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nzjetboating.com Forums => Projects => Topic started by: ruru on January 16, 2022, 13:14:57 PM

Title: J30 Tune
Post by: ruru on January 16, 2022, 13:14:57 PM
Hi, I have fitted a J30 engine to my fishing boat being a 1976 J53. I have been using the boat for over a year now but my issue is I just can't get the starting from cold dialed in and has a slight issue of idle, other wise ok. Am running the microsquirt unit and was wondering if there was someone in the eastern bay of plenty area who may be able to help me with the issues please, am half way between Whakatane & Rotorua but don't mind travelling.
Cheers Ruru
Title: Re: J30 Tune
Post by: JohnR on January 17, 2022, 22:13:37 PM
What timing and afr at idle? Are you running the e throttle or a cable driven throttle? Ya checked for vacuum leaks. Ive had a bit to do with microsquirt and I wasnt impressed compared to link but it should still run the engine
Title: Re: J30 Tune
Post by: ruru on January 18, 2022, 18:03:52 PM
Hi, thanks for your response
From memory I think timing on idle about 10' and cable for throttle.
Title: Re: J30 Tune
Post by: ruru on January 18, 2022, 18:09:01 PM
sorry forgot afr which is 12.8
Title: Re: J30 Tune
Post by: JohnR on January 19, 2022, 07:05:50 AM
Should be more like 20degrees and about 1200rpm.  The v6 like idling a bit higher than the v8 engines and 12.8 is way way too rich for idle.  About 14.7 for idle and 12.8 for wot or even leaner.  Keep it at 14.7 till about 3800rpm and then ramp it too 12.8. About 26deg wot.  And about mid 30s thru midrange
Title: Re: J30 Tune
Post by: SeanC on January 19, 2022, 08:05:51 AM
The Microsquirt only has 2 injector outputs so you will be set up in batchfire mode. Batchfire engines prefer to be a bit richer at idle. 13-13.5AFR is what you're after. Off idle you can increase to 14.7 for economy/clean-running, through to about 13 at WOT.

10deg is not a lot of advance at idle. I have attached my ignition map for my R18a. Your engine is very similar, just with 2 extra cylinders, so ignition requirements should be similar. Notice the slight increase in advance at very low RPM to prevent stalling at idle.
Obviously you will ignore the boost part of the map as you don't have a turbo. This map would put you at about 23deg WOT. Pretty conservative but works well.

You should be able to achieve a perfectly stable idle at around 1000rpm. Do you have an idle air valve of any kind?

Tuning cold startup can be a pain. You need to play with priming pulse and cranking pulse to get it to fire at all temperatures. Then watch AFR's very closely after startup to get after-start enrichment right.
You should always begin by getting a stable idle at operating temperature, because cranking pulse and after-start enrichment are additional percentages of normal operating values.

The Microsquirt's work well when set up correctly. They get a bad rep in NZ because very few people use them, and so there is little support when things go wrong.

If you post your .MSQ file here I can have a look and see if there is anything obviously wrong with it.
Title: Re: J30 Tune
Post by: Jeff B on January 19, 2022, 13:26:41 PM
If you aren't very confident fiddling with the settings yourself, I think there is a guy in Tauranga that sells them, likely help you out? He was the guy selling them on trade me.
I'm not familiar with the megasquirt but sounds joke the cold start enrichment needs a fiddle?

What are you guys running for start ignition timing? Mine is quite low, around 5-10 degrees I think??
Title: Re: J30 Tune
Post by: ruru on January 19, 2022, 16:31:29 PM

 Thanks all, really appreciate your time and help, will try and get on the lake and have a play with what you have given me, also get a file read out to you, cheers heaps
Title: Re: J30 Tune
Post by: ruru on January 19, 2022, 17:09:19 PM
Here's my AFR file hopefully
Title: Re: J30 Tune
Post by: JohnR on January 20, 2022, 07:35:17 AM
This is how I tune myne, ive tuned probaly 20-25 engines and driven them very hard and none have died and theyr good on fuel, the hardest part is tuning the cells that it doesnt stay on for long eg when ya stomp it. Tune in lines (make all values the same left to right) and lean out the stomp bit until it doesnt bog from over fueling.  Smooth to the cell it stays in.  Theres a bit more too the whole thing than that but that may help.

I perfer link, top support and software, i tried megasquirt on a k24 once with poor nz advice and it was a huge waste of time. Ended up with a no start and no support. Your current maps are poohs in my opinion

Usually i target 14.7 at idle and a bit richer with a LS. Maby you have a cold start enrichment or some sort of adaptive timing idle chart throwing things.  Make sure timing is a constant 20 degrees and its not bouncing to try correct idle, (even lock it at 20 while idling to eliminate its not a spark issue) and target about 1200rpm for warm idle.  If ya target 1000rpm it wont start and itl stall when cold with a manual throttle body.  Also make sure there is not big changes between cells.  Eg a 40 next too a 50.  This will cause it to hunt between cells and not settle around idle.

Manually tune idle, dont use any auto tune function and dont tune until you engine temps are at stable operating temp, as they will change massively between cold and warm. I dont even put my wideband in till the engine is warm.  It seem this way my widebands last much longer, also make sure ya wideband controller is direct onto battery with recommended amp fuse.

Also make sure your vtec isnt engaged.
Title: Re: J30 Tune
Post by: ruru on January 20, 2022, 19:07:13 PM
 your afr chart, is that what you are currently running with ?
Title: Re: J30 Tune
Post by: JohnR on January 20, 2022, 22:15:07 PM
Yup.
Title: Re: J30 Tune
Post by: ruru on January 22, 2022, 20:48:00 PM
made some changes today and it does start easier and sounds like its running better but I need to get it on the lake for a good run and check plugs ETC, hopefully next weekend