What are the signs of a bad dizzy? I have an 89 351W that I am having some idling problems with. I have replaced just about every sensor as well as new fuel pumps. My idle problem is bad one moment and then it will be fine the next. It only idles rough or stalls after a good drive on the highway or thats what it seems like. thanks bob

 

Signs to look for include worn shaft bushings, cracks in the plastic allowing spark tracking.

You have changed plugs and leads haven't you? Use Autolite or NGK, I had problems with Bosch plugs in the past

 

I will check for a worn shaft and all tomorrow. As for the plugs and wires I am syre the PO just had a tune done. I have never heard of or seen a bad set of plugs or wires run good and then out of the blue run rough and then good again? I will check them as well. The plugs may tell me something I don't want to know.

I have always been a big motorcraft plug guy myself. I have had good luck Autolite as well.

 

Have you done anything with your EGR valve yet? If not, unplug it for awhile and see if that help the idle problem.

 

Heres what's be done. New EGR and sensor, two new IAC sensors, new TP, new dizzy module, new MAP sensor, new fuel pumps, checked the plugs, all injectors are 15.2 ohms, the dizzy feels tight, new fuel filter, had it checked out at pep boys and they found nothing but at the time they checked the truck it ran great. I may have missed something there because I am a little stressed right now with it.

Yesterday the truck started to run bad for a long period of time which was not normal to the past idling problems. Today the truck is running rich and will not idle smooth at all. I checked the vacuum line going to the fuel reg. but found no signs of gas in that line. My guess for tomorrow is the regulator is bad. It's only a $30 part so I will go buy one and see what happens. This is the first time the truck has shown an idle problem and not gone away. It's also the first time I have seen the truck run rich. So I hope it's the reg.

I will change the reg. and if that doesn't work I will unplug the EGR valve and go from there. I could have a bad O2 sensor but I haven't seen the check engine light come on yet. Thats why I think the reg. is bad, no code yet.

I can hear some kind of noise from the air tube valve thinging that goes to the back of the heads? I will buy more carb cleaner to see if there is a leak.

 

Can you try a trusted shop for a checkup? Sounds like you're spending alot of cash just guessing at parts.

 

By the way, try someone besides Pep Boys.

 

Pep boys where the only place open and I was out of town so I had no choice but to take it to them.. Since then things have been getting worse but they did seem good for ahwile and I what I mean by that is the fuel pump changes appeared to work and then out of the blue things went bad again.

I don't think it's the dizzy. The truck now idles rough and is running rich. The map sensor was swapped out with a new one with no changes. Autozone let my take it back. The air temp sensor, the upper intake gasket, fuel pumps, fuel filter, egr valve and egr sensor, throttle body, tp sensor, iac sensor, dizzy module, pressure regulator are all new. I even moved the PCV valve to the top of the intake. I think the only sensor that hasn't been change is the O2.

I even checked all of the injectors and they measured 15.2 ohms. All of the spark plugs looked good also.

When you first start it the idle will go up like a cold start and then slowly come down. Once the idle comes down it will start to idle rough and rich.

I think it will have to go to the ford dealer on Monday. I have no clue what could be wrong. Just so you know the new throttle body got rid of my throttle sticking problem so that wasn't a waste and it was the biggest cost so far.