I have a 2005 Honda Civic EX A/T with 201,500 miles. I purchased it about a year ago for $1000.00 and it has always had an issue with little power during acceleration and going up hills. The associated code I get is P1129, which is for MAP sensor pressure higher than expected. I have also received codes for miss fire in # 1 and 3 and I have received a code for throttle position sensor. When I get the miss fire code I don't think it is actually miss firing as I don't feel the car shake. When the car goes into limp mode it idles roughly. If the car is not in limp mode it idles ok, a little rough but better than most cars that old. Prior to changing the injectors, cat cranked for a 5 to 10 seconds before starting both hot and cold. After replacing the injectors the car starts quickly on cold start but still takes 5 seconds when hot. When you put the pedal all the way down it seems to sputter a bit. There seems to be a sweet spot on the pedal that it seems to have better acceleration when only giving it a quarter pedal, anything over half pedal it doesn't like. Acceleration seems to drop off over 4000 rpm. Transmission shifts into all 4 gears smoothly.
Live Data when driving:
Short term fuel trim is usually negative when under a load ranging from -3.9% to -28.1%
Long term fuel trim is always negative ranging from -3.1% to -10.2%
MAP ranges from 4.4 kPa to 12.8 kPa
02 Bank 1 Sensor 2 voltage ranged from 0.000 V - 0.975 V
Wide Range 02 Bank 1 Sensor 1 ranges from -23.586 MA to 10.473 mA
Repairs done:
Replaced exhaust from the exhaust manifold back, including muffler and catalytic converter with new
Replaced down stream sensor by the catalytic converter with new
Replaced MAP sensor twice with new
Replaced spark plugs with new
Replaced coil on plugs with used
Replaced injectors with remanufactured
Replaced the battery with new
Cleaned the EGR valve
Replaced the valve cover gasket
Replaced engine ground and frame ground
Checked fuel sock and found no debris on the sock
Thoughts:
I think that it is either a bad ECU or the timing is off by a tooth, but would like some other opinions.
The timing on the cam was off about 1/5 turn. Runs just fine now.
Did you check your air filter or try to clean your MAF sensor and throttle valve/ TPS? The fuel trim is subtracting fuel, which means it's running rich. Running rich means either too much gas, or not enough air is getting into the engine. You replaced fuel injectors, if they're not leaking I would assume there's not enough air, or it's not being metered correctly. The hard start when hot kinda sounds like an injector might be leaky.
A filthy air filter, gunked up MAF sensor and dirty throttle valve can all really mess with airflow readings. A bad TPS can also tell the computer incorrect information about where the throttle is as well, and cause the engine to not respond to the throttle the way it should. If you replace sensors, only buy OEM, not 3rd party.
I forgot to mention I replaced the air filter shortly after I purchased the car. There is no MAF sensor on my car. I checked voltage on the TPS to make sure it was getting about 5v. When I was looking at the data, it looked like the throttle position was correct from the OBD2 reader. The hard starting was a symptom prior to the changing of the fuel injector replacement. The injectors just made it start quickly on cold starts.