RB25 No spark!

[APL]

I just finished an rb25 swap into an r32. R32 wiring and r32ecu for the rb25, rb20 ignitor pack, gtr injectors with resistor pack. I have fuel in all cylinders, but only a weak spark on #2 and #3, no spark anywhere else. Any ideas as what the problem could be?

Thanks!

[Gold Digger]

Maybe because you are using an RB20 harnes, ECU and ignitor?

I would think that the ECU and the ignitor are the problem.

By the way, this should be in the RB forum. If you want, I'll move it there for you.

[APL]

The ecu is tuned for an rb25, the harness and ignitor fit and work fine in this set-up. Thanks.

[kevwa]

i would double check your wiring. make sure you have good ground and power to the coils - when i first went to start mine it had no spark and turned out that the ground wire for the coils was bad. good luck

[APL]

Ok thanks man. Ill take a look.

[USMCgetsome]

[APL]

Alright. The ground for the coils and ignitor is good. Im gonna test the resistance from the ecu to the ignitor, then try swapping ecu's then finally swap the ignitor. Any other ideas?

[kevwa]

i wouldnt just start swapping parts - the best way to diagnose a problem is to start eliminating things - like in your case you have ruled out fuel and compression and know its a problem with spark. you should now focus on why its spark. checking resistance is only going to tell you if the wires from the ECU to the igniter are intact. if you are positive your powers and grounds are good i would search to see what signal you should be getting from the ECU to the igniter, and then what the signal should be coming out of the igniter. this will tell you if the igniter is good. as for the ECU its unlikely that it is bad - the biggest thing my teachers at school said was if you get to the point you think its the ECU start over and double check everything - im not saying the ECU cant go bad, just that there is a much greater chance that the problem is something else. if you start swapping parts and the problem doesnt go away, you have no way of knowing if the part you swapped was good or bad. hope this helps

[APL]

Yup that helps, thanks man. I have another socketed ecu so i wont have to buy one.To test the voltage going to the ignitor from ecu, i ground the multi-meter and back probe each lead. correct? Then the same on the other side for the ignitor output signal. What kind of voltage should i be looking for? Because it should be a pulsating voltage coming from the ecu.Thanks.

[kevwa]

you are correct on testing the voltage - im not sure what you should get for voltage - you can try searching on the forum or just test all of the wires and see if they are all about the same, if they are that would make me think they are alright, i mean they should all be the same, so if 1 of them is way different i would think that would be your problem - and yes it will be a pulsating voltage - actually i remember testing my ignitor a while back and i think the voltages are very small -

thats cool you have another ECU, but i would def recomend not switching that out untill you know for sure the one thats in there is not good, adding another variable to the problem by switching the ECU can cause more problems than its worth.

[APL]

Thanks for the quick/awesome replys.

I tested the voltages that were going into the ignitor from the ecu.. The fsm says 0.1-0.3v on the input side of the ignitor, and 7-9v on the output. Both when engine is running, but keep in mind all i can do is crank.

#1 33mv (something small)#2 1.1v#3 1.1v#4 1.0v#5 (something small)#6 0.75v

There was a very very small spark on #2, #3, and #4. Also the voltages from the output side of the ignitor were no where near 7-9v, they were smaller than the input voltages. A little confused with this as teh ecu is seems to be sending too much voltage and the ignitor isnt doing ****.

[APL]

Forgot to add that the 1.1v i am measuring on the input side of the ignitor are when the ignition is ON and not cranking. wtf?

[USMCgetsome]

if it's not in tolerance consider it broken. Try another ecu. Check your wiring loom for any defects or shoot the wiring harness from the ecu plug to the input plug on the igniter chip. What is it's continuity? should be 1.0 ohm or less if your reading high ohms then consider a weak wire integrity and then fix it!

start there next. Although i would consider the ecu voltages not within tolerance.

process of elimination is rule out wiring then rule out components.

[APL]

The CAS is good. Ive tried 3 ecus. All the wiring is good. Gonna try another ignitor on wednesday. The ignitor is grounded by the little ground wire correct? It doesent actually need to be grounded its self does it?

[kevwa]

thats correct - the igniter does not need to be grounded separately

[APL]

Anyone have any ideas? this is killing me.thanks.