i have a 90 f150 with a 4.9, auto 4x4. While driving in town, it seems to cough/miss/hesitate at a constant speed, with or without the overdrive on. It does not do it on the highway witht he cruise set or without the cruise. The plugs looked fine, the plugs and wires all all fairly new and the cap/rotor look fine also. I replaced the EGR valve, after finding out that it was bad thru a scan with a SnapOn scanner. Any advice is going to be helpful.

Kevin

 

pull the green hose off the EGR valve and plug it. If this solves your problem, make a EGR restrictor plate. By using another gasket (which you will need anyways, and using it as a template, and then drilling a 1/8" hole in it. You can find out more in the inline 6 forum.

 

Will this work with a 5.8 too?

 

Where is the in line6 forum, and I have anew egr valve to install on my 1989 4.9 engine, should I make a restictor plate and install that right now so as not to have to redo it all again if it doesn't work properly without the restrictor plate.... Thank you! Chuck

 

The reason why this works on the 4.9L is because the 4.9L runs lean. With the restrictor plate on this richens up the fuel mixture. Less recycled air in the intake. The 5.0L and 5.8L are rich running to begin with. If you put on the restrictor plate on a 5.8L or 5.0L you will just go through more gas.

If you have problems with your 5.8L hesitating I would check the plugs/wires/coil. I had the same problem and it ended up being improper gap on the plugs. Fixed the gap...fixed the problem.

 

I too had a similar problem with my '94 F-150 4.9 2wd auto recently. Had checked and replaced cap, rotor, plugs, wires and had checked vacuum lines, wiring, etc.

Turns out, it was the coil. New coil... end of problem. I also did the restrictor plate deal. Only difference is I didn't drill any hole at all. If we ever get emissions testing here, I'll probably have to pop it off and drill the 0.125" dia. hole mentioned in other replys.

Once the coil issue was resolved, the restrictor plate did seem to wake the engine up a bit, and improve milage.

Hope this helps.

 

Thanks WS for the info.. another problem I'm having with my 1989 4.9l is that at an
idle I have a bit of a miss, will installing this egr valve with a restrictor plate help with the idiling? Other than the rough idle the truck runs very good, plenty of power and am getting 18 miles per gallon on the highway..