And my engine started knocking. My truck is a 2000 Ranger, 178k miles, 2.5L 4 cyl. It ran fine before I changed the plugs. Right after I changed the plugs, I started it up, it ran rough for about 30 seconds, then it ran fine. After two or three minute of driving, it started knocking. What are the first steps in diagnosing this problem?

 

What type of plugs did you put in?

 

Autolite 764 copper's. They were the same as the ones I took out.

 

I would disconnect battery for a few hours and let PCM reset. See if that helps!

 

Make sure the wires didn't get mixed up and are all on tight. It happens to the best of us. Did it bring up a CEL? If you have access to a code scanner try it. If nothing try letting the computer reset, that might help...might not. Just check out all the connections.

Matt

 

I didn't realize that that's the recommended time for the PCM to reset after disconnecting the battery. If that be true then I need to let mine sit disconnected again for that period of time. I only had my battery disconnected for around an hour while replacing both oxygen sensors.

 

I have heard that a half hour- one hour is good but I also heard a few hours. If you have the time let it go longer, if not the 30-60 minutes should still do the trick!

 

did you use a decent brand of ignition wire? if you get the chain store cheapies sometimes they just wont work right youre better off spending the extra dollars to get the motorcraft ones pr a good brand of wire and make sure you have the connections tight and in the right place

 

I personally think it's the plugs. Most people (myself included) usually swear by AutoLite Double Platinum plugs.

 

When you say it knocks, do you mean detonation ping? A lot of times in an engine that has combustion chamber deposits, when you change the plugs you end up w/ an exposed edge of the deposit because the plug partly knocks it loose when you put in the new plug. The only way to get rid of that is to get rid of the deposit. You can do that (sometimes) by just driving it hard for half an hour, and other times by using some injector cleaner or acetone in the gas, and other times you must use something like Seafoam to take care of it.

 

In response to azu, I'll try that. Projectnitemare, I am positive I didn't get the plugs out of order, as I only changed them one at a time. The check engine light actually came on the last time I drove the truck before I changed the plugs, and I haven't had time to check what code it is. Rubydist, I think I mean detonation ping. I haven't had experience with this before, but from what I've read that's what it sounds like. Last time I filled my tank, I put in a fuel injector cleaner (Gumout brand), but I don't want to drive it at all if there is a chance I could damage the engine.
Some people I talked to over the weekend thought that it could be timing, like maybe the timing belt jumped a cog. Is this a likely cause?

 

Now come to think of it mine had the same problem after I changed mine at about 96K. I reset computer from advise here and switched gas brands as we were having problems in several cars that we traced to the fuel and station. Anyhow I haven't noticed that noise in a while.

 

I unhooked the battery overnight, and it didn't do anything. I can't imagine that it would be a fuel problem, unless related to the fuel injector cleaner I put in, because I regularly fill up at the last station I filled up at.

 

It might just be deposits that need to burn off. Like I said mine made that noise too and thought it was strange as I didn't have it before I changed them. Just take it for a nice long highway drive. See at that helps. After that I would have the PCM scanned. I have the Actron 9145 and it tells me a lot about the various sensors and engine performance. Of course you have to know what they mean. Take it to a reliable station to see what they say.

 

But what if it's not deposits, and is something that could damage the engine? Like I said, a couple people I talked to thought it might be a timing issue.