Slow burn project- T1 Speeduino EFI

[Bruce.m]

Discovered another flaw with speeduino.

I finished the wiring & flushed the pump + fuel line.

So I wanted to test the injector flow + dead time using the tuner studio Test utility. However with the speeduino firmware, you only get a basic option to manually switch on/off each injector with a fixed 50% duty cycle. That’s poor compared to the Megasquirt version which allows you to set the pulse time and number of cycles. So that’s not going to enable a dead time measurement. Will have to figure out another way.

[Piledriver]

Most OEM wiring is great quality as well, fabbed a couple setups using wiring harness & relay boxes from motorcycles, both GSXR, 600 & 1000.
The fuse/relay box alone was almost worth the price.

Unfortunately old VWs have <iffy grade wiring and ~garbage spade connectors/fuseboxes as a rule... not sure what year it got better, or even if it has.

[Bruce.m]

Had a look at the speeduino code to see if I can add the the test routines that are available in tuner studio for Megasquirt. Adding the menu options appeared doable but finding the right place in the firmware for the test code was less obvious.

Considered & rejected a couple of other options.

Ended up writing a simple test utility that can be uploaded to the ECU as temporary firmware. Gives the option to test fire an injector or coil channel, then specify the time of the pulse in milliseconds or microseconds, the interval between pulses and the number of pulses required. So can test dead time / flow effectively and also test fire a spark plug with a realistic dwell period.

Will test it on a spare microcontroller but hopefully it will do the job.

This sort of coding is a bit outside my usual knowledge so 90% of the effort was by AI with prompts from me and a few final manual changes.

[Bruce.m]

Bit of debugging & minor UI improvements to the injector / coil pack tester.
Happy it will do the job but will test it with an oscilloscope to make sure it’s accurate enough.

[Bruce.m]

Got some weird results with injector testing. Big difference between what I got with the tester, compared with the speeduino function (which says it’s 50% duty cycle signal). Will perhaps scope the signal from the speeduino function & see what it’s actually doing.

Engine primed on the starter & around 40psi of oil pressure. The starter motor is a champ. Thanks to Pile’s post years ago, it has a aftermarket hi-torque unit (later wet VW fit) with the mounting holes modified.

First start was ugly. Something is not right. It acts like the HT leads are firing in the wrong order but I’ve checked that umpteen times. The crank / cam signal is super clean & looking good I think. I have a doubt over the crank / cam settings which might mess up the sequential positioning but the coil is wasted spark so that won’t impact the sparking.

The main red flag is the MAP reading didn’t dip below 100 so I suspect there is a vac leak. I’ve checked photos & the vac ports exit below the butterfly so should read proper manifold pressure. To simplify I’d already closed the idle stepper valve for the first run & disconnected it.

I’ve knocked up a simpler tune using batch injection so the cam timing is ignored and also using TPS for load, if I can’t explain the MAP signal issue.

[Bruce.m]

MAP issue was due to a blanking cap coming off one of the unused vac ports. Now seeing the MAP dip on crank.

Engine will fire, sort of, until circa 500rpm then the crank sync errors start clocking up. So the main problem is that. I did take a log under crank with the coil powered up & the pump disconnected which appeared to be clean. However my crank sensor is a cheap Chinese hall sensor & that’s the suspect at present. I’ve ordered a decent quality replacement. I do also have a VR sensor as supplied with the crank trigger kit but I don’t have a conditioner module & prefer to use a hall sensor (perhaps I’ll change my mind!).

So progress has stopped for a few days unfortunately.

[wreck]

My crank sensor is at 9 o'clock , my trigger angle is 270 , I'm using a custom (home made ) 24-1 wheel with a late Toyota cam sensor , it's a hall sensor and readily available, seems to work well so far . my cam sensor is a CB unit . both edges set to falling and trigger filter on medium .
this YouTube channel has a good explanation on setting up timing angles etc . silly question but something that I didn't know till I had an issue , is are the cables to your CAS"s shielded ?

https://www.youtube.com/watch?v=k6gEccn17Ro&t=4s

[Bruce.m]

Thanks.

I’m using the VW speedshop 24-1 tigger wheel & pulley combo. The sensor is mounted at 3o’clock and has an angle of 40 or 50 degrees depending on whether it’s falling or rising in TS. In theory I can set it as -50 or +310 & that will work regardless for the batch fire coil. The cam sync will only impact the injectors but I’ve switched to semi-sequential for the moment to simplify, so the cam signal will be ignored for now.

Sensors fly leads are not screened but I’ve shortened those cables & via a Deutsch connector, I switch to shielded cable from there back to the ECU. The shields are earth at one end only. At the moment I’m leaning toward the sensor being the problem & I’ll have a couple of options (hall or VR) in a day or two. Partly basing that on the clean signal at crank over, even with the coil firing (& pump switched off). If I still get issues after switching to a quality sensor, I will get the scope out to see if / where noise is coming from. The ECU itself is mounted on the internal side of the firewall, so could add ferrite core to the coil switching wires plus 12v feed, if needed.

[wreck]

I would have thought if the sensor is at 3 o'clock ,the angle should be close to 90 degrees if your missing tooth is at TDC

[Bruce.m]

Good spot but yes the tooth is BTDC, allowing for the sensor position. I assume Paul designed it that way deliberately since some older ECUs need the gap before the max advance.





You can see the crank key way above which is at 9 o’clock when the engine is at TDC. That puts the missing tooth well past the sensor by that time in the cycle.

[wreck]

looking at the picture , I would think it would fall around 180 to 190 degrees after TDC .

[Bruce.m]

Maybe this helps?



Red line would be vertical at TDC.
Blue line passes through the sensor at TDC.
First tooth after gap is the yellow line which is roughly 45 degrees earlier, so the marker tooth passes the sensor approximately 45degrees BTDC, with clockwise rotation.

[wreck]

sorry my bad , (work too much on type 4's) I thought the woodruff key was TDC , not 90 after .

[Bruce.m]

ah, makes sense. The only other thought I had was you were thinking anti-clockwise but you have enough oil under your finger nails to know different.

Amusingly (perhaps)…. This engine was supposed to be a quick build and test bed for speeduino & a custom intake system… before I got on with the planned type4 build (have most of the parts needed for the engine & upright cooling). But funnily enough I’m still working on the “quick” build.

[Bruce.m]

Also. New hall sensor arrived. ZF part.