Rep Power: 0

Hello, I have a 2003 Honda Civic EX Automatic that I recently bought for cheap to use briefly as a beater/ Point A to B car. Before purchasing the guy the guy stated he replaced the timing belt, Timing belt tensioner, water pump, 3 motor mounts, Trans mount, Radiator, Radiator fan, Thermostat, Air filter, Spark Plugs, Coil packs, Serpentine belt, wheel bearings, Lower ball joints, Brakes front and rear. On the drive home from the guy's house check engine light came on and started misfiring/ low idle/ running rough. The same day I took it to Oreiley's and had the car scanned it came back with P0301, P0303, P0304, P0300, and P0302 all of the misfires. So I bought new plugs and upon inspection, I removed them cylinders 1 and 2 were not tight at all but the plugs were new but orange. I checked the gap and they were at .4 and the gap I found online was .44. In addition I cleaned the IAC and the Throttle body and confirmed that the parts he replaced were replaced, I torqued plugs to 18ft/lbs and reset the idle. So then I'm driving later that day and the check engine light comes on and goes into a limp mode where the redline is at 3500 RPM so I take it to O'Reilly's again and this time it was MAP sensor High circuit code. So I removed the map sensor cleaned it and the O ring, re-installed it disconnected the battery to reset the ECU, and drove. The check engine light came back and the same code for the map sensor. Suspecting I had a vacuum leak I bought a vacuum tester and took off the hose to the brake booster vacuum tested at 9ft of elevation and came back at around 19in HG which I believe is a touch low but in band. When I tried to snap test it (blip throttle to full open) the vacuum would not go to 0in HG and only 13 or 14in Hg then back to the idle vacuum of around 19 in HG. This leads me to believe the cat is clogged from reading I've done online. Today I went and bought a new map sensor installed it and reset ecu, but nothing changed. Seeing as the spark plugs were installed incorrectly I am weary of the timing belt being a tooth off. My next step is going to be to fuel pressure test and remove the upstream O2 sensor or the cat altogether to see if it helps, other suggestions would be greatly appreciated. Sorry for the long write-up, I just want to be thorough. Mahalo.

 
Rep Power: 125

Did you buy a chinesium sensor? OEM or it won’t work.

 
Rep Power: 0

another suggestion by personal experience. does the misfiring start after engine warmed up?. it could be faulty coils. you have to check one by one and must be in good condition.