chriscook
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| posted on 4/5/07 at 03:44 PM |
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Min Pulsewidth 1.2ms, Max Dutycycle 97% ????
Posted this on msefi but thought some on here might have some ideas?
I've just completed my first MS install on a Vauxhall XE (2l, 16V) engine in my kit car. I have fitted GSXR ITBs and used the Suzuki injectors
at 3bar which I think should deliver 270cc/min. I have taken vacuum line from each port, they join together before going through a
'damper', then 'T' off to the FPR and the MS. The MS is an MS2 on a V3 board, running the v2.6 firmware. I'm set to 2
squirts alternating currently.
I've been using autotune and megalogviewer to tune the VE table with the output from an LC1 wideband unit.
On my last run out I had a minimum pulsewidth of 1.2ms on overrun, I get approx 3.5ms at idle. However, my duty cycle reached 97% at around 6500 rpm
(my red line is about 7700rpm). When I ran carbs (twin dellorto 45s) my max power was ~180bhp at around 6-6500rpm
Should I not worry about the overrun pulse width and just increase my fuel pressure, or would changing my injection settings help at all?
Thanks in advance,
Chris
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mark-wiring
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| posted on 4/5/07 at 04:09 PM |
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I would try increasing the fuel pressure to start.
Are you running them at 3 bar?
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BenB
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| posted on 4/5/07 at 04:21 PM |
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Wow! 97%. I'd up the pressure or change injectors ASAP! Otherwise you're at high risk of knackering the engine by running lean....
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graememk
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| posted on 4/5/07 at 04:22 PM |
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i have this prob of running lean with mine, i have a faulty fuel reg though.
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chriscook
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| posted on 4/5/07 at 04:51 PM |
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The AFR was 12.1 at the time so I wasn't in danger, my target AFR at that load/speed site is 12.4. But I still have 1000rpm to go.
Injectors are currently running at 3bar. Someone on msefi has said the overrun pw is nothing to worry about so I'll be increasing the fuel
pressure i think.
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martyn_16v
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| posted on 4/5/07 at 05:55 PM |
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Yeah, don't worry about the overrun PW at all, in fact i'd recommend turning on the overrun fuel cut then you really don't need to
think about it.
Short idle pulsewidths aren't so much of a problem with MS2 as they were with MS1 due to the much increased PW resolution, changes at small
pulsewidths aren't so granular (within limits of course, the injectors still take time to open and close, but you're nowhere close at
3.5ms).
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TangoMan
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| posted on 4/5/07 at 07:12 PM |
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Chris,
As suggested the overrun PW is irrelevant as you will probably have fuel cut set for overrun.
I sounds worrying that you are getting 97% as I think max DC should be around 85%.
I am not reaching that but I am running 50psi. You may have the 240cc injectors instead of the 270cc ones. I cannot find any info on identifying the
difference other than measuring. I would sort the map out to weaken back to 12.4 and up the pressure a little to see what difference that makes.
If you can't get down to 85% I would suggest sourcing some PICO injectors as I believe these are a straight swap for the GSXR ones.
Summer's here!!!!
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chriscook
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| posted on 4/5/07 at 07:19 PM |
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Doing the maths suggests that I may have the 240cc injectors as the figure work out about right for that. So I have just adjusted my pressure
regulator to 4bar which should give ~277cc if they are in-fact 240cc.
Tomorrow morning I will reduce my req_fuel by the appropriate amount to counteract the increased flow rate and see what happens. (I don't want
to upset the neighbours by playing around with it now)
Thanks for the input, I will report back what I find out.
Chris
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mark-wiring
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| posted on 5/5/07 at 07:03 AM |
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Another thing that may be worth having done is getting the injectors cleaned and having them flow tested.
If you have the time you can rig a make shift flow tester that way you will know.
I have a set of gsxr bodies and when i calculated there flow rates @ 100% duty cycle it worked out that it should support upto 220bhp now i know that
100% duty is very bad but i am only expecting 170- 180 bhp from the engine so it should mean 85% duty cycle and i should be at the power i want if it
works out that way ill be happy but you know it never will unless the injectors are flowing exactly what they should.
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chriscook
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| posted on 7/5/07 at 06:55 PM |
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Well I increased my fuel pressure and reduced my req_fuel and it ran fine. My idle pw is about 3ms and on my way to/from Stoneleigh the max duty I saw
was ~67% at ~6000rpm.
Drove there with autotune, smoothed it out then drove back just logging and had a play in logviewer when I got home. Decided at the same time that my
AFR targets were a bit rich at lower loads so changed the afr table and then ran the log through.
The adjusted table is quite smooth so I think its getting there up to about 6000rpm.
Anyway - off to see if this series of Fifth gear is any better than the last!
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TangoMan
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| posted on 8/5/07 at 09:11 PM |
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Good news then Chris. No new injectors required!!!
Megalogviewer is a great tool and helped sort my map out. I have looked at the other tuning options but have got such good results that I can't
be bothered to play with any of the others.
Summer's here!!!!
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mark-wiring
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| posted on 8/5/07 at 10:49 PM |
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quote:
Originally posted by chriscook
Anyway - off to see if this series of Fifth gear is any better than the last!
Ha ha ha ha ha now you are joking lol
Glad its working ok now
[Edited on 8/5/07 by mark-wiring]
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