Detonation, surging...EGR ?

[Daytonatunnel]

I'm wondering if a stuck (open) EGR can cause; hesitation, lean miss at cruise speeds (2K part throttle, high vacuum), and pinging with moderate throttle (up hill @2.2k). My car has a recent tune up (Ford PCV, wires, n plugs. NAPA cap/rotor). Timing is set @ 6* with spout unplugged (I keep rolling the timing back to stop the detonation, with no luck).

I run Chevron super, with the switch in premuim mode. Car is 100% stock, cat n all, save for a K$N filter, 165K (30K on rebuild, not by me). Been banging my head for sometime now trying to solve this problem. I thought maybe a vacuum leak, did a visual inspection and see nothing unplugged, or broken/cracked lines. Used my vacuum gauge on the line from the intake manifold to the vacuum manifold, put 10lbs. of vacuum on it, no drop after 5 minutes.

Looking for ideas........

[Laredo]

A stuck open EGR will not normally cause pinging, it would cause high/ rough idle (think big vacuum leak). How old is your fuel?? The octane goes to crap as it ages.

[Daytonatunnel]

Car is my DD.

[MikeFleming]

Excessive EGR gas flow will make he engine run rough but not because it's lean - it doesn't add air, it adds exhaust gas. There can also be an air leak around the EGR valve pintle that can cause some leanness but that's usually very minor.

Any pinging under heavier load?

Do you have a wideband sensor installed?

Any EEC codes?

[Daytonatunnel]

Yes, pings under heavier load, for a second, which tells me the KS is working. NO w/b, just stock stock stock. No codes at last test, about 2 months ago. This has been an ongoing problem. I've been racking my brain to figure it out, that's where the EGR idea came from. I know the EGR introduces inert gas to the combustion process, and thought it really wouldn't cause detonation, but it was worth asking anyway.

I keep falling back to a clogged injector, but don't want to be a parts changer.......

[MikeFleming]

Usually too lean from one or more cylinders would make a 41 lean code. but not always. Can I assume you have verified fuel pressure?

Do you have a way to test the injector flow and pattern> Or maybe have a spare, known good set?

[Daytonatunnel]

I have not checked f/p, but have replaced the filter. Could the f/pump cause these symptoms ? No access to pattern or spare set :(

[MikeFleming]

Low fuel pressure (flow)? yes.

[Daytonatunnel]

What's the best pump to replace it with ? Is a fpr an easy part locate new, or is used my only shot. THANKS for the help Mike :)

[MikeFleming]

The three-bolt Ford FPR was the only one used on Fords for at a least a decades worth of all rail-injected petrol cars - should be one of the most common parts next to 1/2x20 lugnuts. Most folks get an adjustable one so they can make sure it's set to the prper pressure.

Note that most non -stock ones will not pass state emissions visual inspection. YMMV.

Back in the old days of SS racing, we used to semi-crush the stock ones a wee bit to increase fuel pressure. Looks like stock, less filing, more pressure. Then swap them around as needed for particular pressures. Made a couple each at 39.5, 40.0, 40.5, 41.0, ...

Typically low pressure is a fuel pump(s) issue and too high is usually a FPR issue (or plugged return line, which is very rare - pinched is much more likely).

[Stinger]

What's the best pump to replace it with ? Is a fpr an easy part locate new, or is used my only shot. THANKS for the help Mike :)

Along with what Mike said, also note that it's much easier and cheaper to check fuel pressure to confirm whether either part is causing an issue rather than to replace them only to find the old parts were working fine.

[MikeFleming]

... it's much easier and cheaper to check fuel pressure to confirm whether either part is causing an issue rather than to replace them only to find the old parts were working fine. That's tagline material right there!

[Stinger]

:cool: