1.6k - Cuts out when starting from cold, "K-click" when hot

[syndrome]

Having a bit of a recent bit issue, two actually at the same time, with my 1.6k 135 Supersport. When starting from cold it pretty much instantly stalls and frequently when starting from hot I get the infamous K-series clunk from the starter and it refuses to start until it cools down for about 30 mins or until I pop a booster pack on it.

Hopefully someone can point me in the right area before I start disassembling everything! My immediate suspect is the Multi Function Relay Unit (MFRU) as it affects Idle Air Control Valve (IACV) and the starter motor, however I was thinking of doing the Idle Air Control Valve (IACV) reset which I understand might be part of the cold start woes, as I understand it is the key to position 3 without starting the engine and smoothly applying and releasing the throttle 5x?

History and specs for anyone interested, 2009 (yep really), no dizzy so I think it's an EU3, long 4-1 exhaust without CAT, starter solenoid does have a heatshield, had it for one year and Tuesday was the first time it has done either but has repeated both performances today, it has been run 2-3 times in the last few weeks before this without issue.
The only thing that changed on Tuesday was I temporarily fitted the CAT for the MOT, which I blamed for the cold start but was surprised when the K-clunk happened at the MOT station, it has been changed back to the straight pipe. When it refused to start at the MOT station the owner whipped out a multimeter and a jump pack, the battery read 12.5v, which seems healthy enough, but the jump pack cured it instantly.

100% sure the MOT station didn't do anything as it never left my sight and was chatting to the owner of the station while he tested it and had it on the ramps. 

Sorry if it comes off a bit "war and peace" but I can't stand forum posts asking for tech help with no helpful info in 

[Jonathan Kay]

Mmmm.... data. :-)

You already know about the MFRU (and whoever named it knew what they were doing): have you found the fix in case it does turn out to be that?

You're probably about to get lots of "It's always x... " and "In my case it was y...". But the main point is that the click and failure to start is a common final pathway for many faults.

I'd start with:

1. Measuring the battery voltage: at rest, at 3,000 rpm, and minimum during cranking or trying to.
2. Taking apart and inspecting the likely suspects amongst the wires and connections: everything at the battery, all the fat ones, including all of the earths, and the one to the solenoid. Look, wiggle, clean connections and reconnect.
3. Rigging a temporary jump feed from the battery to the solenoid, touching it on or using a switch and seeing if that works any better.

Jonathan

PS: Do you have a multimeter? And a wiring diagram?

[shn7]

Assuming the battery's in good condition, 12.5v suggest but doesn't guarantee it, Then the problem I think for both symptoms is lack of current getting to the right places.  i.e. a bad connection. 

As JK has said many possibly culprits and a need to work through everything methodically.

As a get out of jail free card should you get stuck somewhere with the click problem this often gets you going - ignition off, place car in 3rd gear.  Push/pull the car to turn the engine a little.  Into neutral and start.  This very often works simply because the amount of oompphh required to turn the engine over is less with the crank is a different position.

Good luck finding the cause.

[syndrome]

Cheers guys,

Lol, glad someone approves of my verbosity Jonathon! 

Regarding the fixes for the MFRU (yep very apt name) the only ones I am aware of is opening the case and cleaning the relays if the are crudded up or swapping the unit. Not given the latter much thought yet as I'm not in a habit of swapping out parts unless I'm positive they are defective as it's a waste of money and IMHO can end up introducing more problems replacing hardware willy-nilly.

Regarding the suggestions I will have a look to do point number 1, I have a multimeter somewhere in the garage but no wiring diagram for my car, I'll see if I can get some readouts at the different parts of starting, idling etc in the early part of the week as I will be away until Monday.

I did have a quick look around the connections, couldn't get to the starter when the car was hot for obvious reasons, but I will check for corrosion and loose wires, the starter motor looker extremely clean TBH, it is a low mileage vehicle (approx 9k) and I have always garaged it, but that doesn't rule out corrosion.

I was going to look at performing the relay mod such as this: http://www.alcester-racing-sevens.com/relay_mod_illustrated.htm
I'm assuming this would achieve the same goal as a temporary switch but be a bit more permanent.

Cheers Steve, good tip on the starting BTW I will keep that in mind, hopefully I won't need to resort to manual labor as my battery booster pack now has a temporary home in the boot of the 7. Pretty sure purists will hate that from a weight distribution point of view :D

 

[Jonathan Kay]

I was going to look at performing the relay mod such as this: http://www.alcester-racing-sevens.com/relay_mod_illustrated.htm

That's the one. If it comes to that.

If you'd like a wiring diagram please send me a Private Mail with your email address.

That temporary wire was only for diagnostic purposes!

Jonathan

[shn7]

If I remember correctly the relay mod bypasses or supports one of the relays in the MFRU so may be worth trying before replacing/opening the MFRU.

[revilla]

I was thinking of doing the Idle Air Control Valve (IACV) reset which I understand might be part of the cold start woes, as I understand it is the key to position 3 without starting the engine and smoothly applying and releasing the throttle 5x?

This is much misunderstood. This is the procedure for calibrating the ECU to recognise the TPS (Throttle Position Sensor) readings at idle and fully throttle (and by interpolation, anywhere in between). It does not in any way reset the IACV.

In addition I'm not sure this procedure is correct for EU2 engines (but also not sure it isn't) - it does work on EU3 engines. Does your engine have coil packs on top of the spark plugs or down on the block with long HT leads up to the head?

When cold, can you get it to start and keep going if you keep your foot on the throttle a bit - and does it then idle happily if you take your foot off the throttle after keeping it going for say ten seconds? There symptoms seem to be associated with the supply voltage at the ECU transiently falling during cranking to the point where the ECU thinks it has been powered down and therefore resets the IACV ready for the next start. whilst it is cycling the IACV the engine won't idle without throttle, once it has finished all is well again. I've seen this a number of times - Jonathan will no doubt remember my oscilloscope investigations. In the particular case I was looking at back then it was caused by a current draw problem with the starter, but I've since seen exactly the same symptoms with a weak battery on more than one car (my own being one of them).

[Jonathan Kay]

I've seen this a number of times - Jonathan will no doubt remember my oscilloscope investigations.

We talk of little else in Garsington! :-)

Jonathan

[syndrome]

Cheers Jonathon, Pm sent.

Revilla, definitely an EU3 engine, interesting to hear about the TPS, are you saying it would be futile to attempt the TPS reset?
You explain very accurately the issues when cold starting, the only minor deviation is I would say I need to keep revs up for 20-30 seconds, after which there is almost a step in the revs where it seems to change behavior; difficult to explain but it is almost like it has changed from its cold map to a warm map (if my other cars behavior on a morning is anything to go by) then I can release the throttle and it idles fine, if I release the throttle before that it just idles and dies.
Given your experience between the battery and the starter what would you suggest? I was planning to document a multitude of voltage checks when cranking, idling etc as suggested by Jonathon FYI, I could stick the battery back on trickle charge over the weekend to if that cures but am wondering if that would impact any tests, then again both the issues, cold and hot starting, could be caused by a weak battery if I am understanding everything correctly.

Before you suggest Jonathon... no I don't have an oscilloscope 

[revilla]

Definitely not futile, costs nothing and takes two minutes. Certainly worth trying on those grounds but at best it will help with the cold starting if it is miscalibrated, it won't be the answer to the hot issues. I will send you a private message.

[Jonathan Kay]

I could stick the battery back on trickle charge over the weekend to if that cures but am wondering if that would impact any tests, then again both the issues, cold and hot starting, could be caused by a weak battery if I am understanding everything correctly.

No problem with charging the battery before the diagnostic tests, but:

1. If it's the sort that you can check the liquid level then do, and top up if needed.
2. Do you mean a traditional dumb trickle charger or a smart current-sensing conditioning charger such as a a CTEK, AccuMate or OptiMate? It's easy to overcharge with the former.

I don't like the idea of charging the battery in order to see if it cures anything... 

Jonathan

[syndrome]

Will do that recalibration at the same time then, like you say it may help the cold starting at least.

I will check the battery to see if it needs a top-up, I must admit I've only ever dealt with sealed batteries so this should be interesting.
Regarding my charger I have a proper CTEK one.

I do see what you mean, both you and revilla have highlighted a weak battery as a potential culprit so I will probably give this a very good check first.

[SM25T]

When my car wouldn't start without tickling the throttle .... completely out of character .... replaced the battery ... All perfect again.

[Jonathan Kay]

Don't let this put you off doing the voltage tests, but those clever little CTEK chargers have some diagnostic value... let us know how it progresses on the indicator lights.

Jonathan

[john milner]

When my original IACV failed I was able to revive it and get another year or two out of it. It contains a plunger which was sticking due to carbon build-up. Using carb cleaner and WD40 I loosened to up. Eventually it got so I could not bodge it any more. It may be worth inspecting before parting with cash.

 

[MadCat52]

I have a similar intermittent cold start problem with my 1.8K EU3.  Fully charged battery, engine fires immediately first time but then dies - feels like it's being choked/over fuelled.  I can sometimes keep it running through heavy use of the throttle pedal and sometimes it will settle to a normal idle, but on other occasions it just seems to keep over-fuelling and the engine dies.  When it does die, an immediate restart results in the engine idling normally!  I'm guessing its either a sensor (IVAC?) issue or possible injector wear (26000 miles), but would welcome thoughts from those that have experienced and fixed similar issues.

On the K click - this normally occurs (but not always!) when the engine is hotter than usual (somewhere in my mind I remember my physics teacher making a correlation between electromagnetic fields around wires and increased electrical resistance when heat is applied!).  Wires to the starter are heat shielded from exhaust heat with reflective tape and when it happens I can normally lift the bonnet and wiggle some wires to get it going again.  I thought there was a guide somewhere on here on doing the relay mod - can someone point me to where it is please?

Bob

[SM25T]

Or a dying battery Bob. Same symptoms as my 1.8 EU3. Battery replacement fixed it.

[MadCat52]

Ian, you could well be right, but I'm not getting any signals of a failing battery in terms of cranking capacity - what were the signs on yours?  The Yorkshireman in me doesn't want to shell out £60 for a new battery only to find it wasn't the issue  

[SM25T]

I used to press the starter button and it fired instantly with smooth tickover. Cranking was fine. No need to touch throttle. Then one day it cranked and cranked but would not fire. Eventually got it to fire with a bit of throttle while cranking. But it was a swine to get it right. Theory given to me was that a bit of throttle gave slightly higher revs once it fired which increased battery voltage enough to feed ECU enough to make it function properly. I wasn't convinced .... But a new battery fixed it instantly.

[Jonathan Kay]

... but I'm not getting any signals of a failing battery in terms of cranking capacity - what were the signs on yours?

There seems to be something about 7s where deterioration presents differently from ordinary cars, and we could speculate...

But the same initial tests will work for diagnosis: battery voltage at rest, minimum during cranking and at 3,000 rpm.

Jonathan

 

 

[Jonathan Kay]

I thought there was a guide somewhere on here on doing the relay mod - can someone point me to where it is please?

It's linked from post #4 in this thread; is that the one you were thinking of?

Jonathan

[john milner]

I found that a failing IACV needed a partial throttle to get the engine to start and then after 30 seconds or so the engine note smoothed out a bit and I could take my foot off.

I have also had a crankshaft position sensor pack up on me. The symptoms were similar although opening the throttle did not help with starting. With this when the engine caught it would run rough and then run fine after a restart. After a few months it wouldn't start at all just turned over.

I have had to do the relay mod and a couple of years later it also became temperamental. I now carry a spare. Once the wiring has been sorted swapping one is easy. I have also put exhaust wrap on the headers in the engine bay as I believe the most likely culprit is a hot starter solenoid binding and a good relay delivers more power to it than a worn one.

[syndrome]

Well a quick update, I used my CTEK MXS 5.0 battery charger/conditioner over a long weekend and it got through to STEP 7 float which is "Maintaining the battery voltage at maximum level by providing a constant voltage charge".
After this was done I checked the battery levels and they were a bit low, topped up the fluid (about 300ml) and stuck on charge again, however it did release a bit of fluid into the catch pan I keep below the 7, not much about a tablespoon.
Cranked it from cold the next day and it fired up with gusto, have been out to fire it up a few time and been out for a few blats and it has never died on me since. It seems pretty conclusive that dying from cold was due to the battery needing a bit of attention; that being said I still do want to do the voltage tests, however both my multimeters have gone walkies so will need to dig them out or get a new one.

Last but not least, the k-click. I have taken it on a few spirited blats after leaving it on the CTEK when not in use and if it is pretty hot (usually the rule of thumb is if the fan has recently been on) then I try to restart it I get the click. I realised I had a Magnaton starter which looks in fine condition so I was thinking that it might be the battery that is still a bit past its prime, despite the top-up and recharge, as my booster pack always seemed to get it going... however after a spirited blat on Wednesday I pulled onto the drive and the fan kicked in, I let it run until the fan shut off and tried a restart and heard that lovely click. Fine I thought I'll pop the booster pack on and move it back into the garage, the 7 had different plans and simply refused to fire even with the pack on. I checked the connections and even reconnected it a few times including clamping the negative onto another metal part of the engine but it refused.
So today I have implemented a relay bypass. I used this method (https://m7newton.wordpress.com/k-series-starting-problems/) which means there is now a 30amp relay with new cabling to the starter (small wire), crimped a new end to the existing wire which is now the trigger for the relay and plumbed it straight into the battery with a 30amp inline fuse. I know some bypass methods involve cutting and scotchlocking into the existing cabling so that there is no need for an inline fuse, but I'd rather implement this method as I know all the cabling between the starter and the battery is new, pretty beefy and not going round the houses. Just come back from a blat, let the fan kick in on the driver and cycled the engine a few times successfully, even put anything electric on (heater fan, wipers, fog lights etc) for a few of them to tax the electric systems and it fired straight up each time.

Hopefully this is the end of my woes, I'm going to remove the starter and give it a good check when I'm doing some more maintenance later on and I'll check all the voltages when I find/beg/borrow/steal a multimeter. Thanks to all who have helped, big shout out to JK and revilla!