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        General >> Problems >> V24 Cosworth Fuel Rail Pressure - how much?
        
(Message started by: Cosray - The Hague - Holland on Aug 3^rd, 2005, 1:22pm)

Title: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 3^rd, 2005, 1:22pm

My Scorpio Cosworth suffers from bad idling and ditto hotstart.

Before undertaking the Fuel Pressure Regulator, which seems a h... of a job, could anyone tell me the required fuel pressure?

In the excellent article http://www.fordscorpio.co.uk/obd2scan6.htm

On the last page 2 Bar/Atm is mentioned; my local Ford Dealer however says 3 Bar...

I had 3 Bar measured - so who is right?

Anyone have a specsheet or a manual page for the '95 Cosworth referring to this?

Looking forward to your advice,
Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Eric_R on Aug 3^rd, 2005, 9:11pm

Ray,
I used a generic figure for the fuel rail pressure, and I understand that 3 bar is acceptable - I can only find it quoted for the 12V engine but it probably is the same.

Did you test it throughout the idle sequence from cold, and during a hot start? The problem is that the Fuel Rail Pressure Regulator can become sticky, so a momentary test is insufficent, especially when the engine is still hot and the fuel pump first kicks in.

Have you confirmed that it is the FRPR by checking the Long Term Fuel Trims (LTFT)?

If you think Vlad's way is bad - you should see the official Workshop Manual version ...

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 4^th, 2005, 5:21am

Thank you Eric. Unfortunately I have neither tools nor the spine anymore to work on my car myself so my technician told me this figure.

I will get back to him and let him read your test suggestions, cold, warm etc. adn have him measure again.

In fact I had him replace the front HO2S sensors as I mistrusted them and asked him, when predictably working around that part of the engine, to replace the Fuel Pressure Reg anyways. BTW I did see the official Workshop Manual version ...

When I picked up my car he showed me his hands and I could see he had a hard time changing the sensors alone. He reckoned he would have had to spend an extra 2x2 hours for the Reg change so we left that for next time.

Next week we'll test the new DTC's if any + meter the pressure again and make a decision.

We phoned around for the correct 24V pressure but always got 1 of 2 answers... 2 or 3 bar. One tech even mentioned 5.75 Bar but that appeared to be the figure for max. pump pressure on the 12V!

The FRPR, is that Fuel Rail Pressure?
I was under the impression the EEC does not monitor/measure that directly.
Why then would there have been so much elimination &deduction in Vlad's case? Please enlighten me!

Any other clues?

My background is electronics and if anything -- measuring before acting is what we like!

Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Pegasus on Aug 4^th, 2005, 12:52pm

Hi Ray,
the symptoms you mention point to the FRPR. Mine occasionally stalls with a hot start. As Eric says, the LTFTs are an indicator - if they're around minus 10% its an almost certain sign. Make sure the MAF is clean (measures around 3g/s - metric) before testing?

If you decide to go for replacing the fuel pressure regulator you might have a long wait. I ordered mine in May and I'm still waiting :(

HTH

Pegasus

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 4^th, 2005, 2:52pm

Hi Pegasus, MAF's cleaned, IAT Volts & Ohms measured & found spot on, IACV cleaned & lubed, HOS211 & 21 renewed, what else?

I have spoken to both Ford Netherlands & Ford Köln techs who promise to mail me the right pressure value for the '95 24v Cosworth once they unearth the files.

The FRPR - some acronym - FINIS 7 334 684 just checked resources is available from Ford Köln, 1 day delivery once I have saved up the money for the job itself...

It is the right p/n is it not?
Same number you have on order?
Pls Doublecheck!

Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Eric_R on Aug 4^th, 2005, 10:53pm

Ray,
Yes, that is the right FINIS number for the FRPR.

FRPR is the Fuel Rail Pressure Regulator.

And no, the FRPR is not monitored directly by the engine controller (PCM). What points to the FRPR is the Fuel Trims. These are software inside the EECV and they adapt to differing conditions on the engine and try to keep the Lamda value of the combustion correct, even as parts wear.

The switching on the HO2S sensors are constantly being monitored, compared with the leaning and enriching of the fuelling (by lengthening and shortening the duration of the INJector openings) and comparing it with how the HO2S sensors are switching. The LTFT are a reflection of how generally Lean or Rich the fuel system is, so that high Fuel Trim figures mean that the Fuel Monitor is struggling to keep the mixture rich enough, while negative values show that the Fuel Monitor is struggling to lean off the mixture. Very low Negative fuel trims can be caused either by a MAF sending an incorrect reading for air flow, or by excess pressure in the fuel rail. If it is the MAF on an automatic you would expect to feel some hard gear changes because the LOAD data is inaccurate, but on a manual it is less obvious.

When you get the correct fuel pressure, will you let me know? I believe that it will be bar3.

HTH

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 5^th, 2005, 7:44am

Yes Eric, your post confirms my reasoning & deduction process sofar.

MAF was cleaned and autobox behaviour is limousine style smooth, definitely in ECO and of course less smooth in SPORT but -- predictable and consistent considering requested load, revs, gradient, speed etc.

Now it will be a matter of getting the specified pressure from a reliable source and I can make the decision.

As to the fuel trims yes, I've read the relevant articles and spoke to my technician about them. Seems though he is more of a nuts-and-bolts type techy, wanting to cut-and-try. ;-)) Of course he lives by the hours he puts in.

I had the pre-cat sensors HO2S11 & 21 replaced by him this week and I need at least three more drive cycles for any persistent DTC to register.

So I am taking Cossie in next week, hoping I will have the required Fuel Pressure data by then, check the LTFT data on his WDS and decide what to do next!

Any other 'hard' data sources for this FRPR Presuure data?

Will keep you posted.

Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Pegasus on Aug 5^th, 2005, 12:33pm

Hi Ray,
if you do go for replacing the FRPR (yes, same FINIS) I'd be interested in hearing how long it actually took to receive it.

Good luck,

Pegasus

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 5^th, 2005, 9:53pm

Hi Pegasus, yesterday's quotation was for the regulator
ex-stock Cologne @ roughly € 100 landed cost.

Parts timely ordered from stock Cologne is next day delivery The Hague sofar without fail.

I might just order it in any case; I spent more money the other day on a lunch for two. Worth it though :-)

BTW: Tech from a 5th source (Main Ford dealer) called me today claiming required Cosworth Pressure is 3 Bar.
Had his documentation in front of him.

Appointed to go see this man + his doc + Cossie next week in his Ford workshop and have him take the Pressure test again according to the/his book.

If he measures 3 Bar again under varying conditions AND if it is the required Pressure according to the book then I will leave it at that.

Otherwise I will have the regulator replaced anyways. It is 10 years old after all.

If you happen to find any doc to fund the correct Rail pressure on the 24v Cosworth please let me know asap?

Ciao, Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Eric_R on Aug 6^th, 2005, 10:14pm

Thanks Ray,
I'll take that as read, then, and change the figure on the page. :D

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 6^th, 2005, 10:42pm

I reckon the rail should be between 3 - 3.5 bar.
If you drop below 2.75 bar you will start getting problems as the injectors stop working properly, mixtures get weak, bad idle & the engine will not want to rev up cleanly. Also you will loose power espically near top revs & the engine may not even rev over 5000 rpm.
You may find that an aftermarket one is cheaper & it's adjustable. Some even have a pressure gauge on them.
Best way to test is if the engine is under load by the way.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 7^th, 2005, 9:32pm

on 08/06/05 at 22:14:42, Eric_R wrote:

Thanks Ray,
I'll take that as read, then, and change the figure on the page. :D

Ah.... Eric, please hang on 'til I've seen the actual documentation. Once I have conclusive documentation in my hands it will convince me, no earlier.

Since neither Ford Netherlands nor Ford Köln will confirm documentation for this * simple single figure * sofar is, to say the least, fishy.
I would not bank on it.

Meanwhile I will try to get the fuel pump to perform at say 75% by tricking its circuit using resistors and see what happens.

My Cosworth now, after the HOS11 & -21 sensors were replaced, when driving trough town stopping and starting, is idling at 1500-1800 revs, dropping to 900 revs when switching from D to N to D.

I could ride at a comfortable 60 km/h NOT using the Cruise Control, just by the high idling revs.

When switching from D to N at say 100 km/h, just letting the car roll, its engine revs will stay at 1800, only to drop to 900 when, still in N, stopping to full stop at the trafficlights for some 20-30 secs.

So something is amiss and it could still be the FRPR. All other sensors have been tested or replaced.

So please do not change the required/max. Fuel Rail Bar value until I have seen the doc., would be my advice!

Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 7^th, 2005, 9:42pm

on 08/06/05 at 22:42:42, howiedintheplace wrote:

I reckon the rail should be between 3 - 3.5 bar.

Dear howiedinthe place (what on earth does that mean?),

*From what documentation are you reading this? Please copy*

If you drop below 2.75 bar you will start getting problems as the injectors stop working properly, mixtures get weak, bad idle & the engine will not want to rev up cleanly. Also you will loose power espically near top revs & the engine may not even rev over 5000 rpm.

*This is still based on your earlier supposition, not on documentation, is it?*

You may find that an aftermarket one is cheaper & it's adjustable. Some even have a pressure gauge on them.
Best way to test is if the engine is under load by the way.

*This is contrary to available Ford documentation sofar. The pressure is to be measured

*with contact on, engine NOT running
*vacuum hose taken OFF the FRPR

In fact, open pump pressure may amount to 5 Bar from what I understood from Ford mechanic.

However, STILL the required Fuel rail Pressure figure remains un-documented,

Until that figure is found I will not base any conclusions on measurements or replacements.

Thanks you for your contribution; I am sure we'll get there in the end!

Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Eric_R on Aug 7^th, 2005, 11:29pm

Ray,
I have documentation for the 12V that shows bar3 as the correct pressure, and I don't think the 24V will be much different.

The pump itself must of course go higher than bar3 in order to maintain the correct pressure right up to max revs when all of the injectors are squirting away almost continously - otherwise would risk damaging lean running at maximum power.

The standard test of fuel pressure is at KOEO (ignition Key On Engine Off) but that doesn't test properly for a sticking/failing FRPR, especially when the engine is run briefly and then shut off - so the FR pressure needs checking throughout the temperature range of the engine from cold to hot.

HTH

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 7^th, 2005, 11:43pm

Ray

My comments are based on experience mate.
I know for a fact that if the pressure in the fuel rail drops below 2.75 bar the engine can not run properly as I have experimented with fuel pressures. Most seem to be about just over 3 bar which is measured at tickover but if you press the gas pedal straight down you should not drop below 2.75 bar, if you do you need to find out why. Yes the fuel pressure should increase upto about 5 bar at high revs.
I always check fuel pressures on the road or on a rolling road as it is regarded to be the best way. You can get the correct figure following Fords way but still have a problem.
I have loads of Ford & Cosworth documentation for the 24v so I will have a look through for you if you want something from Ford.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 8^th, 2005, 12:54am

O.K
I have looked at some of my stuff & I can not find anything on the BOB 24V but I do have the details for the BOA.

This is what it says:

System pressure without vacuum 2.75 - 3.0 bar
System pressure with vacuum 2.15 - 2.4 bar

I do think that is low but them are Cosworth figures not Fords so I stand corrected as they designed the thing.
On a dyno if you lower the fuel pressure below 2.75 bar @ say 1500 rpm you can hear the engine struggle & the see the power decrease.
I run about 3.75 bar at tick over as I have found that gives best results performance wise.
But then I run non Scorpio management so perhaps that may have something todo with it.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 8^th, 2005, 1:10am

Also I have noticed Auto data give the same figures.

I assume they are @ tickover as it does not say.

What problems are you having then? As upon reading your post it seems to be a high tickover? Have I got that right as low fuel pressure would cause a low tickover ???

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 9^th, 2005, 11:54am

on 08/07/05 at 23:43:45, howiedintheplace wrote:

Ray

I have loads of Ford & Cosworth documentation for the 24v so I will have a look through for you if you want something from Ford.

That would be great -- if you can find/mail me the 24v page on this min. Fuel Rail Pressure I will take it to my technician for discussion.

I had a look under the bonnet myself yesterday and my question would be: where exactly do you connect your pressure gauge? I could not even [/i]see[i] the fuel rails nor the regulator!

I could see the tops and the wiring of the injectors though but no way of getting near them. How does one get at either fuel rail?

Thanks, Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 9^th, 2005, 12:04pm

on 08/08/05 at 01:10:05, howiedintheplace wrote:

Also I have noticed Auto data give the same figures.

What problems are you having then? As upon reading your post it seems to be a high tickover?

Have I got that right as low fuel pressure would cause a low tickover ???

Correct - it is on high tickover, hanging at 1800 revs when hot which is a nuisance for an autobox.

Since most of the other causes were ruled out or replaced I suspect the FRPR to be sticky and cause too high pressure. The engine has execellent coldstart and high power on high revs.

My technician says he measured 3 Bar, though he still ows me feedback on the measuring conditions.

If required pressure is 2 bar then 3 Bar would be 50% over and the costly replacement job would be the cure.

That is why the v24 Cosworth required Pressure information is an important decision factor for me.

Thanks, Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 9^th, 2005, 2:37pm

Ray

List what you have tested or replaced.

I would still check the regulator but not as Ford say, I would check while driving on the road, that way you know it's 100% O.K.
It does not sound like it has a problem tho.
I can send you some info tomorrow but it mainly relates to the pre 95 24V as there is not much info around for the later one.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 10^th, 2005, 2:42pm

The valve is not on the rails on the BOB, it is on the petrol feed pipe on the left hand side of th engine. Follow the two pipes that goto the rail, by the body work there will be what looks like a tyre valve just before it connects to the metal pipes. It should have a cap on it.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 12^th, 2005, 4:13pm

Thank you Dave for taking the effort in forwarding the fuel pressure data contained in the .jpgs.

While studying these I noticed a few details which make me believe they rather refer to the Granada Scorpio Cosworth version i.e. before 1995.

Telltale facts are a.o. 'EEC IV' (the '95 Fords and onwards use EEC V, different kettle of fish); '1991' on the page; idle speed control valve (the '95 Cosworth uses the IACV).

This leads me to be hesitant to use the fuel pressure data to be decisive for my '95 Cosworth.

Remember, I am deciding to have the Pressure Regulator replaced in a minimally € 500 costing exercise...

You know -- the data for both fuel systems on the Cosworth *may* be identical; but then again they may be not...

Thank you for your data search; if you come across any of the '95 onwards Fuel Pressure data I will be pleased to see them.

Thanks, Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by howiedintheplace on Aug 12^th, 2005, 7:44pm

Ray

See my eariler posts in this thread. I can not find out any data for the BOB but there is plenty of data for the pre 95 24v engine. I know your not happy using it but I think you may find it's the best data you can get as there does not appear to be any fuel pressure data for the 1995 onwards BOB 24v.

Goodluck

Dave.

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 22^nd, 2005, 6:40pm

on 08/10/05 at 14:42:41, howiedintheplace wrote:

That's valuable information; thank you!
I will follow that up.
Ray

Title: Re: V24 Cosworth Fuel Rail Pressure - how much?
Post by Cosray - The Hague - Holland on Aug 22^nd, 2005, 8:59pm

on 08/09/05 at 14:37:33, howiedintheplace wrote:

* You mean checking Fuel Rail Pressure while being on the road? Is that feasible?

** Tested, cleaned and/or replaced were

IACV
All vacuum hoses/seals
IAT
HOS11 + HOS21 pre-cat sensors
Plugs
ECT Sensor
VIS
Air Filter

*** The MAF Sensor was cleaned 2nd time round by myself this time; now the engine idles quieter, has not stalled and revs come down quicker when decelerating and stay around 900.
Gearshifting is very smooth both in S and D.

**** Still hot-starting often needs 2 starts; acceleration when driving away feels like a flooded engine, faint smell of petrol noticeable.

***** I would still like to be sure about Fords official required Fuel Rail Pressure for the '95 Cosworth engine before having carried out the laborious and costly replacement of the Fuel Pressure Regulator.
Over here it means a € 500 job for a possibly malfunctioning € 95 part...

Any additional suggestions?
Thanks, Ray