HONDA K20 wouldnt start

Good morning

i have a honda k20 equipped with a link ecu g4 xtreme

car was tuned and was running very well the last event. The car went home and park and clean up awaiting the next event.

i started car and noticed a slight miss just for a few seconds while loading onto the trailer.

the car drove after and just shut down, error indicated the crank sensor bought a new OEM crank sensor but still no start.

When cranking the rpm is showing 17000 rpm 30000 rpm just erratic. The car sounds like the timing is off as it back fires through the intake

checked the timing everything is ok, did a compression test 180 psi all cylinders with 1 psi of each other

what could be the issue if anyone has encountered this before

How did you check the timing? I find it hard to believe you could verify the timing with a timing light, and yet the car would not start and sounds like the timing is off.

The cranking RPM being off all sounds like a broken connection in the wiring to the crank position sensor -- but that wouldn't allow you to verify the timing with a timing light.

Do you have an oscilloscope that could let you look at the crank position sensor signals?

When i encounter this problem i strip the engine down to check pistons if i had any engine failure

and as i rebuilt the engine i check the timing same time.

No i don't have a oscilloscope only the one from the computer

From a mechanical point of view the timing is right and i didnt check via timing light

i strip it down to make sure there is no mechanical problems

You say a "G4" Xtreme, can you confirm if it is a G4 or G4+? If it is a G4+ it has a built-in triggerscope.

it is a g4+ correct it has a built in oscilloscope i striped the wire loom to check the crank sensor wires didnt see anything

Please attach a triggerscope capture of it cranking then.

please find attached

not getting to load the pic up how too

I want the actual scope file. Use the "save as log" button.

please find attached

please find attached base map to see if everything is correct

just change crank sensor again both cam sensors change tps change map sensor

The trigger looks ok in that scope capture, although perhaps something changes at higher RPM. Does it still run? Can you do a short PC log of it running or if it doesnt run do a log of it cranking.

Actually I see the problem. Your Exhaust cam is about 20 degrees retarded from where a stock K20 is. I just tested on the simulator and our ECU will give trigger errors with the exhaust cam more than about 18deg retarded.

Maybe it has jumped a tooth or perhaps it was just on the borderline before and with a little it of cam belt stretch or something it has moved beyond where our ECU is happy.

You are going to have to advance your exhaust cam a little.

i will have to check but i do have adjustable cam gears on the engine but i checked them the bolts are tight and set the same way the cylinder head supplier sent it

the engine doesn't start or run anymore it just cranks over and over and backfire flames and back fire via intake while u do get a start it miss like working on 2 cylinders.

could you explain how u came up with that predication by looking at the base map things i should look for just for my knowledge thanks you

even though the exhaust is retarded the two hole on the back of the cams line up prefect ?

It wasn’t by looking at your map, it was by looking at your trigger scope compared to a known good one. Your exhaust cam teeth (trigger 2) in relationship to your crank teeth (trigger 1)are about 20 deg further to the right than where they are expected to be.

thanks Adam my exhaust cam sprocket had moved and i was over looking this simple thing

thanks for the knowledge and help