89 ranger 2.3 ignition problem

[jfclark27]

Hey guys, I need some help. Engine runs great for about 15 miles. At highway speeds engine cuts off just like someone flipped a switch. After being towed home 3 separate times, I'm starting to think it may be the DIS module overheating. After fiddling with wires, connectors and disconnecting battery, I can get engine started again.

This is what I have done before I started to consider overheating DIS:

• New DIS module
• New crank shaft position sensor
• New fuel pump
• Removed and inspected wiring harness
• Continuity check all ignition wires
• Cleaned all connectors with contact cleaner
• New PCM (computer)
• Wiggle test all wires with engine running
• Voltage drop test grounds and B+ to computer and DIS

I am not getting any codes other than 33 which is the EGR (have had that continuous memory code for years now lol)

Also... I was not just wasting money by guessing. Crankshaft sensor was not sending the CID portion the the sensor (hard start, but would still run). I just replaced to fix the hard start and to eliminate the possibility. Sending unit was not working on fuel pump, so I replace to fix gauge and eliminate possibility. I already had a spare computer and that leaves the DIS I replaced. It seemed the logical offender and has a lifetime warranty, so I figured... can't hurt!!!

So this is what is leading me to believe it may be DIS overheating. I ran engine for years in Florida with no thermostat and plain tap water. Now I live in a cooler climate and needed heat. I bought a Motorcraft thermostat and now heater is nice and toasty. Immediately after coolant flush and thermostat is when problems began.

If I try to relocate the DIS to a cooler area, I will need a heat sink. Does anyone know if remote TFI heat sinks will work with a DIS, or will I just have to make my own custom heat sink? Has anyone had this problem with a DIS? I thought the DIS was the solution to TFI overheating.

I'm thinking maybe the intake manifold is running hotter than normal due to corrosion build-up, causing DIS to fail. I see hundreds of TFI modules suffer from heat, but nothing posted an the internet about DIS modules failing from heat.

Any help would be appreciated. This is my only source of transportation now. It's killing me finding rides everywhere I need to go.

UPDATE: FIXED... Bad ground connection. Details in thread.

 

[a31ford]

This is all I have, VERIFY your's is a MAF, and NOT a MAP.....

 

[zekew64]

Hey, dude, clean your EGR...my guess is that it's stuck, either open or closed. Take some mineral spirits, or some cleaner that will clean up carbon, and make sure your EGR can move under pressure. When I redid the motor for my truck, the EGRs for both motors were completely stuck closed. Also, check your vacuum lines; you could have a crack, break, or separation of your vacuum lines, which could also cause the problems your experiencing.

 

[PetesPonies]

An open EGR will not cause an engine to stop while at highway speeds. Your '89 has a MAP sensor, not a MAF. Crank sensors can act up intermittently, but you replaced that. Your info confuses me on the DIS. Did you replace it first? Also, have you run a KOEO test?

 

[kimcrwbr1]

You can use a computer processor heat sink and mount it on the apron close to the wire harness and then run three wires male one end female the other and isolate the module its real easy to do actually. You may have burnt up that module but would try it anyway you may get lucky. To test the EGR apply manifold vacuum to it as the engine is idleing the engine should stall. You can use a hand vacuum pump or just suck real hard.

 

[jfclark27]

It may be fixed...

I discovered a ground wire that was mounted with the negative battery cable at the starter. The ground wire comes out of the harness just before shield connector for the O2 sensor. Wire is black with a green stripe.

It was bare and wrapped around bolt and torqued down. Looked horrible. I stripped wire back down to shiny copper, attached a proper heat-shrink connector and road tested.

Tried to force the truck to beak down in driveway. Idled for 4 hours. No problems. Drove 10 miles on highway, stopped for gas, another 10 miles on highway, stopped for food. another 5 miles home. no problems.

I believe it is fixed. I could not find which ground this is, or what other components may be connected to it. It must trace back to pins 20,40,60, or 16 on the ECU, but the wiring diagrams I have do not show splices or ground termination locations IE: g201

To clarify... DIS was replaced, but problem persisted... obviously.

Thank you guys for your efforts. I just got bit by the ONE GROUND wire I missed when I though I checked them all.

Tomorrow, I will try a 100 mile round trip test drive. Wish me luck