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Discussion Starter #1
Hi all - new here. Have always been a member of another forum as a Series owner but since buying my RRC, haven't had much luck in their section!

After many years of resisting the urge, I finally gave in and bought an RRC that's had a significant amount of the nasty jobs done, mainly involving the rot removal! However, one annoying issue it has is that once it has warmed up, it hesitates/momentarily cuts out under medium power. If you plod along or floor it, it recovers but it does make cruising quite tricky, particularly at mid-range speeds. Very annoying!

So, it is a 1992 3.9 efi with Lucas 'Limb' system 35DLM8 (ignition module on the side of the distributor). So far, I have done the following:
  • Replaced plugs. Leads, cap and rotor all look new but I haven't ruled them out.
  • Removed and cleaned the MAF - wires weren't touched but actually looked quite clean.
  • Removed stepper motor and cleaned. Again, was quite clean but there's not a lot to see. Am I right in thinking that I shouldn't be able to move this in and out? There was a little sideways movement on the sprung cone shaped part indicating it wasn't stuck. Could anyone confirm what I should look for here? I did unplug it whilst running and the engine revved up much higher so it's clearly doing something.
  • Removed and cleaned the throttle potentiometer. Again, not a lot to see but the central tab seems to rotate easily.
  • Replaced temperature sensor. On this note, this part came from Bearmach and annoyingly, the outer plastic body has detached from the metal threaded core meaning that I can neither remove or tighten it! Fortunately, it is sealed but will be a job for another day. Disgruntled to say the least, particularly as it is little more than finger tight.
  • Replaced ignition module.
So, I'm stuck. No idea what to try next and that's not to say that I haven't missed something from above. Can anyone shed any light?

Thanks
 

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Have you looked at the code reader
Under the passenger seat to see if you are getting any codes
It is located on the side facing the door behind the bottom seat panel
 

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Discussion Starter #3
Thanks for your reply. I don't have a code reading device, unfortunately...
 

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The code reader is already there
It is a black box when you turn on ignition it will display the codes
 

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I had a 91
And now have a 92 it was on
Both
Very useful
 

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Discussion Starter #7
Thanks again - can't see anything capable of giving codes on either side. Picture of the position you mentioned attached.
15648407494572804780658587707947.jpg
 

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you in USA or Britain?
It’s behind this panel
And it looks like this

CD0A58E2-9099-4203-9A3D-448AD5A9F915.jpeg
1DFB7112-454D-46AC-9197-32085059EE31.jpeg
D9210D01-6861-4E0F-8749-6EF99A073CF5.jpeg
 

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I moved mine so I could always watch it
 

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Discussion Starter #10
In the UK. So for me, is it under the driver's seat? Didn't notice that box though. Is the ECU under there too?
 

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It is actually mounted to the side of the seat mount
Might be on the other side
It should be there somewhere
 

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It may be related to cat equipped vehicles, in that the fault code came with that spec.

Mine is a 3.9 UK 1991 build, no cats and no code reader that I'm aware of.

With the other parts of system generally checking ok I feel you'd need to verify the throttle pot to make sure it's response is linear next.

Stepper motor should just control idle speed so not affect mid range.

Which UK area are you located?
 

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Discussion Starter #15
Lol thanks for the welcome and useful advice. The throttle pot looks like a later part so still on my radar. Definitely can't find a code reader. I'm based in Essex but move around all over the place.
 

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Not having the code reader in eather of you guys rovers to me would seem odd

Why would the U.S models have what I would concider a more advanced
Feature
A head scratcher there
 

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Discussion Starter #17
Not sure about the code reader but certainly can't find one, nor a lead to put one in!

Just adjusted the MAF as advised. Was reading 150 so turned clockwise to read 300. If anything, it's made general running less smooth and the issue is still there. I should also say that it can be lumpy when cold. There is a golden period of about 2 minutes when it runs perfectly!
 

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Trying to figure this stuff out can be quite aggravating
I know
My 91 was a major pain
But learned a lot
I learned even though they are a pain
When ya do get it right they are just plain awsome
So
Have you checked the vacuum hose at the stepper motor the connects to the fuel pressure regulator
 

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Discussion Starter #19
I haven't but will do. I did give the engine bay a wood going over with WD40 to check for vacuum leaks but showed nothing.
 

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Not having the code reader in eather of you guys rovers to me would seem odd

Why would the U.S models have what I would concider a more advanced
Feature
A head scratcher there
It looks like it was you in USA export that got the cat equipped 3.9 before us over here. They possibly did either intentionally for USA legislation before UK, and or run out stock parts into domestic if not needed.
 
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