Cold Start stalling

[Dafeimao85]

Valve clearance isn't the problem either.
If you have several out of spec tight valves, you can get hard starts/longer time to crank, especially when the engine is hot, but it's not a big deal.
At 44k miles I wouldn't be suprised if all 16 valves were still in spec either.
They also aren't the cause of that strange compression reading...your bike wouldn't even start, let alone run, if it compression that low, and you would have a mechanical failure, an/or oil or coolant leaking internally and/or externally from a blown head gasket.

Did they not reset the ISC while it was there? As that seems to be the most logical answer at this point.
Can the Heal-Tech you ordered do that?

Thanks for your analysis.

The recent oil change I estimated I drain 3.3L of engine oil with filter change. So I don't think a blown gasket is possible.

AD insist on position is OK even though I have ask for the step value. They refuse to reveal to me.

Healtech stated on their website their obd reset can do what the default sds tools does.

My busa is getting more and more mystery. I plan to wait until the healtec arrival and do a isc reset. Then hook up the cable and go for a ride to get some data.

If isc is stuck open due to u resetted isc. Can the pressure possible leak back to airbox causing a low compression hence the difficult to start?

 

[sixpack577]

Thanks for your analysis.

The recent oil change I estimated I drain 3.3L of engine oil with filter change. So I don't think a blown gasket is possible.

AD insist on position is OK even though I have ask for the step value. They refuse to reveal to me.

Healtech stated on their website their obd reset can do what the default sds tools does.

My busa is getting more and more mystery. I plan to wait until the healtec arrival and do a isc reset. Then hook up the cable and go for a ride to get some data.

If isc is stuck open due to u resetted isc. Can the pressure possible leak back to airbox causing a low compression hence the difficult to start?

No, it is not the issue, and that compression reading is incorrect, your bike would not start or run if it were truly that low.
You may indeed have a small vacuum leak somewhere though.

 

[Dafeimao85]

No, it is not the issue, and that compression reading is incorrect, your bike would not start or run if it were truly that low.
You may indeed have a small vacuum leak somewhere though.

OK.

1 problem at a time.

Let me wait for healtech reset isc first.

Once confirm OK. I will then send to a local workshop to help me do a vacuum test.

 

[GIXERHP]

If the clutch switch is functioning normally, I would not replace it.
I would let the dealer reset the ISC, before I gambled on buying an SDS that may not work.

Agreed!

 

[GIXERHP]

What is your Idle at when it runs?

 

[GIXERHP]

Never mind i went back in the thread,
Your standing idle is to low.
When was the last Valve adjustment?
How warm was the motor when you did the compression test

 

[GIXERHP]

OK.

1 problem at a time.

Let me wait for healtech reset isc first.

Once confirm OK. I will then send to a local workshop to help me do a vacuum test.

Just spray the vacuum lines with starting fluid, if it revs up, there is a Vacuum leak

 

[Dafeimao85]

Never mind i went back in the thread,
Your standing idle is to low.
When was the last Valve adjustment?
How warm was the motor when you did the compression test

Hi sorry for the late reply. Was out of town last week

I never did any valve adjustment at all. Should I be doing it?

The AD did the compression test when the engine was cold.

 

[Dafeimao85]

Just spray the vacuum lines with starting fluid, if it revs up, there is a Vacuum leak

Hi GixerHp

Starting fluid is like carb cleaner or WD40 etc liquid?

 

[GIXERHP]

Hi GixerHp

Starting fluid is like carb cleaner or WD40 etc liquid?

Carb cleaner will make the the bike bog down more if there is a vacuum leak

 

[GIXERHP]

How many miles are on the bike?

 

[Dafeimao85]

How many miles are on the bike?

71k miles.

 

[sixpack577]

71k miles.

I didn't know it was that high, I thought I read 44k somewhere, but the valve clearances should be checked.

 

[Dafeimao85]

Just spray the vacuum lines with starting fluid, if it revs up, there is a Vacuum leak

I just realize what is starting fluid. I don't think there are any to be sold in Singapore. I will try to buy and ship back online

 

[Dafeimao85]

I didn't know it was that high, I thought I read 44k somewhere, but the valve clearances should be checked.

Brought the bike at 44k

Sure I will get it check. Thanks for recommendation.

 

[Dafeimao85]

Hi All,

Its like 12 days since I last touch my busa while waiting for my healtech obd to arrive.

Today with a little bit of my free time, I thought of just warm up my bike.

And when I switch on, I can hear the fuel pump was constantly running which is a little bit abnormal.

Then the dashboard shown FI code, I switch off immediately and jump into dealerships mode and hope that the error still remains (as the ecu does not store codes).

And yes I have my first FI code after so long But it's C41 fuel pump. (I was expecting C40 ISC). As I had just recently replaced the fuel pump plus I can hear the fuel pump running, I wonder why C41.

Because I can hear the fuel pump running, I just proceed to start and the bike start with the usual cold stalling issue but the FI clear immediately after bike started. (and still stall while cold). Later in the evening I check again. No FI error and cold start issue still persist.

Is it norm for a busa to get C41 if did not start for too long? Or is it because I am not using oem fuel pump? I am using QFS HFP-386 (about 1 month old)

 

[sixpack577]

If the fuel pump continues to prime, check the relay first.

 

[Dafeimao85]

If the fuel pump continues to prime, check the relay first.

Hi Sixpack577,

Just unplug the relay and test with multi meter. All looks normal as per manual.

I check ebay an a relay is like $15 bucks. I will just order 1 and replace to eliminate the issue.

But 1 thing do caught my eye in the manual for C41 also did mention to check fuel injectors. Even other ejectors got their own C code. It should display their own C code right?

Then after many thoughts. I thinking possibility of a partial choke on my injector? Will a partial choke injector result a lower reading for the compression?

I am thinking to swap my secondary injector with my primary injector since they are of the same spec.

Thanks for all the help and info in advance.

 

[Dafeimao85]

 

[Dafeimao85]

And so I change the injector and all problem still persist.

I finally gave up trying to fix it on my own and push to a Workshop

According to their diagnosis is all exhaust valve are leaking badly due to valve cannot sit back fully. Hopefully the valve did not bent. And so they say that this might be the cause of the cold hard start issue.