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K Series Starting Issue


Orange

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My car is difficult to start with out touching the accelerator. Once started for the first time it will start again no problem. Seems to idle fine and runs ok. If I then leave it a few mins it will then need the accelerator again to start.

AICV sounds like it is working and I have taken it off to observe it moving, which it is from closed to slightly open when cycling the ignition.

I have reset the TPS and disconnected the battery to try and reset everything.

Any ideas?

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I fitted a new battery about 7 months ago and it is kept on a conditioner. It turns over fast and with ease.

The throttle cable is free moving and not sticking. I assume you are talking about the stop screw that holds the butterfly open very slightly. This is tight and fitted with a tamper free cap on mine. I thought this was only to be adjusted with some sort of specialist equipment?

I will try opening this temporarily with a thin shim to see if this has any affect.

Thanks for the suggestions!

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The throttle stop screw will give you an engine that stalls at junction if too far closed and a very slow return to idle, possibly idle hovering too high and poor engine braking if too far open. And a big on/off power step taking up drive from the overrun. It's a very sensitive adjustment to make it drive nicely. I wouldn't play with it to fix a starting issue, it won't be the problem.

As Ian (SM25T) says, it can be a failing battery. The symptoms are surprising, the engine will still spin over rapidly but the engine won't start without a bit of throttle and you need throttle for a few seconds to keep it going until it settles.

The explanation is that the inrush current as the starter motor first kicks in causes the battery voltage to drop for a tiny fraction of a second, often as low as 5V for a few tens of milliseconds. The ECU sees this voltage on the "ignition sense" input and thinks you've turned the ignition key off. So it recycles the IACV to the correct position for the next start by winding it fully closed to establish the end position, and then open a predetermined number of steps. Once it has decided to do this it completes the process even though the voltage recovers rapidly. Until the IACV recycle has finished it won't idle (as the idle air supply is closed off).

As well as a battery problem, this can be caused by wiring resistance issues and other things.

In particular ... do you know what type of starter motor is fitted? There have been persistent issues over several years with Brise starter motors causing these symptoms. I investigated a couple of cases with an oscilloscope and found that the Brise starters were causing an unacceptable voltage transient even with a healthy battery and electrical system in some cases. At one point I had an engine running in a test rig and a friend had a car with a Brise starter which had these symptoms. We swapped starter motors and my test rig immediately acquired the fault, whereas his car was cured.

What type of battery do you have?

The odd thing is that as you say, there is absolutely no hint from the cranking performance that anything is wrong; the battery is still able to spin the engine over rapidly in most of these cases.

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It is a banner battery and quite new. It appears to not be struggling at all when cranking so I had assumed that this is not the issue. I will try connecting a jump starter to see if it starts, will this prove a duff battery if starts or mask something else?

Once I have started it and turn it off almost immediately it will start without any throttle, leave it 5 mins and it is back to needing throttle to start.

I will have to look at what starter it has.....

I was hoping it was just a failing sensor but which one?

Many thanks for your thoughts and help.

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I have had starting problems caused by a failing crank position sensor. It was playing up intermittently and in the end prevented the car from starting at all. Throttle didn't help with starting though.

Throttle does help with a sticking or failed IACV which I think I have again and need to sort out.

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I have a Brise starter motor fitted.

I have tried a couple of things to see if I can get it to start without throttle when cold. If I connect a jump starter it starts and also it will start if I disconnect the power to the AICV.
 

Does this suggest that I am seeing a dip in voltage too far when starting making the AICV cycle - cutting the air supply at a critical moment?

Any ideas?

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This sounds like an exact re-run of the scenario I described in some detail in my earlier post. You've pretty much proved it's the IACV that's doing it by "paralysing" it (and it can't be that it's sticking, because you've just made it completely stuck and it fixes the issue).

It just seems as though, even with a perfectly healthy electrical system otherwise, the Brise starter model just pulls too much current briefly for the small battery to cope and you get a transient voltage dropout.

I've come across quite a few cases of this now.

As far as I know the only real solution is to swap starter motor ... a standard Magneton, a WOSP or a Powerlite. For what it's worth I think my friend who had this issue switched to a WOSP and never had the issue again.

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Many thanks, I will try a new starter motor. Does something degrade in the started motor making it draw more power over time?

Are WOSP the best to go for and I see that two are listed on their website, any idea which one to go for.

I think I will start with a phone call to Redline.
 

Thanks Revilla for your advice I will post here the result!

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Is it just that the battery has degraded very slightly (almost new - possibly started the car 20 times and been on a conditioner over winter) and with a bit of wear on the starter motor this it enough to upset the balance i.e. pull slightly too much power.

A new battery is obviously cheaper than a new starter but not if I have to buy one every six months.

Does the new starter use less power than the original Brise?

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Yes checked the level in every cell and ok, I do not have an isolator but when not driving it is on a battery conditioner.

I am fairly convinced that the battery is good, I have started/ turned it over multiple times today and it did not show any signs of struggling.

 

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You can see this with any starter motor if the battery is failing, but I've seen issues with the Brise on perfectly good batteries. When we swapped my friends starter onto my engine test rig, that was freshly built with a new battery and a new, short wiring loom. As soon as we fitted the Brise, it inherited the problem.
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@Wrightpayne - Yes they have. With the original car I investigated I sent all the details, oscilloscope traces etc. to them and exchanged some emails. It was a long time ago now so I can't remember exactly what was said but I think they acknowledged the issue and were going to investigate. With another more recent case I helped with, they sent out a transient suppressor component to try to see if it helped. I didn't think it would, and it didn't.

@Orange - If you really want to convince yourself that this is the issue before spending money on a nice new starter, I'm sure I could lay my hands on a spare Magneton starter (the original factor supplied model) that you could borrow to try out? I'd want it back though.

 

 

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Many thanks for the offer, I am convinced by the advice and will just buy a new WOSP starter I think. Last night I was starting to consider that the battery could be defective. Just want it fixed!

I am guessing that my old Brise starter may be of use to somebody without an AICV to contend with.

Thanks again.

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I had these same problems with a Brise starter.  It was quite old and I didn't get any response to an email to Brise (the starter was old and on the car when I bought it to be fair) so I bought a WOSP.  It's exactly the same motor with exactly the same problem.  I've replaced the cables to the starter with new 25mm2 cable with professionally crimped lugs, no FIA switch either.  Same problem on both the original EU2 engine and replacement EU3 with a different ECU and MRFU and I've been through the 12V supply to the ECU cleaning and replacing connectors.

Replacing the original Banner with one of the Ultramax 20Ah units fixed it for a summer but then it started happening the following spring.  Battery on a CTEK conditioner during the summer and disconnected during the winter.  Stored in a warm dry garage.

Replaced the Ultramax with a new Banner, fixed it for a couple of summers then it started again.

I have a LiFePo4 unit to try in a couple of weeks when I put the car back on the road.  

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I have fitted the new WOSP starter motor and the starting issue with the AICV appears to have gone away. Many thanks all especially Revilla. Supplied by Redline, ordered on Wednesday afternoon and delivered first thing next day - great service as always.

I will see how it goes and I may have spare Brise starter motor that would suit somebody without an AICV fitted!

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  • 4 months later...

Andrew is this relevant:

 It is advisable for the connection to the 'S' terminal to be made as directly to the battery post as possible to eliminate voltage drop in cables

and

Be sure to use cables that are rated to carry adequate current.  If the cables are too small in cross section then there will be a high resistance causing voltage drop and overheating.

That was also what Tim Brise told me to do. Heat would also cause a voltage drop over time.

Maybe you recall how you installed my new engine loom in this regard? (as ever thank you for that).

edit: not important, but interesting to me as the whole lot is being refitted now during chassis refurb.

Does my car have an i a c v ? edit ans = no

has Brise been taken over? edit answer faq = yes

https://brise.co.uk/faq.html

ftaod I have a Brise in my KR500 and have never had this problem.

edit: IT SEEMS throttle boddies means no IACV

... is that tempting fate? I hope not.

anthony

 

ouch! "spikes can also be produced if the engine is stopped with the battery master switch rather than the ignition switch."

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