Check this site out. It explains a little about the relationship of the EGR valve and the EVP Sensor. http://www.kemparts.com/tt12/tt12.html

 

Henshaw2001,
Night before last I decided to check my EGR valve itself. I didn't have enough time to disasemble the valve but I took off the Sensor and the resistance checked out very good with a DMM. I decided to put it back together and I discovered that on the back of my EGR valve, I could see the actual diaphram. I rehooked my vac line and fired the engine. The diaphram was moving, but at that certain RPM the engine started its sputtering the diaphram started jumping back and forth. I took a small screwdriver and moved it back and forth. Just as I suspected, when the engine was idling, and I pushed the diaphram back, the engine would almost die. But I kept working the movement with that screwdriver, trying to learn as much as possible in the amount of time that I had. I then decided to quit fooling around for the night and I would stop on my way home from work the next day to buy a new EGR valve. I hooked the vac line up again, closed the hood and fired up the engine one last time to back it out of the garage and it ran so well, I thought I left the vacuum line unhooked. I popped the hood to make sure, and it was all hooked up!!! Drove it to work yesterday and today and still drives like new!!! I think maybe something was wrong internally with the valve and by moving the diaphram with the engine running I losened it up. If it starts doing it again, I'm going to take the valve apart and inspect it a little more closely. But for now its fixed. Sorry this got so long but I wanted to give you as much detail as I could. Especially since I really don't know for sure what fixed it. Keep me updated on your progress.

 

Cowboykent,

Thanks for the great tips and the test procedure. After some thought, some time either this weekend or next I am going to disassemble the EGR assembly and clean the seat. Talking to another mechanic, any dirt or other junk on the seat or keeping it from sealing or moving will definetely cause it to run terrible. If this doesnt help, I am going to pick up the hand vacuum tester kit and run the diagnostics on the EVP itself.

Once again, thanks for all the great help.

 

I would just like to show my appreciation for both of you guys. My truck has been doing the exact same thing. And your info has been very helpful. Keep up the good work.

------------------
1987 F-150 300 L6 4sp 2wd
K&N, flowmasters

 

It's still running great without the EGR hooked up. The engine light gets kinda annoying, but the truck starts better, runs better, gets better mileage, and accelerates like a banshee. I hope to get the EGR torn out either this weekend or the weekend after. I get paid once a month, which makes unannounced repairs a real pain in the rump.
How are you making out Cowboykent?

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1993 F-150 4x4, 4.9L, Superwinch, K&N, Gibson 3" SS Single, Eclipse 5440 Indash CD, Kicker Impulse i-270 Amp, Kicker Solobaric 10" Sub, (4) 5-1/4 Eclipse 8953, Midland Weather Max II CB

1993 Procraft 180 Dual Pro Basser, 18' 9", 150-HP XR6, Hummingbird 400-TX

1999 Kawasaki KDX 220, Boysen Rad Valve, FMF Burly Pipe, FMF PowerCore II Silencer

Play Hard or Step Back!

 

Hey everybody. Sorry it took a while to get back to our discussion. Bigtan and Henshaw2001, have you all fixed your problems yet? My truck is still running like new. Just one more thing, I was told by a mechanic that plugging the vac line to the EGR valve can cause an oxygen sensor to go out!!! Henshaw2001-don't wait too long to hook it back up! Lets all keep this thread updated. I'm curious if your all's problem is the same as mine.

 

I have not had time to work on or replace any parts, but I have had the vac line unhooked for a week or so. I guess I better hook it back up. The truck is running like brand new. Thanks for the warning on the O2 sensor.

 

Update: This week I saved over $35 with the EGR unplugged. With Cooper 31" mudders, the truck will roll smoke off the tires. And all this with the EGR unplugged. At 75, the motor purrs like a kitten. I thought about replacing the whole setup, EGR, Vent Solenoid (for the second time 'cause I think the garage s**ewed me and charged but didn't replace), and O2, but I ask why? I have done some reading on the emmision systems from a book I picked up. Heres a bit of the stuff I picked out. Without the EGR hooked up, the motor is only pulling fresh, clean air, full of oxygen, required for combustion. The O2 sensor works in parallel with the EGR to maintain an excess of O2 in the hot, burned gases. Burning fuel creates water, CO2, and CO, along with NOx groups present due to manufacturers impurities and N2 found in air. The excess O2 at higher temperatures helps two things, to convert CO to CO2 by oxidation, to convert the NOx's to NO2, and with the proper residence time in the exhaust produce a very corrosive liquid, which eats up every part of the exhaust when it condenses. The O2 Sensor also works with the Mixed Air Solenoid and MAF which sets the F/A ratio for combustion. What I have noticed is that the truck is running very lean. The why lies in the fact that the EGR isnt dumping junk gas back into the intake, and the O2 sensor is telling the computer to compensate. The result is a hotter more efficient burn, with less fuel required to make the same power. The purpose of the EGR was to burn unburned fuel in the exhaust and regulate the burn temperature. The catalytic converter with excess O2 present, and the poison they use on the ceramic lowers emissions by catalytic oxidation.

I hate to make this long, but I think you might find it interesting.

I put together a Ford Hi Po 289 some years back from a 302 long block with 65 stamped 289 heads. Bolted on a Holley aluminum square bore intake and a 600 CFM Vac/Sec, A/T kickdown carb. The cam was very radical, the hottest Summit had on the shelf. The idle was so lopey that I had to install a rather large vacuum canister to keep the brakes working right. No EGR, No Cat converter. Hooked it up to a sniffer when I had it inspected. The emissions were lower than a 94 Toyota in the bay next door.

I dont think it's a matter of whether my truck deserves new parts and to be in original condition, but whether it makes economic sense from a fuel usage standpoint to invest in fixing a problem when it may go back to costing me more per week to run it.

What do y'all think? Hmmmm..

By the way, the first things us redneck's do before we take a car to the demo or track is reroute and unplug all the emmisions mumbo, and reset the timing.

------------------
1993 F-150 4x4, 4.9L, Superwinch, K&N, Gibson 3" SS Single, Eclipse 5440 Indash CD, Kicker Impulse i-270 Amp, Kicker Solobaric 10" Sub, (4) 5-1/4 Eclipse 8953, Midland Weather Max II CB

1993 Procraft 180 Dual Pro Basser, 18' 9", 150-HP XR6, Hummingbird 400-TX

1999 Kawasaki KDX 220, Boysen Rad Valve, FMF Burly Pipe, FMF PowerCore II Silencer

Play Hard or Step Back!

 

I totally agree, I think that emissions stuff is all BS. I have a 77 GMC also and it it so much easier to work on and keep running good its not even comparable. Not saying GM is better just saying I prefer working on the old ones a lot better. As for me I am going to try to fix my current EGR valve and replace my O2 sensor (it has 164,000 on it).

------------------
1987 F-150 300 L6 4sp 2wd
K&N, flowmasters

 

Where is the EGR assembly located? Is it on top of the alternator? Mine is also an EFI 300(big6)

 

Big_6,
Look on the very top of the intake towards the back. My '95 EGR valve sits right behind the throttle positon sensor. It looks very shiny, and round (about the diameter of a pop can, but only half as tall) and has a small green vac line running to it. On the back there is a 1/2" diameter or so tube running in. This tube attaches to the exhaust manifold. Hope this helps.

 

Hey guys when i get this problem taken care of, I was thinking of buying a set of headers and uprading to 4:10's. I am running 31x10.5 BFG MT right now w/ my 3:55's. 4:10 is a slight overkill but down the road I plan on a small (2.5 in) lift and a set of 33's. Where did u guys get your new injectors and what did they cost you? Are they hard to put in?

------------------
1987 F-150 300 L6 4sp 2wd
K&N, flowmasters
2 10" MTX 8000 series in my own box design
200X2(RMS) Kenwood amp
stainless rockers and fenders 31X10.5 BFG MT on 15X8.5 Progressive alum

 

I'm wondering if any of you tried cleaning or overhauling the EGR valve as suggested, and if that worked. I've got similar symptoms from my 92 (occasionally stumbles when gently accelerating from idle).

Russ

 

This board is great. My '92 F-150 4.9L, 5 spd has had an awful stumble at very light throttle for months. Everything else was fine, starting, idle and acceleration so I had not bothered to take it in to get it looked at. I found this thread yesterday and last night pulled the vacuum line to the EGR and went for a short drive. The check engine light came on but the stumble was gone! So this morning I pulled off the EGR and EVP. I sprayed carb cleaner up into the EGR port and manually actuated the diaphragm several times letting is slam shut. Put everything back together and went for and extended test drive and it runs as good as new. I could easily reproduce the stumble anytime I wanted before but now it is completely cured. Don't know if this just a short term fix but I will be selling the truck soon and this just saved me mucho $$$

Thanks

[This message has been edited by charliephogg (edited 03-31-2001).]

 

I OWN A 1991 F-250 4X4 WITH A 5.OL(MILEAGE 13,000) WITH A E4OD TRANS.DURING IDLE THE ENGINE HAS A MIS OR A BUMP.LIKE WHEN I'M AT A RED LIGHT IN DRIVE IT GETS WORSE.I'VE TRIED EVERYTHING PLUGS,WIRES,ROTOR,CAP,TPS SENSOR NEW THROTTLE BODY.NEW EGR VALVE,AND 8 NEW INJECTORS.I EVEN HAD A NEW ENGINE INSTALLED 10 MONTHS AGO AND IT STILL HAS THAT MIS IN IT.
THE ENGINE RUNS GOOD BUT THAT MIS IS ANNOYING.I COULD REALLY USE SOME ADVICE HERE.THANKS GUYS!