My friend just bought a honda prelude 91 with the 4 wheel steering and the engine is knocking bad with check engine light on. Any chance this could be cause he's using the cheap gas, lol i mean what kind of gas should it take its the dohc engine 4 cylinder.? I also don't know the gap for the sparkplugs, if anybody could tell me that would help him. thanks ahead of time.

 

87 octane or higher if he's in North America.

hope he didn't pay too much for a car with a bad engine!

 

Figure out the code and put some 91 or 93 octane in and see if anything improves. Your number 1 priority is determining what is causing the CEL and fixing it.