Engine pinging badly. Need help.

[Chrono558]

Vehicle in question is a 93 F150 5.0L V8, 2wd E4OD. Under acceleration it will ping (more noticeable when engine is warmed up) and will ping when I'm cruising on the interstate and just maintaining the same speed. It's pinging bad enough that I'm really afraid I'm going to put a hole in the piston one of these days and then I'll really be in trouble.

Things I have done/checked so far...
1. Running 89 octane (and trying different gas stations to see if any offer improvement)
2. With the engine idling I'm putting a vacuum on the egr valve and the engine starts to stumble so I'm under the impression the egr system is functioning normally.
3. Can't find any vacuum leaks when spraying a can of carb cleaner.
4. No codes stored at all (both KOEO and KOER)
5. I've run 2 cans of seafoam on 2 separate occasions through the intake trying to clean up any carbon and it didn't make much of a difference.
6. Checked timing twice with the SPOUT unplugged and made sure it was on 10*BTDC.
7. Verified with my scanner that the engine temp is not getting to hot (hovers between 180*F to 195*F depending on driving.)


I'm getting stumped on this and it's really getting me worried. The engine has almost 189K on the clock but if this doesn't stop soon then the clock will be counting no more. If anybody has any ideas let me know.

-Chrono




...Also (off-topic) but when I was typing this all up I cannot see the blinking cursor nor can I jump back up to a previous spot in what I've already typed to make an edit or add anything. Whenever I try it just keeps typing on the end of the last line of text. Is anybody else having this problem?

 

[big5oh]

Speed density or mass air flow?

Main causes of ping:

- EGR not opening when the computer thinks it is
- EGR gases not getting to the combustion chamber when the computer thinks it is
- Carbon build up in the combustion chamber

You should monitor the EGR valve position sensor while driving to see if it opens or not. If it doesn't, then look at the solenoid that sends vacuum to the EGR valve, the vacuum line that connects the two and the wiring to the solenoid.

 

[1985 Ford F-150]

Id try premium fuel and see if it helps.

 

[Chrono558]

Speed Density. I'll try testing the solenoid when I can and see if I can test the vacuum line going to it.

 

[subford]

Pinging, knocking and detonation are all terms for a condition known as "pre-ignition". That means some of the gas and air mixture is igniting in the cylinder before it's supposed to. And when that extra flame front crashes into the normal flame front (created by the spark plug), you hear a noise, and that noise is pinging.

There are four major causes of pinging. The first three are related to excessive heat.

The first is severe engine overheating. If the engine is running too hot for any reason, the temperature in the cylinders can simply be too high. In that case, some of the mixture can ignite before the spark plug fires just from the intense heat.

The second major cause of pinging is carbon buildup inside the cylinders and on the pistons. When too much carbon collects, it can reduce the size of the cylinders (increasing the compression and temperature of the cylinder contents) and retain excessive heat itself.

The third cause of pinging is a malfunctioning exhaust gas recirculation (EGR) system. The EGR is supposed to send non-combustible exhaust gas into the cylinders to lower the temperature of the mixture.

How does 800-degree exhaust gas LOWER the temperature in the cylinders? Because it doesn't burn, and it crowds out some of the oxygen that would have burned and made an even hotter flame. And if that EGR is not working properly, the cylinder temperature can be too hot and the engine can ping.

And finally, incorrect ignition timing can cause pinging. The ignition timing determines when the spark plugs fire. And if they're set to fire too early, the stuff will begin to burn too early.

The use of higher-octane gas often makes the pinging stop because it has a higher ignition point. By requiring a higher temperature to make the gasoline burn, you reduce the likelihood of it "pre-igniting" somewhere else in the cylinder.

But premium gas doesn't address the underlying problem. So start by checking the EGR system, the cooling system and the ignition timing. And if none of those things fix it, then you can consider using a higher-octane fuel.

I know you said that you have covered most of these items but I thought I would list them anyway.
Let us know what the fix is and would be most curious if the crossover tube at the back of the motor is rusted out or broken like Paul O said below.

 

[conanski]

It's not going to be easy to get at but I bet the crossover tube at the back of the motor is rusted out or broken. This is part of the Termactor system(air injection), and for whatever reason when it develops a leak an otherwise good running motor begins to run excessively lean.

 

[TexasNomad]

could it be a timing issue, maybe its getting to advanced and making it ping?
If every thing else checks out ok, you could try to do a seafoam treatment.

 

[big5oh]

could it be a timing issue, maybe its getting to advanced and making it ping?
If every thing else checks out ok, you could try to do a seafoam treatment.

He said he checked timing twice and it is at 10 degrees BTDC with the SPOUT out.

He said he ran 2 cans of seafoam on 2 separate occasions and it didn't help.

 

[TexasNomad]

crap how'd I miss that..
Well I'd say you have your self a heck of a pickle.
Hmmm any chance you might have some rust in your fuel? rusty fuel and cause hell on a engine and mimic all kinds of thing.

 

[Skandocious]

Seems like all of the common causes for pinging have already been discussed-- so I'll address this:

...Also (off-topic) but when I was typing this all up I cannot see the blinking cursor nor can I jump back up to a previous spot in what I've already typed to make an edit or add anything. Whenever I try it just keeps typing on the end of the last line of text. Is anybody else having this problem?

I had this same problem for a while to and it was driving me BONKERS. I finally figured out what it was. Apparently Firefox 3 doesn't jive well with our version of vBulletin that we've got running on this site. Here's the lowdown-- there are 3 different options for when it comes to making replies on the forum. You can see them by going to User CP -> Edit Options, then scrolling to the bottom of the page. The 2nd to last option is called "Message Editor Interface". The pulldown menu has 3 options:

1) Basic editor
2) Standard editor
3) Enhanced Interface

The first option is very basic and will not provide very many formatting options when you're making your post. The 2nd option gives all of the formatting options EXCEPT when you apply the formatting, it won't show up in realtime in your message. Instead of seeing something in bold while you're typing the message, you'll see the [b]bold[/b] tags in your message. Now once it's POSTED, the formatting will be bolded for everyone else to see.

Clearly it would be nicer to use option 3 and see your formatting as you're typing it, but apparently Firefox 3 doesn't like it very much. Option 3 will cause the exact issue's that you're describing. Switch it back to option 2 and you'll still have all of the customization-- without any problems.

Lemme know if that helps

 

[surewhynot]

Chrono, I don't have anything helpful to add, but I would like to say one thing. The way you described your problem then listed all the steps you have already taken was great. It makes it a lot easier for people to help out. Kudos!

 

[Skandocious]

Chrono, I don't have anything helpful to add

Tony if you don't have anything helpful to add then don't add anything at all....












freakin.... IDIOTS!!!!

 

[Chrono558]

Well, I got a small mirror and looked over the crossover tube and didn't see any rust on it. Grabbed it and tried to wiggle it and it felt solid. Then had a friend start the engine while I felt around the tube and didn't feel any air escaping from it. On the way home I had the scanner hooked up and was watching spark advance, evp voltages and evr percentage. The computer is commanding EGR when it's suppose to and I plan on verifying it tomorrow by putting a vacuum gauge on the green vacuum line going to the egr valve and revving the engine. I should see vacuum being put on the valve which should tell me the solenoid is working like it should.

...Ironically enough I didn't hear it ping at all today, but the outside air is a little bit cooler and more humid (shrug). When I get time I plan on trying to test the knock sensor. One thing I did notice which is really striking me as odd is the computer is constantly going from closed loop to open loop. 8/10 times when the TPS voltage goes above 1.8V it will throw itself in open loop. I ran the cruise control where TPS voltage remained steady between 1.50V to 1.55V and even still the computer would just switch back to open loop for no real reason I could figure. If anybody here knows the computer strategy on a EEC IV setup that would really be good right now.

I'll add more when I can test more.


...and thanks Skan for telling me to change my forum options. It's nice to see the blinking cursor now

 

[big5oh]

On the way home I had the scanner hooked up and was watching spark advance, evp voltages and evr percentage.

Your rig is (should be) OBD1...that being said, how did you access that data with a scanner? What scanner did you use and how did you hook it up?

I will see if I can come up with any info/advice at a later time.

 

[Chrono558]

Scanner in question is a Snap-on MT2500 aka "red brick"

 

[NeXtras]

I had an issue like this over the summer, although mine threw a code for the EGR.. check that, its pretty easy, putt it off and clean out the carbon just to make sure..

another thing to check, check the manifolds and make sure there not leaking at the seem (where it connects to the y pipe.. ive HEARD its quite common for the manifolds to warp on these trucks, never had that verified...

my "ping" noise ended up being my maifold being loose, there were no more threads to tighten it up so i squeezed the joint together and put some washers in.. i did the same as you, i ran 93 octane in and i still got the noise..

also check the seem where the y pipe meets the cat and where the cat meets the muffler.. i had an issue there too

guy i work with has the Snap-On MODIS scanner, its really nice, shows alot of stuff that you wouldnt expect.

 

[big5oh]

Scanner in question is a Snap-on MT2500 aka "red brick"

How did you hook it up? Data link connector under the dash? I thought that this was just an OBD2 thing. I have never been able to get any data (other than codes) from an OBD1 rig without putting a breakout box in series with the harness and computer.....but then all my rigs are late 80s. In 1996 federal law forced all manufacturers to make all gas vehicles OBD2 and put in a data link connector. I havent seen an OBD1 rig with this.

 

[subford]

How did you hook it up? Data link connector under the dash? I thought that this was just an OBD2 thing. I have never been able to get any data (other than codes) from an OBD1 rig without putting a breakout box in series with the harness and computer.....but then all my rigs are late 80s. In 1996 federal law forced all manufacturers to make all gas vehicles OBD2 and put in a data link connector. I havent seen an OBD1 rig with this.

You may want to read the last post in this thread, the link:
http://www.fordtruckfanatics.com/forum/showthread.php?t=3250

/

 

[conanski]

One thing I did notice which is really striking me as odd is the computer is constantly going from closed loop to open loop. 8/10 times when the TPS voltage goes above 1.8V it will throw itself in open loop. I ran the cruise control where TPS voltage remained steady between 1.50V to 1.55V and even still the computer would just switch back to open loop for no real reason I could figure.

That's interesting, to me that would indicate a sensor is going out of range and forcing open loop. Based on experience with my Tweecer the motor should hold closed loop at cruise without much problem, only going open loop when you get into the throttle to accelerate. May be a good idea to examine the TPS to see if it has any dead spots at partial throttle, and if not have a look at all the other sensor for abnormal output.

 

[Skandocious]

I think these pages will offer some help as to which sensors you should check out first:

Ford Fuel Injection - EEC Computers
Ford Fuel Injection - Engine Load