Turbo
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EGR:
Category: Engine Control
Fords are notorius for EGR problems.
The EGR is a simple system that allows exhaust to be drawn in to the intake tract. If you don't have flow, it won't work. It's purpose is to reduce Nitrides of Oxygen, (NOx).
Clean the EGR valve. The passage in the actual valve gets mighty gummed up with carbon. Look carefully at how the flow works so you make sure it's clean enough to flow. On a few cars, the passage in the upper intake was clogged so badly, that I had to ram it clean with a screwdriver! The connections were flakey on the EGRV solenoid, the "relay" that switches the vacuum when it gets an electrical signal from the EEC-IV. This caused a No EGR condition code 34.
On another car, the connections on the EGRV solenoid, were gummed up. Once the connection was cleaned, code 34 went away, and you could tell EGR was flowing during the beginning of the Self Test.
Quick check:
Run EEC-IV diag, KOER. First the RPMs will come up. Watch the diaphram of the EGR valve. It will open, moving back about a half inch, and the engine will sound, um.. different. If this happens, EGR is fine, no code. IF you get a code, the flow is blocked, most likely with carbon deposits in the EGR valve itself. Clean it.
If it doesn't move, then it's not getting the signal. Connections on the EGRV solenoid, bad vacuum line or an EGR valve with a ruptured diaphram, (unlikely).
Cleaning the EGR valve:
Remove the valve, two bolts.
I clean all of the carbon out from all the valve passages, using screwdrivers, battery terminal cleaning brushes and other pointy things. Brake cleaner spray works good to get rid of this carbon. Be sure to inspect the valve and ascertain which way exhaust gas flows thru the manifold and into the intake. Map out the whole flow path in your head.
You will most likely find, that it flows differently through the valve than you thought, and this will then help you to clean the valve completely. They're particularly confusing looking on the 2.3 Turbo.
The EGRV is an electrical vacuum solenoid. It alows vacuum to flow from the manifold source to the EGR valve under command from the EEC-IV. It's supposed to be around 75 ohms I think (don't quote me). Sometimes it's bad. More often the contacts are grungy, clean it by scraping the contacts on the valve and the connector, and resealing with that silicone goo for ignition wires that drives out moisture.
Checking solenoid:
Use a vacuum gauge in place of the EGR valve, run KOER, or accelerate the engine a couple of times and look for a vacuum spike reading on the gauge as the solenoid opens. If you don't get that, make sure you have vacuum going to the solenoid. Use a hand held vacuum pump, to test the EGR valve. Ford's books say the engine MUST stall if you use a vacuum pump to open the EGR valve fully while the engine is idling. It isn't necessary for the engine to stall, but it should run a lot worse, indicating exhaust gas recirculation (EGR) flow.
Other stuff:
Those little plastic vacuum lines don't last forever! Check em and replace as necessary. And yes, you can use regular rubber vacuum line.
If your mileage goes in the toilet, check the EGR system first. It's purpose is to reduce nox (emissions-speak), but it also effectively fills the cylinders with unburnable stuff (exhaust). The EEC-IV knows this and thru the O2 sensor feedback provides the correct amount of fuel. This system is what allowed my 13 second 1/4 mile Mustang to get 28 MPGs at 80 MPH.
Clean your EGR yearly! I find this problem on at least half of the Fords I work on.