Hi all, I have used this thread to fix many a problems, but this one is harder to understand and I need your help. Problem is more pronounced is warmer weather. Started last summer. Drove down to town all and on the way home the truck started to sputter then stall. I managed to get it started and it went about another mile and stalled again. I finally got it home and let it sit an hour and the truck started right up again with now signs of a problem.
I checked the distributor cap and rotor and they were in bad shape. I replaced distributor cap and rotor, checked and cleaned and gapped each plug and saw starting improvement but problem was still there. I checked the gas from flue pump and gas was not the issue. I ran it some over the winter and the problem did not arise. This spring the problem came back. I changed out CDI module as this can fail as it gets hot. It was ten years since last change so I changed it out. Not the root cause. I bought a computer code tester as the blinking lights can be difficult to interpret. Running the engine off said I had not issues. With engine on I got an EGR valve error. I had to have mechanic change that out as I could not get it free. He had to use heat to get it off. Also changed out Coil as it was originial while he was working on EGR valve. Bought a spark plug tester also in case problem persisted. Sure enough problem was not fixed by EGR. Yes the EGR was bad but now had a new code. The engine coolant Temp sensor was giving an error and the truck was still dieing about ten minutes after turn on. I have replaced the ECT sensor and I am not getting that code any more. Latest fault code is Knock Sensor and Idle high. Engine is now idling at 800-900 rpms. Checked to see If I get sparc after engine goes into this condition. No sparc from coil after engine shuts down. After it sits an hour, it starts right up. I have had the fuel relay give me issues with opening up, but this is not the case this time. I tried this early on last summer and it was not the issue.
I only use the truck in bad weather, and to support my fishing habit. I hope this forum can help me. Not sure the knock sensor is the root cause here. I do not get any additional engine codes captured by the computer. Engine off computer check come back clean with no codes.

 

Tfi module on distributor, may be mounted on fender wall as well, find it and test it after the issue arises and you should be able to solve your issue. Also check your coil resistances, make sure it isn't the coil going under heated conditions. But my guess would be tfi, classic symptoms

 

I changed TFI module as first part change out this spring. As I have had two fail in the past. Also changed the coil when EGR Valve was changed. Output of old coil was quite corroded. How / Where do I check resistance of coil. What pins and what ohm value should I be seeing.

 

99% it's the PIP in your distributor. You have to remove and disassemble the distributor to replace the PIP. Avoid rebuilt distributors as most of them are junk. I would check someplace like O'reillys for a NEW aftermarket distributor.

 

I read where it could be the PIP sensor as well. I discussed with my mechanic and he did not think it was the PIP as the problem is not there at start up. Also I am not getting a PIP code 14 set in the computer memory. Any thoughts on testing the primary coil other than checking for sparc. I know I do not get sparc when this condition occurs. Jagesage mentioned doing a resistance check. I do not know what pins to measure?

 

I have an 1988 F-150 with the same engine as yours and my PIP sensor went bad with about the same symptoms as yours. My PIP finally died completely. Fortunately at the time my local ford garage disassembled my distributor and replaced the PIP.

In your shoes I would be thinking about replacing the distributor with a NEW aftermarket one. It could be your ignition switch, but they rarely go bad on a Ford. Sometimes one just has to throw parts at it until the problem is solved. Good luck.

 

Didn't even think about the pip, I've never personally had one go bad. But the coil you're testing for resistance from both posts on the plug you should get .8 to 1.6 ohms

Then test it from the right side post to where your main plug wire connects. From there you should get 7700-11000 ohms

 

Faulty PIP is very common. Thanks for the coil primary and secondary impedance values.

 

I will try and test out the coil and PIP sensors tomorrow afternoon after work. I downloaded a six step process to go through the ignition components.

 

I'd bet it's either MAP sensor, TFI module or PIP. Easiest to troubleshoot and replace in that order but TFI module followed by PIP is most likely cause.




I'd unplug the hose from the MAP as my first test since it's so easy.

 

Finished troubleshooting this evening. It is the PIP sensor in the distributor. Downloaded some ignition troubleshooting instructions from EasyAutoDiagnostics.com and determined it is the PIP sensor. Ordered a new aftermarket distributor that comes with new TFI module as well. Hope to have this issue behind me by Monday. Plan to do distributor change out on Sunday. Any concerns with taking to old distributor out? So say the oil pump sticks to the bottom of the distributor when pulling the distributor. Plan to line up the rotor and make a mark on the engine so I can align the new distributor into the same position. Also saw that sometimes the distributor does not engage the oil pump when put in and author said after you fee the lower gears make contract you can just pulse the starter until the distributor falls into the oil pump. has anyone tried this?

 

Still not fixed after new distributor. PIP signal is now good. Measured coil resistance about 15.5 kohms on high side and 1.0 ohms on low side. I am getting spark to the distributor. I was monitoring the fuel pump relay and saw that when the engine shuts down the computer shuts off the fuel pump relay even with the key in the run position. This must be a safety feature. I am getting no running fault computer codes when this engine shut down occurs. I will look into MAP sensor. Only sensor left I have not changed it appears. So to summarize, New distributor, new coil, new TFI module second one came on new distributor, new cooling temp sensor and new EGR Valve. All computer codes are clear except running knock sensor and this book says this could be a false error code. Engine is running smooth and I do not here any knocking going on. After I wait ten or fifteen minutes the truck starts right up again and will run a short while again before shutting down.

 

I know you said you checked the fuel pressure but I was just wondering how? If I were you I'd be double checking things like fuel pressure, preferably have a gauge on it and be watching it when it quits. Spark is sometimes a easy thing to mis diagnose. Seems like you've cover most of the ignition problems already. Hope this helps. Good luck.

 

Thanks J Ballon. I rented a fuel injection test kit last year, and had good pressure doing cracking, back them I had bad distributor cap and rotor. Going to talk to my mechanic some more and see if he has more monitoring equipment to catch what is happening at shut off. I replaced rear gas tank and sending fuel pump two years ago. I did not have any issues until late last summer. It was fine during the winter and started acting back up this spring. EGR was definitely bad, PIP in distributor was not firing when engine went into shut down mode. New distributor seems to have corrected that. New coil and does not seem to be cutting out when engine shuts down. Engine does not shut down like running out of gas, does not sputter it just shuts off. RPMs go from 2000 to zero just like turning the key off. Thank you all for your advice. I will let you all know what I find out when it is fixed.

 

Just throwing this out there, but have you changed the ECM & Fuel Pump relays? They can do some funny things when they get warm...