Classic Where’s my ECU?

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AdamHarley

Member
Posts
58
Evening, i’m on a process of elimination to try and find my poor running issues. Tried a MAF from a well running car and it made no difference so am on to the ECU now. Is it under the passenger or drivers seat?

Its a 91 RRC

Thanks
 
Found it. Under drivers side (right hand drive car). Phew - Passenger side had loads of stuff under there!

Any suggestions for good people to sort it out? Want it repaired rather than replaced

Thanks
 
What difference did the ECU from the car you tried the AFM off make?
If you didn't try it then you should to be sure that it clears the fault.
 
What difference did the ECU from the car you tried the AFM off make?
I haven’t tried another ECU yet. I was nervous to borrow my mates just in case anything happened to it! His RR is his daily driver. He did offer though.

Could it be damaged? His is a 93 soft dash
 
Note the advice given in this link:
http://www.carelect.demon.co.uk/rrp2.html

Mine's a 1986 3.5EFi with the flapper afm & the 4CU ECU. The 4CU does have something of a reputation! I've had two ECU failures in the 24 years I've owned it. Onset was sudden & permanent.
First was rough running accompanied by lots of black smoke.
Second was just very rough running.
I also have LPG & switching to it restored normal running.
Substituting another ECU also cured the fault. I've never had one rebuilt though as I picked up a couple of spares for not a lot some years ago after the second failure & a spare lives in the car!

Air leaks can cause issues - includes poor sealing between plenum & ram housing & damage any hoses. Again on mine sudden onset of rough running a couple of months ago turned out to be a split air hose.
 
Thanks. I’ve seen that link before so may get in touch with them. I would really like to try and find one to borrow first just to check if it really Is the problem. Issues started with intermittent misfire and have progressed to a full blown lack of power. The engine revs fine in neutral but has nothing under power. Have changed distributor, coil, leads, plugs. Tried a MAF from a running car and that made no difference hence looking at the ECU
 
Try with the fuel filler cap off/open. If this gives an improvement then you have a blocked tank breather. Don't go fast round corners with it open to avoid fuel spillage.
 
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