightly unplugged or not plugged all the way.

I was informed by the staff at AutoZone I may have to replaced the Oxygen sensor, MAF sensor, spark plugs & wires. I already tried cleaning and disconnecting the MAF sensor and no improvement. Can someone guide me in the right direction or where should I start?

I would fix the misfire and 449 before supporting about 102. 102 may be consequence of the misfire. Don't know what 449 is off hand.

I made a quick trip to AutoZone and got these trouble codes:
A) P0449
B) P0300 - Possible bad engine coil CAUSING MISFIRE
C) P0102

P0449 (Mass Air Flow) can cause a random multiple missfire (P0300). A bad ignition coil would typically cause a specific cylinder missfire, along with the cylinder that shares that coil pack.

The P0102 is just an evap code, most likely caused by a loose gascap.

I would suggest clearing the codes by disconnecting the battery for 10 minures, take the car for a ride to trip the check engine light again, then see what codes are in there again.

I was informed by the staff at AutoZone I may have to replaced the Oxygen sensor, MAF sensor, spark plugs & wires. I already tried cleaning and disconnecting the MAF sensor and no improvement. Can someone guide me in the right direction or where should I start?

Never EVER follow their advice; stick to having the codes read and drive away ASAP, otherwise you will likely end up throwing a bunch of parts at it without actually fixing the problem.

P0449 (Mass Air Flow) can cause a random multiple missfire (P0300). A bad ignition coil would typically cause a specific cylinder missfire, along with the cylinder that shares that coil pack.

The P0102 is just an evap code, most likely caused by a loose gascap.

I would suggest clearing the codes by disconnecting the battery for 10 minures, take the car for a ride to trip the check engine light again, then see what codes are in there again.

It's the other way around, P0102 is for the MAF and P0449 is for the EVAP, he's right though.

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1.- If you tried disconnecting the MAF sensor AND you didn't drive the car after, then that's likely the reason from the P0102 code. It should go away after 2-3 ignition cycles.

2.- The EVAP solenoid could be either bad, OR there might be a broken line between the canister and intake manifold. With the permanent flow of air form the atmosphere, it would trick the PCM into thinking the vent valve is connected but stuck open and not allowing vacuum at the fuel tank. Check those lines from the EVAP canister (rear driver side on quarter panel) to the intake manifold.

3.- A vacuum leak can cause random misfires if big enough, HOWEVER, it's not the only cause for it. Low fuel pressure can also cause random misfires and would definitely cause rough idle and sluggish acceleration; an ignition problem (bad ICM) could do the same but you would likely smell the unburned fuel in the exhaust.

If you could get ahold of a fuel pressure tester and a scanner that reads live data, it would surely be easier to diagnose. I have a friend in Washington who rented both items from autozone (got his money back after returning them); maybe your local autozone has the same items.

If you can rent the scanner with live data, before you erase any codes, WRITE DOWN any information contained within the FREEZE FRAME option.

I hope this helps,

Oscar.

Hey guys,

I discovered the rough idling was caused by a faulty ignition coil (5/2). I used a multimeter to test the resistance on each coil and I found the (5/2) coil was dead or faulty. The other set on the pack shown a normal reading between 0.3 to 1.5 ohms approximately. Any reading below or higher than the normal considered faulty.

I'm still having trouble solving those code: P0449 (EVAP), P0206 (Fuel Injector), P0300 (Cylinder misfire).

Its possible the P0300 is due to spark plugs being un-gaped. I would have to check those out.