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Wheeldon46

New Member
I’ve been having rough running at idle and smells quite rich, it has power through the range it just misfires at idle and plugs are black wet and oily. Done a vacuum leak smoke test that the only place it leaks is from under the distributor cap (not sure if that’s normal?) vacuum pressure test is 11hg so on the low side. Compression test lowest 155psi and highest 170psi. I’ve checked the sensors with a dmm and in roverguage and they all checked out. Injectors are refurbished and checked the fuel pressure 36psi when disconnected fpr and 27 when connected with engine running, also holds pressure when not running. It’s had a new ignition system with new distributor leads and plugs. I’m confused why it’s leaking from the distributor? It’s a 3.5 with a 3.9 plenum and 14cux ecu I guess a leak down test would be the next thing to do. Any ideas?
 
Vacuum shouldn't be leaking at the distributor, that's how the ignition timing is adjusted to engine load. That won't explain rough idle though but maybe losd of power
 
if its leaking vacuum.. is it a split/brittle pipe/connector? if the smoke is coming from inside the dizzy then its probably knackered and you need a new one
 
It sounds like the vacuum bell has rotted on the side of the dizzy. This will stop dizzy timing adjusting🤔
Does it have exhaust lambda sensors on it?
Not familiar with this era but.... 👍
 
Hi it’s running non cat map and no lambada it’s Hotwire maf setup. I have sucked on the advance pipe and I can see it advancing with a timing light.
 
Just tried that and It holds vac. Tomorrow I will try another distributor to eliminate that, it’s very strange! I’m starting to lose patience with the thing lol
 
Was kind of hoping that a smoke test would find something simple like that but no the hoses are fine. I’ve checked them individually as well. Also got hold of another ecu to compare and still have the same rough idle although not taken it out on the road yet to give it a run
 
The ecu is standard to my knowledge but I haven’t opened it up to check the chip, I’ve played about with the timing and it seems best at around 6-8deg btdc. Plugs are standard Ngk BP6ES
 
The ecu, is it for the 3.5 or 3.9?
Have you checked tappet gaps and do you know the condition of the valve heads and seats? 👍
 
Looking at the ecu codes the one that was fitted was from a 4.0 and the other one that I tried is 3.9 I must admit the 3.9 did smell a little less fumey but not had the chance to take it out on the road to test it properly. Compression seems ok but not perfect, lowest 155psi and highest 170. I’m just gathering the kit to do a leak down test this weekend to determine if I need to bite the bullet and pull it apart!
 
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