I have a 88' F-250 with a 300 I6 and a ZF. There is a small engine stutter when it's idleing. I have replaced wires, cap & rotor, plugs, fuel filter, and the stutter is still there. Not sure if it's an timing issure or what? It's not not like it's completely miss firing but every 4-6 seconds it has a stutter in the idle. It still runs fine down the road, but i know when I start pulling with it I'd like to have all the power I can. And, I know I'm losing power with that stutter there. Oh, I've also ran 2 full tanks of gas through with EFI cleaner in it. Any suggestions on what to do next? What it might be? I have some money to through at it but was hoping it was something small... Thanks!

 

What kind of EFI cleaner did you use?

I use SeaFoam in my carb'd engines and it does a good job of cleaning varnish deposits off of the carb internals. You might try it and see if it smoothes your idle out. Wal*Mart has it for under $6 a can.

If that doesn't help, then the next thing to look for is a vacuum leak. Small ones can be a real problem to find. I use a 3 foot piece of 3/8" ID latex tubing for this. Insert one end into a convenient ear and then move the other end around various places on the idling engine where vacuum leaks are likely... mostly in the area of the carb and intake manifold. You will hear a hissing sound when the end of the tube comes close to a vacuum leak.

Be sure to inspect all of your vacuum lines. Replace any that are hard, brittle, or cracked. The ones that I have had that went bad seemed to go bad on the end of the vacuum hose, so replace any that are bad on the ends even if the rest of the hose looks OK.

Ed

 

vaccume issues, timing or anything that will affect spark at the plug, idle air controll,egr older obd systeyms don't pick up on some things as well as the newer ones another possibility is uneaven engine compression also an easy way to find vaccume leaks is to spray propane at ereas that can leak it will change idle pitch when pulled into an engine