Hesitation/Judder and misfire

[Micro]

Hi all,

This morning drove my car (in the quite severe piddling rain), and noticed it was juddering when accelerating hard. Left it parked up for an hour and drove it home, and again noticed the juddering. This afternoon drove it again at which point the engine management light came on and was flashing - stopping and turning off the engine, and turning back on, fixed it. Whilst the light was flashing, the engine seemed to have a misfire and was running rough. Torque Lite did not show any error codes whilst the light was flashing or off. The dash test shows codes 9600, and E510.

Driving the car gently, going through the gears in sequence, the car drives fine. If you, however, apply a large amount of throttle, or try to negotiate roundabouts in 3rd, it will begin juddering again. In 1st gear it is fine through to 6k rpm, 2nd 4k rpm, but 3rd 4th or 5th it does it more.

It was driving fine yesterday, i'm not sure what has changed (except the rain!) - the engine is dry, there is no apparent water ingress into where the plugs are. I haven't yet got around to getting Forscan onto the car, but will do in due course.

Suspecting

• Fuel/air mix - reduced/unmetered air flow, or fuel flow (when the light is flashing or it is juddering Torque shows the fuel system as "Open Circuit") or *shudder* fuel pump.
• Spark - plugs or coil pack

Any further troubleshooting ideas?

[Micro]

Checked all connections are fully home, will check leads for corrosion and stuff tomorrow when it's light, along with making sure the air flow is all clear, sensors all plugged in, etc.

Eurocarparts (with the discount code) have a Bosch coil pack for £21 (Normally £32) so have bought one just in case - I can return it if I don't use it.

New ELM cable in the post as i've left mine somewhere safe... maybe some data logging will show some results. It does this whether the engine is hot or cold.

Hopefully get this sorted without the car completely conking out!

[Tdci-Peter]

8 hours ago, Micro said:

Torque Lite did not show any error codes whilst the light was flashing or off. The dash test shows codes 9600, and E510.

That dash "secret menu" DTC readout always seems to be virtually useless! Sometimes it gives nos like Cxxxyy, which can be interpreted as DTCs P0xxx -yy. But 9600 & E510 could be anything.

A good ELM327 plus Forscan, as you propose to use, is the best available diy diagnostic system. There should have been some potentially useful codes there.

From what you say, ignition is a suspect, as wide throttle gives the highest compression pressure, needing the most spark voltage, and damp in the leads or coilpack could reduce the available voltage. But the "open circuit" comment confuses that a bit.

 

[Micro]

17 minutes ago, Tdci-Peter said:

That dash "secret menu" DTC readout always seems to be virtually useless! Sometimes it gives nos like Cxxxyy, which can be interpreted as DTCs P0xxx -yy. But 9600 & E510 could be anything.

A good ELM327 plus Forscan, as you propose to use, is the best available diy diagnostic system. There should have been some potentially useful codes there.

From what you say, ignition is a suspect, as wide throttle gives the highest compression pressure, needing the most spark voltage, and damp in the leads or coilpack could reduce the available voltage. But the "open circuit" comment confuses that a bit.

 

Bought a new coil pack from Eurocarparts as they had them for £21 with discount code - a steal and at the very least I can take it back if I don't need it.

The "open circuit" was something I quickly remembered - on going back and trying it, the car runs in open circuit until up to temperature, then reads "Closed circuit" when accelerating or idling. It goes open circuit again if the engine light flashes and it reads "Open Circuit - System Failure", or if you decelerate "Open Circuit - Engine Load or Deceleration" - so a bit of a red herring I think.

I normally drive quite briskly, usually accelerating using 3rd then popping into 4th/5th, so this is totally unusual. Reading online it seems to be quite a common thing with Fords, and reading other peoples adventures changing fuel filters, injectors, spark plugs, etc and it ending up being the coil pack make it seem worthwhile just changing it.

Bought amazon prime for The Grand Tour... who knew a few days later it would be coming in handy for getting a USB Elm327 next day, for the princely sum of £6 10pm at night! Almost as cheap as the bay. The bluetooth ELM thing I have flags up as a "bad elm327 clone" in Forscan.

[Tdci-Peter]

8 minutes ago, Micro said:

The "open circuit" was something I quickly remembered - on going back and trying it, the car runs in open circuit until up to temperature, then reads "Closed circuit" when accelerating or idling.

Ahh, that makes a bit of sense now. I think it means open loop & closed loop. When the engine is operating normally, the O2 sensor(s) are used to fine tune the mixture, and this is closed loop control. After starting, or maybe under rapid changes, or if there is a fault, it just uses MAP (or MAF if fitted) readings to estimate air flow and hence the fuel needed, this is open loop.

If there is misfiring due to an ignition fault, then it will probably revert to open loop, as the O2 sensor will get confused. (unburnt fuel, plus excess oxygen)

Hope the coil pack fixes it! (Does this engine have plug leads, or are they integral to the coils?)

[Micro]

10 minutes ago, Tdci-Peter said:

Ahh, that makes a bit of sense now. I think it means open loop & closed loop. When the engine is operating normally, the O2 sensor(s) are used to fine tune the mixture, and this is closed loop control. After starting, or maybe under rapid changes, or if there is a fault, it just uses MAP (or MAF if fitted) readings to estimate air flow and hence the fuel needed, this is open loop.

If there is misfiring due to an ignition fault, then it will probably revert to open loop, as the O2 sensor will get confused. (unburnt fuel, plus excess oxygen)

Hope the coil pack fixes it! (Does this engine have plug leads, or are they integral to the coils?)

I'm not sure about what you mean - it's got the long plungery type sockets that attach onto the plugs, which then go over to the coil pack which sits on the passenger side of the engine.

 

[Tdci-Peter]

10 minutes ago, Micro said:

I'm not sure about what you mean

Yes, that answers the query. (I meant are they separate like that, or come with the coil, or even don't exist as the coil fits on the plug, I should have looked it up really). Traditionally, ignition problems are tested in the order plugs, leads, coils. But at £21, the coil pack may be the cheaper bit, so why not do that first? I have never been a stickler for tradition!

[Micro]

13 minutes ago, Tdci-Peter said:

Yes, that answers the query. (I meant are they separate like that, or come with the coil, or even don't exist as the coil fits on the plug, I should have looked it up really). Traditionally, ignition problems are tested in the order plugs, leads, coils. But at £21, the coil pack may be the cheaper bit, so why not do that first? I have never been a stickler for tradition!

I'll be testing the resistance of the cables in the morning when I check them all for corrosion and checking the insulation too. Granted, it'll only be at 2v or whatever my DMM puts out but should show any major differences in the leads. Surely the plugs would run better at higher voltage (WOT) kind of ruling them out?

ECP have leads too, once I know which length I need i may order some of those too so I can use the same code!

[Tdci-Peter]

1 minute ago, Micro said:

Surely the plugs would run better at higher voltage (WOT) kind of ruling them out?

The higher compression pressure at WOT means more volts are needed per mm of plug electrode gap. So a wide gap would be harder to jump, and if there was a easier route via damp leads, or coil pack, or cracks in the plug insulation, then the power from the coil would go that way rather than sparking over the gap. So I think plugs have to stay in the suspect list.

[Micro]

1 minute ago, Tdci-Peter said:

The higher compression pressure at WOT means more volts are needed per mm of plug electrode gap. So a wide gap would be harder to jump, and if there was a easier route via damp leads, or coil pack, or cracks in the plug insulation, then the power from the coil would go that way rather than sparking over the gap. So I think plugs have to stay in the suspect list.

Right, gotcha.

Should there be any issues driving the car (whilst the flashing light is not on, and not causing it to judder)? I'm a bit stuck without it  I understand the risk to the cat if unburnt or very rich fuel mixtures are allowed to pass through the engine. 

I'll be able to remove the plugs Saturday to have a look, unfortunately I don't have the tools sufficient to do that here!

[Tdci-Peter]

1 minute ago, Micro said:

Should there be any issues driving the car (whilst the flashing light is not on, and not causing it to judder)?

I believe that the misfire detection systems are quite sensitive. They are designed to protect the cat from just what you describe. If you can not hear or feel misfiring or pinking, and the engine systems also do not detect it, then I would say it is ok.

It would take an appreciable amount of unburnt fuel to overheat the cat, or do other damage. I am sure that now you are alert to the problem, and stop or slow down if you detect it, you will be ok.

[Micro]

2 minutes ago, Tdci-Peter said:

I believe that the misfire detection systems are quite sensitive. They are designed to protect the cat from just what you describe. If you can not hear or feel misfiring or pinking, and the engine systems also do not detect it, then I would say it is ok.

It would take an appreciable amount of unburnt fuel to overheat the cat, or do other damage. I am sure that now you are alert to the problem, and stop or slow down if you detect it, you will be ok.

Absolutely, the first couple of times I did drive with it doing it to try and get a code stored but now much more aware. Got quite used to the gear changes now - reminds me of the driving test where you have to "eco drive".

Carparts4less have the HAAS ignition leads for £11 for a set of 4 (the shorter ones), or £13 for a set of the longer ones with discount codes (pretty sure this is an ECP sister site).

Will let you guys know how I get on, thanks Peter for all the help and advice, it is much appreciated! I will have a chat with the mechanics at work and see if they can quickly whip out my plugs a bit earlier than Saturday too.

[Micro]

Update for you all. Today it drove fine, until my return journey and it started playing up again. Either that or i'm getting used to the changing of gears.

P0300 code is set as "pending". Random/Multiple misfire.

Notice that on pressing the accelerator briskly at a standstill there is an appreciable "woosh" noise, but i'm not sure if this is a new thing or to be expected from a sudden increase in revs/air movement.

Disconnecting the hose from the air box, there is a good amount of suction there, doesn't appear to be any splits in any hoses i've checked.

Reseated all HT leads, all the connectors seem shiny and bright, no corrosion. Didn't measure the resistance of them though as didn't have time. Plugs all look clean, plug wells look clean, no water, oil, etc. What at first I thought was water, turns out to be some dielectric grease on the rubber of all the leads. Exhaust gas is definitely reaching the end of the exhaust pipe under some pressure. 

My new OBDII cable was a dud from the onset, so no Forscan, but from OBDII:

• Vacuum - 20ish at idle, dropping on raising revs in neutral.
• Long term fuel trim - i've had readings from -5% to 0.5% on the journey
• Throttle position appears to correlate with the accelerator pedal.
• Temperature appears good
• Atmospheric pressure sensor seems good
• Fuel system is staying in Closed loop when it should

Bit lost, at this rate it's going to a garage next week if the coil pack doesn't fix it!

Edit: After reading this whole thing again, it's made me realise - P0300. Multiple/Random misfire. So either multiple spark plugs are dodgy (pretty sure they were replaced in Jan when it was serviced), or if it is ignition side, perhaps it is the coil pack after all...

Or something else. Life isn't going well at present... 

[Tdci-Peter]

8 minutes ago, Micro said:

P0300 code is set as "pending". Random/Multiple misfire.

That code is the first positive indicator of ignition problems, that you have reported. And it suggests multiple cylinders, so making coil pack a more likely suspect.

While changing the coil pack, if you have a DMM, check the continuity of the power supply wire (middle pin of coil) to F34 in the engine fuse box. It goes via some connectors & joints, and can give problems.

[Micro]

55 minutes ago, Tdci-Peter said:

That code is the first positive indicator of ignition problems, that you have reported. And it suggests multiple cylinders, so making coil pack a more likely suspect.

While changing the coil pack, if you have a DMM, check the continuity of the power supply wire (middle pin of coil) to F34 in the engine fuse box. It goes via some connectors & joints, and can give problems.

Will do. Coil pack is apparently in the post.

Hopefully this fixes it as it will lighten my week up a bit! - only today had someone decide to kiss my rear bumper at a roundabout  and my dash cam decided to do it's "recording stopped" just as he hit me... no damage, no injuries, details exchanged, hope thats the end of it.

[Micro]

On 22/11/2016 at 8:23 PM, Micro said:

Will do. Coil pack is apparently in the post.

Hopefully this fixes it as it will lighten my week up a bit! - only today had someone decide to kiss my rear bumper at a roundabout  and my dash cam decided to do it's "recording stopped" just as he hit me... no damage, no injuries, details exchanged, hope thats the end of it.

Coil pack is not in the post, apparently the ECP guy told me incorrectly (the guy today said he was new)...

Borrowed a colleagues ELM cable, so have a bit of live data. This wass a bit quick (didn't realise Forscan only shows 8 data sources on the oscilloscope), but gives a bit more info. I'll maybe get some better data tomorrow. From what I can see there does appear to be a drop in the O2 sensors value  (which from what i've read means there may be unburnt oxygen getting to them).

Fuel system status has 3 states, open, closed and fault (it went into fault mode when I accelerated the second time and the eml started flashing).

[Tdci-Peter]

15 hours ago, Micro said:

I'll maybe get some better data tomorrow. From what I can see there does appear to be a drop in the O2 sensors value  (which from what i've read means there may be unburnt oxygen getting to them).

Interesting data, though I don't see the problem, yet!

I guess O2S11 is the pre-cat O2 sensor, and O2S12 is post cat. The section at the end where it is in closed loop, and O2S11 is oscillating looks like what I have heard it should be, except that the post cat sensor stays reading rich, I would expect it to drop more towards the mid (0.5v) value. Does that suggest a mismatch between the two sensors? One giving wrong readings.

The STFT values range is odd, 8% to 16%. That is quite a lot of fuel being added above nominal (I think it works that way round). That would be needed if there was an air leak into the manifold, if the O2 sensor being used was reading wrong, if the MAP calibration was out, or the fuel pressure is too low.

The APP (accellerator pedal) would be useful, though the rpm does show when the car is under load. But it is hard to tell if the open loop periods are due to over-run (closed throttle, rpm above idle), or to an error. The Load% does not seem to clearly show this.

On your system, is there a button on the bottom right of the Forscan screen that changes the graph colour from black to white? The pics tend to come out a bit clearer that way, I found.

[james_60]

I will be interested to see how this plays out, 

 

Jamie

[Micro]

9 hours ago, Tdci-Peter said:

Interesting data, though I don't see the problem, yet!

I guess O2S11 is the pre-cat O2 sensor, and O2S12 is post cat. The section at the end where it is in closed loop, and O2S11 is oscillating looks like what I have heard it should be, except that the post cat sensor stays reading rich, I would expect it to drop more towards the mid (0.5v) value. Does that suggest a mismatch between the two sensors? One giving wrong readings.

The STFT values range is odd, 8% to 16%. That is quite a lot of fuel being added above nominal (I think it works that way round). That would be needed if there was an air leak into the manifold, if the O2 sensor being used was reading wrong, if the MAP calibration was out, or the fuel pressure is too low.

The APP (accellerator pedal) would be useful, though the rpm does show when the car is under load. But it is hard to tell if the open loop periods are due to over-run (closed throttle, rpm above idle), or to an error. The Load% does not seem to clearly show this.

On your system, is there a button on the bottom right of the Forscan screen that changes the graph colour from black to white? The pics tend to come out a bit clearer that way, I found.

I'm not quite sure why the trim values are so high in forscan, I'm not sure if it can correctly plot negative percentages. Monitoring both with torque and a bluetooth elm it sits less than +-5%. 

I monitored just the o2 sensors on the way home,  if I force the issue to occur there is a notable drop in voltage to the rear sensor for a short moment. Otherwise the pre cat sensor oscillates as I think it should and the post cat sensor stays pretty constant. It is cold here when I'm doing this (< 5 degrees) would that account for the extra fuel or higher o2 sensor readings?

The MAP readings read around 28ish at idle, they increase when accelerating (is this correct?). 

The MAF readings increase on opening the throttle.

No codes other than Multiple or Random misfire.

And ECP are still giving me different answers about my order depending on who I speak to!

 

 

[Tdci-Peter]

12 hours ago, Micro said:

It is cold here when I'm doing this (< 5 degrees) would that account for the extra fuel or higher o2 sensor readings?

I do not think cold air should change the O2 readings, at least not once the engine is warmed up a bit.

The cat needs near stoichiometric mix to work properly. Insufficient O2 would lead to CO emissions, and unburnt fuel. Excess O2 will tend to raise the NOx emissions, so I am sure it will aim for the optimum, which should be 0.45v about on the post-cat sensor.

When replayed stored data from Forscan, you can use the dash or table modes as well as the graph, and scan through the data that way. That would check if it a graph display related problem. I would be a bit surprised if it was reading wrong, it is usually a very reliable & well tested tool. Is there anything on the Forscan Forum about this, I wonder?

I think the MAP sounds about right, I can check with another thread. It should certainly rise with throttle, approaching 1000mBar on WOT.

[Micro]

Replaced the coil pack today, had a look at the air filter too, aside from looking a little crushed it seemed clean.

Revs don't dip at idle any more when you open the throttle and let go, and it pulls like new. Problem solved!

Now for a well earned beer  so much thanks to everyone! 

[RayPJunior]

Very useful thread, having a similar problem, so I guess either coil pack,  air-flow meter or plugs.

[David Phillips]

I have a similar problem with my 55 reg 1.6 petrol. Took it to the garage and have had new plugs, leads and a coil pack. The next day it started doing its occasional misfire thing again and the management light come back on. Took it back to the garage but they think it's now an electrical problem with the wiring from the coil pack to the ecu. They say it's common for the wiring to blow at the same time as the coil pack fails.

Does anyone have any advice? Does anyone know of any independent ford garages around the Wrexham area? Feel like I'm getting ripped off!

Thanks.

[Micro]

On 27/11/2016 at 11:13 AM, David Phillips said:

I have a similar problem with my 55 reg 1.6 petrol. Took it to the garage and have had new plugs, leads and a coil pack. The next day it started doing its occasional misfire thing again and the management light come back on. Took it back to the garage but they think it's now an electrical problem with the wiring from the coil pack to the ecu. They say it's common for the wiring to blow at the same time as the coil pack fails.

Does anyone have any advice? Does anyone know of any independent ford garages around the Wrexham area? Feel like I'm getting ripped off!

Thanks.

Update so far - reapplied the silicone grease to the HT leads to keep the water out. Journey (consisting of 44 miles of city driving, motorway and country roads) returned 40mpg... Much more than the 34mpg I've been getting from it for the past few months. Guessing that may settle back to 36ish once I've taken it to work and back for a few times. I also managed to lose part of the HT lead clip, I think it's just a spacer (the remaining half is cable tied to the HT leads to keep them there) - anyone know if it's strictly necessary? They're £7ish new... 

Forscan still shows the downstream sensor at 0.6v but a much steadier line, the upstream sensor swings as it should. LTFT is near enough bang on zero.

David, do you have access to an elm cable and forscan to check for codes and view live data?

[Tdci-Peter]

54 minutes ago, Micro said:

Forscan still shows the downstream sensor at 0.6v but a much steadier line, the upstream sensor swings as it should. LTFT is near enough bang on zero.

That sounds good. Looks like poor sparks from the coilpack were allowing enough unburnt fuel through to upset the O2 sensors, then the mixture went out of balance. A nice plot of it working properly might come in handy for others to see, if you can.

On 27/11/2016 at 11:13 AM, David Phillips said:

They say it's common for the wiring to blow at the same time as the coil pack fails.

That comment puts my bull-dung detector into amber alert. I am not sure what "blown wiring" is, in this context. It is more likely that a wiring fault was the original cause, maybe there was nothing wrong with the coil pack. The 12v feed to the coil pack has been known to develop intermittent faults. It goes through various connectors & splices.

But to be fair to the garage, replacing the coil pack is quicker, and hence at garage labour rates cheaper, than investigating the wiring, so they may had little choice than do it that way round.

The error codes that must be being generated might give some clues. The more, the better. Is it one cylinder, or all, or maybe some other sensor is giving an intermittent error.