Knock with a helping of Misfire

[The1KingBob]

Hi, I haven't made many post here but I bought a mx-3 a few years ago and it has been sitting in a field for sometime now. The car being true to awesome I went out and tried to start it and couldn't believe it but it fired right up. So I have been thinking about getting it running either selling it or keeping it. Problem is the engine sounds as if it has a small monkey with a hammer running a muck. The engine did this before it sat for two years. The engine would also misfire at sub 3000 to 4000 rpm but after that ran great. Was just wondering if anyone can think of what could cause both issues or should i address issues seperatly. Any insight would be helpful.

[Inodoro Pereyra]

The first thing you need to do, if the car has been sitting for a long time, is a full tune up, flush, and fluid change. You can't judge an engine effectively if it's running on parts (plugs, wires, etc) and fluids (oil, coolant) that have been rotting away for a long time. Also, flush the gas tank and put a few gallons of fresh gas in it, and run the engine for a while. If it keeps giving you trouble, let us know.

[The1KingBob]

Thank you! I will get that done within the next week. Before it had sat for this past few years the car behaved in the same manor. It had a bad knock ( worse now.. but can you expect from it sitting so long right? aha ) and would misfire at sub 4000ish rpms. I have replaced the plugs but not cables. I surly need to do the oil and gas, those are first priority. Recommend cheap oil, run it for a bit, then mobil1? For gas run a few gallons, any fuel adatives i should use? 87 or 91 octane?

Again thanks for the help and quick response.

[Inodoro Pereyra]

When you say "knock", are you referring to a very loud ticking noise, that fades away over 3500-4000 rpm? If that's the case, you need to replace your FGS's. Look in this same board, and you will find a great tutorial by Ryan, on how to do the job.

Initially, I'd suggest cheap oil and filter to do the engine flush (obviously, with the added oil flush), and then a good quality filter and oil.

You can use either 87 or 91 octane, shouldn't make a difference. When it comes to gas octane ratings, experiences vary, and you will find plenty of different opinions here, but, bottom line, the engine should work perfectly with either. A good injector cleaner (Lucas or Seafoam) would be a good idea to add to the gas.

You're welcome. Let us know how it goes.