I have a 1989 F150/302/AOD/2wd.

The truck misses and for awhile was pinging badly at times. I replaced the plugs and wires and inspected the cap and rotor. It seems like the missing starts after the engine warms up.

I am getting 2 codes - 33 and 45. 33 I think I have narrowed down to a bad EVR, maybe. I took the truck to a shop down the street and he hooked up his smoke machine to look for vacuum leaks. The only place smoke appeared was from under the filter end of the EVR. I'm not sure how the EVR works, so I don't know if under pressure (instead of vacuum) it would leak out or not. I did apply vacuum to the EGR valve and it moves fine.

The 45 I'm not sure about. Can somebody tell me whether the air should be going to the cat or the heads with no vacuum applied?

One other thing, I didn't get any TAB/AIRB codes, but I noticed when I apply a vacuum to the bypass valve, it doesn't hold. Either that, or maybe it's sticking, so when I apply a small vacuum, it holds for a moment and then after the diaphram moves, the vacuum appears to go away. Maybe more research is necessary, but this doesn't seem right.

Any help is appreciated.

Dave

 

The code 33 could mean alot of things affiliated with the EGR system. Could be a bad vacuum hose, EVR (EGR vacuum regulator), or the EVP (EGR position sensor).

To test the EGR valve properly....keep the truck running.

1. Pull the vacuum tube off the top of the egr.
2. Plug in a vacuum tester and pump up to 10-15 in.
3. If the truck runs fine...your EGR valve is shot. (and it's not a cheap part!) Do not purchase an EGR valve that is not from FORD.
4. If the truck sputters and stalls with the vacuum increase at idle, the EGR is opening as advertised.

Next check the vacuum line that runs around the upper plenum from your EVR to the top of the EGR valve. It should be a green line. Plug one side of the line and pump your vacuum tester to 12-15 in. If the line holds the vacuum, they are fine. If it doesn't, this could easily cause your misfiring and code 33. Cheap fix.

To test the EVP, turn the key to run but leave the motor off.

1. Test the voltage at the EVP pin at closed throttle/idle.
2. This should read between 0.2 - 0.5. Ford fuel injection states that it could be up to 0.67. However, any ford tech manual suggests an idle reading BELOW 0.5.
3. If this reading is too high...this can throw the 33 code.
4. You can manipulate the sensor to grab a lower reading by pulling the unit and grinding on the bottom of the metal pin.
5. Grind off a hair of it, and recheck voltage. It won't hurt the device.

You can also have a leak in the EVR solenoid. A vacuum leak in this device will not open/close the EGR valve properly and cause the motor to shake and sputter at idle. EVR runs about $40 from Ford.

Check www.fordfuelinjection.com for any further insight.

Good Luck,
Mike

 

Thanks, Mike!

All of the vacuum lines are new hoses that were replaced last winter when I think I broke all of the remaining plastic lines. I have double checked the routing.

Should the EVR leak at all? I think I read somewhere that a small leak was okay, but it didn't say what that meant. I don't know if it means that a little bit of vacuum at the EGR side is okay when the valve is closed, or if it not holding a vacuum on the manifold side is okay. Seems like either would be bad. BTW, when I plugged the vacuum line going to the EVR, my pinging all but went away, which is another reason I think it might be bad.

I'll check the EVP as soon as I get a chance. I did block off the EGR the other night just to eliminate the EGR system as being a cause, though it didn't seem to change anything. The only thing that has had any effect so far was the vacuum line to the EVR.

Right now, because I haven't had much time to really t/s this, I have blocked off the vacuum line from the manifold to all the emissions stuff. The only stuff getting vacuum now is the brake booster, the MAP, climate control and cruise control, and all of those have been leak tested. The engine still misses, especially at low RPM under a load.

I did have the plugs out when I changed them, and they all looked okay to me. I would think if I was having any fuel issues, it would show up there, wouldn't it? I did check the fuel pressure and it's 35 w/ vacuum and 42 without. I did a WOT check and it didn't drop, but that's without a load, so I suppose it's possible that there's insufficient flow. I don't notice any miss or other anomoly when accelerating at WOT. I did have to replace the FPR a few months ago because it wasn't regulating and the FP was high. I have another set of injectors, used and untested, that I could put in just to rule out injectors, but it's a pain and their untested.

Anyway, as I understand it, if the emissions stuff is isolated from the engine management, it should run fine, right? So, if I block off the AIR diverter lines, thus isolating the bypass and diverter valves and smog pump, and block off the EGR for now, the engine fuel economy may change, but it should run correctly, right? That would at least confirm that it is something emissions related, then I can start putting stuff back in. I would like to test the individual valves and such, but it would be nice to at least have an idea of the area first.

Sorry for the long post.

I'm sure there's more info that I have, but haven't thought to put here, but I will as I think of it.

Dave

 

The amount of money you will lose in fuel economy will easily purchase a new EVR in a week or so. It's $38 from ford.

You can always buy an EVR, clear the codes, install it and see if your CEL goes away.
If it doesn't work, take it back!

Sometimes the EGR will stick open once the system is hot... a cool down test of the valve itself doesn't always clear that as a suspect. The EGR is not a cheap replacement...

Mike

 

Same codes same missfire when engines warm up all my emissions things are pluged egr. and almost everyline from the EVR and the other vacuum lines next to it.. .. if you fix the problem PLEASE letme know.. im chasing ths problem for a while now... thank you

i suspect its a fuel problem tough

 

Checked out the AIRD and AIRB valves and solenoids and found that the bypass valve has some holes in the vacuum actuator diaphram. So I opened it up and coated the backside with a layer of RTV. Now it's sealed and holds. I still need to replace the EVR and found one of the other solenoids.

I also replaced the injectors with a set I got off of Ebay awhile back. Now the truck runs! So, this did turn out to be a fuel problem. I still think it's strange that nothing showed up in the plugs, but oh well.

I did notice something a bit strange though. A couple times the truck did seem to act up, and when it did, the tach would jump up a few hundred RPM. It was only momentary - it didn't stay at the elevated RPM at all, just jumped up and back down. This was also happening before, but I thought maybe it was related to the missing and pinging. Now, I'm not sure what is causing it. Any ideas?

Dave

 

Replace the EVR if its suspect. A leak in your EGR system can cause this fluctuation.