1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

[philcoyle]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

You are completely correct Chris, if the crank sensor goes then you are going nowhere.
When you turn on the ignition the ECU runs the fuel pump for a second or two.

Turn over the engine and the crank sensor does exactly that , senses the crank is rotating and it is responsible for informing the ECU that it should run fuel pump until you switch off and signal the injectors to open and close as per timing, and send and receive signals to all other sensors and switches, so quite an important £12 worth.

Some times the tip of the sensor can become dirty or covered in iron filings due to its location in the bell housing, whip it out give it a clean and put it back. Don't mess with it as most of these sensors operate on very low voltage and a 12volt battery can fry them.

I see that you are Somerset based, my favourite run is from Minehead, Porlock Hill, Lynmouth for fish and chips by the funicular railway, Heaven!

[davidmartin720]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I have recently bought a Hunter [2litre DOHC efi] and the alternator was faulty under load. I disconnected the battery and had the alternator repaired. Put back in, but car did not go as well, failed MOT on emissions. I came home read on this Thread about resetting Throttle and hopefully problem solved. By the way I am in Somerset near Langport and regularly go to Lynmouth via Exmoor from Bishops Lydeard. We were there on Friday and in Exford on Saturday. What about a meeting? David.

[philcoyle]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

David I would really love to, but! I live in the shires, Worcestershire to be precise, and I do envy where you live on the edge of Exmoor another favourite place. What's the name of that old pub in the centre of Exford, a great watering hole.
Can I come and camp in your garden LOL.
Phil

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I know you said that a new fuel pump was fitted, but is there anyway that you can check fuel pressure, on some Ford engines the fuel rail has a Schrader type valve for checking fuel pressure. At ignition only it should be about 4 bar or just under 60psi, with engine running 3bar 45psi near enough as damn it (I'm not the pedantic type).

I ask this because from experience I know there are some looky likey fuel pumps about £25 and genuine FSE Sytec are twice that price.
I fitted a cheapo one some years ago not thinking anything about quality, a fuel pump is a fuel pump right! WRONG about 8 months later, pop bang, engine runs but lacks power and acceleration, I knew this symptom, change intank pump for FSE Sytec pump and away we go.

Do you have an intank pump or are THEY BOTH external, in which case you have a low pressure pump feeding a High pressure pump, was only one changed if so which one?

I have one external pump which is inline with all normal cars that I have worked on from that ere. I have a sump in the tank for the pickup so no need of a swirl pot system. Remember this is a factory built hunter so I would hope in the 34k miles it wont have been modified much?

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

You are completely correct Chris, if the crank sensor goes then you are going nowhere.
When you turn on the ignition the ECU runs the fuel pump for a second or two.

Turn over the engine and the crank sensor does exactly that , senses the crank is rotating and it is responsible for informing the ECU that it should run fuel pump until you switch off and signal the injectors to open and close as per timing, and send and receive signals to all other sensors and switches, so quite an important £12 worth.

Some times the tip of the sensor can become dirty or covered in iron filings due to its location in the bell housing, whip it out give it a clean and put it back. Don't mess with it as most of these sensors operate on very low voltage and a 12volt battery can fry them.

I see that you are Somerset based, my favourite run is from Minehead, Porlock Hill, Lynmouth for fish and chips by the funicular railway, Heaven!

I will give this a whirl as I have seen this on jags in the garage but then it was a problem throughout the rev range

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

First thing that comes to mind is to reset the throttle position sensor, a 2 minute job.
1. Ignition only on.
2. Quickly fully depress throttle pedal fully down and fully up at least 10 times, some models take less, but belt and braces is always best.
3. Switch off and wait a few minutes and then start engine.

It may work for you, if not start looking at other parts, incidentally I hope you have a high pressure fuel pump.

Right when I changed the pump I disconnected the battery should I disconnect the battery then do the reset? plus do I need to learn the ECU again like on older escorts?

[philcoyle]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

Hi scott , there is a tool for diagnosing EECIV ECUs made by Draper number 68080, I don't know if they still manufacture them (or should I say the Chinese) and they are rather rudimentary and basic. If you manage to find one don't be tempted to remove the back of it, no don't, your first reaction will be what the!
It works on a system whereby you count the number of times an led flashes and then relate this to a booklet of codes, oh and don't blink.
Remember this was the forefront of EFi technology 40 years ago, and yes I do have one. It has 3 wires and an on/off switch and a red LED, all for £30 fifteen years ago.

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I tried the disconnect battery and then reconnect pump accelerator etc still the same I will have to be a mechanic this weekend check tps and clean airflow meter[hot wire type] If that doesnt cure it further investigation required

[andyf]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I like the description

PS I've not found it s to find a fuel pressure gauge

[droverpete]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I have the same problem with my Hunter (same engine) as peterboat so avoiding 'town' driving as its very embarrasing when it happens! Only done about 400 miles so far and most of that was Somerset to Stonleigh and back last May, fine on the motorway but a serious overheating problem in traffic so sorting that first before the 'misfire'.

A useful source of information about the 2.3DOHC is www.fordscorpio.co.uk where I found the following[copyright Ford]

DRIVEABILITY CONCERNS
In normal operation the EGR system should be undetected by the owner. If the system fails with the EGR valve closed there will be no driveability concern. No MIL light means that the owner will remain unaware of it. Since emission testing is at idle (when the EGR does not operate) the vehicle will not fail the MOT.
However, if the system is not gas-tight then air can be drawn into the inlet system instead of inert gas. This can weakens the mixture sufficiently to cause misfiring, and manifests itself as a noticeable misfire/hesitation at speed and light throttle, not present when accelerating. If the leak is serious enough it may manifest itself as a hunting/rolling idle, caused by an unmetered leak of air into the inlet.

I find the problem only starts after the engine has warmed a bit which I think is also when the EGR starts to work.
2 more questions
Does anyone know if Marlin included an OBD socket in the wiring, where, and what does it look like?
The 2.3DOHC uses EEC V ECU how does this differ from the EEC IV used on the 2.0?

Peter

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I thought I would give you my basic knowledge on EECIV ecus and early ford fuel systems as it would seem that this information is becoming difficult to come by, with some people converting back to carburettors instead of trying to understand how some of the systems work.

So in my own inimitable, hopefuly non techie and non pedantic style I will try and give you an oldmans guide to EFi.
By non pedantic I mean if something is 14.7 I will call it 15, and if there is a valve or something I wont bother you with the correct termininology as knowing the exact and correct name will not help you understand any easier, such as do you know the difference between an air flow meter and mass air flow meters, ignition module, engine control module, you get the idea.

So lets have a look at FUEL PRESSURE, many think it has no importance whatsoever. Yes I have great fuel pressure because I turned on the ignition and undid a fuel pipe slightly and fuel squirted out, brilliant you have fuel pressure.

Now , was that a 5psi squirt or a 12.5, 31, 17.5, 45, 22, see where this is going,fuel sprayed over the engine bay so I must have fuel pressure. If you can tell by a squirt of fuel what the correct pressure was you could corner the global market in pressure gauges because we would not need them thanks to your super skill of accessing pressure of a fluid from a dribble to blowing your socks off. Guessing aint gonna get you nowhere. Use a gauge and check before the fuel rail and after the pressure regulator/ exit of fuel rail or return fuel line, does it have at least 45psi engine running and does it maintain the pressure or does it fall off.

Heres a little story. Three ford 2ltr engined Marlins going down the road side by side,

A) has a brand new pump and Pressure Regulator and 45psi in the fuel rail.

B) has an older car and an older pump and PR and 38psi in the fuel rail.

C) Is on its last legs and manages 18 psi in the fuel rail.

All have fuel in the tank, all have pressure in the fuel rail, all trundling along.

The accepted combustion rate of air to fuel is about 14.7 to 1, 1 part fuel 15 parts air, or 1 kg of fuel to 15 kg air. This is what your ECU is maintaining from the time you switch on. This is done by controling the injectors by adjusting their flow rate to each cylinder in milliseconds. Has the light bulb moment happened yet?

Meanwhile all three of our Marlins decide to go a little faster and simultaneously press the pedal, the TPS (throttle position sensor) signals the ecu and all ecus open their injectors a millisecond or so more to allow more fuel into the cylinders.

So answer this, will more fuel under pressure go through a tiny hole in a given time or will the lower pressure fuel rail give the same amount as the high pressure in the same time.

Put your finger on the outlet of your cold tap, turn it on a little how much water comes out? now do it and turn the tap full on, wet trousers anyone?.
Now relate this to your pressurised fuel rail. The ecu maintaining 15 to 1 combustion, 45psi in the fuel rail will squirt how much compared to an underpressured system i.e. (20psi) in the same millisecond the injectors open.
Jerking, stuttering, lack of power, revs like the clappers standing still, but not when it's on the road under load.
So yes your car will run, is fuel pressure REALLY important, go and have a cup of tea and a dark chocolate digestive, and send your answers on a postcard to wgaf.uk.co. And this is only one bit of the puzzle, so some archivist or plagiarist will be copying this for future information, and all because some old lady hung her handbag on the choke cable ha ha ha.

I did say I owned a garage I used to work on Rolls Royces, Aston Martins and mostly Jaguars of all ages. I have a fuel pressure gauge it was the first thing I tried when I fitted the new pump fuel pressure is good and under throttle rises.

Up to 3000rpm hard acceleration and in the lower gears [1-2] all is good 3000-3500 slight hesitation beyond that accelerates hard. Higher gears the hesitation gets worse the higher the load. I am tempted to blank the egr just in case this is the issue as an experiment.

I was saying yesterday I disconnected the battery reconnected the battery and then did the tps reset nothing achieved by this.

I will this weekend clean the MAF, blank the EGR and also make a shield to stop hot air getting to the air filter

[scott h]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I found this http://www.fordscorpio.co.uk/topfaq.htm

If you scroll down you will find this.

Photo011.jpg

[droverpete]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

When the battery is disconnected the ECU looses what it has learnt and reverts to factory default settings. It can take 20 miles or more of varied driving to re-learn your settings, gradually improving as it goes. Interested in the 'hot air shield' idea as the problem could be triggered by temperature change there when the thermostat opens.

[droverpete]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I found this http://www.fordscorpio.co.uk/topfaq.htm

If you scroll down you will find this.

[ATTACH]7715[/ATTACH]

My fuel cut-off loom has cracked insulation from heat mainly at injector plugs but I have already spoken to the main ford dealer here about getting a new one. Part no. is 1063557 or 1063559, description *WIRE ASSY. If they could get one it would be about £250 but they also said Ford no longer make them and there are none left in the whole wide world! Anyone know a good loom maker?

[peterboat]

Re: 1997 Marlin Hunter 2.3 inj ford runs rough at 3000 RPM under load

I will look at all the above stuff, its so annoying as below and above the engine pulls like a train! As I said earlier when the fuel pump failed I thought that maybe low fuel pressure had been the problem but clearly this is not the case