Hi guys,

I recently purchased a '81 E-150 Club Wagon with the 5.8L (351 windsor) engine. It starts up and runs great (well.. OK)

The only issue I am having with it is this:

When the van is first started, it seems to idle fine while cold. I can hear and feel some slight missing in the engine while it fast idles cold. I put it in gear and it drives fine around town etc.

As the temp gauge reaches Normal (operating temperature) the misfiring gets worse and more noticable and the engine feels like it wants to stall.

What I have done that has not rectified the problem:

1.) Changed the Oil
2.) Changed the Spark Plugs, wires, distributor cap and rotor

The problem still persists and did not change even after doing all that. Ihave to set the throttle idle up in order to keep it from dying without two-footing it and I don't like that because it's real hard on the tranny, brakes, and differential.

A buddy of mine said that the valve timing or timing might be off considering how old it is. It has 137,000 original miles.


Any ideas on where I can check next? Any input would be appreciated!

 

It sounds almost like a vacuum leak. There are so many places that could be leaking, it could take a while to chase down. My initial reaction would be that one of those round "heat/vacuum" switches is not working, but..who knows. Carb gasket, EGR stuff, intake manifold gasket, vac advance, etc..? Do you have emission tests in your state for vehicles that old? If not, you'd probably be better off to start eliminating (permanently) some of that stuff. You might get better mileage as a bonus.

 

Hi Badge,

No we do not do emission testing in Wisconsin. What are some emissions items that might be causing some of these leaks and how would I go about removing them?

Also to note, it does miss at high rpms it's just not as noticeable and is infrequent (i.e. it only does it while idling, and not while under load [driving]).
I was told this was valve timing,... but from what I read the 351w does not allow for valve adjustment and a rebuild is the only option?

And lastly, I haven't done a compression check, but let's say I did and all the cylinders turned out to have good compression, what could it be then?

 

When you changed plugs did you carefully examine the condition of each in order to try to determine if your misfire was isolated to specific cylinders?

1st thing came to mind is the ever popular cold climate Snake Oil Remedy called Dry Gas. While the addition of ethanol to gas tends to accomplish this, the use of some of the fuel system conditioners is an act of faith to many & may be worth a try. Even if results are modest & temporary it may point to fuel instead of ignition issues.

Some head gasket issues are temp related, as are marginal electric connections.

 

Hi Club Wagon,

I'll give the fuel additive a try. Any suggestions?

Also worth noting is I recently filled up the tank all the way using Premium fuel (93 octane) instead of the 87 I had put in it before, and it seems to not misfire as much when hot idling. Do you think the timing is getting retarded from something, and higher octane fuel is "making the issue seem less aparent"?

 

I wouldn't expect timing issues or temp related misfiring to be associated w/87 vs. 93 octane fuel. Traditional favorites include Marvel Mystery Oil, Lucas, Seafoam & Chevron Techron gas additives.

Can I presume you did not examine the old plugs?

As noted "a vacuum leak" can easily disrupt idle & is a likely suspect on an '81. After rigorous visual inspection, some use flammable aerosols like penetrating oils (even starting fluid) to search for vacuum leaks on running engines. The idea is probe likely areas for leaks w/plumes of flammable spray that gets sucked in, raising RPM.

 

I'd rather not tell you what to remove.. What I will tell you is what to keep. Fuel line to the carb. Vacuum line from vacuum advance bell to the carb. Automatic choke stuff ( wire, heat tube). Any vacuum line that runs to the heater/ AC unit. If your AC dosen't work and you can live without it, remove it all. Same with the cruise control. Plug up every newly opened port on the carb and manifold with appropriate NEW rubber port plugs. You'll be amazed that now you can actually SEE the engine. Check EGR valve behind the carb. Take it off and clean it ( probaly plugged up with carbon) If you eliminate that system, plug the exhaust manifold with a pipe plug. Then after all that..if it still is sucking air, start the spray down process till you find the leak. Like I said..this could take a while.

 

unhook the egr valve and block off the vacuum line with a screw or something. and see how it runs, i no there is some people that will disagree and say it ain't the problem but just try it and see, only takes a couple minutes. had the same problem on a f250. my 78 e250 had a bad egr valve that did the same thing, the diaphram in the egr was leaking vacuum all the time, just a couple suggestions

 

Hi Crazz,

Where is the EGR valve on the 351w? Is it on the carburetor?

 

 

Great! I appreciate that! How do you remove / unhook it? Does it just unscrew counter-clockwise, then I stick a small screw in the vacuum line that was connected to it?

 

just pull the hose off of it, it just slides on then plug the hose off tight

 

Alright. I'll give it a shot possibly tonight. There's some pretty heavy snow out now so I don't really feel like trekking outside at the moment.

Is there something I should be noticing after the hose is plugged off (besides it running better while idling)...?

 

just see if it acts the same, or see if it is running better. when it warms up and is idling bad and wanting to stall take the dog house off and air cleaner off and see if the choke is open or trying to close. the choke pull off could be bad as well

 

> A buddy of mine said that the valve timing or timing might be off considering how old it is.

Nothing like going for the most expensive and unlikely problem first

Put a timing light on each spark plug wire and see if you can narrow it down to one plug by an obvious visual miss. I have had bad autolites right out of the box.

If not, put a spark tester between the plug and wire and see if the spark is the same color on each plug. Or use an induction type, those are kind of iffy and dangerous if the wire itself is bad (zap).

If it passes, it might be the duraspark module. Just like the TFI modules, they can go bad after a while and they get worse as they get warmer. Usually not a problem in trucks, but, under the hood in a van is much hotter then a truck.

Usually if you remove them and flip them over, you can see a track mark in the epoxy.