2002 gtx 4tec no spark cylinder 2 + 3

[lprince]

Ok so i have been working on this project and I am down to not having spark on cylinder 2 and 3. I have checked CPS 240 ohms at pins 5 and 19 "A" harness ECU and 2.4vac while cranking checked at the 2 pin connector for the sensor. I have checked all the coil packs on cylinder #1 and they are good. I have checked for dc voltage at each coil and had 12.4 vdc. I removed the injector rail and cranked the ski witnessing all injectors firing, I assume the injectors are firing based on info from CAPS and CPS if this is true then both those circuits are good allowing injectors to pulse. I am almost convinced i need a new ECU.

If I replace the ECU with a used one do i need to make sure it comes with the keys?

If i install a used ECU is there any thing else that has to be done as far as programming?

If programming needs to be done can that all be accomplished with Candoo system?

 

[ski-d00]

ECUs rarely fail unless they have been jump started or somebody has messed with the wiring, more likely you have a bad connection. have checked spark with new and known working spark plugs(not just looks good)? check all pins and connectors for corrosion. has the motor or encoder wheel or pto been apart since it's been running? need a little more info on the situation as to what happened and what's been done.

if you buy a used ECU, you will either need the key or get it programmed to another key, that's all that needs to be done as far as changing the ECU.

I use BUDS, so I can't tell you what CanDoo can do but I certainly would hope it can do simple key programming.

 

[lprince]

i have taken the coil packs and plugged each one indiviually into cylinder 1 and they all spark on cylinder 1.

the engine was just rebuilt it had been hydro locked and bent a rod. it has been bored out and completely gone over proffesionaly. i have no codes and i have checked all connections and checked ohms for each wire for cylinder 2 and 3.

is there a way too bench test ECU?

i followed repair manualfor diag of cps and caps. both appear good. if encoder wheel was problem would i still make ac voltage at cps plug 2.4 vac?

 

[ski-d00]

Are you sure the magneto and encoder wheel were properly installed? If one of the balancing holes or divots on the magneto is aligned with the opening on the encoder wheel it will do exactly what you are describing because it isn't getting the proper trigger to tell it to fire for some of the cylinders. Yes, it would still make voltage.

No easy way to bench test your ECU but I can put it in another machine and put it on BUDS for $30 if you like. I can also program more keys to it if it tests good.

 

[lprince]

Are you sure the magneto and encoder wheel were properly installed?
I would hope so the engine re-builder does a lot of these engines but hey any body can have a bad day.

If one of the balancing holes or divots on the magneto is aligned with the opening on the encoder wheel it will do exactly what you are describing because it isn't getting the proper trigger to tell it to fire for some of the cylinders. Yes, it would still make voltage.

No easy way to bench test your ECU but I can put it in another machine and put it on BUDS for $30 if you like. I can also program more keys to it if it tests good.

I just ordered a CANDOO home system and I can force a spark on a specific cylinder just like BUDS. If i can not get the ECU to fire cylinder 2 and 3 through candoo I guess the ECU is bad.

Is there any way to get a fiber optic camera into the pto housing to see the encoder wheel? Possibly down through the valve cover along the timing chain? Just like you would use an oil evacuator to remove oil from the PTO housing. I have a super small Snap-on Camera (5.5 mm diameter) and I was thinking maybe I can see the encoder wheel and the balance marks without having to pull the PTO cover. I reviewed the section in the manual and I see the note about the improper installation and a no start condition.

 

[ski-d00]

Not sure you will have a 5.5mm gap between the timing gear and the head but is worth a try. If you can get the camera past the timing gear on the head and between the timing chain you should have plenty of room and be able to see the encoder wheel clearly if you can get enough light in there.