Car Won't Start In The Rain/off-idle Bog

mattyv · Feb 4, 2016

Hey everyone, I just joined here and I love it so far. I've learned a lot from lurking but I want to start this thread to document my issues and to get advice.

1993 LX 5.0 T5 127,500 miles, all stock except exhaust, 70mm BBK TB, 70mm spacer, BBK fenderwell intake, MAC shorties, no cats, MSD coil

I bought the car a month ago on a wet day. Drove fine on the test drive and the ride home, besides a slight off idle bog that I knew about already. After having it about a week, it started shutting off randomly while I was driving. It would always restart, but only if I cycled the key. I figured it was the PIP so i ordered up a reman distributor which included a new TFI module, cap, rotor, etc.

I installed the distributor, new FRPP wires, new Motorcraft plugs. Then cleaned the MAF, IAC, and TB. The previous owner had put on a new IAC and TPS not too long ago. It wasnt until now that I realized that the SPOUT connector was missing. Set the timing to 14 BTDC and got a new SPOUT from Ford. I then set the idle to about 700 with the IAC unplugged, adjusted the TPS, reset the computer, etc. All of this solved the random cutting out problem. I also had to do a steering rack, not that it affects any of this. I checked running fuel pressure: 33-34 at idle, bumps up to 43-44 when you crack the throttle. This was with the vacuum still connected though, I didn't realize I had to disconnect it. The fuel filter looks new as well.

I drove it around all night, it rained a little but not too much. The next morning its raining pretty hard and the car would just crank and wouldn't start. i didn't have time or another set of hands to help me diagnose, but the coil was getting juice with the key on, the coil tested out OK, and continuity from the coil to the cap was good. The cap and rotor were also dry. The fuel pump comes on with the key as well.

***EDIT Also check the salt and pepper connectors. They were clean and had dielectric grease in there.

After I set the idle and TPS etc, I started getting a surge problem. I flipped the IAC over but that made my idle about 1200. I dropped the idle with the TB to about 800 and the surge is still gone. I'm not sure I go back down to 700 if the surge will stay away but - that will be another day.

This is pretty much where I am now, besides getting a MAF code and swapping it out to a SN95 MAF. It was raining yesterday and I tried to start it, so I will have to pull codes tonight and see if anything has changed.

Also when I unplug the IAC the idle drops, unplug the ECT it gets rough, and unplug the MAF it gets rough. There doesn't seem to be any vacuum leaks anywhere.

The car will not start even after I wash it on a dry day.

Last thing - if it is a wet morning (dew, etc) it may start but it will run rough

My Saturday to-do list:
1. Check EGR valve to see if it's stuck.
2. Install new 2.5" O/R Hpipe with brand new O2s, and Flowmaster cat back
3. Install new ACCEL cap and rotor (not sure if I trust the crap parts store one)
4. Wet down engine and see if it misses/shuts off, check for spark and injector pulsing.
5. Unplug SPOUT and try to start.
6. Replace fuel filter.
7. 84.5" belt, eliminate smog pump
8. Check EEC for any water/moisture

Did I miss anything? Anything else to try?

Thanks!

jrichker · Feb 4, 2016

Check the inside of the distributor cap for moisture, spray it with WD40 and wipe the inside dry.
Ceck the coolant hoses up next to the distributor. You may have a pinhole leak or seep that tends to cause moisture to condense on and inside the distributor cap.

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 200,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

mattyv · Feb 4, 2016

Thanks jrichker! I will check the coolant hoses and respray the inside of the dist. The last code dump only gave me a MAF code. Haven't had a chance to code dump again since it has been raining

mattyv · Feb 4, 2016

So it was raining when I got home. No start. Pulled the spout and started right up. Only code is 18 - spout circuit open

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jrichker · Feb 4, 2016

The start when the SPOUT jumper is removed is a sign of a failing PIP. PIP failure increases as engine temp increases.

The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

PIP Sensor functionality, testing and replacement:
The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. A failing PIP sensor will often set code 14 in the computer. They are often heat sensitive, increasing the failure rate as the temperature increases.

Some simple checks to do before replacing the PIP sensor or distributor:
You will need a Multimeter or DVM with good batteries: test or replace them before you get started.. You may also need some extra 16-18 gauge wire to extend the length of the meter’s test leads.
Visual check first: look for chaffed or damaged wiring and loose connector pins in the TFI harness connector.
Check the IDM wiring – dark green/yellow wire from the TFI module to pin 4 on the computer. There is a 22K Ohm resistor in the wiring between the TFI and the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 22,000 ohms +/- 10%.
Check the PIP wiring - dark blue from the TFI module to pin 56 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the SPOUT wiring – yellow/lt green from the TFI module to pin 36 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the black/orange wire from the TFI module to pin 16 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the red/green wire; it should have a steady 12-13 volts with the ignition switch on and the engine not running.
Check the red/blue wire; it should have a steady 12-13 volts with the ignition switch in Start and the engine not running. Watch out for the fan blades when you do this test, since the engine will be cranking.
If you do not find any chaffed or broken wires, high resistance connections or loose pins in the wiring harness, replace the PIP sensor or the distributor.

The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, and the SPOUT out, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.

See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.

mattyv · Feb 4, 2016

Awesome thanks! Any harm in running it with no spout for a day or two?

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mikestang63 · Feb 4, 2016

no. it will just lock out the advance, The car won't run optimal . set the timing to 26-28 degrees with the spout out . Don't drive it hard until you get the PIP fixed.

mattyv · Feb 8, 2016

To close out this issue, it was the TFI. I danced around that since it was a brand new TFI. Don't always trust new parts! Swapped it out and it runs great now, and starts all the time. Thanks everyone

mikestang63 · Feb 8, 2016

mattyv said:
To close out this issue, it was the TFI. I danced around that since it was a brand new TFI. Don't always trust new parts! Swapped it out and it runs great now, and starts all the time. Thanks everyone

Ford or parts store TFI? Only use a Ford one. Rock Auto sells them

mattyv · Feb 8, 2016

Yeah, it was a whole parts store distributor. Originally my PIP was bad so swapped a whole new dist on there. Now I'm running the new dist with the TFI from the old dist. Ford TFI and tool is already ordered to keep in the glovebox

What do you guys think of the TFI relocation kits? Any good? Worth it?

stykthyn · Feb 8, 2016

For simplicity sake I would leave it in the stock location. As long as you used plenty of contact paste it should work as designed for at least another decade.

mattyv · Mar 21, 2016

Just to tie up this thread, I finally found the slight off-idle bog. Someone, at some time, put in a set of 24lb blue tops. Stock MAF, stock everything. I should have checked that sooner but it never crossed my mind. Swapped in a set of 19 lb ers this weekend and its like a whole new car! Thanks guys

Car Won't Start In The Rain/off-idle Bog

mattyv

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I want to measure mine. It doesn't look that tall.

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I want to measure mine. It doesn't look that tall.

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