I’ve been looking at civics/accords to buy and ideally something I can work on to help build my knowledge of cars, I’ve been an apprentice for about 3 months working on Lexus’s. I came across this civic and was wondering if anyone could give me some pointers or steer me towards or away buying it. My main concern is the CEL but seller says it’s because of the ECU being newer than the motor, is this something that can he fixed?

 

That means that you need to replace the ECU to get the light to go out. WHY didn't the seller do this ? Is it because they are cheap or just don't give a F**k ? Either way, this says something about the seller... and the likely condition of the car. Buyer beware.

 

Usually when someone is selling their project car its for a reason. If your concerned about the CEL for legal smog reasons, depending on the area some states won't even let you use a motor older than the car (California).

 

I would go take a look at it. These cars are very easy to work on and since you are a mechanic (apprentice), having some work to do on it should not scare you. If the body and chassis is as good as the seller claims, the rest is really straight forward to work out. The most challenging would be wiring but it could be as simple as an obd1 ECU and a conversion harness. It depends on how the seller converted the engine harness over to the OBD2 setup.

Other than that, motor swaps and ecu swaps are easy on these cars and seems some decent after market parts are already present saving you some cash on stuff you may likely have spent money on yourself.

A clean chassis is probably the hardest thing to find now a days. I would still be cautious, but would take a look. "Body Mint with dent here and there....." Lack of rust in the rear fender wells has me curious, is it a bondo job, truly never wintered or proper body repair with metal panels?

 

I don't believe that's the case. The ad clearly states an OBD2 ECU and harness were used with an OBD1 motor which likely means the CEL is on for Crank and knock sensor; two items that the OBD1 engines do not have.

OP is an apprentice mechanic, so I would assume he wants to fix it the right way meaning he'd have to change the oil pump and lower timing cover, lower crank sprocket, drill/tap the block for a knock sensor, and buy the new sensors, but a wise man once said "sometimes doin the right thing ain't always the right thing", so I personally would just wire in a CKF bypass and plug in a knock sensor, then zip tie the sensor to the intake manifold bracket to save myself 3-4 hours of work. He can accomplish all of this in about 10 minutes while he's changing that leaking oil pan gasket.

 

The ad doesn't say that the ECU is an OBD-2 LS computer... and my suspicion is that the ECU is in fact the original one to the "D" series engine found in the chassis as new. This means that because the car cranked up with this ECU, it is running fine according to the seller (Yeah, right). Yes, there will likely be a CKF and Knock code stored... or maybe there is already a CKF bypass done and this is why the engine will rev beyond 3-4K RPM. Nobody really knows until the OP starts really looking into the issues. You have outlined one method of fixing the engine and I am certainly on board with this path... but we are not even sure that the OP has an OBD-2A P75 ECU. If in fact the current ECU is wrong, I would be more inclined to purchase an OBD-1 P75 along with an OBD-2A -> OBD-1 ECU adapter harness and plug it in... this takes LESS than ten minutes. The only way I would go the long route would be if I lived in an area/state that had annual inspection/emissions requirements... but the OP didn't share that information either, so we are here tossing out possible options instead of a truly targeted response.