305 tuning issues. Please help

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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305 tuning issues. Please help

Postby BARBS » Sat May 16, 2020 1:02 pm

Hi all.
Have been tuning a 355 with a blower and E85 the last few days.
It has 60lb injectors and we have tuned it sweet on those until full duty cycle is used. We have since put in both 80lb and 1000cc injectors but both cause issues.
I have set the inj flow to suit (or thereabouts) and have tried single fire etc but no matter what I do I cannot get rid of a misfire at low RPM and causing the car to run on 6-7 cylinders. I'll attach the 60lb tune and the 80 lb for compare. Can the 305 drive a larger injector or have I missed something here.

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Re: 305 tuning issues. Please help

Postby BARBS » Sat May 16, 2020 1:06 pm

Tunes attached. $12p
Attachments
447HP blown 355 E85 12psi.bin
(32 KiB) Downloaded 4 times
447HP blown 355 E85 12psi 80lb Just wont work.bin
(32 KiB) Downloaded 4 times

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Re: 305 tuning issues. Please help

Postby BARBS » Sat May 16, 2020 1:08 pm

I have tested injector pulses and the spark from the dizzy, both are present. It appears i cannot get the minimum pulse width down enough to make it run clean?
ANY ideas would be helpful. Even a base tune for a ECU that has 80lb or 1000cc injectors that i can use please

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Re: 305 tuning issues. Please help

Postby yoda69 » Sat May 16, 2020 1:21 pm

Not on my computer at the moment but check what you have the minimum injector pulse width set at. The ecu calculates the pulse width required then checks it against the minimum allowed, if it is less than this it uses the minimum value, with large injectors this is enough to flood the engine at low speed low load conditions.

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Re: 305 tuning issues. Please help

Postby vlad01 » Sat May 16, 2020 2:01 pm

Yoda has a good point, I had the same issue with 40LB injector on my car, it bucked, backfired at part throttle and kept flooding upon start up.

Found the min pulse width to be too high for the large injectors and was effectively flooding it at low speeds/load. reduced it down to iirc 2ms and it was perfect.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: 305 tuning issues. Please help

Postby BARBS » Sat May 16, 2020 2:21 pm

It makes sense to me also. Can yo utell me where in the $12p XDF i can find it though? I cannot see it in version v112

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Re: 305 tuning issues. Please help

Postby vlad01 » Sat May 16, 2020 4:03 pm

should be these 2.


min bpw.PNG
min bpw.PNG (9.82 KiB) Viewed 115 times
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: 305 tuning issues. Please help

Postby yoda69 » Sat May 16, 2020 4:17 pm

Also have a look at "Injector - Injector bias add-on vs Injector pulse width"
For low pulse widths it adds some additional time, for large injectors this may need reducing.
Really need to get a log of it happening and see what the pulse width is, if it is in this region may be worth a try, don't just go blindly changing things or you'll end up in a real mess.

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Re: 305 tuning issues. Please help

Postby BARBS » Sat May 16, 2020 6:58 pm

Vlad I have zeroed both of those parameters out,
Yoda I have also zeroed that whole table out.

It appears no matter what I do the injector BPW won't go less than 2.5 m/s. And the car would not run on all cylinders at low RPM.
For a trial I wound the base fuel pressure down to 30psi (the regulator minimum) the car did start to run on all 8 as checked with a temp gun on the exhaust but it still has a misfire.
Any ideas why the ecu isn't commanding less than 2.5m/s? I have the ecu forced in single fire mode to try and get the BPW better but no luck.

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Re: 305 tuning issues. Please help

Postby delcowizzid » Sat May 16, 2020 10:00 pm

Any logs of the big injectors running
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem

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