Another 'Mysterious' BAD IDLE 1995 DISCO 1 (3.9 V8)
#11
#13
How confidant are you on the MAF hose to plenum connection? It's a little askew. Doubt it's sucking unmetered air but hey, worth checking.
Thanks so much for all the input by everyone here so far. Some great info provided by you guys, I've not heard of the base idle passage screw across any forum before so hopefully that will help others out there. Sorry for the lack of communication, I have not had much of a chance to test everything suggested but here is a brief update since last time and a few photos.
> Vacuum advance appears to be in order, gave it a suck test, I can hear the diaphragm pop back an forth.
>The loose hose I found on the right of the air filter box was actually the headlight washer that has been disconnected by someone
> Cruise control has been disconnected at some point ( I don't 'think' this vacuum network has anything to do with what we are talking about here or am I wrong?)
> It's had a bottle of Seafoam in 1/4 tank of gas, no change
> cleaned the connection with paper clip and intake cleanerbetween air filter box and valve cover, no change
> cleaned connection off plenum to vacuum advance with paper clip and intake cleaner, no change
> Checked PCV Tee again, all clear
> I have not done Seafoam / Nulon on the plenum yet due to the issues it has caused in the past, I'll do that when I am sure I don't need the car for several days
> As per suggestion '94Disco1' "A quick check would be squeezing the rear vacuum line from the throttle body to the steeper shut and see if that drives the idle down to stall, or it if just stays as is. If it stays as is you've got a blockage or a bad stepper I think." I did this, I'll check again in case I got the the wrong hose, it sent the idle down to an almost stall then recovered, reading this now I could
have done the wrong line between the fuel regulator and the back of the plenum / stepper.
I've attached photos here..these are the 'chips' I was referring to in the coil to pickup sensor line
Also is this the screw I need to remove to clear the base idle line?
https://photos.app.goo.gl/ijnVfqz5k166Bfsv9
> I've not looked for the following screw suggested here by JohnZo this will be next "There is a metering screw just downstream of the port for the IACV. The factory covers the screw with an aluminum cap, so that will need to be removed to adjust or back out for cleaning. Count turns so you can get it back in."
> A salty old dog at Napa advised me to to spray intake cleaner around the hoses bit by bit to see if revs increase to find a leak, might be a common trick and for a Land Rover fire! .. Any suggestions on this hack?
Will keep you all updated and this thread going until it is solved! even if it's quiet for a while.. this bastard idle will be fixed!
Thanks again to all so far
> Vacuum advance appears to be in order, gave it a suck test, I can hear the diaphragm pop back an forth.
>The loose hose I found on the right of the air filter box was actually the headlight washer that has been disconnected by someone
> Cruise control has been disconnected at some point ( I don't 'think' this vacuum network has anything to do with what we are talking about here or am I wrong?)
> It's had a bottle of Seafoam in 1/4 tank of gas, no change
> cleaned the connection with paper clip and intake cleanerbetween air filter box and valve cover, no change
> cleaned connection off plenum to vacuum advance with paper clip and intake cleaner, no change
> Checked PCV Tee again, all clear
> I have not done Seafoam / Nulon on the plenum yet due to the issues it has caused in the past, I'll do that when I am sure I don't need the car for several days
> As per suggestion '94Disco1' "A quick check would be squeezing the rear vacuum line from the throttle body to the steeper shut and see if that drives the idle down to stall, or it if just stays as is. If it stays as is you've got a blockage or a bad stepper I think." I did this, I'll check again in case I got the the wrong hose, it sent the idle down to an almost stall then recovered, reading this now I could
have done the wrong line between the fuel regulator and the back of the plenum / stepper.
I've attached photos here..these are the 'chips' I was referring to in the coil to pickup sensor line
Also is this the screw I need to remove to clear the base idle line?
https://photos.app.goo.gl/ijnVfqz5k166Bfsv9
> I've not looked for the following screw suggested here by JohnZo this will be next "There is a metering screw just downstream of the port for the IACV. The factory covers the screw with an aluminum cap, so that will need to be removed to adjust or back out for cleaning. Count turns so you can get it back in."
> A salty old dog at Napa advised me to to spray intake cleaner around the hoses bit by bit to see if revs increase to find a leak, might be a common trick and for a Land Rover fire! .. Any suggestions on this hack?
Will keep you all updated and this thread going until it is solved! even if it's quiet for a while.. this bastard idle will be fixed!
Thanks again to all so far
#14
Ok sorry been a while!.. Still no further forward with this. I removed the idle control screw and cleaned out that passage, it was pretty filthy so was hoping that was the issue, no change. I have checked what I thought was bad wiring on a few key parts, injector, coolant temp sensor, fuel temp sensor but they are all fine, just an ugly finish on the job but inside the wiring it secure and tight. I've tried swapping the coolant sensor connection with the fuel sensor connector in case they got muddled at some point, no change there. A friend suggester marvel Miracle Oil in the tank, it's had a few gulps of that, no change.
Thanks 'CantComplain', yeah that's all fine I had undone it before I took that shot, should have mentioned thanks / sorry.
I've been looking at the distributor more closely, the job of moving the amplifier to the right side of the radiator has been done but the distributor is not using the dummy amplifier supplied. There is just some tired looking wires and a half damaged connector running between the distributor and the amplifier. In the parts that came with the vehicle from the previous owner (who owned since 2000) there was a bag with a used (perhaps the original distributor) the dummy amplifier and the brand new harness to run between the dummy and the relocated amp. I can't understand why they decided to do it this way when all the components are there to do it neatly and correctly. My on thought is that maybe the pick up in that spare distributor had and issue? (possible?).
If this was a distributor / pickup sensor issue / amp issue would I not be experiencing deeper issues through the rev range over than a rough random idle?
I've attached photos on the link below of the spare parts and how the distributor is currently set up.
https://photos.app.goo.gl/J3YjyE3EL6oXn1Py8
I've also got a random purple wire come from ECU side of the cabin, it's been wrapped around the jack (could be to do with fog lights, it's go some pretty serious ARB lights on the the bull bars but no connections for them to hook up to, In the cabin I've taken shots of a loose connector floating around and another which has been tinkered with.
https://photos.app.goo.gl/prBukDLpctirfDFBA
I've looked into the cruise control, I used to have a manual one in South Africa but this is a US auto, from what I recall on the manual it was hooked up to the clutch pedal (somebody had hooked that one up to the washer fluid so after multiple clutch pumps your feet would get wet ..), I couldn't see anything on the pedals of this Auto one, what should I be looking for?
Under the hood i don't see any hoses for the cruise control. I see these two coming from the cabin but do not connect to anything (third photo on link below, hoses are beyond the stepper in the back).
https://photos.app.goo.gl/r4j35yBvqzmjGVFt7
If you think I'm getting off trajectory here with the distributor any other suggestions moving forward?? Thanks to everyone as usual!
Thanks 'CantComplain', yeah that's all fine I had undone it before I took that shot, should have mentioned thanks / sorry.
I've been looking at the distributor more closely, the job of moving the amplifier to the right side of the radiator has been done but the distributor is not using the dummy amplifier supplied. There is just some tired looking wires and a half damaged connector running between the distributor and the amplifier. In the parts that came with the vehicle from the previous owner (who owned since 2000) there was a bag with a used (perhaps the original distributor) the dummy amplifier and the brand new harness to run between the dummy and the relocated amp. I can't understand why they decided to do it this way when all the components are there to do it neatly and correctly. My on thought is that maybe the pick up in that spare distributor had and issue? (possible?).
If this was a distributor / pickup sensor issue / amp issue would I not be experiencing deeper issues through the rev range over than a rough random idle?
I've attached photos on the link below of the spare parts and how the distributor is currently set up.
https://photos.app.goo.gl/J3YjyE3EL6oXn1Py8
I've also got a random purple wire come from ECU side of the cabin, it's been wrapped around the jack (could be to do with fog lights, it's go some pretty serious ARB lights on the the bull bars but no connections for them to hook up to, In the cabin I've taken shots of a loose connector floating around and another which has been tinkered with.
https://photos.app.goo.gl/prBukDLpctirfDFBA
I've looked into the cruise control, I used to have a manual one in South Africa but this is a US auto, from what I recall on the manual it was hooked up to the clutch pedal (somebody had hooked that one up to the washer fluid so after multiple clutch pumps your feet would get wet ..), I couldn't see anything on the pedals of this Auto one, what should I be looking for?
Under the hood i don't see any hoses for the cruise control. I see these two coming from the cabin but do not connect to anything (third photo on link below, hoses are beyond the stepper in the back).
https://photos.app.goo.gl/r4j35yBvqzmjGVFt7
If you think I'm getting off trajectory here with the distributor any other suggestions moving forward?? Thanks to everyone as usual!
Last edited by BADidOl; 03-05-2023 at 09:20 AM.
#15
I would check the gap between the reluctor wheel and the pick up inside the distributor. If it is too wide, that could cause idle problems. Make sure base timing is set correctly, spec is 5 deg btdc, you'll need a timing light with the vac advance disconnected. There isn't much room there to aim the light well. I recall an online video LR mechanic sets it to 10 deg btdc to make up for timing chain stretch. Did you ever measure base idle? Base idle and base timing are important. I would check those before opening up the distributor. Let us know the numbers.
You mentioned a chip between the coil and pickup sensor. Rave doesn't show any resistor there, and does show shielding around the two wires from the amplifier to the coil. The resistors go from the coil to the ECU (and Speed Trip for manual transmissions). Check the wiring diagram carefully in case the PO messed up.
One other thing I noticed about the PCV tee. The orifice going to the plenum is a specific size. If it has been hogged out and too big, that could cause idle problems. Maybe get a new one.
Hope this helps.
You mentioned a chip between the coil and pickup sensor. Rave doesn't show any resistor there, and does show shielding around the two wires from the amplifier to the coil. The resistors go from the coil to the ECU (and Speed Trip for manual transmissions). Check the wiring diagram carefully in case the PO messed up.
One other thing I noticed about the PCV tee. The orifice going to the plenum is a specific size. If it has been hogged out and too big, that could cause idle problems. Maybe get a new one.
Hope this helps.
#16
I think you're on the right track with the distributor. I go through a new amplifier at least once a year and one of the precursor symptoms before total failure is hunting idle. When my amplifier or pickup is on the way out I also notice the rpms drop when turning the wheels back and forth while stationary. The power steering pump takes energy from the engine and the weak spark can't quite compensate.
Also - just one more plug for RoverGauge. Once you visualize all of the EFI sensors on that system and confirm all of those are okay, distributor and timing would also be next on my list.
Also - just one more plug for RoverGauge. Once you visualize all of the EFI sensors on that system and confirm all of those are okay, distributor and timing would also be next on my list.
#17
#19
One other thing to consider - make sure your ignition coil is actually wired correctly. I accidently switched my positive and negative terminals in chasing down something else recently. To my surprise the car still ran (albeit with some idle hunting) and other symptoms.
Positive side of the coil = green/white wire (and positive for amplifier)
Negative side of the coil = black/white wire (that potentially links to a blue/white wire) as well as the negative for the amp
Attaching a diagram I've been building to help myself understand the 14CUX system for 94/95
Positive side of the coil = green/white wire (and positive for amplifier)
Negative side of the coil = black/white wire (that potentially links to a blue/white wire) as well as the negative for the amp
Attaching a diagram I've been building to help myself understand the 14CUX system for 94/95
#20
Electrons or holes?
One other thing to consider - make sure your ignition coil is actually wired correctly. I accidently switched my positive and negative terminals in chasing down something else recently. To my surprise the car still ran (albeit with some idle hunting) and other symptoms.
Positive side of the coil = green/white wire (and positive for amplifier)
Negative side of the coil = black/white wire (that potentially links to a blue/white wire) as well as the negative for the amp
Attaching a diagram I've been building to help myself understand the 14CUX system for 94/95
Positive side of the coil = green/white wire (and positive for amplifier)
Negative side of the coil = black/white wire (that potentially links to a blue/white wire) as well as the negative for the amp
Attaching a diagram I've been building to help myself understand the 14CUX system for 94/95