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I have an Australia-built Ford Falcon which has a 4.0L multi-point fuel injected straight 6 and is manual. I rebuilt the head in the car myself last year (blown head gasket) and it has been running fine since.

It’s always had a funny slight flat spot under acceleration. Around 2,500 RPM it struggles to move past until I accelerate harder, then it kind of jumps up to where it should be. Semi-violently.

This more recent problem is that it will stall while driving. I can be doing any speed and be at any point into the journey (10 minutes or an hour, it doesn’t matter) and it will just die. Typically the RPM will just drop to 0, the battery light comes on, and I will just be coasting along along in gear. Knowing that it’s turning over, I usually plant my foot, and it all of a sudden will roar back to life after no specific period of time. This morning it was a good couple of seconds (I was doing about 80 km/h, and it kicked back in when I had slowed to about 60 km/h). Other times it dies and then comes back in almost straight away.

It also can die while stationary at traffic lights etc, it will usually start back up but again today it just turned over and over and over and didn't start for about 30 seconds.

I’m thinking it could be:

  1. Fuel pump
  2. Coil / Dizzy
  3. Some kind of air / exhaust sensor

The problem is because it’s so intermittent and hard to replicate, I don't know how to diagnose it better myself and don’t know where to start.

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If your revs drop to zero while you are coasting along in gear then I'd be very concerned - is the speedo electronic? –  Rory Alsop Feb 19 '13 at 17:52
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2 Answers

up vote 1 down vote accepted

The problem was finally fixed.

After reading the manual I suspected a piece called the TFI Module which is attached to the distributor ($30 piece). All of my symptoms were pointing to this part except the manual (and forums) said usually you need to let the car cool down for up to 5 minutes before it will restart.

New distributors come with TFI modules already attached and a complete Bosch distributor for my car was only about 150 bucks so I thought may as well take that out of the equation as well.

Long story short, replaced distributor (with TFI module) and boom - no more issues :)

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There is a laundry list of things that can cause these problems.

  1. Grounding issues.
  2. Alternator
  3. Battery Connections
  4. Computer
  5. Faulty wiring

To be honest it can be a nightmare trying to sort these things out, and you are better off taking it to a automotive electriction who can plug in diagnostic tools, and take it out for a test drive to replicate the problem. (A couple hundred $$, and a couple hours for a pro, or a couple hundred $$ and many many hours to do it yourself.

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Thanks for your answer and you're absolutely correct. I went through a number of items (fuel relays through to distributor) before the problem was fixed. Ironically, I took it to an autoelectrician and a regular mechanic and neither could pinpoint the issue. Autoelectrician only wanted to replace one of the terminals, mechanics were more eager to replace parts (fuel relays etc). Eventually I ran with my gut instinct and some advice from forums and the manual and replaced the dizzy + tfi module. –  James May 12 '13 at 10:36
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