"old hillclimb car FREE!!!" - '78 Fiesta + Honda V-4 swap (Page 3 of 3)

The clunking sound was either going to be a known issue, not enough clearance between a bolt head and the jackshaft u-joint, or the chain drive.

https://cdn.discordapp.com/attachments/ … /clunk.mp4
Welp, it's not the u-joint, so my sprocket alignment is off or something...

RCC wrapped the cage up and it's on the truck, but it won't be here for another two weeks. I think that between those two challenges our fate is sealed and we'll be showing up to Smells Like as spectators this year.

I would really like a re-do the chain drive too, with a hy-vo chain instead of roller chain.
https://www.tayloredge.com/reference/Me … tChain.pdf

Otherwise, progress is steady.

Hy-vo in oil or grease is a great way to go. GM FWD autos (among many others), from the TH425 to the TH125, use that style of chain to good effect.

Love this project as a builder of a bike engine car (Honda Z600 with VFR800 power - all shaft drive with an output shaft adapter )

Bummer. Well, come by our paddock spot and say hi. This build has been entertaining enough that I owe you a beer.

Log:

- An exhaust pop shot a bung plug out the unused exhaust hole and I had to go find it.

- The roll cage pipes got delivered. There was a cat sized hole in the box but nothing seems to be missing.

- There is this bent metal coolant pipe with a tee in it from off the fiesta's parts heap. It had/has a rubber cap on one outlet that looks like the foot from a metal folding chair. It blasted even further than the exhaust bung.

- The ecu is clumsily rev-limiting at about 4,700. (because the code I added is slow?)

Above 4,700 RPM the ecu can't run instructions fast enough to keep up with the engine and it looses track of the timing wheel ticks for one revolution. That translates to a negative RPM spike, it does its math wrong for a cycle and it misfires. Then the engine is no longer spinning too fast, nature heals itself.

Edit for clarity: In this chart, the Sync Loss Count is actually the crank timing wheel tooth # when sync is lost.

- The exhaust is piped all the way to the back of the car, but there is a ground clearance concern.

- The suspension bushings made out of hardhat material make this car feel like driving a big shopping cart. The bushings need to be greased.

Thank you, thank you!. That is exactly the kind of thing I've went spelunking for for, but I missed that setting. I'll give it a try tonight.

I was hoping to find an -O0 or something dumb in the cflags, but no.
I'm not completely sure about my diagnosis either.

Here are some other things it might be:
- primary/secondary phasing
The signal conditioner converts an analog waveform into a digital signal.

The fundamental frequency of the cam timing pulses is half that of the crank pulses. So while the TDC teeth of both timing wheels pass their respective pickups at the same time, one is generating a lower frequency pulse because it's moving slower. So depending on where it is in the rev range, the falling edge of the cam pulse can be ahead of or behind the falling edge for the crank pulse for the same tooth. Maybe this is happening at 4700? Need to get scope out and look.

- serial i/o Maybe the serial communication (which takes priority over ecu calcs) is too expensive?

- bad logic Speeduino decoders have to re-calculate the "end tooth" for each ignition channel every time the timing advance changes. This isn't common logic in the code, each decoder has to implement it. Maybe my implementation is bad and when the timing gets advanced past ?? degrees it calculates the end tooth wrong.

I'll probably have time to work on it mid-week. It's not worth dialing in the VE table if I can't get it past 5K. All the power is between 5K and 8K.

The picture on your scope shows that you have a rising edge which is almost certainly wrong as those look like VR waveforms. Are you backprobing using the same polarity that it's wired to the ECU? If all of the above is true, afaik that's backwards. VR sensors need to be falling edge, as the voltage swing remains fast across the full RPM range. If it's wrong, you'll get timing drift at high RPMs, which could be your issue. If you have a max9266 conditioner you'll need to swap the VR leads and set rising edge in tunerstudio as it inverts the signal. With the mini dsc you'll need to swap the VR wires and set to falling edge in TS.

So ultimately, there are 4 ways to configure the primary trigger but only one is correct.

For reference, this is what mine looks like (on an ej20 which has a weird tooth profile). The crank and cams are flipped from yours. I just had the misfortune of going around in circles on this for a while, eventually finding that it was a integer overflow bug in the ej decoder code in speeduino.