I've been having a spark knock type noise on my 2002 explorer, 4.0 SOHC. The timing chain TSB has been performed, the engine has been decarbed, the MAF has been replaced. The thing is, it seems to get better when outside temp is up and worse when outside temp is down. Does not give off any codes, everything appears to be normal, except for the rattle. Dealer is stumped.

I've been reading about DPFE sensors and EGR valves and have read that if an EGR valve is stuck open, it could cause a lean condition in the engine causing a "pinging" or "rattle", and that this could happen, although not likely, without giving off any codes. Any advise on this matter would be appreciated. I'm thinking about trying to change both of these myself because I don't have the time to take it back to the dealer a 4th time for the same concern. Don't get me wrong, they've been great and I understand that they can not just change parts on a hunch but the last trip took 9 days. Also, where are the DPFE sensor and EGR valve located? I think passenger side firewall? Everything I've read says they are not hard to change and I'm not completely mechanically ignorant (my wife would disagree) so I thought what the heck, it's out of warranty now anyway.

Again any help would be appreciated.

 

Koolhand,

I'm in the same place as you are with my 1999 5.0L Moutaineer. I don't think it is unusual for there to be an EGR problem without the computer showing a code. It's not as if the EGR either works perfectly, or not at all. It's a progressive problem where the EGR is not necessarily stuck, but just does not open at the proper pressure. This can cause the combustion chamber temps to get too high.

I've figured out where the DPFE is (which I intend to replace) but like you, I need to figure out where the EGR is. I also think there are multiple EGR parts and not all of them need to be replaced.

If anybody out there can help describe EGR locations (for 4.0L and 5.0L) and what needs to be replaced, it would be very helpful. I've had no luck with the search on this.

Thanks

 

Changed the DPFE this morning. Did not solve the problem. Still the same knocking noise. May try the EGR later. Mine is on top of the engine. It's round and has two vac line's coming off of it. A little more involved than the DPFE sensor. Not bad for either part though. Dealer has DPFE sensors for $67.00 and EGR valves for $65.00 or $70.00. Oh well, maybe next time.

 

the sohc has a knock sensor so you will not get any spark knock what you are hearing is the timing chains get them fixed under recall

 

Timing chain TSB already performed supposedly. How do you tell for sure?

 

Knock sensors are not foolproof. I've heard plenty of engines ping with a working knock sensor.

I just confirmed that my 5.0L has one and I've had pinging issues since the engine had 5000 miles on it. The ECU will only back off timing so far if the knock sensor triggers. If the combustion temps are too high, the motor will still ping/knock.

 

i would seafoam the engine a couple of times to get most of teh carbon out replace the plugs and go from there

 

My 4.0 was decarbed by the dealer. Don't know if it was Sea Foam or not, but is what Ford Hotline recommended. I'm gonna try changing out the EGR valve next, Sometimes when I shut the engine off there sounds like a loud vac leak coming from somewhere around the intake manifold. Dealer says normal with plastic intakes, but this is very loud. Of course, won't do it in front of them. EGR valve on mine is right behind the intake manifold. Will check vac lines first. If that's not it then I'll change the plugs, but I think that's a long shot.

Does anyone know where the knock sensor is? Could this be malfunctioning? Also, does anyone know how to verify the timing chain tensioners have been replaced? I don't doubt that they have been but you know the old saying, trust in the Lord, everyone else verify. I've read on some older models you could tell by the looks of a bolt on the top of the engine. Not sure on mine. Thanks again for all of the suggestions. Ric, maybe one day we'll get this thing licked.