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Discussion Starter #1
I am in the process of replacing my distributor on my 95 3.9 with 140,000. Symptoms were while driving down highway it started to hesitation, back firing, very rough idle. I had it towed home. I tried a few days later to start and it started and ran smooth for about a one minute then start with rough idle. I had recently (less than 200 miles) replaced all leads, spark plugs cap and rotor and ran fine. after the breakdown, I replaced the remote located ignition control module. the vehicle ran fine for one day about 100 miles, next day went to back out of the driveway and have same problems as I mentioned before.

So I bought a used distributor on line quoted "from working Vehicle" but I am having reservations about installing since when I rotate the shaft the it spins freely then feels like its catching on something but then will spin smooth again. is this normal or should it be a consistent smooth operation? The one from my vehicle spins freely with no hesitation or "catching while rotating shaft.

What I have done:
new black Lucas cap
put used Lucas rotor with non pop riveted arm in, removed after market rotor arm
new leads
new plugs
cleaned MAF
checked and replaced any cracked vacuum lines
 

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1970-1995 Range Rover Classic
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100 Posts
Hi

Distributor rotation should be smooth all the way round, if you hold the drive gear still and try to turn the rotor arm it should move about 1/4” and spring back to the original position.

Have you replaced the coil? To me that sounds like the more likely problem than the distributor (you’ve already changed the ignition amp which in my experience they work or they don’t there isn’t really any in between).

HTH

Steve


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Discussion Starter #3
Yes, I did replace the coil, with a new one. it has one that I usually don't see on range rovers in the Junkyard a UF304?

UF304 Coil.JPG
 

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1970-1995 Range Rover Classic
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100 Posts
That’s a weird looking coil! Has your car had changed made to the ignition system from standard?

I would be looking to get a new standard Bosch coil, these engines are quite fussy about a good spark


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Discussion Starter #5
The ignition system (remote located coil and ICM) has been in it since I bought it about 12 years ago and has ran perfect till recently.
 

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Discussion Starter #6
Update on the used distributor I bought. I took the dust cap off and pickup plate off and found springs were off the vacuum advance weights. I reassembled the distributor. installed in rover with rotor arm pointing and #1 lead on cap. Motor fired right up, and ran the smoothest it has after a minute or two of run time since I started having problems. It appears my original distributor was my problem. I ran out of time to finalize timing adjustment and I need to clean up harmonic balancer so I can read the timing marks.

should the timing on 95 3.9 NAS be set at +/- 5° BTDC
 

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1995-2002 Range Rover P38A
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359 Posts
Check air gap butterfly valve, check voltage MAF sensor.
Use Champion plugs, runs better as NGK's
 

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Discussion Starter #9
So I did get it running, had it set to 6 degrees. ran good but had hesitation with acceleration. then things went south. stopped running and had no spark from coil. since it stopped and no spark I have replaced coil, ignition control module again (lucas), new distributor pickup plate new battery had the alternator tested, output is good, and current loss. Plugs are champion, air gap set within specs with new pickup plate. Any suggestion would be appreciated. again nothing from coil
 

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You seem to have changed most things that would eliminate faults generally seen in these, maybe something has faults on replaced item which is not unheard of.

But a rough and dirty check on the coil supply side could be useful.

Connect a piece of wire to the + terminal on your coil securely, then connect it to the battery + terminal direct. This will supply an independent constant volts to the coil (the ignition circuit is supposed to do this) now see if it runs.
Leave it loosely attached to battery so that you can pull it in emergency to stop the motor as you've no other means of switch off.

Let us know if it runs like that.
 

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Discussion Starter #11
perfomed the test no go. so i went back through manuals and some where I had managed to get the wires out of sequence. put the wire back in proper sequence and fired right up. timing set to 6° running great. go for short test drive and died. no spark. so I went back through the electrical ignition test and everything was good on test 1 and 2. test 3 i did not get increasing voltage when cranking. On test 4 my Ohmmeter reading was 3.5K. so after doing the test and not changing the amplifier or pickup, since both are new, 3 different amplifiers and 1 pickup plate. I started getting spark again. truck fired and ran then quite within a minute. back to no spark checked all test again and had spark using test 5. tried test 6 with coil to rotor arm. got shocked even with insulated pliers since there was a crack in handle insulation. tried again with plastic clamp and the coil lead was grounding out with spark to rotor arm. tried 2 other spare rotor arms I have and all sparked between rotor arm and coil lead?
 

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Distributor just can't work if the HT side can get to earth via rotor arm, it's got to insulate to allow the HT to travel onwards out through the cap.

Looks like the rotor is bad.

Looks like all your other ignition is functional as you'd get no coil charge/discharge routine without switching.

With all leads and other hardware appearing ok it just looks like you need a known good rotor.
 
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