Ping Happens!

[tbagtim]

Got a lot of pinging uphill and/or with wide throttle.

As plugs and leads were probably not replaced before I bought the car at 42000mi, and now it's done 100000, I put in the Bosch Platinum 4+ plugs and a set of Bosch wires.

All old sparkplugs looked reasonable.

Mucho improvement in power and feel and engine running smoothly. Same pinging under hard conditions.

The check engine light has been rampant recently from before and after the replug.

I know I need to reset computer and check for vacuum leaks etc.

What bothers me is I would occasionally get a code saying EGR valve problem but it was very intermittent.

I read someone say the MAF sensor could need to be cleaned for pinging, I'll do that tomorrow. Someone else said EGR valve (like the computer did) problem is I can't find reference to the EGR valve in the Haynes manual.

Does a 1994 4.0L engine have EGR and if so it is operated by vacuum or electrical, where is it licvated? How do you test/replace?

Thanks Tim

 

[ntrpriz]

I can only say that 94's do have the EGR. Its on top somewhere. I am not sure how to test it though. I had mine replaced at ford for about $150.

Thanks

 

[tbagtim]

Follow up on pinging

Thanks Steven, I found my EGR junk to the driver's side of the intake manifold cover. It looks like it has vacuum actuation and electronic positional feedback to the computer.

When I read the codes out of the computer I got:
327 (4 times) - EGR Valve Pressure Transducer/Position Sensor Circuit below minimum voltage.
117 - Coolant Temperature circuit below minimum voltage/indicates above 245 degrees F.
116 - Coolant Temperature sensor out of self test range.
189 - Adaptive Fuel rich limit reached, left side
181 - Adaptive Fuel rich limit reached at part throttle, right side.
186 - Injector pulse width highter than expected.

I then looked at the MAF sensor. There are two little glass beads that look like filaments of a light bulb. They were both encrusted with carbon stuff that I removed using a cotton swab soaked in carb cleaner.

On replacement I cleared the codes and the power maps by disconnecting the battery, filled up with 87 octane and drove. The pinging is gone, completely. There is much more acceleration and power and there is only one code recurring now, 327 the EGR one.

I figure that the clogged MAF really does a number on the fuel mixture causing the pinging and some hesitancy and surging problems I noticed. I expect all those Adaptive Fuel codes are fully history now.

I still feel I need to get the EGR sorted out but I'll probably leave that up to a mechanic because I hate dealing with stuff that needs gaskets and hi temp connections made. Also there is no detail in the Haynes manual about this system.

If anyone has more information about the EGR system please feel free to share!

Seems like that MAF is a biggy when it gets clogged though. Took a full ten minutes to completely eliminate my pinging and performance issues!

Take care.

Tim

 

[vmastrog]

Tim,

Your EGR code may be due to the DPFE sensor. It is an Aluminum bodied part about 3"x1.5"x.5" w/ two rubber tubes running from it to the EGR hot tube. This sensor measures the pressure delta across a orifice in the EGR tube thus measuring flow. I replaced my DPFE sensor a while back (80 to 100K) and just replaced a frozen (rust) EGR Valve and tube at 145K. EGR tube rusted through.

If this sensor fails, the EGR system shuts down. The system fails closed so as not to have drivability issues. The only noticeable symptom is fuel economy and even that is debatable.

 

[fordkrazy]

if its intermittant....check the wires going to the DPFE and the EGRVS....intermittant problems are most likely electrical connections and can be remedied by some tape and dielectric grease.