Cold start problems

[Howard J]

My new to me 2011 twin cam GS.

was running rough when I got it so the first things I’ve done are new air filter, oil and oil filter and plugs. It’s running a little better, but is still reluctant to fire straight up, maybe second go it starts, but any throttle input makes it stall until it’s up to temp, even when up to temp it stutters if you try and blip the throttle, I’m thinking primary coils?

 

[AustinW]

….Or throttle position sensor.

 

[TLSgazza]

My new to me 2011 twin cam GS.

was running rough when I got it so the first things I’ve done are new air filter, oil and oil filter and plugs. It’s running a little better, but is still reluctant to fire straight up, maybe second go it starts, but any throttle input makes it stall until it’s up to temp, even when up to temp it stutters if you try and blip the throttle, I’m thinking primary coils?

When my primary coils/coil was breaking down it always started without a problem. Just saying.
I had more difficulty when the fuel pump was failing

 

[Howard J]

Just waiting for a GS 911 to arrive, so will see what it tells me.

 

[Howard J]

Ok GS 911 arrived and no fault codes. Started her up and reluctantly fired up second time with engine lumpy but idling, little bit of throttle and stalls, also a strong smell of fuel, any ideas ?

 

[Mistacat]

Just waiting for a GS 911 to arrive, so will see what it tells me.

When the GS911 arrives check the real time values . air temperature sensor, See if it looks right ( it is the one in the airbox).
Also reset the idle actuators and check that they are working .
Just a couple of starting points after checking and clearing fault codes.

 

[Mistacat]

Ok GS 911 arrived and no fault codes. Started her up and reluctantly fired up second time with engine lumpy but idling, little bit of throttle and stalls, also a strong smell of fuel, any ideas ?

You are ahead of me Ignition on but engine not running -- real time values -- Throttle angle / TPS Turn the throttle slowly from off to full it should read 0 to 100.01% without any jumps. or erratic readings especially just off idle.
This is all assuming that the basic mechanical checks have been done throttle cables not snagging etc. and throttle bodies have been balanced.

 

[Howard J]

You are ahead of me Ignition on but engine not running -- real time values -- Throttle angle / TPS Turn the throttle slowly from off to full it should read 0 to 100.01% without any jumps. or erratic readings especially just off idle.
This is all assuming that the basic mechanical checks have been done throttle cables not snagging etc. and throttle bodies have been balanced.

Thanks for that, just tried it before you posted it seemed to go from ….. can’t remember the exact figure so will do it again, but I think it was something like 1.75 to 98%. Didn’t really look to see if it was erratic, but now you have to;d me how I’ll try it again

Once warmed up it runs a lot better, so seems to be an initial thing when cold

 

[AustinW]

When checking the sensors using the gs911 use the menu to deselect all except the sensor you are looking at. Then “zoom” the readout by maximising the sample rate. It’s a while since I did it but you should get the idea - get the most info you can. On the tps turn the throttle very slowly, the readout should be steady at each position and an even progression. I’m sure mine went 0, 0.3, 0.6, 0.9, 1.2 etc. rough running had uneven readouts with little spikes every now and then.

 

[Howard J]

Ok just nipped out again, engine not running throttle position readings went from 0 to 98.4%, opened throttle slowly seemed to go up in increments of around 4-5%. Started up no problem as it’s warm (air temp sensor on gs911 read 28?) not really any hesitation when warmed up.

 

[Howard J]

Have been out…..yet again and ran all the tests and re calibrated all I could see, just seems to be cold start as once warm it runs fine?

 

[Santa-2512]

Whats it like at idle at cold / at warm ?

Cutting out when coming of throttle to idle , is a sure sign of a dying TPS

https://www.ebay.co.uk/itm/31365993...Ugc0s9Bibzd33veXsX70bWUSubA=|tkp:BFBMoNOnkPlg

Its a cheap fix, you can strip & clean your old tps if you feel brave enough , there is a linky somewhere if you go looking


My 06 wasnt the smoothest of bikes , but resetting the valve clearances, end float, Idle actuators and then doing a balance with a harmonizer made all the difference

One thing you could try is set up your GS911 with the bike cold and unstarted.

Set the GS 911 to datalog all channels and start the bike , once the bike is running, wait 20 seconds for it to settle down and save the data logs

Mthen you can look at all logged channels and see what is going on

The advantage of capturing all channels, means you wont have to go out multiple times to recheck something

MIstacat is a whiz when it comes to reading the data logged stuff

 

[Howard J]

Cold idle is lumpy and occasionally stalls, any throttle input and it stalls, when warm idle is fine and throttle input ok. It’s just starting from cold that seems to be the problem as mentioned a bit reluctant, but will start…..also very strong Rich fuel smell on cold start.

 

[Mistacat]

It would be interesting to log all of the "real time data" to .CSV file from when the bike is cold at idle and when imputing small amounts of throttle. ( the problem area)
I would be interested to see the .CSV data file if you have it available PM me and I will give you my email address so that you can send it as an attachment.

 

[Howard J]

It would be interesting to log all of the "real time data" to .CSV file from when the bike is cold at idle and when imputing small amounts of throttle. ( the problem area)
I would be interested to see the .CSV data file if you have it available PM me and I will give you my email address so that you can send it as an attachment.

That would be great, thanks

I’ll see if I can do it later, presume I connect everything and let it run through normal checks, then go to real time and start log, then start and run engine with throttle input, then stop log and save as excel? (It’s all a bit new to me this GS911 )

 

[Santa-2512]

That would be great, thanks

I’ll see if I can do it later, presume I connect everything and let it run through normal checks, then go to real time and start log, then start and run engine with throttle input, then stop log and save as excel? (It’s all a bit new to me this GS911 )

Sounds about right, you need to make sure the bike does its failed start, and then its normal start

what you should see, is a block of data, a blank section, and then data again

 

[Howard J]

Files sent to Mistacat for his expert analysis (many thanks )

My bet is on air temp sensor in air box, but a thought has occurred to me that I know the petrol is probably old as the bike came from the USA a few months ago and I don’t think has had any fuel put in since.

 

[Santa-2512]

Files sent to Mistacat for his expert analysis (many thanks )

My bet is on air temp sensor in air box, but a thought has occurred to me that I know the petrol is probably old as the bike came from the USA a few months ago and I don’t think has had any fuel put in since.

and prolly 90 ron or some stupid us spec

 

[Mistacat]

I have had a quick look through the data. One file has no info the other is at 1400 M/s sample rate which allows for a general impression.
Air temp sensor ok , Lambda sensors look ok. Idle actuators ok. Difficult to see TPS as the throttle is having to be moved so much to keep it running, however it goes to 0% after 19 seconds and idles.
I would defiantly change that fuel it has every chance of being your problem then reset the adaptations to start from scratch.

 

[RallyeGS]

Given the state of the air filter, I would drain the tank out, put decent fuel in it, and change fuel filters. You have a baseline then. I would also check the tank breather. Have you taken the charcoal cannister off yet? These can both offer symptoms that you mention.