Hey all. So my civic wont go over 3000 rpm/30mph it just shudders when I hit that... its in limp mode I suppose. It started when I heard and exhaust pressure sounding leak like a loud salt/pepper shaker coming from around the exhaust manifold to the downpipe area/cat...the engine runs very sluggish. So I took the pipes apart, took the cat out and looked through with light and I could see the light on the other end, everything looked intact with the cat as I thought that was the problem possibly being clogged. I bought a new flex exhaust donut gasket where the downpipe meets the cat and that stopped the loud leak finally. But now the car doesnt go over the 3000rpm/30mph. Before I got the new gasket and sealed the leak in the exhaust the car would go above 3000+rpm and 60mph like normal but the car would be very sluggish. I do have a CEL light on and I got the codes using the paperclip method. The codes are 41 and 65....now my primary o2 sensor wire I noticed has been dragging on the axle and has worn wire and frayed it open so I dont know if this would be causing the limp mode or what. I hooked up a vacuum gauge and the car does have great vacuum. Anyone ever have this problem? Where do I go from here. I really need to get this fixed as it is my only daily driving car.

 

id start by replacing the o2 sensor, check fuel pressure, and make shur you are getting good spark.

 

I replaced the distributor wires and the spark plugs with NGK ones about 5 months ago. But I will still check anyways ..the fuel pressure today and unplug the o2's and test drive to see what happens. Car has 214k miles so I believe im due for some anyways. Thanks!

 

the o2 sensor would put it in a open loop mode if it wasnt working. it is most likely your ecu. this was an issue on my sr20det.

 

Did you just replace the ecu?

 

yes, if you can borrow one from a friend to try out that would be the easiest. or you can get one from a junk yard and if that doesnt fix it then you can always take the ecu back to the junkyard and get your money back

you need a p2p ecu i believe

 

Found out what the problem was. I removed my primary o2 sensor. That relieved pressure in front of the cat and it runs over 60mph no problem. Also that was the cause of when I came to a stop the RPMs would drop to almost zero. Its doesnt do that anymore with the o2 removed I took it for a test drive..I already ordered a magnaflow 51093 (the better OEM cat for my car that they have with a higher wash coat and more of the precious metals....) well see how it works when I get it installed.. Thanks anyways man!