3SGTE rebuild starting issue

[Zmit]

G'day all,

After a few days of trying to get my rebuilt 3SGTE started for the first time on a P'n'P G4+, I've run out of ideas and hoping for a little bit of guidance.

I've had the ECU for a few years and it was running on the car in 2018. It was tuned by me at the time, and was never fully dialled in, nor pushed too hard. At that point, the thrust washers gave out and destroyed the block/crank. Fast forward a few years and I've made a few changes including a new block/crank, changing the turbo from a GT35/CT26 hybrid to a GT28 and redoing the entire engine loom (yes, with a P'n'P).

It's a Gen 2 3SGTE with:

• 86.5mm forged pistons
• gen1 3SGE intake manifold
• GT28
• 540cc (gen3) injectors)
• Tomei FPR
• Walbro 255 fuel pump
• 1ZZ COPs
• OEM dizzy triggers
• 2AZ E-Throttle

 

Where I've gotten to:

• I've confirmed base timing is correct with a timing light and the calibration sequence (note: from a UI/UX perspective it would be really nice to have an 'apply' button for that dialog so that idiots like me don't have to resort to the forums to find the 'press enter' trick)
• I've tested spark and all COPs are firing the plugs correctly.
• I've tested injectors and they are all triggering correctly as well. The combination has meant combustion a few times when I've tested the COPs after cranking it a few times
• Trigger 1 and 2 are present but trig2 seems really low at 0.25v being the lowest arming voltage before noise (at -0.18v) creeps in.
• I've switched my map from modelled to traditional while the WB hasn't been hooked up, but haven't made much headway with either equation type.

 

Most of what I knew in 2018 in terms of tuning hadn't been used for years and has vaporised in that time. Any help would be greatly appreciated!

 

I've attached a couple of recent attempts. Please note that the fuel table and ignition table around the 0-1500 rpm region will likely be nonsense as I'm just trying anything at this point.

MR2_20211121.pclr Log 2021-11-21 3;49;34 pm.llg test_start_attempt.llg

[Adamw]

I haven’t looked at the files yet as not at a pc until the morning, but just one thought based on your description.  Try adding or subtracting 360 from your trigger offset, possibly sparking on the exhaust stroke rather than compression stroke.

[Zmit]

Hi Adam,

Thanks for the comment. I've tried that and definitely have it on compression rather than exhaust.

[INSW20]

From the logs it doesn't look like your MAP sensor is reading anything.  My 3SGTE shows about -0.7 to -1.0 during cranking.  Yours is showing 0.0 to -0.1.

[Adamw]

I dont see too much out of place that would prevent it from running.  Dwell is a bit erratic so possibly a trigger issue.  Can you do a triggerscope while cranking.  

I would also suggest try starting with a squirt of starter fluid as a good test to eliminate fuel issues as the culprit.  

[Zmit]

I haven't got a capture of the trigger scope, but I've done it a few times as a sanity check. I've got consistent (reluctor) trigger 1 and 2 signals, but trigger 2 peaks at +-0.4V with a fair bit of noise at -0.2V. The arming threshold should be able to handle that.

@INSW20 That's a fair point. I went back over some of my other attempts and it doesn't look like it's moved much either. I'll check that out and see if I'm getting any signal off it. 

Thanks for the suggestions, gives me some direction when I give it another go on Friday

[Adamw]

Please do the scope and the starter fluid test.  There is nothing wrong with your MAP.

[Zmit]

Here's a trigger scope.

Trigger Scope Log 2021-11-26 5;27;08 pm.llg

[Adamw]

The trigger 2 sensor is the problem, it is only reaching about 0.15V so it will never arm.  Open the dizzy up and see if you can move the trig 2 sensor closer to the wheel.  

[Zmit]

Thanks Adam,

that particular log seemed lower than previous ones, but I must have put the wrong dizzy in. This one is now reading -0.8 to + 0.66.
Since changing the dizzy over, it seems to kick 2s after cranking to about 400-600 rpm. This is very consistent but then never goes anywhere after that. 
 

We’ve confirmed compression on all 4, spark from each of the plugs (visual inspection, even though they were quite wet)

i’m not quite sure what else to check. Any other thoughts?

[Adamw]

On 11/22/2021 at 10:15 AM, Adamw said:

I would also suggest try starting with a squirt of starter fluid as a good test to eliminate fuel issues as the culprit.  

Have you done this yet?

Give us a new log.

[Zmit]

Hi Adam,

forgot to mention that. Yes I did try the starter fluid but honestly didn’t seem to make any difference. 
 

I’ll post the log tonight, I don’t have it with me now. 

[Adamw]

How did you check ignition timing - did you remove a coil and place an HT lead between coil and plug?  

[Zmit]

Many months later, I'm going to admit to screwing this up.

The reason it didn't start was due to the exhaust cam mechanical timing being out by a significant amount. (somewhere near 70-80 degrees)
One Friday night 18 months ago I must have decided to use the right-hand pin hole to notch the cam a couple of degrees, but then when I put the cam gear on I put it into the centre hole and just didn't check it.
When I checked the cam gear timing, they matched perfectly. I didn't check the cam notch timing until much later though. That's where it became painfully obvious.

Anyone who has worked on an MR2 before knows that once the engine is in, you can't really do anything with the timing belt. Me and a mate did come up with a solution.
Using a magnet on the match pin didn't work, so we had to slide the cam gear onto a turned down collar so we could get the pin out.

 

Thank you all who offered suggestions. It all helped. When we finally did resolve the timing issue, it started up within a second of cranking. Since then, it's been starting instantly every single time.

Cheers,
Tim

 

[koracing]

I know it's not fun, but it is possible to do the timing belt whilst in the engine bay.  I can't count how many timing belt jobs/replacements on 3SGTE MR2s I've done this way over the past 20 years.  Resetting cam timing by pulling the tensioner and re-aligning the gears I have done on a tuning trip to NY while the car was strapped down on a dyno - took about an hour, but 2-3 hours should be no problem for most people.