Help with building your Speeduino, installing it, getting it to run etc.
#69770
Hi Speeduino Community,

I’m working on my G4JS turbo project. This engine is essentially a Korean clone of the 4G64 bottom end and 4G63T top end. The engine has been rebuilt with forged pistons, 535cc Bosch 0 280 158 117 injectors, a Walbro fuel pump, a TD04-13THL turbo from a Volvo, and a custom-fabricated manifold, running boost at around 0.7 bar.

I’ve set up the engine using a Speeduino v0.4 board. Once the engine starts, it runs perfectly—there are absolutely no issues with acceleration, idling, or cruising. The trigger pattern for this engine is the same as for the 4G63.

The problem, however, is with cranking. Typically, it starts on the second or third attempt. The prime pulse is essential—without it, the engine has a hard time starting. I’ve been struggling with cranking for a few months now, and I’ve tried countless combinations of adjustments to spark, fuel, IAC, trigger skip revolutions, trigger filter, trigger re-sync every cycle, fixed cranking timing with trigger, dwell, and who knows what else...

I'm attaching the setup and logs for three consecutive cranking attempts. The engine didn’t start because the prime pulse was missing. The strange thing is that the ECU seems to lose trigger sync just as the engine tries to start (RPM above 300). As a result, it sounds like it’s about to start but dies right after.

Here are my observations:

Timing is synced with a timing light.
Setting skip revolutions to 3 and maxing out timing to -10 during cranking is necessary—otherwise, the engine kicks back hard (I’ve already gone through two starters).
When "fixed cranking timing with trigger" is ON, the engine kicks back really hard.
Setting the timing to -10 seems to help the engine start more easily.
The IAC setup appears to be a good fit.
I’ve tried more and less fuel, but the results are nearly the same.
The prime pulse has had the most noticeable positive effect as far as I can tell.
I’m really frustrated with this cranking issue and have run out of ideas. I’m starting to think there may be a hardware issue or possibly a bug in the Speeduino code related to the 4G63 trigger setup.

Please take a look at my logs and setup. I’d appreciate any ideas or recommendations on how to improve the cranking/starting process. Thank you very much!
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#69771
Hi
To me
Setting skip revolutions to 3 and maxing out timing to -10 during cranking is necessary—otherwise, the engine kicks back hard (I’ve already gone through two starters).
When "fixed cranking timing with trigger" is ON, the engine kicks back really hard.
Setting the timing to -10 seems to help the engine start more easily.
Sounds like the trigger angle is off. I think I would be checking the timing marks against TDC. And look for mechanical faults.

Are you waiting for the pump to finish priming? The injector prime should come after the FP prime.
Raise the cranking rpm to 400. This ensures the engine starts on the cranking values and then transitions to the running values.

ASE is set to zero! This will not help sustain the start of the engine. Especially when this issue is added the low cranking transiton value.

In the VE table. I find it easier math if in the first column, the values you have set at 70, are set at 100. Then you can see the cranking Gammme at a glance rather than have to multiply 70 x 210% This will also add fuel to craking, so you may need to reduce cranking enrichment. But only do this if you find it necessary.

Assuming this is a relatively new tune. You have the MAP sensor calibrated to a legacy value. Set it to NO.
#69773
"fixed cranking timing with trigger" has not been used for a while, so check you are on latest stable code. I would use SpeedyLoader to first run EEPROM_Clear (at bottom of code list), then load latest code.

+1, lock your timing to any low value, and check that it is correct with a timing light. If necessary, remove the spark plugs and ground them to the engine for smooth cranking and to see/test spark. This timing check cannot be avoided.

Post the cranking log as @jonbill requested. Begin the log, then crank a few seconds, then end the log. Post it up!
#69785
thank you for all the suggestions I really appreciate that.
Just to clarify:
- I'm on the latest 202402 firmware - was not trying eeprom_clear yet
- I triple checked the timing with lamp, all good there, as I mentioned the "skip revolutions" = 3 solved the kickbacking problem, which is kinda expected for low resolution pattern like 4g63, the timing table is kinda tuned and final so the timing values seems to confirm all is good, looks like the pattern needs 3 revs to get fully synced - which correlates with the pattern description form the documentation. But this is not the issue here
- I was not using ASE as I was relaying on warmup enrichment

What I have changes:
- added ASE just to check
- bumped cranking RMP to 400
- logged cranking on cold and hot
- on cold started at 2nd attempt
- on hot started at 1st but with some hesitation

issue is still there:
- hard start usually 2nd or 3rd attempt on cold, sometimes on hot
- i'm curious why I can see no RPM and sync los just before engine starts, marking them on screenshots

Again attaching logs for hot and cold and setup, if you have any more ideas please share, thank you
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#69786
I still think there is something wrong with you having to put in -10* ...

Did you load a base tune? You don't appear to be showing a lot of 'default' values in the summary.

And ensure the battery is charged for starting. Also, don't try starting with the battery charger connected as it messes with speedy.

I suggest you Save As the current tune so that you can come back to it. Though you can pick it up from here. :)
#69789
thank you LPG2CV

1. About the timing: Just to be 100% clear, setting -10 doesn't mean that kickback returns if I set it to 0 or +10. The "skip revolutions" set to 3 resolved the kickback issue. The engine is simply more likely to start with -10, which I've determined through hundreds of trials and errors.

2. Base tune: The tune I'm sharing is the result of about 7 months of work. I initially started with a base Mitsubishi 4G69 tune (if I recall correctly), then made a lot of adjustments. Aside from cranking, everything else is dialed in and working great. The timing is tuned safely with no pinging, and the fuel is within the target AFR range. This is all set up for E10 (EU) fuel.

3. Battery setup: I have two batteries that I swap, and I keep them charged before tuning the cranking, so battery charge is not a factor here.

4. Save points: Yes, I’m safely keeping rollback points along the way.

The question about the RPM drop in the logs just before the engine starts is still unresolved, and I have a strong feeling this is the issue I'm facing with cranking. Any ideas?
#69790
If the timing pattern is early 4g63, i.e. 4 signals per 720degree cranking, you absolutely need to be on the right trigger edge!
Imagine having a too early trigger edge, like 120degrees, engine goes into compression on the cylinder, and slows down, but speeduino has NO way of knowing the exact speed and position on the engine, its only based on an average between trigger signals and doesnt account for the compression slowdown.

Megasquirt back in the old days had a saying, that you needed such trigger signals (basic distributor in essence) to be around ~60degree before tdc. Several reasons however, but starting was one of them.
Some ecu's even use both trigger edges, one early for running, and the later trigger edge for starting, and then fixes the starting spark with the trigger edge.

So, some quick thinking, beware here, is that your trigger signal absolutely needs to be between 300 to 350 (since speeduino calculates in ATDC which is different from most ecu's doing BTDC), for it to have reliable starting.
Or, -60 to -10, i think speeduino does negative as well by memory.
#69792
Hi runesm,
Thank you! Yes, it is indeed the old 4 signals / 720 + CAM pattern. I’m attaching a photo of the crank sensor plate. It should generate the pattern as shown in the documentation: https://wiki.speeduino.com/en/decoders/4G63

I understand the concept from your description and post.

But what I don’t understand is whether my setup in TunerStudio is correct and how I can verify it against what you've just explained.
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#69804
Piotr Pakulski wrote: Tue Oct 08, 2024 12:09 pm Hi runesm,
Thank you! Yes, it is indeed the old 4 signals / 720 + CAM pattern. I’m attaching a photo of the crank sensor plate. It should generate the pattern as shown in the documentation: https://wiki.speeduino.com/en/decoders/4G63

I understand the concept from your description and post.

But what I don’t understand is whether my setup in TunerStudio is correct and how I can verify it against what you've just explained.
From what i can find its a hall sensor. First off, i assume you've verified your timing with a timinggun with the engine running, and it's set correctly.
What is your trigger angle set to right now?
#69811
Thank you, @runesm.

Yes, I've checked the timing with a timing gun many times. Everything looks good—if I fix the timing to 10, it's 10 when the engine is running.

After giving it some thought, I investigated potential differences between the 4G63 and G4JS timing hardware yesterday. And guess what?! When comparing the crank timing plates, I found that the G4JS is different (screenshots attached). Based on my quick and rough calculations, the signal from the crank is around +30 degrees off.

What this means is:

1. When the engine is running, the timing is fine (confirmed by the timing gun), likely for one of two reasons: either Speeduino compensates for this when the CAS sensor is synced, or the CAS is also offset compared to the 4G63, which I can't verify right now.

2. Before full sync with the CAS, during cranking, Speeduino relies only on the CAM signal, expecting the crank plate to generate the same pattern as the 4G63. But in reality, the signal is +30 degrees off—at least until Speeduino fully syncs with the CAS, which happens around 430 degrees, I believe.

As a result:
1. When I set “Skip revolutions (cycles)" to 0, the engine kicks back, especially when cold (slow cranking speeds). Why? Because until it syncs with the CAS, Speeduino fires the spark as soon as the first crank signal appears (which is fine since it's a wasted spark system). However, the timing is +30 degrees off, and with fuel ready from the prime pulse, the spark fires too early, causing kickback. That's why I had to set the cranking timing to a maximum of -10, which still results in around +20 degrees. Despite this, I still experience kickbacks, even though the timing readings are correct when the engine is running.

2.Setting “Skip revolutions (cycles)” to 3 mostly solved the kickback issue because the engine is fully synced before firing. However, as mentioned in my previous post, this causes other problems like RPM dropouts. The prime pulse can't be used efficiently, and cranking takes a long time before anything happens.

What I’ve changed and tried so far:

1. I set back “Skip revolutions (cycles)" to 0
2. I changed the trigger angle (degrees) from 0 to -10 to compensate for the timing before the CAS is fully synced, in an attempt to resolve the kickbacks.
3. I added +10 degrees to all cells in the spark table to compensate after the engine is synced with the CAS and running.
The results are:

The engine starts perfectly when hot. The prime pulse does its job, and after about half a second of cranking, when the first signal from the CAM arrives, the engine starts smoothly.
When running, checked with the timing gun—all good there.
I haven’t had time to test this setup with a cold start yet to confirm. My plan is to check it on a cold start, adjust the settings if needed, and give it a few more tries over the next couple of days. Thank you for all your help! I’ll get back to you as soon as I have more information and results.
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