Thread: RRC 3.5 EFI running rich

Originally Posted by basic

Hello all,
I recently got an RRC 3.5 EFI that's running very rich. I have it booked in for a service but they couldn't get me in for about 2 weeks so I'm wondering what I can do until then to try and fix it myself and maybe save a bit of cash. I'm handy with a spanner but don't know anything about general electronics or EFI systems.
When I first got the car it wouldn't idle, raised the idle speed via the throttle screw and then it started running rich, uses a lot of fuel and blows huge clouds of black smoke under load with a constant stream of not so thick smoke at idle, still enough to smoke out anyone behind me at traffic lights.
I changed the plugs today, they were all very black and sooty but the new plugs haven't made a difference. I have been doing some testing and looking around on these forums for help, so far I have checked the vacuum for the FPR which seems fine, I'm not really sure how to use the multimeter to check the TPS or the CTS though I did notice the plug on the CTS is broken slightly.
One thing I should note is the previous owner told me the AFM had been "serviced" before I got it, the top cover has been taken off so I dunno if maybe that's the problem? The car blows NO smoke with the AFM disconnected but opening the throttle even slightly without it causes the engine to die. The CO adjusting screw on the AFM doesn't seem to change anything either.

Aside from being unsure how to test the TPS/CTS can anyone suggest other things I can try?

TPS will have zero volts on one wire, 5 volts at another and a voltage varying between these limits with throttle position at the third wire.

Idle speed should be adjusted by a 3/16 inch allen key down the hole for the bypass screw. Have you knocked off the vacuum hose of the fuel pressure regulator? Disconnect the wires to the cold start injector, high on the rhs of the manifold. Crimp the hose if it isn't perished to see if it is flowing fuel.

The prime candidate in this problem is IMHO the water temp sensor.
This is not the one on the front of the manifold with a single wire. that is for the gauge.
There will be one on the top of the manifold just behind the gauge one. it should read 300 Ohms or less at hot engine temp.

The second thing on one of these "flapper" engines is the cold start injector , which is controlled by the Thermo time switch.
Disconnect the fuel hose to the cold start injector and see if that fixes it. if so you have narrowed the problem to the injector being stuck open or a crook Thermo Time switch.

TPS and flapper sre unlikely to cause extreme richness. TPS will cause a stumble off idle or not run at all, and the Flapper will cause just poor running if the AF ratio is crook. Its possible that the spring in the flapper is broken but you can check this by GENTLY lifting the flap and seeing if it returns to position. If teh flap moves smoothly and returns to closed its unlikely this is the problem.
Regards Philip A

Didn't knock the hose off but I just took it off to check that it didn't have any holes or anything and it and the one that comes from the manifold is ok too. I couldn't see the cold start injector though, by RHS do you mean driver's side? Everything else is under the intake gear so I can't see what's there.

Originally Posted by basic

Didn't knock the hose off but I just took it off to check that it didn't have any holes or anything and it and the one that comes from the manifold is ok too. I couldn't see the cold start injector though, by RHS do you mean driver's side? Everything else is under the intake gear so I can't see what's there.

Sorry yes drivers side. Like the temp sender idea though, you could procure a variable resistor set it to 300ohm and plug it in, see what goes.

I couldn't figure out which one was the coolant temp sensor, there is 2 at the front of the manifold, just above the thermostat housing and right next to each other, just behind the radiator hose. They look exactly the same, have injector style plugs and both have 2 wires.
The AFM seems fine the flap smoothy returns shut if i open it.

They look exactly the same, have injector style plugs and both have 2 wires.

Are you sure that one doesn't actually go to the injector on no2?

I cannot remember the layout of a 3.5 flapper but I am pretty sure there is only one sensor there and the gauge sensor is on teh front next to the thermostat.
Regards Philip A

I had a 89 Vogue 3.5 that did the same thing. Went straight to the AFM, checked O.K. but replaced it with a know one that was good, no change. If you disconnected it the engine idled fine until revs were increased then died.

Checked and replaced EFI temp sender (thermo time sender that controls cold start injector) still no joy. Checked cold start injector O.K. Pulled dizzy and checked O.K. Fitted new leads, plugs, cap and rotor, still no joy.

Replaced injectors, still no joy. Kept blowing black smoke (running rich and idled like it had a hugh cam but over fueling bad).

After I had checked all I could (and as I was about to set it on fire) I took it to a mates work shop (Land Rover specialist) and turned out to be bad earth connections and ECU problem. Check all your earths are good to ECU etc and if you can get a known ECU try changing it.

If you still have problems I can find out exactly what earths were R/S and probably give you a more detailed run down on what to do.

Hope this gives you some direction (as I had none).

Cheers Gavin

Took this picture from another post on here, this is the plug I'm talking about. Is this the right one?