I have been a member now for a while but not very active...I have looked on for solutions to my problems and now I am at my wits end...I have 92 f150 4x4 with the famous 300 and last summer the truck started stumbling really bad...I wish I could just isolate it too certain rpms or gears but its all over and usally when you are crossing a busy highway...nice huh? I checked the other posts about the stumbling with egr's but I dont think its that...this truck prior to mine was my dads and he "fixed it" by replacing the TPS but then he sent his truck to have the oil changed and they screwed up something and the engine locked up...well they "replaced" the engine and now the truck is doing the same stuff...all they did was swap a diff engine in...so is it safe to say that the problem is on the truck and not the engine? I tried a new tps on this engine and that didnt work...so I parked it for a while and now that its winter out and freckin cold most of the time I wanted to try again...no sputter at all...so its temp sensitive? I changed wires, plugs, and all the other tune up stuff...oh yeah the light comes on after the truck warms up even in winter so I dont know...I ran codes a while ago but they came back egr I unplugged it and plugged the vaccum line and that didnt do anything at all...I thank you for any suggestions you may have. I am willing to try it all.

 

You tried disconnecting the vacuum line to the EGR....o.k.

That vacuum line ONLY controls the EGR valve's opening and closing allowing in a METERED amount of exhaust gasses.

If you have a vacuum leak in the EGR system (valve or sensor) , disconnecting that vacuum line WILL NOT stop the valve or sensor from leaking !!! you'd in a sense have a "hole" in your intake letting in extra air which will cause your truck to run lean. Your PCM won't be able to step up the A/F mixture and you'll get the lean "stumble".

Just for grins and giggles, I'd try capping off the EGR completely (for testing purposes) at the upper plenum then see how your rig runs. Ignore the CEL while testing...just drive it and see how it runs THEN start checking for faulty components.

Sounds to me like your EGR problem(s) is/are:
1. A leak at or around the diaphram.
2. A "sticky" EGR valve--not opening or closing smoothly or properly.
3. There is a major vacuum leak at the EGR sensor.
4. Your EGR solenoid isn't operating.
5. You have a vacuum leak in the line going to the EGR solenoid--If I remember correctly that's the line that comes from the coffee cannister.

Let us know what you find !!

Bob

 

why would it be temp sensitive to outside air?

 

Hmmmm......

I don't know why it would be temp sensitive.

You do understand though that your emission system works with the intake air temp and block water temp to richen or lean the system along with all of the other "things" under the hood to make your six run properly......... all of which may have an effect on how your truck is running.

And......
Your EGR valve mount is made out of steel and your intake mounting flange is made of aluminum (dis-similar metals) and they expand and contract at different rates which "could" mean that your EGR valve may just need to be tightened up a little or the EGR gasket needs to be replaced......I dunno.......

Have you tried ANYTHING else yet ????

We'll get you through this, just keep on posting.

Bob

 

this is great...I just broke a head off of the egr bolt? now what?

 

Remove the EGR completely if you can. The get a pair of vise grips in there and back the bolt out. Let it soak in some PB (that's Parts Blaster, not peanut butter ) before you try it.

Before you go pulling anything else off, I would strongly recommend this: Pull the codes on the truck. It may point to what's wrong. It's free and easy to do, and is really the first step when pinpointing a problem. If the EGR is fubar, the computer knows it.

Now, the second thing is this: My EGR is hopelessy clogged and stuck open. My truck runs like a sewing machine, so I might start looking elsewhere for your problem. Do you have dual tanks? Does it happen on both tanks? The reason I ask is that it sounds like low fuel pressure. It would be worth checking out the fuel system with a pressure gauge and seeing if it's low. It should be 55-60psi at idle. Low fuel pressure can be caused by a line blockage, bad FPR, clogged filter, or weak fuel pump.

The filter is easy to change and probably should be done regardless. The FPR can be checked by pulling off the vacuum line to it and seeing if gas shoots out of it. If so, replace it. The lines have to be inspected visually. If everything checks out but you still have low pressure, it's the pump in the tank. You can isolate it by switching to the other tank.

Let us know what you find - there are a ton of people here willing to help!

 

That sounds like the infamous throttle body gasket sucked in and leaking stumble. When it's cold out my truck stumbles because the IAC opens too fast.

 

[QUOTE=andym]Before you go pulling anything else off, I would strongly recommend this: Pull the codes on the truck. It may point to what's wrong. It's free and easy to do, and is really the first step when pinpointing a problem. If the EGR is fubar, the computer knows it.

Actually if you read the origional post, he did pull the codes and they pointed to the EGR system.

As for the broken off bolt........ read this thread. It should help you remove the EGR valve if you so decide.
https://www.ford-trucks.com/forums/s...d.php?t=335648

Tell us how it's going !!!

Bob

 

I havent been able to get at my truck for a little while...I was gone on a army weekend training....anyway, today I got to play with it a little now that its getting warmer out (60F) I wanted to run my truck today and see if it studderd at all before I just went ripping the stupid egr off...The only time it studderd is when I applied a heavy load on the engine by shifting to low and holding the brakes...it stumbled quite a bit then...its the same stumble as when it gets really warm out. once I let off the brakes the stumble is gone and I also got on it pretty good down the road and no stumble...I hate this truck....what else could it be? I tried a new tps and ignition module just cause I had them sitting here...maybe pvs? I just dont feel like ripping the egr off unless I have to

 

Hey there Mr. lucky3380,

Sounds like you're a little dis-heartened with your truck.......

Don't give up yet !!!!

How'd you do with the broken off EGR bolt head ???

You're going to need to put in a little time in this "quest" to get rid of your stumble.
There isn't a "magic" screw to turn to make it go away.
Most of all, and I say this from experience, don't start throwing your cash at parts that aren't broken !!!!!
You should be able to test most, if not all of your emissions parts before you have to replace anything.

I wouldn't go "ripping the EGR off". If you can (hopefully you already have) get that broken off EGR bolt out of your plenum and replaced, then things will be a little "easier" to deal with.

Once the EGR bolt thing is resolved, you might start by loosening up the two bolts that secure the EGR valve to the upper plenum and then slip a piece of thin metal (perhaps from a soda pop can) between the EGR valve and upper plenum to block off ALL of the EGR flow from the system THEN see how your truck runs.

This will block off any and all EGR from being introduced to your system AS WELL AS blocking off the possibility of a vacuum leak in the EGR valve or sensor which can cause the stumble.
You will probably get a CEL (check engine light) after you do this, but you're trouble shooting at this point. IGNORE IT for the time being !!!!!

I'd be willing to bet you the stumble will disappear and the truck will wake up and run like a Big Six should.

This is an "EASY" test you can do without too much wrenching.

Give it a try and let us know what happened. There's lot's more no cost tests you can do after this......just let us know what the "results" were.


Bob