Ford Ranger Forum - Forums for Ford Ranger enthusiasts!

Go Back   Ford Ranger Forum - Forums for Ford Ranger enthusiasts! > > >
Forgot Password? Join Us!

Welcome to Ford Ranger Forum

Reply
 
Thread Tools Search this Thread

  #1  
Old 10-25-2009, 04:54 PM
jim22 jim22 is offline
Ford Ranger Owner
 
Join Date: Aug 2009
Posts: 54
Question diagnose spark knock or ping

Ok, I've been through my new (to me) truck and performed lots of maintenance and done lots of inspections. Now it's time to address the dreaded "spark knock" (ping, pre-ignition, detonation, whatever you want to call it). Here are the specs...

1999 XLT Sport, supercab
rear wheel drive (2WD, RWD)
3.0L flex fuel motor
automatic transmission
156K miles

At the moment, I've run a couple tank-fulls of Shell 87-octain no-lead regular gas through it. It's getting between 16 and 20MPG, and pings more than enough to bother me climbing hills or merging onto the highway. It seems to lack power under these conditions as well.

I have replaced the fuel and air filters. I pulled one spark plug, and it turned out to be running Autolite XPP103's, which appear to be in good shape. The one I pulled looked "normal" and had a normal gap.

I have seen the TSB which describes changing the coil AND the PCM, and my coil does, in fact, have a number in the "bad" range. I wouldn't mind changing the coil, but the PCM sounds expensive.

I know there are other conditions which can lead to pinging, such as a misbehaving MAF sensor, vacuum leak, combustion chamber carbon deposits, hot spark plugs. What I'd like to know is what to check and in what order to try to diagnose my particular problem. Also, is there any benefit in changing the coil without changing the PCM? What coils are recommended (motorcraft?).

Thanks in advance,
Jim
Reply With Quote
  #2  
Old 10-31-2009, 02:20 PM
jim22 jim22 is offline
Ford Ranger Owner
 
Join Date: Aug 2009
Posts: 54
Default

Hmmm, no takers, eh?

Well, lacking suggestions, today I removed and cleaned the MAF sensor. I didn't have the security torx bits, so I used a Dremel with a cutting disk to cut a slots in the screws. I looked, even under a microscope, and the wires looked clean even before I cleaned them. I sprayed them good with CRC MAF cleaner, put the sensor under the microscope one more time, and reinstalled. Engine started and ran ok.

While I was under the hood, I checked that the air intake was securely clamped to the throttle body, and looked over the vacuum lines. Everything looked ok, but I need to research the vacuum system a little more.

We'll see next time I take it out for a run.

Jim
Reply With Quote
  #3  
Old 10-31-2009, 04:08 PM
STL STL is offline
...............

 
Join Date: May 2009
Posts: 23,398
Default

try running some sea foam through the system
__________________
2005 Edge

Reply With Quote
  #4  
Old 11-16-2009, 05:24 PM
jim22 jim22 is offline
Ford Ranger Owner
 
Join Date: Aug 2009
Posts: 54
Default

Sea Foam... Yup, I've seen it at the local Autozone. It seems a little scary to use. I suspect it WILL foul the spark plugs, and worry about downstream sensors and CATs. I do suspect the chambers are filled with carbon.

Anyway, an update: Last time I filled the tank I filled it with super (93 octane). Within the first minute on the road, it still pinged, but since then it's been purring like a kitten - no hint of a ping at all. That's the first step in the service bulletin.

Anyone know any more details about why the service bulletin includes changing the coil? I could buy about a year's worth of super for the price of a coil, and I don't even want to TALK about replacing the PCM.

Later,
Jim
Reply With Quote
  #5  
Old 11-18-2009, 04:20 AM
joldtown joldtown is offline
White Trash Ballin' MFer
 
Join Date: Oct 2009
Posts: 764
Default

My .02 here. I just Seafaomed my 02 4.0. I put 1/3 through the brake booster, 1/3 in the crankcase, and the last 1/3 in the gas tank. I let the hot engine sit for about 8-10 mins, and recranked (step one done). Drove around for about 15-20 miles, changed oil (step two). After the gas ran out in that tank I swithced to 89 octane.
While it didn't foul my plugs I changed plugs and wires, fuel filter, air filter, and will probably change the oil again this weekend my truck seems to run like a pretty much new one. No more knock for now, but we'll see how long it lasts.
__________________
'02 XLT ext. cab 4.0 4x4 Off Road
Usual mods
Unusual color
Only a real man can pimp DWB

Quote:
Originally Posted by Johnbaum13
What really impresses us is power, originality within reason, and a nice clean rig that makes us say "damn!"
Quote:
Originally Posted by Ranger Sport
ew, don't touch me smakes
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Spark Plug Help Bear 3.0 Vulcan Tech 37 12-09-2010 06:23 PM
Spark Plugs RangerLuc General Ford Ranger Discussion 27 02-15-2010 09:44 AM
2004 v6 with no spark nathancrx 4.0 SOHC / 4.0 OHV Tech 0 10-24-2009 02:20 PM
spark plugs RangerLuc 4.0 SOHC / 4.0 OHV Tech 10 10-12-2009 06:48 AM
metal ping sound in reverse doomrus26 Drivetrain Tech 0 09-03-2009 01:39 PM