random Miss

[RBrown]

I have removed the EGR valve and cleaned it. What should this thing be doing because I still have the exact same condition as before. Please advize me on the next thing to do

[RBrown]

I have removed and cleaned the EGR valve. I still have the same condition as before. How do I verify that the vacume line is doing the things I need it to do. I have no vacume gage and need some of your experience with this. And what should I be looking for next in this increasinly long list of things.
Hey way to old, Can I email you to continue this discussion if the board is down/

[RBrown]

Hey, I just noticed that I have graduated to Junior member!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Venturi]

If I correctly understand what you said about the codes, the first set of codes (on demand) you got was a code 11 for system pass. The code 34 was displayed during the second set of codes (continuous memory). Or do I have this backwards?
If I have this correct the code 34 is most likely do to the EGR valve not opening. If the valve is not opening I seriously doubt that you would be experiencing the drivability problems that you are.

Actually you should be able to verify the EGR operation if you can do a running test. The computer will raise the RPM and command the vacuum control solenoid to open the EGR valve during the test. If you look at the under side of the EGR valve you should be able to see the diaphragm and the pintle stem move at some point during the run test. If no movement is seen repeat the run test but this time remove the vacuum hose from the EGR valve a hold a finger over the end of the hose. You should feel a slight vacuum on the end of the hose when the computer commands EGR operation. If you feel the vacuum the EGR valve most likely has a ruptured diaphragm. If no vacuum is felt there is a vacuum supply problem such as a broken or split vacuum line or a problem with the vacuum control solenoid circuit.

I hope all that made sense……………<br>

Have you by any chance checked the fuel pressure on this thing yet?

What did the plugs look like the first time you removed them. Were they black, white or a normal light tan color?

Hopefully you’ll get chance to read this before the forum goes down for the update.

RBrown said:

Hey, I just noticed that I have graduated to Junior member!!!!!!!!!!!!!!!!!!!!!!!!!!!

Congratulations, too bad that will most likely reset during the upgrade. I’ll fix it when I get chance so you’ll only temporarily be downgraded to a new member.

[RBrown]

I just got back from a little road tip and will definatly check to see if the operation of that EGR valve is normal. Did I understand that you DON'T feel that a falty EGR would result in this type of problem? How do I check the fuel pressure? The original plugs were normal tan and found none of them fouled.
My e mail is [e-mail].

[DanD]

Why I suggested that maybe the EGR valve was not closing all the way was due to the code description in Mitchell
1989 Ford Pickup F150
1989 ENGINE PERFORMANCE Self-Diagnostics - EEC-IV 5.0L

KOEO Code 34:
Code 34 indicates EGR valve and/or EVP is not fully seated in the closed position. EVP voltage signal, in the closed position, is greater than the Self-Test maximum of 0.67 volt. Because of the preload on the installed EVP sensor it is very difficult to determine if the EGR valve is seated or the EVP sensor is in contact with the EGR valve stem. Possible causes are: poor continuity at EVP sensor, non-seated EGR valve, faulty EGR valve or faulty EVP sensor.

[Venturi]

Yea, I understand your thinking Dan, I’m just trying to establish whether this is a KOEO (on demand) code or a continuous memory code. If it’s an on demand code the EGR may not be seating properly. If it’s a continuous code it may have set because the valve isn’t opening which wouldn’t cause these types of problems.

RBrown, you would need a fuel pressure gauge to check the fuel pressure.
We need to establish whether the code 34 was displayed during the first code display or the second. I think this might help clear up some confusion, on my part anyway.

[RBrown]

Hey guys! That code sequence went 11 first then after the pause I got the 34, EGR.

[RBrown]

Just wanted to try out this Quick Reply box. Any one there?

[Venturi]

rbrown said:

Hey guys! That code sequence went 11 first then after the pause I got the 34, EGR.

Ok, that means that the EGR valve was in the proper position during the KOEO (on-demand) test, at least as far as the EGR position sensor is concerned. In other words it wasn’t hanging open. This also means that the circuit from the EGR position sensor to the computer is most likely ok.
The code 34 during the second set of codes (continuous memory) indicates the EGR valve was not in the proper position at one time or another while the engine was running. This could be from the valve not opening at all, not far enough or from the valve opening too far.
I really don’t think that if the valve was not opening at all or was not opening far enough that it would cause the problems you’re having.
However if it was opening too far it could cause problems but you could easily check for this by disabling the EGR valve. Just disconnect the vacuum hose at the EGR valve and test drive the truck. If the problem is still there it’s not related to the EGR system and you can probably ignore the EGR code for the time being until you find out what’s really going on.

Anyone agree or disagree?

[RBrown]

Have a tandem car hauler that i was

towing around today and noticed that the same behavior with out towing as with towing. Load seems to have no effect on it. I figured that I couldn't move it well. Thats not the case. Any one?

[Venturi]

It’s a bit strange that a heaver load doesn’t make the problem any worse.

Going back the first page you stated that when first started the idle is very unstable. Have you checked this thing over really good for vacuum leaks (PCV valve, vacuum lines & hoses ect)? I’ve found a bunch of these with leaking gaskets between the upper intake plenum and the lower intake manifold. I usually spray a little carb cleaner along the mating surfaces of the upper and lower intakes at idle while watching for any change in idle speed or quality. Be very careful if you do this, carb cleaner is extremely flammable.

I’ve also found that these are very susceptible to devolving deposits in the throttle bodies around the throttle plates. These deposits can choke off the air to the engine at idle and cause a very unstable, “hunting” idle. You might want to try cleaning the throttle bodies with carb cleaner and an old tooth brush to see if this helps the idle if you haven’t tried this already.

At this point I don’t know if the misfire and the unstable idle are symptoms of the same problem or if they are unrelated. That’s why I mentioned a couple of the more common conditions I’ve seen with these that may be causing the idle problems you mentioned.


Have you tried test driving with the vacuum line to the EGR valve disconnected like I suggested to see if it makes any difference in the misfire?

One thing that I mentioned on the 10w-40 forum that should be checked is the base ignition timing. Have you been able to check this yet?

We really need to try to determine whether the problem is related to the ignition system, fuel system or whatever. From what you said that you have checked and replaced in the ignition system (plugs, cap & rotor and wires) I think we can look past the secondary ignition system (provided the wires are actually in good shape, I’m not a big fan of ohm testing). There may be a problem in the primary ignition system (dist pick-up, module, coil, ect) but that can be very hard to determine without viewing the primary waveform on an oscilloscope.
You can however check to be sure that all of the primary wiring from the dist and coil is in good shape, i.e. not pinched under something, intermittently shorting to ground ect. Remove the electrical connector at the ignition module on the dist and look for any signs of corrosion in the connector, clean as needed. Also be sure that the module is tightly mounted to the dist. A loose module can cause poor grounding and over heating of the module. Speaking of poor grounding, make sure that all grounds; battery cables, engine ground straps, ect are clean and secure. Poor grounds can wreak havoc with ignition and computer systems.
Also remove the dist cap and check the Hall Effect sensor (dist pick-up) for any sign of oil contamination or degradation of the sensor. The plastic parts of the sensor should be hard not soft. You can check this by tiring to press a fingernail into the pick-up connector just above the module. If your finger nail leaves an indentation in the plastic the pick-up should be replaced. This was a big problem in earlier years. Ford changed the composition of the plastic in the latter ‘80s so you’ll probably be OK but it’s worth checking. Check the vanes mounted to the dist shaft under the rotor for any signs of damage or corrosion also.

I mentioned checking the fuel pressure earlier, this is one of the first checks I like to make when faced with a any drivability problem. Improper fuel pressure or low fuel volume can cause many different problems with many different symptoms. I don’t recall you mentioning anything about the fuel filter. Has this been changed lately?
If we move past the ignition system the first place to start in the fuel system is with fuel pressure testing. If you don’t have access to a fuel pressure gauge you might try contacting a parts stores to see if they will loan or rent one. Most major parts stores have some type of tool loan program.
One quick test you could make without any tools is to check for a leaking fuel pressure regulator diaphragm. With the engine off remove the vacuum hose from the fuel pressure regulator (located on the drivers side of the fuel rail) and have someone cycle the ignition key on and off several times without cranking the engine. If any fuel is seen escaping from the vacuum nipple on the pressure regulator the internal diaphragm has ruptured and the regulator will have to be replaced. Usually this will cause fuel fouled plugs which you didn’t seem to have but it’s a common problem on these engines and checking for a leaking regulator is quick and easy.


Hopefully this will give you a few more things to check so we can eliminate some possible problems. Let us know what you find out and if you need further explanation on some points just ask.

[RBrown]

Thanks, I haven't had an opportunity yet to try these suggestions and it seems I need to go back and verify that all the basics that I have covered to this point have indeed been validated and DO work correctly. I noticed later in the afternoon yesterday that after placing 5 gallon in each tank that the tendency to load up during acceleration did diminish a bit. (fuel system?) The miss is till there.

[Venturi]

I’m not really sure what adding fuel to the tanks would change if it’s actually loading up (running rich). Do you see any black smoke from exhaust when it starts “loading up”?
Not being able to drive the vehicle it’s hard for me to get a feel for what’s happening but is it possible that it’s actually starving for fuel at times?

Double check everything when you get a chance and let us know what you find if anything.

[fxqvsy]

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