[FIXED] CSR / Duratec 2.3: Intermittent engine 'cough' under load

[vertew]

​Hi, can anyone help with this ...
My 7 is a standard CSR 260 with the Duratec 2.3 and MBE992B ECU.

​Under full acceleration I get a very occasional 'cough' or 'hesitation' from the engine.  It doesn't really feel like a misfire on single cylinder, more like a short loss of power across all 4 for perhaps half a second.

Other than this annoyance, it runs fine.  It's been on a rolling road for setup / remap with 2 Steves and no issues with the power.

It's done this for the 3yrs I've had the car, but as it's been a rare occurrence, I've adopted a 'wait and see' approach.  It now seems to be getting slowly worse, so I probably need to find out what it is before I get stranded ...

My hunch is that it's fuel related, given that it seems to be hitting all cylinders at the same time (but can't be sure about that either).

A few things I've tried:
- replacing the fuel filter
- cleaning various connectors including water sender, ECU and MFR (mentioned in other posts)
- I only run it on V-Power

Any suggestions very welcome.
tks, Andrew.

>> UPDATE >> see post #50 for (what hopefully continues to be) the fix.  Yay!!

[aerobod - near CYYC]

Might be a coil pack going out. On my R400D I had a small hiccup in acceleration especially at mid revs and mid throttle, felt almost like turbo lag, just annoying to begin with a year or so ago. The past couple of months it has quickly worsened to the point that the car would sometimes misfire on light throttle after hard acceleration. Checking the plugs would never show any variation between cylinders, they all looked perfect. Also checked and wiggled all wiring in the ignition, TPS, CPS and other sensors with no effect. Once it became repeatable and started to do it at idle, I put an infrared thermometer on the primary exhaust pipes and found that #1 cylinder would cool rapidly while it was misfiring. I swapped the coil pack on #1 and the problem has disappeared.

[vertew]

Thanks for that aerobod.  Definitely worth a try.  I just bought a set of four used coil packs to experiment with as swap outs.  I also checked cleaned all the loom connections under the coil pack cover though they all looked fine).

[John Vine]

I had a similar experience on my R400D.  The cure (like aerobod's) was a new coil-on-plug (COP) for #1 cylinder.

Another possibility is damaged/fractured COP wiring.  Does the 260 come  with the flexi-loom as standard?  If not, have a thorough check of the COP wiring inside the connector (pull the pins out for the best results).

JV

[aerobod - near CYYC]

I just received a set of new coils today, I had a spare of the old ones, but the old part seems to have been superseded, so I thought I would put in the new part number across the board, assuming overall enhancement (perhaps a bit of a stretch) as the part has evolved. $38CDN (£23) each for the Ford / Motorcraft part. Original part number was 4M5G-12A366-BC, new one is 4M5Z-12029B (DG541).

[vertew]

To John Vine and aerobod ...

I'm away in summer hols at moment so haven't been able to try new coil (+ other) suggestions.  Will have to be a job when I get back next week,

@aerobod - I ordered used versions of the original part, not the updated version.  Let me know if you notice an improvement from the updated part.

@John Vine - don't know which version mine has but it's a 2006 so possible not the Flexi-Loom.  I'll check when I get home.  Either way, I'll clean the pins again.

Other suggestions I've had ---

> From Rob at Rat Race Motorsport - check/clean connections on fuel pump.

> Via PM - check MFU connectors carefully ... I've done this, but I'll try again.  I'll try wiggling connections when engine is running.

tks Andrew.

[aerobod - near CYYC]

The new coils seem to be running very well, as smooth as the old coils when the car was brand new, but the part number mystery continues. The bags on the new parts indicated 4M5Z-12029B (DG541), but when I took the coils out of the bags the part number printed on them was 4M5E-12A366-AA. They are all brand new and shown as the same fitment as the original 4M5G-12A366-BC, I'm not sure if the parts are revised, older, equivalent or exactly the same with different part numbers printed on them.

[vertew]

I've checked out the fuel pump connector and couple of the pins were looking slightly green - now cleaned up.  Thought that might have done the trick, but no.  Went out for a long spin last night and noticed the 'cough' again.

Thanks aerobod, my 'test' coil packs have arrived and I'll fit these just (probably) to rule them out because I've noticed something else that may be related ... I don't often drive the 7 at night so hadn't seen this before, but under hard acceleration, the ignition light glows / flickers dimly.  Then goes out. under all other conditions.

These two things may or may not be related, but thinking the underlying problem could be alternator related - perhaps a voltage drop which is enough to affect power to the fuel pump?  I'll have a poke around in this direction, but again, any ideas very welcome.

[Jonathan Kay]

... the ignition light glows / flickers dimly.  Then goes out. under all other conditions.

Can you replicate that while you're stationary?

1. Check the alternator mounting and belt condition and tension.
2. Measure the battery voltage at rest, minimum during cranking, at idle and at 3,000 rpm.
3. Measure the voltage across the battery when this happens.
4. Is your 2.3 the type that is known to have problems charging at low engine speeds that led to a discussion of pulley size?

...

... the ignition light glows / flickers dimly.

Does the flickering occur at the same time as the coughing?

Jonathan

[aerobod - near CYYC]

Hi vertex, do you have an MBE lead and Easimap available? It would be easy to datalog the battery & charging voltage over all conditions if you do.

[vertew]

Hi aerobod, thanks, I don't have it, but probably a good a time as any to get hold of the mapping dongle + software. I'll give SBD a call.

[ChrisC]

If you do get one, keep and eye on the reset count and the bad tooth count.   If they go up while the engine is running you have a problem.   If the reset count goes up your ECU has a power supply problem and the bad tooth counter is the crank sensor. 

Its possible to diagnose problems beyond the ECU using the datalogger.   JimD spotted a small voltage rise before his duratec interminably died, just after the voltage rise the lambda showed a lean reading, but  the fuel compensation rising.   Basically the fuel pump had stopped running causing the small voltage increase, which turned out to be an intermittent inertia switch.   

[vertew]

Hi Jonathan - thanks for suggestions - re. your points ...

1. Replicating issue while stationary - I'll have a go when it gets dark, but a I expect it won't appear.  The 'dim ign light' only happens under full acceleration and full load.  Even backing off a little seems to make the light go out.  The misfire / 'cough' similarly only happens at full accel / under load and in usually around the 4,000RPM area.
2. Belt - is under 2yrs old and looks ok with good tension (still may be slipping though).  I've also just cleaned the alternator connections (which looked ok).
3. Battery voltages are as follows - resting = 12.8V; cranking = ~10V; idle = 12.9;  3,000 RPM = 13.8V. Battery is OEM Banner and is kept on a conditoner is 18 months old.
4. Low RPM charging issue - not heard about that before, could you share a link?

My alternator looks like this Caterham part which looks same as the 40A Cosworth 'Race' alternator (PR6932) here.

tks, Andrew.

[Jonathan Kay]

Battery voltages are as follows - resting = 12.8V; cranking = ~10V; idle = 12.9;  3,000 RPM = 13.8V. Battery is OEM Banner and is kept on a conditoner is 18 months old.

Less than 10.5 V during cranking might indicate that the battery is pining for the fjords. There also seems to be a tendency for some ECUs and possibly some other electronics to drop out with low voltages.

If the battery can be topped-up I'd check the levels. And repeat those voltage measurements every so often so that you can spot deterioration before it lets you down somewhere awkward.

...

Replicating issue while stationary - I'll have a go when it gets dark, but a I expect it won't appear.  The 'dim ign light' only happens under full acceleration and full load.  Even backing off a little seems to make the light go out.  The misfire / 'cough' similarly only happens at full accel / under load and in usually around the 4,000RPM area.

Turning the headlights on might increase the load on the alternator enough to help discover if the voltage is dropping.

..,

Low RPM charging issue - not heard about that before, could you share a link?

Previous discussions: 1, 2, 3.

Jonathan

 

[vertew]

The Easimap CAN dongle turned up quickly (thanks SBD).  Wow, loads of interesting data, I should have got one of these ages ago (even if I can't change anything)!

I've attached a graph of 'battery voltage vs engine RPM' sitting stationary (basically the test I did above, but now with the mapping tools).  From what I can glean from the net, the operating voltages look a bit low -- it's not making 13.5V at operating speeds with no accessories on.

Jonathan - I'll check the battery fluid levels.  When the glorious summer drizzle stops, I'll take the car out with the software running and try to catch it doing it's hesitation / cough thing.

ChrisC - I'll also watch out of any dropped data (had to google 'missing toot count!) 

Thanks again everyone, think I'm getting closer now.  There's so much info coming from easimap, I'm sure this give some more good pointers if I can log the fault happening.

Any views on the 'static' pls let know.  I'll upload the 'driving' one when ready.

[Jonathan Kay]

Mmmmmmm... data.

Very interesting.

I'd add the effect of headlights to that run.

Does it sound as if it's cranking normally and start reliably? Even after a long run?

Jonathan

[vertew]

It does seem to spin up pretty quickly, I'd certainly not say it was chugging slowly.  I keep the car on a CTEK conditioner most of the time, so the battery should be maintained in a reasonable state.

I don't recall any problems with cranking speed after a longer journeys.  Suppose it's possible that the CTEK conditioner is masking an alternator issue - eg. the battery always gets charged up after a run, so I'm not noticing a longer-term discharge.

I just topped up the battery cell levels which were ~5mm off the indicator, though plates were well covered.  I'll see if that knocks up the resting voltage a bit ...

Now REALLY interested in seeing the data for this mysterious 'cough'.  I'll see if I can work the headlights on/off into the test as well (though possibly not at night though ... ).

tks Andrew.

[Jonathan Kay]

Suppose it's possible that the CTEK conditioner is masking an alternator issue - eg. the battery always gets charged up after a run, so I'm not noticing a longer-term discharge.

Same thought here.

Jonathan

[vertew]

Alternator would be a ~£250 pain in the wallet, but would be so good to ger rid of the intermittent misfire. Could look into alternator diagnosis / repair, but one step at a time ...

[ChrisC]

I suspect the flat line voltages are between each stop are not true readings, but "no signal estimates" from easymap.    The voltage before the first start is how I would expect to see a signal, showing the noise from fuel pump etc.      But as said, it looks a bit low. 

It looks to me like alternator raised your voltage during your first start/idle and again during the second run.    I think it more likely the CTEK is masking batter issues, given your average idle voltage rises during the test.   I would expect an alternator problem to see a reducing idle voltage over time. 

Get some data on the cough, that's the interesting bit. 

[Piers300]

Looking at the graph at 1000 rpm idle speed, the alternator output is approx 12.00 volts. It does rise with a speed increase and mention has been made previously of alternator drive ratio. This should be around 13.2 to 13.5 at idle when first started. I suspect your alternator regulator is on its way out. Also you mentioned the red light coming on during hard acceleration. This is symptomatic of a diode failing to half wave rectification - i.e glowing rather than full bright.  I would have the alternator serviced by a local starter motor/alternator shop.

Piers

[vertew]

ChrisC + Piers - yep, battery is a suspect and the alternator readings look low.  

Rain still coming down - road test data will have to wait .

I am starting to check out local alternator servicing shops though ...

[vertew]

I managed to dodge the showers today and went out for a long road road test with the easimap logger running - and I did manage to capture a few instances of the misfire / 'cough' in action - see here.

The good news is that the misfire is visible and does seem to coincide with a steep drop in battery voltage, down to as low as 9.5V.  It's most noticeable on page 4 - the test with accessories turned on.  Page 3 shows a what looks like a cough in engine RPM with no drop in volts, which is a bit more ambiguous.  The data also seems to confirm that the misfire usually (but not always) happens around the same 4,200 RPM range, which is damn odd.

I also did a couple of simple rectifier tests using a mulitmeter: (a) AC test looked within normal range and (b) diode test also looked ok.

My take from this and everyone's advice so far is that the voltages look generally low and the big negative voltage spike almost nails it - this all looks very electrical, with the alternator being prime suspect.  I'm also not convinced by the 'passed' rectifier tests either, as these are static / limited load.

I'm no expert in alternator failure modes, but the negative spike around 4,200 RPM still strikes me as very weird.  Still wonder if it could be something else ...

For now, I'll now move on to repair / replacement of the alternator.
Again (sorry), would be great to hear your views on this new info.

tks v much, Andrew.

[ChrisC]

Can you check the reset count, it's a random number when the ECU starts, and it increases when the ECU has a power supply problem.

[Jonathan Kay]

For now, I'll now move on to repair / replacement of the alternator.

The presenting symptom isn't typical of an electrical problem (why at that engine speed, under load etc?). But the story told by the voltage observations needs a happy ending. So bench testing the alternator sounds like a good idea.

I'm also still suspicious about the battery. That low voltage during cranking doesn't suggest a charging problem... but was it done soon after being on the conditioning charger or after you'd been out on the road?

Jonathan