Misfire on Group A Escort Cosworth

[greencroft]

Just found this forum so thought I would post details of a problem we have had with a misfire on our YB engine in our Escort Cosworth rally car:

Car is a GpA Esc Cosworth with Pectel T6 management.

Car ran fine for a 14 mile stage.

Next stage, slight misfire about a mile in then progressively worse as stgae progressed. Seemed OK on v light throttle. Initially thought it was only happening when on boost but have since got it to do it off boost as well.

We changed plugs (which looked fine), fuel pump and fuel filter.

Each time we changed something, the thing ran fine up the next road section and initially in the stage until the missing started again.

It seemed unaffected by the antilag ie was just as bad with it on or off. Temparatures on the monitor were all fine as was fuel pressure.

The misfire was more the engine cutting out completely than just one cylinder going off.

After 4 more stages of stuttering and farting, on one of which it ran absolutely fine for about the first 5 miles of an 11 mile stage, we gave up.

Since that rally, we have changed the following components:

Crank sensor
Map sensor
Air charge temp sensor
Throttle position switch
Fuel pump
Fuel filter
Alternator
Ignition coil
Plugs

We tested the car and it ran perfectly for 25 stage miles around Phil Price's 2 weeks before the event then ran fine again for the whole of SS1 and SS2. About half way through Wigmore SS3, it just missed two or three times - a minor hesitation only. Then right off the SS4 Blackhill startline, it was cough cough cough and it farted the whole way through the stage.

On the test, we had noticed low volts from the alternator on our test, had this rebuilt. It was then producing 13.6-14.0 volts on charge but the problem reoccurred.

Before the last stage, we even slightly naughtily, removed the entire master switch and ran the whole system live just in case that was the source but no, still there.

This time we at least have a data file of it when it was misbehaving so whoever knows about Pectel systems is welcome to look at it if you give me an email address.

At present the ECU and engine wiring loom is back with Pectel. They have found a problem with the loom connection to one of the air injectors but I am far from convinced that this could cause the symptoms that we have experienced i.e a misfire that can happen off boost.

I would welcome any thoughts. This is driving us round the bend.

Simon.

[Tone]

give pauls hills at ENGINE ADVANTAGES in witham essex
i don't have his number but it starts with 01376
if not if you can get hold of clint on here is a mapping GURU
good luck m8
and welcome to the forum

[wes]

Some thoughts:

Have you tried the fuel pressure reg? How long does it hold it's fuel pressure for AFTER you have turned the engine / fuel pump off? It should hold pressure for quite a while. All vaccuum pipes to pressure reg / MAP sensor in good working order? What voltage are you getting at the fuel pump terminals when the engine is at idle? How much fuel is in the tank when this misfire occurs?

Do you run the original dizzy setup? If so have you changed distributor phase sensor? (common missfire cause with this type of ignition). Did you set the air gap correctley for the dizzy and the CPS sensor (checked the gap on all 4 lugs?)



Also have you checked each plug lead / king lead for continuity and resistance?

Pics of the car / engine / fuel pump setup would be nice!

Good luck in finding your problem

[Clint]

Ignition Amplifier ?

As wes said Pics would be good, zip the file up and attach it to a post.

[greencroft]

Thanks for the suggestions guys, I think you may well have cracked it. Just to clarify a few things:

The car runs with a "dummy" distributor ie the phase sensor is still down there picking up off the crank. I feel that this may well be our problem and am going to get this investigated. If it works on the same principle as the crank sensor, then I am aware that these sensors can become erratic.

The leads have all been changed, the fuel pressure is fine, the crank sensor has been changed and gap checked, map sensor changed, all pipes are in good condition. I am banking on the phase sensor.

Ignition amps are within ECU and have been the subject of the testing Pectel have carried out and have passed as OK.

I will post if/when it is sorted.

Thanks again.

Simon.

[greencroft]

Hard to believe this problem is still persisting but there you are.

As an update, the ECU and engine loom were the subject of rigorous testing by Pectel. The only fault that they identified was a faulty connection on one of the air injectors on the loom and some minor corrosion within the ECU casing. The air injector problem would have caused some deficiencies in the boost control but not, in their view, given the symptoms of the problem we were experiencing. The connector was replaced and the ECU given a new casing.

We then put everything back together and the car ran fine (as it always had on the road). It was stored through until after the New Year whereupon I wanted to do a test event to ensure the problem was nailed before getting back into a few ralllies in 2005.

Out it came from under the covers in early January and it would not start at all. All it would do would be to turn over, then produce a huge backfire. Eventually on changing the phase sensor, the car was back running just fine.

The test event was the Ludlow Gravel Sprint run over a single 4.5 mile stage in sub-zero conditions. The car ran faultlessly all day, doing the stage 6 times without missing a beat, performed OK getting 5th overall and a 3rd fastest time on the last stage.

Thinking we had finally nailed the problem, we entered the Red Dragon Rally the other week in S Wales. First stage was fine, then straight off the line into the second one, the dreaded misfire was back just like last year and as described at the beginning of this thread.

By the time we got back to service, the road section was too long so had logged over the top of the stage info so we could not get a data file into the laptop.

We can only produce the problem on a rally and then only when the car has been worked hard, then rested (like on a road section), then worked hard again. I have taken the car testing and it has never once misfired in the same manner, despite my best efforts to reproduce rally-type conditions.

Causes we have thought of included:

Sensors
Wiring
Fuel
ECU
Cracked block/head
Fuel

i.e all the normal components that let an internal combustion engine run.

I now think that the phase sensor problem may have been caused by running on the misfire rather than an original cause of the misfire itself.

Just to clarify, this is not a single cylinder misfire. It is like all the sparks stop momentarily. On refiring, there is a plume of black smoke out the exhaust or a flame suggesting the injectors are doing the job fine.

Anyone any further ideas?

Feel free to ask anything further if you think it may be relevant.

Someone must have suffered a problem like this before.

As you can imagine, this is driving us nuts. I very much look forward to posting on here to tell everyone when we have solved it but will only believe it when the car has run for the duration of a proper welsh rally in decent temperatures.

Many thanks in advance.

Simon Rogers.

[TSAdministrator]

I had a similer issue with a car, I eventually traced to an earth breaking down on the ignition amp.

[greencroft]

Is the ignition amp not integral within the T6 ECU?

When you say "breaking down", what does this mean exactly and how was it fixed?

Thanks for the suggestion.

Simon.

[Zetec_Escorts]

Have you tried voltage dropping the various components?

It may be worth putting a sheilded cover over your phase sensor wires as these are prone to problems from interference.

Is your ignition amp correctly mounted on an alloy plate with lots of heat shrink gel?

Some igniton amps earth through the mounts so check those.

[greencroft]

Have you tried voltage dropping the various components?

It may be worth putting a sheilded cover over your phase sensor wires as these are prone to problems from interference.

Is your ignition amp correctly mounted on an alloy plate with lots of heat shrink gel?

Some igniton amps earth through the mounts so check those.

Thanks for your reply Zetec.

I should add if it's not clear already that this is very much an intermittent problem which only occurs under certain conditions. I had therefore pretty much ruled out any interference issues as I would have thought these would produce a constant problem i.e. the thing would never run smoothly.

In terms of the ignition amp idea, as above, I am pretty sure that the ignition amp is internal to the T6 ECU and not mounted somewhere else like it is on standard Cosworths. If this was the problem, I would have hoped that Pectel would have nailed it when they had the ECU for testing for 3 weeks. This test included heating the whole unit up in an oven specifically to examine the effects of heat on the unit's performance. They said it was all functioning fine.

One idea that someone else came up with is that there was a problem in transferring the ECU map from laptop onto the ECU that may have left a bit of it with null or corrupt values. Thus when it hits these conditions, the ECU is reading a table that is saying "don't give it any sparks". I find this q hard to believe as I thought the ignition mapping only controls the timing of the sparks and not whether there are any. Happy to be told different though if only so I can rule out this as a possible cause.

Thanks for the suggestions guys.

Simon.

[Clint]

The ignition amps are internal, I personally would talk nicely to Pectel and ask them if you can borrow or hire another ECU for a couple of events and see if the propblem disapears.

[wes]

What you could do is wire in a voltmeter to the middle pin of the coilpack and keep an eye on the voltage levels when driving hard, perhaps a wire or relay is getting abit too hot? Is the alternator heat sheilded?

Also what spark plugs do you run and what are they gapped to?

[greencroft]

What you could do is wire in a voltmeter to the middle pin of the coilpack and keep an eye on the voltage levels when driving hard, perhaps a wire or relay is getting abit too hot? Is the alternator heat sheilded?

Also what spark plugs do you run and what are they gapped to?

Answering the second part of your question first, plugs are Champion C57 and gap is 0.020" - this is what we have used ever since we had this engine. It has had 4 different sets of plugs in it from 3 different batches so I am pretty confident I can rule out a plug problem.

Once into misfiring it will even do it off boost but the problem always appears first when the engine is under load and boosting.

I am aware that too large a plug gap can induce similar type of problems but unless you say otherwise from the above, I don't think we can lay it at the door of the plugs this time (much as I'd like it to be that simple!).

The alternator is in the same configuration as it has always been and is freshly rebuilt. The volts it is providing are not fluctuating when the misfire is happening (reading off the Pectel monitor).

Re your idea of a relay getting a bit hot, back on one of last year's rally, we did find that the main ignition relay was partially melted and badly scorched. Thinking we had found the problem, we changed it in service but the misfire remained. If it was not the relay at fault, then what might cause the relay to overheat? Could this be another symptom of the underlying fault?

Sorry to answer a question with a question and thanks for your interest.

I have sent an email to the guy I dealt with at Pectel begging for a loan of a substitute T6 plus for him to upload and download the map. I await an answer from him.

Simon.

[wes]

Just some thoughts here: Even though you have a pectel loom, 3 wires are still needed from the car to make it all work, the 2 relays (ECU relay and fuel pump relay) still need to get their power from the battery, and the ECU relay needs to be switched on via the ignition switch, usually the original wires are reused. When i made my loom i ran 2 new wires from the battery to the relays (pin 30 of the relay). Pin 87 then goes into the new loom.



It could be that the wires you have going into the relays are corroded / breaking down under heat, abit like what happens to the cooling fans on the rad, the wires get VERY hot as they get older, and the fuse box normally melts around the fan fuse! Although you do say that the voltage at the ECU is OK according to your monitor, it might be worth looking into this and replacing the relays for new items?

If you have a FULL pectel CAR loom then forget what i have just said as this should replace everything.

As for the spark plugs, i used to go through C57's at a rate of a set a month, and i only drove the car at weekends! 0.5mm is small considering you don't run the old dizzy setup. May i suggest you try a set of NGK 9's (R7234-9), and run as big a gap as you can get away with (0.6mm /0.024" is a good statring point). They cost about £75 a set, but i've only had to buy 2 sets in the past 2 years! I run 30 psi+ boost from a T4, and it doesn't miss with these plugs.

[greencroft]

Just some thoughts here: Even though you have a pectel loom, 3 wires are still needed from the car to make it all work, the 2 relays (ECU relay and fuel pump relay) still need to get their power from the battery, and the ECU relay needs to be switched on via the ignition switch, usually the original wires are reused. When i made my loom i ran 2 new wires from the battery to the relays (pin 30 of the relay). Pin 87 then goes into the new loom.



It could be that the wires you have going into the relays are corroded / breaking down under heat, abit like what happens to the cooling fans on the rad, the wires get VERY hot as they get older, and the fuse box normally melts around the fan fuse! Although you do say that the voltage at the ECU is OK according to your monitor, it might be worth looking into this and replacing the relays for new items?

If you have a FULL pectel CAR loom then forget what i have just said as this should replace everything.

As for the spark plugs, i used to go through C57's at a rate of a set a month, and i only drove the car at weekends! 0.5mm is small considering you don't run the old dizzy setup. May i suggest you try a set of NGK 9's (R7234-9), and run as big a gap as you can get away with (0.6mm /0.024" is a good statring point). They cost about £75 a set, but i've only had to buy 2 sets in the past 2 years! I run 30 psi+ boost from a T4, and it doesn't miss with these plugs.

Thanks for those further ideas Wes.

As you rightly suspected, I have a Pectel engine loom but a home made/modified loom for the rest of the car. This may well be showing its age now so I will certainly look at putting in new feeds and switching circuits to the key items like the ignition and fuel pump relays.

Re the plugs, these were the ones recommended by my engine builder. For rallying, we put a fresh set in per event (think they are c. £27). As I mentioned earlier, I am prety convinced that this is nnot a plug problem as we have run with this type and this gap for a number of seasons with no problems before now. I will however have a word with my engine builder re the NGKs.

Thanks again.

Simon.

[andremarca]

So have you found the problem?

[greencroft]

So have you found the problem?

no.

I am weighing up my options at the moment on who I get to fix it but the ideas and suggestions above will be v helpful in narrowing down possible causes.

The car does not stay at my house, in fact it is about 250 miles away in W Wales but this particular problem has beaten both me and the guy who looks after the car between events. I am keen to go down the route of substituting the ECU for another one and trying it on a few events if only to rule this out.

I will of course post the result as and when it s fixed.

Thanks again guys for your continued interest and ideas.

Simon.

[greencroft]

Here's another suggestion to dwell on.

If the injectors are in certain circumstances getting to their maximum duty cycle, then they will shut down, only to start up again moments later. This will give the sensation of a complete engine cut out and will also produce some unburnt fuel out the exhaust when the engine comes back on tap.

I have had this idea from someone who runs a hillclimb car who picked out the symptoms I was suffering as very similar to his. The solution to his grief was to install new higher rated injectors and remap. These new injectors were then running well within their max duty cycle.

As with me, most people looking at his problem thought it was on the ignition side and he went round replacing all sensors and all the loom. All sounded very familiar.

I will find out what injectors I have and also try to clarify what mapping changes were made after my engine was rebuilt. It was after this that this problem first occurred.

I am willing to look into anything now so if anyone has a further slant on this theory or any others, then pls post.

Thanks

Simon.

[Clint]

I have never seen this happen, 803's are commonly run flat out on cossies, I have never heard of one 'shutting down'.

[greencroft]

I have never seen this happen, 803's are commonly run flat out on cossies, I have never heard of one 'shutting down'.

Clint

What symptoms do you think you would get if the injectors were asked by the ECU to perform at in excess of 100% duty cycle?

How could you find out what % duty cycle they might be running at?

I might well be clutching at straws here but this guy was so convinced that the symptoms were just as he had experienced on his hillclimb car.

Another question - which you may want to answer by PM - who do you really rate on the mapping/diagnostic front, specifically with Ford Cosworths running on Pectel management?

Thanks

Simon.

[greencroft]

At long last, I have been able to arrange a thorough test with the car spending a whole day at an airfield with a very knowledgeable electronics engineer.

We ruled out an ignition problem and now believe it to be a fuel system issue.

Previously, we had shied away from this as fuel problems yend to be fairly consistent irrespective of temperature.

I just wondered if anyone else has ever suffered any temperature-related problems with a fuel pressure regulator?

We have a Weber one on my car and under certain temperature conditions, we are seeing a dip in fuel pressure as boost rises i.e. just when the fuel pressure should be increasing. This is causing a bad misfire.

This is only happening when under bonnet temperatures are high i.e the car has been given a hard run in high ambient temperatures, then rested so there is a real heat sink to all under bonnet components.

We though at first it may be a voltage drop to the pump but have ruled this out by wiring a separate supply direct from the battery and switching it on as the misfire occurred. This had no effect on the fuel pressure or the misfire.

Interested in anyone's comments on this.

Simon.

[sillymofo]

i dont want to sound simple but i have to ask have you attached a fuel pressure gauge and moniterd it during driving?
could it be that the fuel pump isnt upto the spec of your engine?

[sillymofo]

ignore me plz ive just read the first page of this topic and realised you have done these checks

[greencroft]

Update.

Had another all day test yesterday back at the same airfield. We had bought a new fuel pressure regulator. Once fitted, we eventually got the problem to reoccur once the temperature was up. So back to the drawing board.

We had a trace reading of the fuel pressure onto a lap top and a dial guage as well. It was clear that this is most definitely a fuel pressure problem. When the engine stutters, the fuel pressure is dropping away and the lambda reading is leaning right off. I am amazed we haven't holed a piston yet.

We ran with two different pumps, also running a separate power supply for the pumps just in case this was at issue. The problem remains.

One thing we did see was that there was a hell of a lot of "noise" on the fuel pressure trace ie the wave form always had q a high amplitude at a high frequency. We ruled out interference on the wiring of the sensor by pressurising the pipe with a bicycle pump while the engine was running and it gave a perfect flat trace.

Given the fuel system is q a straightforward thing, it seems amazing we can't nail this. Next step we are planning is a complete replacement of all the fuel lines from front to back just in case there has been some kind of internal delamination that is obstructing flow once there is temperature present. Sounds unlikely I know but we are clutching at straws now.

Any comments welcomed!

Just withdrawn from another rally on Sept 3rd because of this.

Your frustrated and increasingly poor!

Simon.

[sibster]

Simon,

What fuel pressure reg are you using?

Are the fuel lines PTFE or rubber lined?

What pumps are being used? in tank or external?

Regards

[greencroft]

Ian

I will give you a call.

Lines are normal goodridge fuel lines - not sure of their construction type but they are fit for purpose albeit at least 5 years old now.

Does Carless fuel eat them?

Old fuel pressure reg was a Weber one. Now replaced with a Bosch one. Adjusted to 3.5 bar static.

Pump is a Bosch one external to the tank. Inside the tank, there is a central collector box. We have opened it all up and it is clean as a whistle in there and is the same installation that has worked for 4 seasons!

Is your car finished yet?

Simon.

[sibster]

Simon,

We are tantilising close now with the car...just business commitments preventing me from the finishing touches.....and waiting for gems with the upgrded diff controllers....if the fuel lines are rubber inner stainless steel overbraid goodridge 200 hose then yes the carless could be de-laminating the lining...usually the car smells very strong in the cabin if you are using 200 hose...we always use ptfe stainless steel overbraid with swaged fittings...the ptfe can take the pressure and is dense enough to retain the fuel more effectively.....if you have had the same lines in for the last 5 years I suspect you may already have ptfe....

Fuel pressure reg...we use the genuine world car item not sure of the make but its external to the fuel rail..they actually class it as an 8 bar fuel press reg...i can only assume the range is better fueling wise on the rise versus boost.....I have seen this type of problem on standard fuel pressure regs especially where people break the solder seal and then puncture the diaphram...

Fuel pump wise we run/standby 2 bosch 044 fuel pumps...but check some have a gauze inlet strainer...i have seen these partially blocked.....

Lastly...which injectors are you using?.....i assume he has checked the injectors are working as they should...

After that i'm scratching my head.....

Sorry to hear youve withdrawn from the event...

Best regards

Ian

[greencroft]

Just thought I would update this one to say that, instead of chasing this problem around the fuel system, I have gone for a more extreme solution and bought another rolling shell complete with an entire new fuel system. This has now been built up with most of the components out of my old car and touching wood and crossing everything, it has now completed 2 rallies without a cough. I guess it will remain as one of those unsolved mysteries but who cares so long as I can get back to the stages!

Thanks to everyone for their help and suggestions along the way.

[Cosnada]

Clint

What symptoms do you think you would get if the injectors were asked by the ECU to perform at in excess of 100% duty cycle?

How could you find out what % duty cycle they might be running at?

I might well be clutching at straws here but this guy was so convinced that the symptoms were just as he had experienced on his hillclimb car.

Another question - which you may want to answer by PM - who do you really rate on the mapping/diagnostic front, specifically with Ford Cosworths running on Pectel management?

Thanks

Simon.

These guys: remapping.co.uk

[tin]

had the same problem with a punters vauxhall.
in the end it was crank sendor not screened properly and picking up interferance from alternater. once sheilded no more problems .
hope it helps.
tin

[Andre]

i take my hat off for you... I would have commited suicide after the first month... Cheers mate, and glad everything is going just fine now

[greencroft]

Just to update all, the car has this weekend completed its fifth rally on the trot without so much as a splutter let alone a misfire. The rally just gone was also done in q hot conditions with some decent length stages so I hope that I can now safely classify this problem as sorted, radical though the solution had to be.

Thanks again to all who contributed ideas on this grief.

Simon.