Hot start problem - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #1  
Old 10-14-2015
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Hot start problem

When I start my truck if it has been sitting more than 10 mins Up a hour it will not idle or very rough at best for about 20 seconds then gets better .it takes another couple minutes to smooth out completely. If I sit and idle as I frequently do for buissness it will be even harder to keep running. This has been going on for a year with easily 3000.00 in parts and shop fees. Ford has replaced MAF, PCM to no avail. Please don't laugh I have replaced the TPS ,IAC ,COOLANT TEMP SENSORS, O2 SENSORS, FUEL PUMP ,INJECTORS, FUEL PRESSURE VALVE , SENSOR INSIDE AIR FITER BOX , FUEL PUMP AND EEC RELAYS REBUILT ENGINE 8000 miles ago. I have cleaned to the best of my ability the connector ends. ANY EXPERTISE WOULD be greatly appreciated
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Old 10-14-2015
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So I assume it runs perfect when cold.
When started cold(without touching gas pedal) the RPMs go up to 1,500+ and then come down to about 1,100rpms, thats the IAC valve, ECT sensor and Computer all working correctly.
Idle RPMs should steadily drop to about 750(automatic), 650(manual) after engine is at operating temp.

After warm up is the only time you have a problem.
1994 3.0l still used the TFI ignition system, so a distributor and single coil setup.
These commonly had warmed up ignition problem, usually the TFI module on the distributor.
Good read here on checking TFI system: Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting

One trick to test module, after warm up and a problem is occurring, shut off engine and put a bag of ice on the TFI module for a few minutes, then remove bag and start engine, if it seems to be running better replace module.
Coils can also become heat sensitive, but they take longer to cool down, they are not too expensive so replacing the coil on this type of system every 10-15 years is not unusual
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Old 10-14-2015
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Hi Ron ,thx for reply, the ICM which is mounted behind the battery went bad last Friday had to have it towed . In the morning it starts pretty decent runs like a top on freeway . Definitely related to heat . Thx for linking me to the ignition test page looks like good info .
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Old 10-15-2015
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Coil is about 3 months old , tfi module 1 week. Never engine code . Anybody know of a qualified mechanic around Pompano beach Florida ?
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Old 10-15-2015
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ICM = Ignition Control Module
You don't have one of these?

ICMs were used when distributors were eliminated and CKP(crank position) sensors were added.
TFI module on the distributor is technically an ICM but wasn't usually referred to as that.
Because of the heat issues there was a modification some owners used.
Seen here: Ford Ranger Remote Mounted TFI Ignition Module
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Old 10-15-2015
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You were right it is a TFI, and mine has always been mounted behind the battery to the left of the radiator . I like the ice idea . Probably put it by the distributor and maybe TFI and see if it maws a difference . I then may try to find a simplified wiring diagram of the eec and TFI and ohm the wires Also do some of the testing described in the info lst night . Something for sure it only acts up when hot after its off for 10 or so minutes. I'm an elevator tech and on the phone or doing paper work a lot then in a building for 10 to 20 minutes . It's noticeably worse than when I drive up shut it off right away . Hey thanks for help .
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Old 10-15-2015
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One more test would be for Flooded engine.
Long shot but could happen.
All fuel injected engines have a computer and all have a "Clear Flooded engine" routine you can enable.
Turn on the Key
Press gas pedal down all the way and hold it down(this tells computer to enter "Clear Flooded engine" routine, fuel injectors are shut off but spark stays on).
Turn Key to START, engine should just crank and not fire at all, it is getting no fuel.
If engine tries to start then you could have a fuel leak in to the intake.

As soon as you release the gas pedal injectors will start working.

This is also a nice trick to know when buying a used car...................
Most people, even dealers, do not know about this computer routine.
When starting the engine the first time do the above, and look puzzle, i.e. why won't this POS start????, what are your trying to sell me??

"Hey it's never done that before"
You could get a few hundred dollars off the price.
Knowledge is power :)
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  #8  
Old 10-15-2015
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Did not know that I'm willing to try everything, I've pretty much decided it's up to me to solve it can't afford anymore shops on this problem.
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