Range rover flapper problems
Discussion
Hi everyone,
I'm hoping someone might be able to help me out with a few problems with my '87 3.5l EFI lump. It's overfueling badly, ie: choking itself when left to idle and black smoke out of the exhaust.
I've checked the usual suspects, coolant temperature sensor reads ok, extra air valve operates correctly, and the throttle position sensor is giving good readings apart from the test between the green and yellow wires, which should give a result of 4.3 v, i'm getting 3.6 v, i've swapped the TPS (twice!) and still get the same result, which appears to be what the ECU is supplying it. While I don't think this is causing the overfueling issue, could anyone shed light on why this may be happening, it always used to give the correct reading. I've also checked fuel pressure, approx 30 psi and it holds pressure for about 40 mins with engine switched off, so i'm guessing the injectors are ok. This is as far as i've got, I need to retest the air flow meter, but the car hasn't really been run since it's last test.
If you need anymore info please ask,
Cheers, Ratty
'71 109" series IIa station wagon, with '87 3.5 Efi V8
I'm hoping someone might be able to help me out with a few problems with my '87 3.5l EFI lump. It's overfueling badly, ie: choking itself when left to idle and black smoke out of the exhaust.
I've checked the usual suspects, coolant temperature sensor reads ok, extra air valve operates correctly, and the throttle position sensor is giving good readings apart from the test between the green and yellow wires, which should give a result of 4.3 v, i'm getting 3.6 v, i've swapped the TPS (twice!) and still get the same result, which appears to be what the ECU is supplying it. While I don't think this is causing the overfueling issue, could anyone shed light on why this may be happening, it always used to give the correct reading. I've also checked fuel pressure, approx 30 psi and it holds pressure for about 40 mins with engine switched off, so i'm guessing the injectors are ok. This is as far as i've got, I need to retest the air flow meter, but the car hasn't really been run since it's last test.
If you need anymore info please ask,
Cheers, Ratty
'71 109" series IIa station wagon, with '87 3.5 Efi V8
If yours has the 4CU ECU these are notorious.
I've had my 1986 RRC 3.5EFi since 1994 & IIRC I'm on my 4th. I carry a good spare in the car.
When they've failed it's been instant - as in fine one minute then bad the next & never as an intermittent issue.
One ran rough with lots of black smoke & another ran rough but without smoke. I can't remember what the other did.
I have LPG - manually switched - & that does give me a bit of a diagnostic as if it runs rough on petrol but fine on LPG it's a fuelling issue & if it runs rough on both it's an ignition issue.
The AFM has never given me a problem.
Have a read:
http://www.carelect.demon.co.uk/rrind.html
I've had my 1986 RRC 3.5EFi since 1994 & IIRC I'm on my 4th. I carry a good spare in the car.
When they've failed it's been instant - as in fine one minute then bad the next & never as an intermittent issue.
One ran rough with lots of black smoke & another ran rough but without smoke. I can't remember what the other did.
I have LPG - manually switched - & that does give me a bit of a diagnostic as if it runs rough on petrol but fine on LPG it's a fuelling issue & if it runs rough on both it's an ignition issue.
The AFM has never given me a problem.
Have a read:
http://www.carelect.demon.co.uk/rrind.html
Thanks Paintman, I have swapped the ECU for another to check, although i'm not 100% on how good the 2nd ECU was, it did give exactly the same result on the TPS test, the odds of two seperate ECU's giving the same fault are pretty unlikely (although possible), i'm going to try going through the EFI tests in the manual with the original ECU and the 2nd one just to see if there are any differences.
Thanks for the reply
Thanks for the reply
Ratty109 said:
Thanks Paintman, I have swapped the ECU for another to check, although i'm not 100% on how good the 2nd ECU was, it did give exactly the same result on the TPS test, the odds of two seperate ECU's giving the same fault are pretty unlikely (although possible), i'm going to try going through the EFI tests in the manual with the original ECU and the 2nd one just to see if there are any differences.
Thanks for the reply
You need to be certain the test ecu is good so that means from a running car. They do turn up on ebay but it's difficult to know whether they are good until you try it on the vehicle.Thanks for the reply
FWIW the 4CU comes with various part numbers. I have 4 different numbers on the ones I've got & notice no difference. I did ask Lucas a few years ago & the opinion was that they're all the same. Whether that's entirely accurate I don't know!
Hi,
I had mega problems with my Range Rover classic after a restoration, could not get my mixture co down below 4.5 to 6 % on tick over it chocked up badly etc etc. For information my throttle pot has always only gone to 3.6 volts on test it’s still the same checked it yesterday,,
My issue after changing everything was the flapper valve I managed to borrow another one put it on and mixture / co went straight down to 1.2 % , carefully cleaned the original unit and found the flapper was sticking its all ok now running around 1.5% took me around 2 months of weekends to sort!!!!
Another thought have you unplugged the 9th injector just to eliminate it, also have you tried adjusting the mixture Allen screw to see if it makes any difference,, just keep a note how many turns you have made so you can always put it back.
Must admit I learnt an awful lot about the flapper system over those few weeks Lol!!!
I had mega problems with my Range Rover classic after a restoration, could not get my mixture co down below 4.5 to 6 % on tick over it chocked up badly etc etc. For information my throttle pot has always only gone to 3.6 volts on test it’s still the same checked it yesterday,,
My issue after changing everything was the flapper valve I managed to borrow another one put it on and mixture / co went straight down to 1.2 % , carefully cleaned the original unit and found the flapper was sticking its all ok now running around 1.5% took me around 2 months of weekends to sort!!!!
Another thought have you unplugged the 9th injector just to eliminate it, also have you tried adjusting the mixture Allen screw to see if it makes any difference,, just keep a note how many turns you have made so you can always put it back.
Must admit I learnt an awful lot about the flapper system over those few weeks Lol!!!
Edited by jensencars on Friday 2nd August 16:28
A quick update, I seem to have cured the problem for the moment, turns out the idle control screw, and mixture screws were way out, I sprayed some carb cleaner into the bypass channels and adjusted the idle screw to 2 and a half turns from full in (it was 8 turns!) And did the same with the mixture screw, the engine now fires and goes to fast idle straight away, CO is probably still out but until I can afford a gas tester I can live with that, but the idle seems good, gonna get a timing gun on it next weekend and set it to 850 rpm as recommended.
The weird thing is I've never touched the screws before, they've been that way since I got the engine, maybe the bypass channels were blocked with crud, or they were set that way to compensate for a previous air leak??
Thanks for everyones help and if I figure out more i'll let you know.
Cheers, Ratty
The weird thing is I've never touched the screws before, they've been that way since I got the engine, maybe the bypass channels were blocked with crud, or they were set that way to compensate for a previous air leak??
Thanks for everyones help and if I figure out more i'll let you know.
Cheers, Ratty
Edited by Ratty109 on Sunday 4th August 18:25
If yours has the breather on top of the offside (UK driver's side) and a hose leading from the top of it to the front nearside of the plenum chamber then the wire filter in the breather can block.
The passage in the plenum can also block - it turns 90 deg to the offside for a short distance then 90 deg towards the rear where it opens into the plenum behind the butterfly. Mine was blocked solid when I bought it but all it did was to cause the crankcase to build up pressure & result in oil leaks from all sorts of interesting places! No apparent effect on the running/idling once cleaned out.
The passage in the plenum can also block - it turns 90 deg to the offside for a short distance then 90 deg towards the rear where it opens into the plenum behind the butterfly. Mine was blocked solid when I bought it but all it did was to cause the crankcase to build up pressure & result in oil leaks from all sorts of interesting places! No apparent effect on the running/idling once cleaned out.
Edited by paintman on Saturday 10th August 10:50
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