3.5 Vogue 1988 running problem help

[Ladge]

Hi people I have a classic 3.5 vogue efi and the problem I’ve got is this, I can start the car from cold it runs up fine but as soon as the engine reaches normal temperature the engine revs start to rise and drop until it stops. I have replaced Plugs / HT leads / Distributor amplifier / dizzy cap and rotor arm / I can’t find any air leaks temperature sensor I changed about 6 months ago, I changed the coil. As I say from cold it runs fine but once warm it plays up, keep the revs up and the engine is lumpy, Can anyone help I can’t think what else to look at

[rocksteady]

Hi there, i'd give the fuel pump a quick look if i was you. Not saying it is, but i'd have a look at the fuel supply.

[Ladge]

ok thank you for you reply

[Ladge]

I did notice the fuel pump seem noisey, but thought oh that's just me hearing something

[Bille]

Does it appear to be over fueling? If so I had a similar experience and it was traced to the temperature sender screwed into the water jacket on top of the engine, cost me a lot of frustration and time but only $AU30 for the part once I determined it was probably the problem.

It was telling the computer that the engine was still cold so it was pumping in the extra fuel.

I know you say you replaced yours 6 months ago but it could still be the problem if it has gone faulty.

Good luck.

[ThreeSheds]

It sounds like fuel to me too, over-rich seems most likely. Perhaps you could have a look at the plugs to see if they are sooty/wet?

Other ideas:

Not sure about the 3.5, but on the 3.9 there is also a fuel temperature sensor.

Check fuel pressure in the rail.

I believe there is an enrichment jet on the side of the plenum on a 3.5 which could be stuck?

Air filter?

[Ladge]

Does it appear to be over fueling? If so I had a similar experience and it was traced to the temperature sender screwed into the water jacket on top of the engine, cost me a lot of frustration and time but only $AU30 for the part once I determined it was probably the problem.

It was telling the computer that the engine was still cold so it was pumping in the extra fuel.

I know you say you replaced yours 6 months ago but it could still be the problem if it has gone faulty.

Good luck.

Thanks Bille It’s certainly worth a check.

[Ladge]

It sounds like fuel to me too, over-rich seems most likely. Perhaps you could have a look at the plugs to see if they are sooty/wet?

Other ideas:

Not sure about the 3.5, but on the 3.9 there is also a fuel temperature sensor.

Check fuel pressure in the rail.

I believe there is an enrichment jet on the side of the plenum on a 3.5 which could be stuck?

Air filter?

Thanks for your help I’ll check what you have suggested and put up and update later

[ramon alban]

I have replaced Plugs / HT leads / Distributor amplifier / dizzy cap and rotor arm / I can’t find any air leaks temperature sensor I changed about 6 months ago, I changed the coil .... from cold it runs fine but once warm it plays up, keep the revs up and the engine is lumpy.

Hello George, your scattergun approach, replacing all those very robust and expensive components does not generally work.

First, I'm guessing its a Flapper AFM System, running on petrol and/or lpg? As you have replaced so many components without success one needs to turn to analysing the symptoms. I'm also pretty sure that upon inspection you'll find the Spark Plugs will be black or wet.

Thus, it's clearly a temperature related fault with (assuming) wet/black spark plugs as I describe, so I'll wager its starting to run too rich During and After the warm up process resulting in your reported Hunting, Stalling and Lumpy Combustion process.

The problem, therefore, must be the Coolant Temp Sensor or its connections are open circuit causing overfuelling when warm/hot. Just changing a component will not expose dodgy connection problems, so test all the aspects of the CTS and its wiring as per the following link:

http://www.vintagemodelairplane.com/pages/Rover_Technical/TempSensor01.html

You should be looking for broken CTS connector contacts, broken wire in the Efi loom, dodgy/corroded earth connection on the engine block studs behind and below the L/H rocker cover, faulty connection in the contacts of the ECU multiplug. Fix the latter carefully with a wooden kebab stick.

For good measure, and to last a lifetime, clean and spray WD40/Switch cleaner into all Efi wiring loom connectors and fill with vaseline before reconnecting.

Regarding air leaks, although unlikely to be the primary cause, they are also a contributing possibility. To run a full set of tests, see here:

http://www.vintagemodelairplane.com/pages/Rover_Technical/Plenum01.html

Its a sad statistic, approx 80% of all Flapper System faults are due to air leaks and/or electrical connection issues.

For more info on the flapper system similar to yours, check out all the Efi system component essays in the Efi archive on my website. In addition you may wish to study an Efi Operations Manual, where the whole kit'n'kaboodle is fully explained. You'll be amazed!

If you car is not a 3.5 flapper, None of the above applies.

For anyone curious about the common cause of Efi Hunting - look here:

http://www.vintagemodelairplane.com/pages/Snippets/EfiHuntingSolutions01.html

[Ladge]

Hello George, your scattergun approach, replacing all those very robust and expensive components does not generally work.

First, I'm guessing its a Flapper AFM System, running on petrol and/or lpg? As you have replaced so many components without success one needs to turn to analysing the symptoms. I'm also pretty sure that upon inspection you'll find the Spark Plugs will be black or wet.

Thus, it's clearly a temperature related fault with (assuming) wet/black spark plugs as I describe, so I'll wager its starting to run too rich During and After the warm up process resulting in your reported Hunting, Stalling and Lumpy Combustion process.

The problem, therefore, must be the Coolant Temp Sensor or its connections are open circuit causing overfuelling when warm/hot. Just changing a component will not expose dodgy connection problems, so test all the aspects of the CTS and its wiring as per the following link:

http://www.vintagemodelairplane.com/pages/Rover_Technical/TempSensor01.html

You should be looking for broken CTS connector contacts, broken wire in the Efi loom, dodgy/corroded earth connection on the engine block studs behind and below the L/H rocker cover, faulty connection in the contacts of the ECU multiplug. Fix the latter carefully with a wooden kebab stick.

For good measure, and to last a lifetime, clean and spray WD40/Switch cleaner into all Efi wiring loom connectors and fill with vaseline before reconnecting.

Regarding air leaks, although unlikely to be the primary cause, they are also a contributing possibility. To run a full set of tests, see here:

http://www.vintagemodelairplane.com/pages/Rover_Technical/Plenum01.html

Its a sad statistic, approx 80% of all Flapper System faults are due to air leaks and/or electrical connection issues.

For more info on the flapper system similar to yours, check out all the Efi system component essays in the Efi archive on my website. In addition you may wish to study an Efi Operations Manual, where the whole kit'n'kaboodle is fully explained. You'll be amazed!

If you car is not a 3.5 flapper, None of the above applies.

For anyone curious about the common cause of Efi Hunting - look here:

http://www.vintagemodelairplane.com/pages/Snippets/EfiHuntingSolutions01.html

What a brilliant and informative answer, I must have read the naff Haynes manual back to front; I also have two cd discs claiming to be land rovers own workshop manuals that I have been through time and time again, where as they cover the basics and for that are pretty good neither give any information anywhere close to the articles you have given me, the explanation in your articles are brilliant. I will be e-mailing you for a copy of your book shortly. Thank you

[geoffbeaumont]

If you look in the tech archive on here there's definitely the official fault finding procedure for the hotwire EFI system - I think there's one for the older flapper system (as ramon says, probably what you have) too. You may have already come across these in the workshop manuals though, in which case I presume you'll have been methodically through them? Time consuming and dull, but worthwhile.

[Ladge]

Hi chaps well I’ve been through the air leak check all ok, I’ve had the distributor out again and taken the advance retard unit off it seems ok I can move it with a good suck, gave internals a good clean out and put it back on, no difference although I did notice this morning when starting from cold and reaching normal running temp the engine continued to run ok until I turned it off and restarted it then it dropped it’s revs up and down until it stopped as before, I let it cool down again and started it from cold and again let it run up to temp and it continued to run until I turned it off and restarted. I have exhausted all my thought’s on what this problem is caused by now and am coming to the conclusion a sledge hammer may help

[geoffbeaumont]

Have you done as suggested and run through the full diagnostics check, or at least rechecked the most likely problem areas above? There are too many variables for randomly poking things to get you far unless you get very lucky.

[ramon alban]

then it dropped it’s revs up and down until it stopped as before ..... I have exhausted all my thought’s on what this problem is caused by

George, I am completely mystified by your comment when its been explained with several replies that we are primarily dealing with a temperature related, and possibly intermittant, fault due to dodgy coolant temperature sensor and/or its associated connector and wiring and only as a secondary suggestion, perhaps air leaks might come into play.

The problem, therefore, must be the Coolant Temp Sensor or its connections are open circuit causing overfuelling when warm/hot. Just changing a component will not expose dodgy connection problems, so test all the aspects of the CTS and its wiring as per the following link:

http://www.vintagemodelairplane.com/pages/Rover_Technical/TempSensor01.html

You should be looking for broken CTS connector contacts, broken wire in the Efi loom, dodgy/corroded earth connection on the engine block studs behind and below the L/H rocker cover, faulty connection in the contacts of the ECU multiplug. Fix the latter carefully with a wooden kebab stick.

For good measure, and to last a lifetime, clean and spray WD40/Switch cleaner into all Efi wiring loom connectors and fill with vaseline before reconnecting.

Regarding air leaks, although unlikely to be the primary cause, they are also a contributing possibility.

Yet you have rechecked air leaks and the distributor when there is very low possibility of an ignition fault and totally ignored the prime suspect - Temp sensor and its wiring.

Also no feedback from you what is the condition of the spark plugs, a key indicator for mixture problems.

Its just occurred to me that you dont have a multimeter or the skills to use one and if that is the case, please either read about using a multimeter here: http://www.vintagemodelairplane.com/pages/Snippets/Multimeter01.html or get some help from someone who can use one.

[Ally V8]

Classic symptoms of a flapper ecu dying - just plug another one in and try it.

[Ladge]

Roman I have changed the temperature sensor no change wiring is ok, connector is ok 3.5 has single wire to sensor remove connection from sensor no change. Plugs are clean. I do know how to use a multimeter. As said previously I am picking up a miss on the engine when this condition occurs, which to me suggests electrical problem hence i looked at distributor.

[steve_d]

If you are saying the sensor has only one wire then you have replaced the wrong sensor. That is the one for the temperature gauge.

The one that always causes problems is at the front of the inlet manifold on the right as you look at the engine.

There are two sensors side by side. The one you want is difficult to get at as it is right behind the 'Thermotime switch' which controls the Extra Air Valve.

To replace the sensor it is easiest to remove the TT switch first so you can get a spanner on the temp sensor.

Steve

[Ladge]

If you are saying the sensor has only one wire then you have replaced the wrong sensor. That is the one for the temperature gauge.

The one that always causes problems is at the front of the inlet manifold on the right as you look at the engine.

There are two sensors side by side. The one you want is difficult to get at as it is right behind the 'Thermotime switch' which controls the Extra Air Valve.

To replace the sensor it is easiest to remove the TT switch first so you can get a spanner on the temp sensor.

Steve

My apologies Ramon and to all who pointed me there, my god I took the car to a land rover one man band mechanic about 8 months ago, and he pointed to the sensor with the single wire and told me that is your problem the temperature sensor. As soon as I’m mobile again I will visit him and point out his mistake. Thank you Steve

[Ally V8]

The coolant temp sensor is not going to cause surging,if it goes open circuit the engine will just stop - simple as that.The AA/RAC used to just cut a piece of fence wire to bridge the coolant temp sensor as a get you home method,bit of a bodge but it works.From very distant memory the temp sensor gets down to about 60 ohms when the coolant is up to temp.

I have seen many 3.5 flappers play around like this,I even still keep a good ecu on the shelf as a test unit - not that I've used it for a few years.Why not just try plugging one in off another car ?

[Ladge]

The coolant temp sensor is not going to cause surging,if it goes open circuit the engine will just stop - simple as that.The AA/RAC used to just cut a piece of fence wire to bridge the coolant temp sensor as a get you home method,bit of a bodge but it works.From very distant memory the temp sensor gets down to about 60 ohms when the coolant is up to temp.

I have seen many 3.5 flappers play around like this,I even still keep a good ecu on the shelf as a test unit - not that I've used it for a few years.Why not just try plugging one in off another car ?

Ally you think it’s ECU, and not connected to temperature sensor at all.

[Ally V8]

For the 3rd time - yes.

[ramon alban]

If, after you have tried a known good working ECU, the fault persists, you may choose to look again at the temperature sensor that has a 80 to 100 degree C resistance of 300 to 150 ohms, and yes, the early flapper engine will fire and run from cold with an open circuit sensor, running progressively more rich up to the point where it croaks, somewhat as you describe in your first post.

Surging or hunting is a possible symptom of a fault condition usually induced by a rich mixture occuring somewhere in the warm-up cycle. Mostly at idle, but capable of occuring at higher rpm. It is usually transitory, but when severe, eventually manifests itself in a "surge too deep" where-upon the engine dies.

Read about Flapper system Hunting here: http://www.vintagemodelairplane.com/pages/Snippets/EfiHuntingSolutions01.html

The ECU can and does play up but it has multiple fail modes so none are particularly "classic" except perhaps gross overfuelling on one bank of four cylinders in which case the engine floods from the getgo. Lets hope it is the ECU, for an easier fix.

[Ladge]

For the 3rd time - yes.

Look don’t beat about the bush are you sure

[Ladge]

If, after you have tried a known good working ECU, the fault persists, you may choose to look again at the temperature sensor that has a 80 to 100 degree C resistance of 300 to 150 ohms, and yes, the early flapper engine will fire and run from cold with an open circuit sensor, running progressively more rich up to the point where it croaks, somewhat as you describe in your first post.

Surging or hunting is a possible symptom of a fault condition usually induced by a rich mixture occuring somewhere in the warm-up cycle. Mostly at idle, but capable of occuring at higher rpm. It is usually transitory, but when severe, eventually manifests itself in a "surge too deep" where-upon the engine dies.

Read about Flapper system Hunting here: http://www.vintagemodelairplane.com/pages/Snippets/EfiHuntingSolutions01.html

The ECU can and does play up but it has multiple fail modes so none are particularly "classic" except perhaps gross overfuelling on one bank of four cylinders in which case the engine floods from the getgo. Lets hope it is the ECU, for an easier fix.

Thanks Ramon I'll try the ecu firstly as I can get hold of a spare, But I think I will also change the sensor too

[Hybrid_From_Hell]

Flapper systems are by nature now old, and even when they were new they were not

exactly qulaity systems, rememeber BL / Rover etc were in cash probs even back then.

As such these systems inc hotwire can be problematic, and there are no diagnostics as such

its sort of hit and miss. and that in itself is an issue, I've spent years with V8s and the one

thing I've learnt is they can drive you insane.

IMVHO the way to deal with this is in 3 steps

1st - is the engine in KNOWN good health ?

Thats GENUINE Dizzy Cap (pattern one just cause greif more times than I can recll)

GENUINE or very high quality Leads inc King lead, that excs ebay specials, mates 2nd hand

freebies from his shed (Thems good uns them is) etc and a Bosch coil pref, and NOT a intermotor

bagain special, genuine Dizzy Arm, cleaned tight earths on back of head and battery to chassis etc, NGK Spark plugs, new

and gapped properly, air filter new, timing set with strobe and advance working, AFM and other connectors cleaned

proper fit, CTS KNOW good genuine pref and a spare BRAND new genuine as a test unit, known OK comp test, fuel pressure

tested fine, Fuel filter new, no air leaks (spray WD40 on trumpet / inlet joint hoses when running

and don't set fire to yourself of course etc etc etc

2nd

Try 50/50 approach.

Its either spark probs or fuel prob, make a stab and an educated guess then go into the Tech forum and look for the

diagnostic manuals for both Flapper Systems and Hotwire system, pick the right one and then METHODICALLY work through

each of the tests, starting with those on the 50% side you think it is, if that doesn't work then its the wrong inital guess

The tests are also good when known good units - KNOWN PROVABLE Good units can be inteerchanged, again not a ECU wot i avad under

me bench m8 for 4 years thats a goodun that is, more from a OK running V8, removed and tried THATS known good

Patience, and a structured methodical approach will often be the only way to fix real tricky probs, by all means

have educated guesses - as you may well get it right, but after a few of these if they don't do it (and often they do) then

use the Manuals I posted in the Tech forum.

And again, make sure the basics cap / dizzy lead etc is 101% done, DON't use patten c**p intermotor coil 4 pronged whizzy chav plugs,

and some unit of unknown "but its a goodun m8" type - you'll just miss the fault

HTH

Nige