Discovery 1 1997 (or 96) 3.9 v8 127.000km

I´m having a hell of a time fixing an issue with how my motor is running. Pinpointing where or what is causing the problems has been a looong and confusing process. All the issues seem related unless I suddenly have more problems than known. I have read through so many threads, guides, etc and feel its time to be more direct via discussion.

Problems:
-Running rich. Exhaust smells like that of a 2 stroke lawn mower (smelling rich) and the fuel consumption is not good at all
-Hard failing emissions test. Suppose to get under 0.2 or something. Its reading a solid 10! Already done fuel additives, heated up motor etc. The engine runs really smooth though.
- surging idle. Half the time I'm at idle it will rhythmically go between 600rpm to 1000rpm.
- Turns off sometimes. When driving through deep snow or water and having to really push it, it will die when I suddenly let off the throttle causing the car to stop quicker due to being bogged down (think deep in snow).
-Can't read ecu. I tried my Icarsoft reader, a friends universal reader, even the local mechanic can't get a reading (won't connect)

The background info on the car which is wordy:
Before I got it it had been sitting for 5 years as the last owner died. I got it and left it in my garage for a year, starting it periodically. When I got around to working on it I put new fuel in and took it to its first inspection in years. At this time it was hard to start(10 seconds of cranking) and had an issue with just cutting out. It passed the inspection just fine which I was surprised by.
So in time I get to working on the car trying to figure out what it needs. So I just decide to replace everything I can as its an old car that was sitting for a while even though it wasn't used much so better to start off fresh.
At the same time I'm looking into replacing everything(sparkplugs, wires, cap, rotor, several sensors, fluids, all filters) I have an issue with it not starting up and when taking the spark plugs out they were wet with fuel. When I dried them off and put them back in it started up easier. So I took apart the fuel system and found the fuel rail and tops of the injectors gunked up with crap and rust. The car had sat so long that there was a buildup of gunk and some erosion after the fuel filter. I cleaned everything out and replaced all the injectors and the fuel pump. Also replaced the fuel pressure regulator as it also had crap in it. Also replaced the fuel temp sensor and both coolant temp sensors. Cleaned the hell out of the intake plenum and the idle control.
After all the parts replacing and cleanup, the car started up great, and ran strong but it had the surging idle now which was not there before replacing fuel system. I could not tell if it was more or the same smelling in exhaust terms but when it went to inspection the next time it failed emissions SO BAD. Looked all over for vacuum leaks and could not find any. Shop could not either. So thats where I am

So the simple list of what parts i replaced that I can remember:
spark plugs (champion)
lead wires
cap and rotor
ignition coil
fpr
O2 sensors (only has 2, not 4)
fuel pump and filters
vacuum advance
fuel temp sensor
coolant temp sensors

I am at my wits end here. Not like I have many garages to take it to either. I live like 50km from the edge of the arctic circle in Iceland.

My thoughts that need answers incase if these things matter as many parts were changed at the same time before problem arose:
-the new fpr was different than my original. Mine is the one with the male nipple connection(ETC8494) The one I got had a female screw in connection(ERR6185). I managed to hook it up with a combination of items. Are they the same or are they different beyond the one fitting difference?
- with the idle surge, would the throttle tension spring affect this? One of them is broken (ERC3792L). I do not know if it was already broken or happened during the injector swap. It is impossible to find a replacement online.
-could it be spark plugs not burning well enough? Current are champions, previous ones were some kind of NGK+
-Might I have a wrong sensor replacement (fuel or engine temp) that fits into motor and plug but is incorrect?
-The lack of a check engine coming on and inability to read the computer would answer everything if I get it corrected, if possible. There is a check engine bulb in the dash btw. I see it illuminate like everything else right and startup.
-tried unhooking maf while it runs and it gets rough as expected then back to fine when hooked up again. Not able to get readings from MAF due to ECU not connecting for read. I have checked the satellite fuse for ecu. It is good.

Any help, pointers, etc would be great. I need to pass the inspection in spring and not waste more money on fuel than needed. It is WAY expensive here.

Thanks!

It seems that you have giving the engine it a good shake down, with the ten parts u replaced also Champion plugs are ok.
I can’t say I ever seen the engine check engine light in my 3.9 illuminated, so it thats so then that may be a clue to a faulty EFI ECU, something which I had with my 3.5 which was showing black smoke on starting, a few components had failed in the ECC so I had it repaired by Lucas… but thats in the good old days.

A blocked crankcase breather ( flame trap) will stall the engine when an additional load is placed on it, so unscrew it and wash it in petrol and refit check the pipe from it to the plenum also.

I’m on my way home now so will have look at the part numbers u provided plus reading the rest of your post tomorrow.




Send from my iPad on a train

Ok, the fuel pressure regulator ETC8494 is fitted to vehicles with a TA Vin and ETC6185 is fitted to later vehicles with a VA Vin.
Throttle spring ERC3792L is correct… but now obsolete


Your issues with idle the first thing to checking vacuum hoses, and then the base idle selling, info on that for adjustments is in D1 workshop manual.

The owner manual states if the Amber Check Engine (if fitted) illuminates at any time it indicates an engine fault and avoid high speeds and seek qualified assistance urgently. So sounds as serious

discool said:

Ok, the fuel pressure regulator ETC8494 is fitted to vehicles with a TA Vin and ETC6185 is fitted to later vehicles with a VA Vin.
Throttle spring ERC3792L is correct… but now obsolete

ERC3792L TENSION SPRING V8 EFI ACCELERATOR LAND ROVER DEF RRC DISCO 1 - Land Rover Treasure Shop

NOS GENUINE LAND ROVER V8 EFI ACCELERATOR TENSION SPRING DEFENDER RANGE ROVER CLASSIC DISCOVERY 1 ERC3792L

landrovertreasureshop.com

Your issues with idle the first thing to checking vacuum hoses, and then the base idle selling, info on that for adjustments is in D1 workshop manual.

The owner manual states if the Amber Check Engine (if fitted) illuminates at any time it indicates an engine fault and avoid high speeds and seek qualified assistance urgently. So sounds as serious

Click to expand...

Are the working values of both fpr the same? Whatever pressure they maintain has been an idea to think about unless that does not actually matter or else they are the same, just one connection point differs.

That Broken throttle spring annoys me. Only way I will get a replacement is from a completely broken v8 that doesn't need its throttle body anymore.

I have sprayed checked, sprayed again for finding vacuum leaks but nothing yet. I can adjust the idle with the plastic screw on the throttle cable. I don't have access to any other way to change the idle other than removing the plastic plugs and turning that screw. I want to avoid that as the idle issue is something else. When it is not surging it idles smooth and nice.

The amber light does not come on ever in any manner indicating a problem uness this is a new way for it to vaguely whisper something to me. I only ever see it along with all the other lights flash for a split second when turning the car on. Still, not being able to connect to the ecu at all is concerning.

I will check the flame trap you mentioned to see if that helps with the load issue. I wonder if the issue causing the dying under load is also just related to whatever is causing the running rich.

On start up there is no black smoke but in time the exhaust is noticeable in it's amount. Its a light grey color. No funny smells besides the unburnt fuel smell. Coolant levels are fine, no mixed fluids, all cylinders pressure checked also.


I'm left thinking that all the possible culprits are between faulty/wrong sensor, vacuum leak, faulty MAF, fpr(questions about it unanswered atm), and now ecu.
The possibility of electronics being at fault somewhere could be a possibility as there is a leak from the rear sunroof and/or whatever the curved roof glass is called, so there is moisture getting in at times. Sourcing a spare ecu to swap out is a challenge given my location. Fun times.

With fuel pressure the TA is 1996 model year and VA is 1997 model the engine is the same as the 1995 MA Vin so any component change or addition is simple a design change.
The last D1 model year was 1998 had a few design changes to the vehicle, then the 1999MY disco was a D2 which appeared in the show rooms in late 1997 in the UK.

I don’t expect the throttle spring is unique to the Land Rover V8 so a similar spring with a similar spec could be adapted (hooks each end) can be found.

The EFI ECU looks after the idle, adjusting rpm to the load etc placed on the engine, so forget the adjustments of the throttle cable unless you have play in the cable, its not for adjusting the idle rpm.
The Base idle was set in the factory thats why a anti tamper plug fitted, so there not need to touch it. unless it has been tampered with in a strip & rebuild.

A quick google found this spring, similar maybe or not but theres pages of similar stuff.

discool said:

With fuel pressure the TA is 1996 model year and VA is 1997 model the engine is the same as the 1995 MA Vin so any component change or addition is simple a design change.
The last D1 model year was 1998 had a few design changes to the vehicle, then the 1999MY disco was a D2 which appeared in the show rooms in late 1997 in the UK.

I don’t expect the throttle spring is unique to the Land Rover V8 so a similar spring with a similar spec could be adapted (hooks each end) can be found.

The EFI ECU looks after the idle, adjusting rpm to the load etc placed on the engine, so forget the adjustments of the throttle cable unless you have play in the cable, its not for adjusting the idle rpm.
The Base idle was set in the factory thats why a anti tamper plug fitted, so there not need to touch it. unless it has been tampered with in a strip & rebuild.

A quick google found this spring, similar maybe or not but theres pages of similar stuff.

Click to expand...

Still at it and did a few things you mentioned.
I checked the flame trap and it was gummed up really bad. Overnight soaked in petrol did little. Brake cleaner did far better. Rinsed it well, let it fully dry and then back in.
I also took the MAF out to have a look at the hot wire. One or both seemed dirty. Cleaned with electronic cleaner and I noticed a visible difference.
After this starting up and getting to idle was a challenge but leveled out after a few starts and revs.

Still has most of the same issues. When high revving then letting off the throttle completely the revs fall below 500 to almost zero actually, almost stalls completely but managed to keep idle and balance back up to about 700 . The idle has some surging still.

I am inclined to have a better look at the stepper motor if its condition is as it should be. I would like to be able to reset it or reset my new one I have sitting on the shelf but that takes some computer add on stuff I do not have access to. Or I have not managed to find a walkthrough to do it if there is such a way. Of course the motor itself should not be the culprit and I have already cleaned it before. I am thinking on this as the only way the car stays at idle is because I have adjusted it from the throttle cable. If I remove the extra tension from the throttle cable it wont idle at all. Just dies. Of course everything idle related is needed to be looked at. The stepper should be the only thing controlling idle. Side note: I can manually turn the plunger on the currently installed stepper, but not the brand new one.

Still can´t read the ecu

New details thoughts:
All spark plugs are completely carbon fouled as would be expected of a running rich motor.

I got an airlock in the coolant system. I just remembered it earlier and did a search on it. I can hear water sloshing through the heater system from the passenger dash. That means air in the radiator system. Could this air be fouling up the sensor readings?

1. The flame trap is or was a service item and replaced when I had my RR by the main dealer service dept.
Fo the ten years I owned it. When I started doing my own service on my disco I fitted a new replacement and with the old one cleaned in petrol (engine is low mileage so only had to remove the oil) became the spare, both used alternately and changed every three or so years now.
2. The ECU found something different so was doing best and just readjusting with an optimum setting.
3. When high revving and the letting the revs fall and then picking back happened a few years with my 3.9 but I couldn’t find any issues. So someone suggested using Redex or similar in the petrol and the issue disappeared so a result, now use the stuff a couple of times a year… something else that a main dealer uses in a service, its shown on their bills.
4. If the stepper motor u have is doubtful then replace it, no computer required and check the base idle. Tip, always use a new fibre sealing washer.
5. Can’t help with an ECU function testing, here in the UK we can send it off for testing, and then returned in a few days with replacement and upgraded parts fitted.
6. Do you have the correct grade of spark plugs Brand doesn't matter in my experience, I had annoying cold start issues with my disco after a service by an independent, it found out that had fitted 3.5 plugs, lucky I had asked for the old ones back at the time which were still newish.
7. Air lock in the cooling system showing as the gurgling/bubbling etc in the heater matrix is common if the system is filled incorrectly… filling the system quickly. So fill slowly via the reservoir so the matrix fills first, check the rad is full, run the engine and top up when cool, the system is self venting on the 3.9.
No is the answer to your question.
8.

I had very rich running on my 3.9 and it failed test off the scale and exhaust smelt of petrol. Mine turned out to be a blown fuse in the engine bay which supplies power to O2 sensors. Just incase you are not aware the D1 is not OBDII compliant so a "normal" code reader wont connect. The ECU 14cux needs a special cable and serial port to communicate. There are some diagnostic articles on here somewhere.

Get Rovergauge. the car is NOT OBD compliant.


The hunting idle, if not related to a vacuum leak or poorly set idle bypass etc, often comes from running rich. If the emmisions are that bad, it probably IS runing rich, but SO MANY people try to "fix" these things by bodging stuff up and fiddling with the MAF etc though, you really need to go through the whole system and set it all up correct;y.

You need to get rid of ALL vacuum leaks, including the dipstick seal and crankcase breather system, etc. (which also includes the inlet bleed into the rocker cover, the Tee behing the dizzy, into the plenum etc). Then set the base idle correctly (you should be able to get a smooth idle at less than 550RPM, but the lower the better, really. 500 is possible if everything is set really well). The bypass possibly needs a good clean out too - they gunge up with blowby gasses etc - I remove the screw entirely and use foaming upper engine cleaner in there, and a sturdy cable tie to poke around.

Check the ignition timing correctly and try advancing it. Be aware the outer ring on the crank pulley may have turned on the rubber too. Also see if the vacuum advance is intact - they fail a lot, and create a vaccum leak - it doesn't affect running too much, except less cruising advance, so the economy at cruise/part throttle is worse)

It's actually pretty rare for the Idle stepper to "fail". They often just need a clean (You can use rover gauge to drive it open, when removed, until it falls apart, then reverse the process to put it back together, being VERY careful to line up the indexing notches), then a lube with VERY light oil, or even a quality silicon spray. Nothing with any viscosity or body to it.

If you are running O2 sensors, you can get quite a lot of info from Rovergauge. It's still very handy, if not. The advantage, is that you can see exatly what the ECU is reading, which means whether a sensor, wiring or even the ECU have the fault, rather than assuming a (for example) new coolant temp sensor should be reading OK. Or if someone has pluged things in wrong etc.

The O2 sensors will allow Rovergauge to show you both short and long term fuel trims on each bank.

If you have manifold leaks, near or before the O2's, the ECU sees that as a lean mixture - there is excess air sucked in the leaks bewteen exhaust pulses - so the ECU pushes the fuel trims positive/richer, even though the actual engine is running too rich... but it still appears lean to the ECU... so it goes further, until full trim is reached.

PaulJM said:

I had very rich running on my 3.9 and it failed test off the scale and exhaust smelt of petrol. Mine turned out to be a blown fuse in the engine bay which supplies power to O2 sensors. Just incase you are not aware the D1 is not OBDII compliant so a "normal" code reader wont connect. The ECU 14cux needs a special cable and serial port to communicate. There are some diagnostic articles on here somewhere.

Click to expand...

I was aware of that 14cux is not obd2 compliant but so much online info it threw me off. What threw me off the most is that there is a obd2 plug under the steering wheel! Why the hell is it there? After tons of online reading and searching I got more info on 14cux and had a look and viola I found the plug sticking out of the ecu. Ill be ordering the usb plug online for it and download roverguage so I can get a look at whats up.

AllanWorms said:

Get Rovergauge. the car is NOT OBD compliant.


The hunting idle, if not related to a vacuum leak or poorly set idle bypass etc, often comes from running rich. If the emmisions are that bad, it probably IS runing rich, but SO MANY people try to "fix" these things by bodging stuff up and fiddling with the MAF etc though, you really need to go through the whole system and set it all up correct;y.

You need to get rid of ALL vacuum leaks, including the dipstick seal and crankcase breather system, etc. (which also includes the inlet bleed into the rocker cover, the Tee behing the dizzy, into the plenum etc). Then set the base idle correctly (you should be able to get a smooth idle at less than 550RPM, but the lower the better, really. 500 is possible if everything is set really well). The bypass possibly needs a good clean out too - they gunge up with blowby gasses etc - I remove the screw entirely and use foaming upper engine cleaner in there, and a sturdy cable tie to poke around.

Check the ignition timing correctly and try advancing it. Be aware the outer ring on the crank pulley may have turned on the rubber too. Also see if the vacuum advance is intact - they fail a lot, and create a vaccum leak - it doesn't affect running too much, except less cruising advance, so the economy at cruise/part throttle is worse)

It's actually pretty rare for the Idle stepper to "fail". They often just need a clean (You can use rover gauge to drive it open, when removed, until it falls apart, then reverse the process to put it back together, being VERY careful to line up the indexing notches), then a lube with VERY light oil, or even a quality silicon spray. Nothing with any viscosity or body to it.

If you are running O2 sensors, you can get quite a lot of info from Rovergauge. It's still very handy, if not. The advantage, is that you can see exatly what the ECU is reading, which means whether a sensor, wiring or even the ECU have the fault, rather than assuming a (for example) new coolant temp sensor should be reading OK. Or if someone has pluged things in wrong etc.

The O2 sensors will allow Rovergauge to show you both short and long term fuel trims on each bank.

If you have manifold leaks, near or before the O2's, the ECU sees that as a lean mixture - there is excess air sucked in the leaks bewteen exhaust pulses - so the ECU pushes the fuel trims positive/richer, even though the actual engine is running too rich... but it still appears lean to the ECU... so it goes further, until full trim is reached.

Click to expand...

Did all of these suggestions aside from the roverguage and advancing the timing from where it currently is set. Rovergauge will be in a week or two depending how long the cable takes to reach me.

I had already cleaned the hell out of the plenum, throttle etc. I did starter spray at every connection and crease and even did a smoke test blowing smoke into the intake after the MAF. Nothing noted.

Vacuum advance is good and not leaking. It is new as the old one had a broken diaphragm.

I ordered the 14cux cable for rovergauge so while I have to wait for that I may take a few day break from this. Refresh myself as I got so many possibilities but feeling blind without being able to get any readings.

The Diagnostic plug give access to other ECU's ABS SRS etc but uses JLRs own protocols.

Where did you source your Rovergauge cable from? I've been looking for a while and the three pin plastic connector to fit the ECU loom is no longer available.

Rangieman123 said:

Where did you source your Rovergauge cable from? I've been looking for a while and the three pin plastic connector to fit the ECU loom is no longer available.

Click to expand...

ebay
This guy is selling them

And I found this site in USA (don´t know if they ship internationally)
usa site

I would make my own but I lack every component and there are no electronic stores near me or my part of the country

Rangieman123 said:

Where did you source your Rovergauge cable from? I've been looking for a while and the three pin plastic connector to fit the ECU loom is no longer available.

Click to expand...

You don't HAVE to use the correct plug - I just got a plug off a VW loom in my junk pile, and soldered it's wires to the pins in the original socket, then wired my Rovergauge to the matching VW plug.

I still have both plugs under there, if I ever require the original Rover one.