Engine pinging badly. Need help.

[flareside_thunder]

I just wanna say that when i rebuilt my top end on my truck I set the timing numerous times with the spount unplugged but once I'd plug it in it'd ping get horrible mileage and would be an absolute dog.....now I time it with the connector in...runs like a champ....just a though you might wanna time it with the spout connector IN.

 

[Skandocious]

I just wanna say that when i rebuilt my top end on my truck I set the timing numerous times with the spount unplugged but once I'd plug it in it'd ping get horrible mileage and would be an absolute dog.....now I time it with the connector in...runs like a champ....just a though you might wanna time it with the spout connector IN.

Doesn't make much sense for that to be happening... Unless the timing ring on your harmonic balancer has rotated and thus gives you inaccurate timing readings...

The point of the SPOUT is to connect/disconnect the circuit which controls dynamic timing advancement by the computer. When the SPOUT is in, it completes the circuit and allows the computer to play with the timing freely as the trucks engine load/RPM/etc change while driving. If you time the truck with the SPOUT connected, it is possible that the computer is ALREADY advancing the timing at the engine speed, so setting the base timing of 10* may actually be setting it to 18 or 20*.

 

[flareside_thunder]

Don't know what to tell ya just sayin what i learned from personal experience...and who said I got one of them there fancin timin doohickies......I'm a redneck, we time by ear, and I'm one of the only guys around here that can do it worth a dang.

 

[big5oh]

Don't know what to tell ya just sayin what i learned from personal experience...and who said I got one of them there fancin timin doohickies......I'm a redneck, we time by ear, and I'm one of the only guys around here that can do it worth a dang.

If you go by ear with the spout OUT you will set it way too far advanced. It doesn't sound "right" with the spout OUT and set to 10*, once you plug the spout IN it will then sound 'right".

 

[Chrono558]

Watched the spark advance with the scanner and when it did ping it was retarding the spark back quite a bit, so I'm pretty sure the knock sensor is doing it's job. I haven't had a chance to test the egr vacuum supply but plan on doing that tomorrow morning. Can an exhaust leak cause a ping as well? I know there's a leak somewhere on the passenger side I just can't find it. I'm assuming it's the manifold cracked, manifold not sealing or the collector. I'll try and get some garden hose long enough to see if I can hear where it's coming from.

On the open loop issue, I've been trying to watch all the sensor data when it does this and I don't see anything out of the ordinary. TPS got replaced almost 1.5 years ago, MAP sensor was swapped out about the same time, IAC as well, o2 sensor is about a year old. I plan on printing out what the sensor data should be and go from there.

 

[big5oh]

Can an exhaust leak cause a ping as well?

If you think about it, a leak before the o2 might cause the sensor to richen the mixture due to the increased amount of oxygen in the exhaust. A rich mixture would not raise combustion temps. But then if there is enough of a leak to where exhaust gas velocity/back pressure is significantly lowered little/no exhaust gases will flow through the EGR valve and into the upper plenum. This could potentially be the problem. I would think that the leak would have to be fairly big though. One way to test this is to remove the vacuum supply to the EGR valve (leave everything else hooked up). By doing this, the EGR valve will never open thus the EGR position sensor would send an EGR closed signal at all times to the computer. If the EGR closed signal is seen be the computer (at all times) then the EGR function is disabled and the computer no longer advances the timing like it does when the EGR position sensor tells the computer that the EGR valve is opening. You will get a few "information only" codes, but there are no consequences beyond that assuming that the EGR valve does not leak. If you do this and ping goes away, finding the root of the problem will be fairly simple. The above scenerio falls into the "EGR gases not getting to the combustion chamber when the computer thinks it is" category.

If the computer thinks that EGR is flowing into the plenum due to the EGR position sensor signal, it advances the timing. If the timing advances like this yet the EGR gases are not making it to the plenum then the result is ping. The EGR gases displacing the AF mixture allow for a certain amount of advance in the ignition timing because of the reduced combustion temperture.

At this point I would consider a compression test. This would tell you if any of the cylinders are full of carbon since carbon deposits raise compression. Make sure the motor is hot when you do it. This would also tell you if all this ping has damaged the motor.

 

[Chrono558]

Ok. Worked on it some more today and was able to verify some stuff. When the engine is running and a vacuum gauge is hooked up to the vacuum line for the egr valve, I revved the motor and was seeing a steady vacuum being applied such as the computer commanding egr to flow into the engine. After that it set a code for the evp sensor not moving so I believe this pretty much confirms that the egr system is functioning like it should be.

I did do a compression test just to see what compression was and the fact that I've never done one to the engine either. The results are:

Cyl 4: 180 Cyl 8: 180
Cyl 3: 190 Cyl 7: 185
Cyl 2: 180 Cyl 6: 185
Cyl 1: 180 Cyl 5: 180

Cylinder 1 actually showed 170 the first time I tested it but went back after testing the rest of the cylinders and got 180 the second time. This engine is 17 years old and has almost 190K on the clock but if those numbers aren't from carbon buildup then those seem like damn good numbers for a motor this old. Like I said though I'm not sure if these numbers are skewed due to any carbon buildup or not.

Another person was wondering what plugs I'm running in here and they're Motorcraft ASF42C. When I removed them there was just a little white film on the ground electrode on all of them but not even close to fouling out or anything. Again no surprise that my engine is burning oil (just not that bad yet... knock on wood for me). The only other things ignition related that I have are a msd cap and rotor and msd coil. Don't know if running a hotter spark with the coil can be an issue or not.

I think what I'm going to do again is the seafoam treatment but this time use a full bottle on the engine while it's hot, then let it sit overnight and start it up the next morning. I'll probably do this on Monday since my brain is fried on this and needs time to recuperate in order to think more clearly on this problem. So I'm taking the rest of today and tomorrow off on it and will get back on it Monday. Sorry for the long post.

 

[big5oh]

Ok. Worked on it some more today and was able to verify some stuff. When the engine is running and a vacuum gauge is hooked up to the vacuum line for the egr valve, I revved the motor and was seeing a steady vacuum being applied such as the computer commanding egr to flow into the engine. After that it set a code for the evp sensor not moving so I believe this pretty much confirms that the egr system is functioning like it should be.

But is the exhaust gas actually getting to the intake plenum even though the EGR components are functional?

I did do a compression test just to see what compression was and the fact that I've never done one to the engine either. The results are:

Cyl 4: 180 Cyl 8: 180
Cyl 3: 190 Cyl 7: 185
Cyl 2: 180 Cyl 6: 185
Cyl 1: 180 Cyl 5: 180

Is this PSI? Was the motor hot?

Based on what I have seen those numbers are high. On good running 302s I am accustomed to seeing more like 150 PSI all the way around (warm engine).

 

[TexasNomad]

Those are some good numbers..
Have you tried putting some saw dust in the crank case

 

[NeXtras]

Yup, good numbers... a good PSI is 150 at each cylinder

 

[Skandocious]

But is the exhaust gas actually getting to the intake plenum even though the EGR components are functional?



Is this PSI? Was the motor hot?

Based on what I have seen those numbers are high. On good running 302s I am accustomed to seeing more like 150 PSI all the way around (warm engine).

You seem to know your stuff pretty well. Just realized that I don't think I know your name. Did you even get the standard-issue introductory thread?

 

[Chrono558]

Motor was hot when compression testing was done. Numbers are in psi. I have hooked up a hand pump vacuum onto the egr and pull a vacuum at idle. The engine does stumble and tries to die when I do this.

 

[blacksnapon]

try this

TSB
94-4-10 BUCK/JERK - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER
IGNITION - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER
MISS - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER
SPARK KNOCK - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER
SURGE - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER
ENGINE - 5.0L - SPARK PLUG WIRE ROUTING AND FIRING ORDER

Publication Date: FEBRUARY 23, 1994

LIGHT TRUCK: 1987-1994 BRONCO, E-150, E-250, F-150, F-250


ISSUE:
Engine miss, spark knock, buck/jerk, surge and other driveability concerns may be caused by induction crossfire. This occurs because of improperly routed spark plug wires.

ACTION:
If spark plug replacement is performed, the correct firing order and spark plug wire routing is essential to prevent the possibility of induction crossfire between cylinders. Refer to the following procedures for inspection of the spark plug wire routing and firing order. Properly reroute the spark plug wires if required.

FIRING ORDER

The firing order for 1987-1993 vehicles is 1-5-4-2-6-3-7-8. If #7 and #8, or #2 and #4 spark plug wires are routed next to each other at the separation bracket, an induction crossfire condition can occur.
The firing order for 1994 vehicles is 1-3-7-2-6-5-4-8. On these vehicles the #1 and #3, or #5 and #6 spark plug wires must be separated to eliminate the possibility of an induction crossfire.
To eliminate the possibility of the coil wire becoming disconnected, route the coil wire under the spark plug wires at the distributor cap.

 

[Chrono558]

^ Yup. I know that TSB quite well and have made sure that I've got 7 and 8 routed as far away as I can get them.

Sorry for the lack of updates but life and work caught up with me and I'm still getting back on my feet from it. I decided to just put 91 octane in both tanks and the ping is now gone (not to mention gas mileage went up ). Since my weekly commute is about 30 miles a day it's not hurting me too much to run the premium in both tanks. I haven't had a chance to seafoam it again and let it sit overnight but still plan on doing it when I get a chance. At this point I'm fairly certain it's carbon buildup. Only other theory I can come up with is the 10% ethonal blend they're adding into the gas causing a slightly leaner A/F mixture and raising combustion temperatures.

Just keeping people apprised of what's going on. Need to get tires for it soon as well as front shocks, leaf spring bushings, blah blah blah... The joys of owning a 16 year old truck .