bigern26

Hello, I am new here.

I have a 91 ford f150 4x4 with the 4.9and a 5 speed.
It has new plugs, wires, cap and rotor.

When I first start it up in the morning and its cold it runs really good with no engine light. then if I drive about 5 - 10 minutes the engine light comes on and it seems like the truck is shuttering. (driving at 55 mph)
If I am in town and going around 25 mph or any time I am just pressing lightly on the gas pedal it acts like its missing.

I ran the codes and I got
key on engine off,
172 = HEGO (O2 sensor) show system always lean
327 = EVP or DPFE (egr position sensor located on the egr valve) cicuit below minimum voltage
328 = EGR closed voltage higher than expected
452 = insufficient input from vehicle speed sensor (located on the rear differential on my 93)

key on engine on,
172 = HEGO (O2 sensor) show system always lean

The speedo cable is broke so thats why 452 came up.

Does anyone have an idea of anything I can test or check before i go and buy a new egr valve? or is there a way to test my egr to make sure its bad?

or any other ideas that might be causing it to act this way?

Just call me Sean

iTrader: (1)

You need to fix the speedometer. Look through the holes in the bottom of the EGR to see if it is moving while you rev the engine. It sounds like it's stuck. Also make sure the control solenoid is getting vacuum in and out and make sure the vacuum is reaching the EGR valve.

bigern26

I checked the egr valve and there is vacuum, when i give it trottle it does move and then move back but it take quiet a bit to get it to start moving i would say about 2000 - 2500 rpms. also it starts to miss around there if I am getting on it.

Just call me Sean

iTrader: (1)

If you goose the throttle it should move back and forth. Even if it's moving I would pull it and see how dirty it is inside because it may be stuck from closing all the way.

bigern26

I pulled the egr and it was not to dirty. I cleaned it a bit and put it back on along with a new gasket. still runs the same. missing right around 2000 - 2500 rpm. I unplugged the Idle air control and sucked the vacuum a little on the egr and it did the rpms did fall and it started to miss bad(haynes manual said to do this to test the position sensor). I have some small vacuum on the tube that goes to the egr when it is idling.

I still am not sure if its the egr, position sensor, selonoid or something else.

Is there a way to test anything else or the things i said above?

I drive this truck to work 50 miles a day and really need to figure this out.
thanks for the help so far.

tailgatefisher

I had the same EGR codes (327-328) and pulled the EGR, cleaned it well with trottle body cleaner. You want to clean the valve that goes into the tube; not the inside where you attach the EVP. Spray the trottle body cleaner into the side port hole and with a screwdriver or the blunt end of a ink pen, push in and release the valve that goes into the tube several times to clear out the exhaust build up. I replaced the EVP sensor with a junkyard swap and so far my codes have not come back.

I also had the 452 code and replaced the VSS with a new one. $20 doller fix but keep in mind that the speed cable retainer clip was a bitch to reinstall without bending so if you can get the old one out without bending it up, that will be a plus to have it as a back up. A new clip comes with the VSS but if you happen to bend it, No one seems to carry them at the parts stores. Take a look first to see why your speedometer isnt working because as it turns the VSS uses it to pick up signal.

I have not had the 172 code fall on my shoulders yet so I cant really steer you in the right direction with it. My guess (Just a guess) would be related to the VSS or the EGR.

As far as the misfire at lite trottle, I really wish i could tell you whats the cause. I have had this problem forever and am almost to the point of running the darn thing over a cliff. We are not alone with this problem, Ive came across several here on the forum that also suffers from it. If I ever find this cause I will post it on here to help others along and hope they will do the same for us.

bigern26

The speed-o dont work because the previous owner broke the speed sensor and also the retainer bolt. I already knew about that before pulling any codes.
I need to figure out a way to get the broken bolt out so I can replace the speed sensor.

I already cleaned the egr as I stated in the previous post.

thanks

bjafeman

Like tail gate fisher said, the mid range miss is more common than it should be on these trucks. Some times it's an intake manifold gasket, sometimes it's a throttle body gasket, sometimes EGR, sometimes EVP, fuel starvation, gamma rays, or the economy itself; you get the point.

I had the same thing going on with mine. Via some form of elimination or another I ruled out everything except for the throttle body gasket and the EVP sensor. I changed the EVP sensor because it was out of spec from what my repair manual said it should be - not much though - and I think I'm good now. There have been a few suspect "bumps" that might have been a bump on the road, but I'm probably just being paranoid.

Basically, you may need to start systematically ruling things out and then follow that up with a guess or two in the form of new parts. Start cheap though and keep things clean enough to return if possible.

tailgatefisher

Inorder to get that bolt out of your tranny that held your VSS, you will need to go to a parts store and pick yourself up a Easyout kit, or could also be a bolt retractor. Parts guy will know what your looking for. To use these requires a drill bit smaller than the bolt itself. The easy outs come in several different sizes so match the drill bit size to the specs written on the package of easy outs. The inner portion of the bolt is softer metal than the outer so once you have drilled a hole into the center of the bolt (not needing to go clear through) you will use the correct size easy out matching the bit specs. With a hammer, tap the easy out into the hole as far as it can possible go without damaging the bolt or making it expand and with alittle pressure, reverse screw the easy out. Keep in mind that these easy outs are made to remove the broken bolt so make sure you are turning it to loosen and not tighten as I mistakenly did at one time. (Made more of a problem for myself) Once it catches the hard outer edge of the bolts material it will grab as long as you are still applying pressure. Take your time at it and im sure you be able to extract it. I dont own a torqe wrench and have broken bolts many of times over followed by a whole lot of cussing. My easy outs saved my dumbass many of times.

tailgatefisher

Before running to the parts store for that easy out. I cant remember now but something makes me think that the bolt that mounts the VSS to the trans may have been reverse thread. Someone will hopefully come along and correct me on this.