K series running issues / possible misfire?

[Smithy77]

Also I have noted the comments about cam timing, it has briefly been mentioned previously. It seems like it would be a good place to visit next after electrics, especially with the characteristics of the supersport spec k-series. All I also mentioned I'd be looking to get some properly set up verniers at some point, so I guess I could kill two birds with one stone

[oldbutnotslow]

Ive never had a disappointed customer after fitting verniers and setting the lift correctly. They really do make a difference across the whole rpm range

 

I run a 1600K producing just below 190bhp using 633 cams Very similar to Supersport spec. The car is only used on track so it can have periods of inactivity. It fires on the first flick of the starter switch and has a very smooth idle at around 900rpm so it is very possible for a tuned car not to be lumpy at idle but I do have an Emerald ECU which probably helps.

 

Again do excuse me if you have already investigated this. A poor battery can cause all sorts of'electrical problems' that can manifest themselves in all sorts of strange ways. I have from experience spent hours trying to chase electrical faults only to find that the battery was the culprit. It may be worth having the battery checked professionally using the new style test kit and charged using one of the latest 'smart chargers' Any hint of a problem and I would install a new batery.

 

[Smithy77]

I have just booked the seven in with New Techniques for a fortnights time ☹️

 

I'm still intrigued by the fact that the work I have done so far has at least cleared the manufacturer DTC of P1590, and we don't really know what that related to. I might swap back the sensors in turn to see if any of them get that code come back.

 

I would like to thank all those who have dedicated their time to help my cause. We may not have got to the bottom of it, but we have improved something on the car at least and I have learnt an awful lot along the way

[revilla]

Oh well, we all did our best ...

 

Do let us know what they come up with, we're all learning on here (unless anyone wants to admit to knowing it all 😬) and the archive of old cases, especially the unusual ones, and their ultimate solutions is one of the very valuable resources of BlatChat.

 

Hope it's something silly and simple and they get it running like it should.

[evotell]

Could it be a broken loom?

[Smithy77]

Could well be the loom. It was a shame we never got to test the voltage of the loom via the earthing point.

 

Revilla - I was looking for my earth point for ages that night after you sent me the picture of where yours is; I definitely don't have an engine loom earth point along the bulkhead shelf. My loom does look rather 'modified', shall we say, as can be seen from the pics below.

 

In the first picture you can see a pair of black connectors not connected; I have always wondered if they should be, and if not, what they are doing there?

 

In the last picture it shows the only earth connection I could find which comes directly off the engine loom. It is located just inside the nose cone on the drivers side and is fixed to the brake line t-splitter body. It did look rather dirty/corroded so for what it was worth I cleaned it up nicely.

 

http://i75.photobucket.com/albums/i315/pullpete/20140417_210908.jpg

http://i75.photobucket.com/albums/i315/pullpete/20140417_210957.jpg

http://i75.photobucket.com/albums/i315/pullpete/20140417_211006.jpg

http://i75.photobucket.com/albums/i315/pullpete/20140417_210937.jpg

http://i75.photobucket.com/albums/i315/pullpete/20140417_210947.jpg

http://i75.photobucket.com/albums/i315/pullpete/20140417_211422.jpg

[oldbutnotslow]

Nah the loom is very much as CC make em!

"Don't worry they all look like that Sir"

[evotell]

What I meant to say was maybe it has a break in the loom 😳

[CharlesElliott]

Back again - sorry, was away racing at the weekend....

 

Earth points are bell housing bolt on nearside, engine bracket on offside, brake union on offside (you found that), wiper motor stud under scuttle and there is also one at the rear....can't remember.

 

And yes, would be happy to take a look.

[Smithy77]

Quoting CharlesElliott: 

Back again - sorry, was away racing at the weekend....

 

Earth points are bell housing bolt on nearside, engine bracket on offside, brake union on offside (you found that), wiper motor stud under scuttle and there is also one at the rear....can't remember.

 

And yes, would be happy to take a look.

 

I checked the earth to the bell housing and this was new two years ago and looks as good as new.

 

The wiper motor earth I checked when trying to solve my erratic rev counter problem. I sanded off the black paint from the motor bracket where the earth made contact - should I also make sure there is bare metal contact where the bracket bolts to the chassis??

 

The only one left would be the engine mount so I will find and check that too.

 

Charles, as previously mentioned I have the car booked into New Techniques in 2 weeks time. Would it be worth a visit to you before this??

[CharlesElliott]

Personally, it still sounds like a loom or sensor problem to me. Yes, I am definitely happy to look (I'm cheaper than New Techniques!) but obviously that does mean a long drive here and back so really up to you. I could do something this weekend if that works. I could even try to drag Roger Ford over as well 😬

 

 

[Smithy77]

So as not to look like an ignorant bastard...

 

@Charles - YHM (belatedly)

[CharlesElliott]

Well, what did we find.

 

The butterfly in the throttle body was loose and moving around, with one of the screws not far from letting go so we fixed that. The throttle cable was also past it's best and needs replacing as it doesn't move freely.

 

Apart from that the sensors looked ok, except for the lambda that continued to trigger a closed loop fault although we weren't entirely convinced it was a sensor issue.

 

Charles

[revilla]

So how is it running now?

[CharlesElliott]

Tickover was a bit lumpy but exactly what I would expect from Megagrad spec. It was quite difficult to drive at low speed, but I think the throttle cable would put that right. Pete said that replacing the TPS and IACV had improved the overall running and it seemed fine in my short drive round the block.

 

In summary, I thought it was pretty much ok following the sensor changes and sorting out the throttle body. The cable will hopefully be the last piece.

 

But it isn't my car, so we'll have to see what Pete thinks!

 

Edited by - CharlesElliott on 4 May 2014 12:17:05

[Smithy77]

Hi all! Sorry for the late update but have been enjoying the sunshine and haven't had access to a computer until now. Firstly, big thanks to Charles and Roger for their help on Saturday, really top guys and I really can't thank you enough. THANK YOU!!

 

So just to recap, I fitted a load of replacement sensors last week (O2, MAP, IACV & TPS). I first fitted the O2 and MAP sensors and there was no change. My OBD2 scanner still showed a CL fault and the DTCs P1590 (undefined), P0195 (Oil temp) & P0135 (O2 sensor circuit). I then fitted IACV & TPS which seemed to clear the P1590 DTC and also seems to have regained my top end performance. The poor starting and poor cold running at low revs still remained before my trip to see Charles.

 

The loose butterfly was a great spot by Charles! I obviously could have been facing a lot of serious engine damage if that screw let go, so thanks again 😶‍🌫️ The throttle cable was admittedly past it's best and wasn't entirely smooth, so when I got back home I fitted a Revilla special throttle cable here. Although it feels nice and smooth under foot now, I can't say it has made a great deal of difference to the poor cold running at low revs. In fact, I still feel a slight sticky throttle at the point of going from no throttle to minimal throttle. This will obviously not be helping but I'm not sure what the cause is - it's a new cable and the TB butterfly doesn't stick.

 

I do feel however that fixing the butterfly has improved the starting and cold/low revs running somewhat. Since then it has started fine every time, but time will tell, and it does feel more easy to drive at low speeds.

 

So my next plan was to try and establish which of the sensors may have been faulty, so I tried re-fitting the originals in turn to see if any of them made it worse or brought back the P1590 DTC. Fitted the TPS and saw no change, I then re-fitted the MAP sensor and saw no change. My new OBD2 scanner decided to play up at this point (keys decided not to function so could not navigate the scanner) so it put a halt to this process. However, I probably did 60+miles on Monday and she seemed to run fine, suggesting the TPS and MAP sensors were fine. As the CL fault and P0135 DTC have also remained present with old and new O2 sensors, one would assume the O2 sensor was also not at fault - perhaps this points towards a wiring fault? Therefore by process of elimination I would say the IACV was a cause of some of the issues. Hopefully I can confirm this when I have a functioning OBD2 scanner.

 

So I think it's safe to say we have continued to make progress and the car appears to be running fine now. All that remains an issue (potentially) is the remaining CL fault and P0135 DTC - both of which were not present on Roger's 1.6K when scanned with the same scanner.

 

All in all, a happier seven owner (and Mrs Smiffy)!

 

Edit: The car is still booked in with New Techniques next week. Is it worth keeping the booking to see if he can trace the CL fault and P0135 DTC?

 

Edited by - Smiffy7 on 6 May 2014 15:31:52

[revilla]

Pete,

 

Glad to hear things are better.

 

The P0135 DTC decodes as "O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)", i.e. it is specifically relating to the HEATER circuit for the lambda sensor. The sensors don't work until they are at operating temperature, which I think is above about 300C. They incorporate a heater to get them up to temperature more quickly. In your previous post you said that the live data from the scanner showed the sensor voltage cycling between about 0.2V and about 0.8V when hot; this is exactly what it should do and suggests that the sensor is working fine and that the ECU is modulating the fuelling using the sensor readings in closed loop mode. So I guess what is happening is that the heater drive circuit has failed somehow and the sensor is just being heated more slowly by the exhaust gasses but eventually gets up to temperature and settles down to working correctly.

 

The heater drive wiring for the lambda sensor is quite simple. It is driven directly from ECU pin 1 (controlled ground) and the main engine supply 12V wiring. The pinouts of the ECU connectors are shown here. To make life simple, the ECU has two plugs, one smaller and one larger. In the larger plug there are a lot of smaller pins and four larger pins. Pins 1 is outermost larger pin, right in the "pointed end" of the larger connector (you'll know what I mean when you look at the plug). The ECU plugs have little "handles" on the outer end which you pull outwards to release the plugs. As you pull the outwards the plugs unlock and move forward.

 

The black wire with a blue stripe at the lambda sensor connector is connected to ECU Pin 1. The brown wire with (usually) a pink stripe at the lambda sensor is connected to +12V, possibly through a Main Relay depending on the wiring of your car. If there is a wiring fault with the heater, it will be one of these wires.

 

You could check the continuity of these with a resistance meter - there should be no measurable resistance between the black/blue terminal on the lambda sensor and the ECU connector Pin 1 and with the engine running (or shortly after switching off as the ECU holds the Main Relay on for a little while) there should be very little resistance between the brown/pink wire and the battery positive terminal. However just checking the resistance like this can be misleading as even a tine resistance equates to a sizeable loss of voltage with the kind of current load imposed by a heater. Ideally you need to measure the voltage across these two wires at the lambda sensor during the first few seconds after startup (when the heater should be operating) WITH THE SENSOR STILL CONNECTED which may involve either some ingenious probing into the plug terminals or cutting into the wires. There are a couple of other ways of checking the wiring that I can think of:

 

i) Wire a 12V light bulb up to the heater pins of a connector the same as the one on the lambda sensor. Plug this in instead of the lambda sensor itself. When you first start the engine, the bulb should come on (instead of the heater!). If not, you can connect either the positive side of the bulb to the battery or the negative side to ground to see which wires is faulty.

 

ii) (THE BODGE - AT YOUR OWN RISK!) Stick a fine pin through each of the wires and measure the voltages across those, but don't let them short against anything and put a bit of insulation tape around the holes after you've pulled them out.

 

I'd be more than happy to have a look at it for you if you were ever up in the East Midlands area but it's quite a drive for you! Let me know if you want me to make a test bulb for you :)

[Smithy77]

Revilla, thanks for the post. Yes, things seem much better, it's just a case of getting to the bottom of these remaining faults. I assume the P0135 DTC and CL fault are directly linked? I think you have provided enough info for me to at least try and find the fault myself, so I think I'll postpone my visit to New Techniques.

 

What symptoms would you expect with an O2 sensor heater circuit fault?

 

I will try and measure the resistance and voltage as you describe. Electrics isn't my strong point so forgive me if I'm talking rubbish, but would it not be possible check the voltage of each wire with a volt meter instead of a bulb? I.e. measure the voltage between the black/blue ground wire and the battery +ve, and then between the brown/pink +12v and the battery -ve? With the engine running cold should these not read ~12V?

[revilla]

Pete,

 

Taking your points in order:

 

i) Yes I would guess that the P0135 DTC and "CL Fault" are the same thing. I think "CL Fault" is telling you that the ECU is managing to use the lambda sensor in closed loop mode but has nevertheless detected that there is a fault with it, which will be the fault described by the P0135 DTC.

 

ii) Probably not many symptoms at all. Once everything is up to temperature, no symptoms whatsoever as the heater would no longer be needed anyway. The voltages you reported from the lambda sensor and the fact that it is running "CL" seem to imply it is working quite happily once hot. The heater is there to get the lambda sensor up to its working temperature (over 300C) quickly. I think typically within 30 seconds. Without it all I can say is it will take longer (otherwise it wouldn't be needed) - not really sure how much longer though. Maybe a few minutes? I'm not quite sure what the ECU will do during the extended warm-up time. If it can understand that the sensor is still not hot it will probably just run open loop off its map which may lead to poorer emissions control and maybe slightly rougher running, if not it will probably try to go closed loop and run with an incorrect mixture due to the wrong readings from the sensor. Either way it will all clear up once the sensor is hot.

 

iii) Just measuring the voltage by unplugging the sensor and checking the voltage at the plug pins is not a reliable way to check it. When an electric current flows through a resistance, voltage is "dropped" across the resistance. The voltage is proportional to both the resistance and the current. With the sensor unplugged there will be no current flowing, so even with significant resistance in the circuit (a "bad connection") there will be no voltage dropped. So even with dodgy wiring you will probably read +12V on the supply wire and 0V on the ground wire, but as soon as you start drawing current by connecting a load, such as the sensor heater or a bulb as a test load, the voltage will drop off. It's always best to test a circuit by looking for the voltage drops under load conditions. I think the sensor heater is about 16 Watts so draws a bit over 1 Amp, so you either need to measure the voltages with the sensor plugged in by tapping into the wires somehow or you need to wire up a similar load across which you can easily measure voltages. A 12V 10W 245 sidelight bulb like this would do the trick.

 

Under load I would expect you to find one of the following (remember that the heater may only be powered by the ECU for a few seconds after starting):

 

i) The bulb lights brightly. The supply side voltage reads around 12V or more (14V+ if the engine is running, measured from a good ground point). The ground side voltage reads something small, less than 1V (not sure what the driver circuit inside the ECU is). In this case all is as expected and I've no idea why you're seeing the fault codes.

 

ii) The bulb doesn't light, or lights dimly. The supply side voltage reads around 12V or more (14V+ if the engine is running, measured from a good ground point). The ground side voltage reads a lot higher than expected, leaving a reduced voltage difference across the bulb or heater. This would indicate a fault in the ground side wiring from the sensor back to the ECU, a dirty connector pin to the ECU, or possibly a fault with the driver circuitry inside the ECU. Not sure what the ground side voltage would rise to, it would depend on the exact fault. With a completely broken wire it would be the same as the supply voltage, but anything much over 1V would be suspicious.

 

iii) The bulb doesn't light, or lights dimly. The supply side voltage reads a lot less than the battery voltage, leaving a reduced voltage difference across the bulb or heater. The ground side voltage remains low. This would indicate a fault in the supply side wiring from the battery to the sensor or a high resistance through the ECU fuse wiring or main relay. As the positive supply to most of the engine components (injectors, coil packs, sensors etc.) is all common, unless it was just a wiring fault between the common junction point and the lambda sensor I would expect this to cause other running problems too.

 

Happy to knock up a little test load for you if you want and check it on my engine to give you some idea of what to expect on a normal working engine.

[Smithy77]

I have just got in from my light bulb testing and can report the following:

 

With ignition on and engine off I measured 12V at the live feed wire and 0.3V at the controlled ground wire.

 

Plugged in the test bulb and it lit, neither dimly nor brightly, but kind of moderately lit. Started the engine and the bulb dimmed momentarily while cranking and returned to it's moderately lit state once the engine was running.

 

I then took the voltages of the wires again. With the bulb still connected I got 14V at the live feed and 7V at the controlled ground wire. With the bulb removed I got 14V at the live feed and 0.3V again at the controlled ground.

 

Does this sound normal?

[revilla]

Pete,

 

My initial reaction is - no, not normal.

 

The supply side sounds fine. Remains at battery voltage even under load, so connection is good.

 

Driven ground side side sounds suspicious. If it's rising to 7V, the heater is only seeing half the voltage it should, which equates one quarter of the heater power, say 4W instead of 16W (this assumes the bulb was the same nominal wattage as the heater but even if not the numbers change but the principle is the same - what bulb did you use?). It also leaves another 4W being dissipated in the driver circuitry somewhere (wherever the "missing" 7V is being dropped).

 

There is another possibility - and I'm at the edge of what I know here - and that is rather than the heater really getting 7V its actually getting the full 14V but for about half the time with the driver circuit switching on and off rapidly to modulate the heater output. Your voltmeter could be showing an average of a rapidly switched voltage. The only ways to know for sure would be i) to put an oscilloscope on it, but I don't have one handy and I guess you don't either ii) somebody who really knows what they are talking about comes along and tells us about the heater drive circuit!

 

However, I would have expected the heater to be driven 100% from cold even if it is modulated to maintain temperature when hot. So when first switching on, I would not expect to 7V even as an average on the ground lead. A quick read around things on the internet shows people testing lambda sensors by wiring the heater directly to a 12V feed, so it seems like that's what they need. I'll do a bit more research but on balance I would say they is a fault with the lambda sensor heater drive from the ECU - either a wiring fault or a problem with the ECU's drive circuit.

 

This would be consistent with what you have seen - lambda sensor warms up more slowly than it should, ECU is recording a fault with the heater drive but sensor works once heated by the exhaust gasses.

 

Unless anyone else on here can put us on the right track, leave it with me for a bit I'll see what I can find out. I'll see what I get from my engine for comparison when I get a chance too.

 

Andrew.

[revilla]

My reading of things like

is that there is no modulation, the heater is ON or OFF and never half and half as yours appears to be.

[Smithy77]

So it indeed looks like a fault in the heater circuit then. What would be the next logical step - take it to someone who can locate the fault?

 

By the way I used a side light bulb rated as per your recommendation. It may also be worth mentioning that the bulb stayed at a constant illumination during the 5mins or so of running - should I have seen the bulb dim as it warmed up?

[revilla]

Pete,

 

I've done a bit more research and done some diagnostics on my spare engine for comparison.

 

Firstly, it seems as though lambda sensors can be driven 100% ON/OFF in some cases but some ECUs do use pulse width modulation (i.e. switch them on and off in quick succession to allow shades of grey in between when controlling the heater power, so if ON for 80% of the cycle and off for 20% of the cycle you get 80% heater power etc.). So both of the possibilities I described in my earlier post are realistic cases. I can't find any documentation at all covering the heater drive strategy of MEMS3, even in Rover technical documentation, so I was left with trying to fathom out what my working engine did.

 

I wired up a bulb exactly as you did. The results I got were VERY different to yours, and to be honest a lot more sensible:

 

i) Ignition on, engine not running, bulb OFF. ECU does not drive lambda heater when engine is not running, not even to pre-heat it. This agrees with what I have read which suggests that ECUs don't normally drive the sensor without the engine running to extend the life of the sensor.

 

ii) Engine started, bulb flashes on and off. The pulse width modulation is slow enough to see clearly without an oscilloscope. Initially looks like about 80% ON 20% OFF pulsing maybe twice per second and increases over the first few seconds to more like 100% ON, which is what I would expect when the ECU wants to heat a cold sensor as quickly as possible. When ON the bulb is fully ON. I didn't measure the voltages with it running as I didn't want to run it very long as there is a big hole in the exhaust (where the lambda sensor normally goes, which you have got at the moment, which is currently capped off with a 2p coin held on by a jubilee clip 😬) but it was clearly driving the bulb to approximately the same brightness as when I touched the negative lead to the engine block, so approximately full battery voltage and certainly not 7V like yours which would only give 25% brightness.

 

My initial thoughts before I checked mine out were that there were three possibilities:

 

i) A wiring fault between the ECU and the lambda sensor.

 

ii) Failure of the driver circuitry inside the ECU.

 

iii) A wiring fault to one of the four earth pins to the ECU (it has four separate earths which are not internally common and therefore seem to be earths for different parts of the internal circuitry, so it could have been that one was the earth for the lambda sensor drive and this could have a fault without the whole ECU being disabled).

 

However, having now seen what mine does and how different your behaviour is (my engine is a VVC but we have the same basic ECU hardware and the same lambda sensor, so I would have expected a similar if not identical heater drive strategy), I don't think a wiring fault would explain it, unless it was somehow just confusing the ECU. It seems more likely that the lambda sensor drive inside the ECU is burned out to be honest. I'm now pretty sure it shouldn't sit at a constant 7V under load, it just seems to have failed and the ECU has no control over it.

 

If you want to prove the point as to whether it is ECU or wiring, I'd be happy for you to send me your ECU and I can plug it into my spare engine and see how it behaves. It won't run my engine properly as it won't have the VVC control but if I unplug by VVC solenoids and cam sensor it should I would think at least run it well enough for a few seconds to see what the lambda heater does. It won't do the ECU any harm. If it does the same as mine, it's good news and we need to track a wiring fault. If it does the same as it does on your car, you've got an ECU problem.

 

Standard MEMS3 ECUs are available cheaply on eBay (as little as £15-£20) but yours will have custom programming and mapping, given the state of tune of your engine. If you do have an ECU problem, I would recommend talking to Mark Stacey at Z&F Tuning. He was one of the MG Rover development engineers who worked on MEMS3 mapping and now he is the only person I know of who is offering remapping of MEMS3 units. He did a remap of mine and sharpened it up a lot. I think he has kit that will give him full access to the contents of the internal 256kB 29F200 EEPROM memory chip. As far as I know, all of the MEMS3 units are exactly the same hardware with different software and mapping data loaded into the EEPROM. I think Mark would probably be able to clone yours across onto a replacement ECU for you.

 

Let me know if you want me to have a look at your ECU for you.

 

Andrew.

[evotell]

Thought I'd join the party

 

1.4SS K Series done just 600 km. Started this morning as always without issue, noticed within 50 yards that idle was very high almost like throttle was stuck flicked the throttle and it went back to slow idle speed. So the issue doesn't make any difference whether the car is hot or cold. Sometimes maybe 3 out of 10 time when changing gear instead of the idle dropping it rises. I have also noticed that when it starts the rev counter doesn't work and then all of a sudden works fine.

 

I'm going to take it to a friends tomorrow and plug a scan tool in and see what it says. Apart from the rev counter causing issues when its starts you would think it is symptomatic of frayed throttle cable, but it isn't. Except for the revs rising occasionally when changing gear the car runs fine. doesn't miss, hesitate and idles smooth.

 

Any suggestions.