'99 Accord is a slug
 

We have a '99 Accord that we have had for about 1.5 years. We have put 40k miles on it since we got it. It now has about 142k on it. When we got it the head gasket was bad. I replaced that and have had no more coolant trouble. That was about 25k miles ago. All that back story, so now the trouble. The thing has always been a slug. We also have a '91 Accord with 302k miles that has MUCH more pep from a stop light. I can feel it missing some, but the check engine light is always just the evap system or occasionally the knock sensor. I have a decent code reader. We have switched to mid grade gas, but it hasn't really helped that I can tell. I have replaced the plugs, plug wires, distributor cap, rotor, and the timing belt (it was time, not because I thought it would help). Anything else I can check or something that needs to be done that I don't know about? Its a 4 cylinder and a 5 speed and the PO from what I can tell didn't do much maintenance at all.

Let us know the actual codes.

Switching to midgrade probably won't fix the problem.

How about changing the manual transmission fluid?

What kind of gas mileage are you getting?

Have you checked the compressions? Head gasket often = overheat = glazed cylinder walls and low compression.

I did actually change the trans fluid with Honda fluid just last week. We get around 27mpg mixed driving, up to 34mpg on the highway. I'll get the actual codes later today.

The two codes are P0325 knock sensor, and P1457 evap system.

Just me but address the codes. If the ecu/pcm is seeing a fault then it goes to "limp mode".

Once you do that and if the "lack of power" is still there, check the timing to be sure you are not a "tooth or two off".

Agreed I'd the car is in safe mode it is going to run rich and feel sluggish. "Running" mid grade fuel will further hinder the performance of the motor. The mid "grade" fuel has more additives in it to prevent pre ignition in higher compression engines. If you put that fuel in a lower compression motor the fuel and air mixture isn't even ready to be ignited when compressed and won't burn efficiently giving you poor performance. That is a big misconception and many people throw away money at the pump. Use the fuel the motor in the car was made for. :)

I don't think those codes will put it into "limp mode". You said it was always a slug right? Did it have those codes when you bought it? Doing a compression test is far easier I think than pulling the timing cover and valve cover to check cam timing. With a screw in compression gauge, it should take like 20 minutes.

P1457 will definitely cause some sluggish acceleration. Usually thats a problem located on the valve that attaches to the canister. Or it could be the canister itself. Knock sensor. CHANGE it. It can throw off the ignition timing, which will cause the ****tiest acceleration. Mine was split in two and my vtec switch failed, and boy even with the bad vtec switch, the new knock sensor made the engine run much nicer. Also, be sure you bled the air out of the coolant. Otherwise it overheats the engine, causing another head gasket issue

Great stuff kobiewan, that is why I love this board.