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Discussion Starter · #1 ·
Hi,
Just joined to hopefully get my bike fixed and currently reading through the old threads - so sorry if this has been addressed before.

Got an '08 S4RS, ~35,000 kms, and it's currently taking forever to start. Once started it runs fine and hauls - no problems at all (no warning lights etc), but not acceptable to take anywhere as the battery is almost flat by the time it starts. As it cranks it will back fire intermittently and finally start after 5 or more starting cycles.

The problem originally started one day on leaving work, it just cranked forever - finally started and got it home (ran fine on the way home), but it has been parked up ever since as I can't figure it out.

I have an OBD reader and get no error codes and have slowly worked my way through the workshop manual and replaced a few older parts (plugs, coils, starter brushes, battery) but no improvement.

Any ideas as to what I can check next?

List of what I've done so far:
1. New battery
2. ECU swap test (have two, std and DP + termis)
3. starter brushes replaced - were getting worn
4. New plugs
5. New coils
6. tested and swapped CPS (have two)
7. intake air temp sensor tested (multimeter)
8. fresh fuel last week and a 60 min ride to blow out the cobwebs
9. new fuel filter
10. checked start input sensors (neutral, sidestand etc - all fine)

Before this problem started it was ridden every day, I have had issues in the past (reg/rec, a few leaking seals etc) but usually runs fine and has all of its servicing so far, but is due for belts and clearances, which I usually do myself. It runs on the recommended fuels and fluids.

Any suggestions appreciated as I am stumped with this problem.

Cheers,
Owen
 

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For the most part sounds like your doing what most of us DIYs would have done. When you swapped the ecu did you do a TPS reset? After that I may start troubleshooting the throttle body. Is the backfiring coming from the exhaust or the intake?May not be getting enough fuel or the fuel pump isn’t supplying enough pressure. Here is a link for a pump I have been watching on eBay in case I need one; INTANK FUEL PUMP DUCATI MONSTER S2R S4 S4R S4RS 2002 2004 2005 2006 2007 2008 | eBay .
 

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Discussion Starter · #3 ·
thanks for the reply.

Didnt do a TPS reset but tuneECU says its at 2.4% and I am back on the ECU the problem started, so may be worth trying the spareECU with a reset.

yeah the popping is from the exhaust. both intakes have fuel smell in them and idle stepper motor functions as expected (I thought maybe that had crapped itself), but I have not checked fuel pressure, although once running doesnt seem to have any lean problems. will keep working on it, feel like I've gone to far too give up now, haha.
 

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2.4 on TPS is low, it should read 2.6 or 2.7 when reset. If that doesn’t help might as well give the spare ecu a try with reset to. Make sure you give the throttle cable some slack before doing the ecu reset so it isn’t slightly open. Popping from the exhaust may be due to a leak in the exhaust. If a proper reset doesn’t help then I am curious if it may have something to do with one of your sensors such as the air temp sensor or O2 sensor.
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Discussion Starter · #5 ·
Ok, thought 2.4 was ok but hadn't really confirmed the value, was just going off memory, will give it a try.

O2 sensor removed - DP ECU runs without it, but I didn't re-install it when testing with the spare std ECU, so will re-test std ECU with the sensor - may still be an issue with the installed DP ECU.

IAT - yeah, checked that as thought maybe not broken but just sending inaccurate signal to ECU, seems fine, had it out and put the multimeter on it and it responds to temp changes well, reads correct ambient temp through TuneECU

Thanks again
 

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Since the DP ECU has deleted the O2 sensor what air your air bleed screws at on your throttle intake boots? If still an issue after the TPS reset you may need to adjust the bleed air mix screws. Most people start with one turn out before adjusting CO to get a stable idle. If they are too far out may be an issue. I think if I remember correctly DP ecu tunes horizontal cylinder leaner and the vertical richer.
 

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Discussion Starter · #7 ·
Since the DP ECU has deleted the O2 sensor what air your air bleed screws at on your throttle intake boots? If still an issue after the TPS reset you may need to adjust the bleed air mix screws. Most people start with one turn out before adjusting CO to get a stable idle. If they are too far out may be an issue. I think if I remember correctly DP ecu tunes horizontal cylinder leaner and the vertical richer.
not clear on the question, but I haven't touched any bleed screws etc yet. Its been without O2 sensor for 8 yrs, so wouldn't think it would need adjusting all of a sudden but will keep in mind.
 
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