New question: What prevents the ignition from firing?!

[FriedEGs]

Obvious components come to mind... Iginiter, relay's and ECU...

My problem is NO spark. The car ran fine a week ago when I fired it up for the very first time after dropping in this motor. Car started 3 times with no problems, and ran for a total of 10-15 minutes max. (No load) Now it won't fire. (Car turns over, with fuel, but no spark to fire over)

Igniter? Is testing this thing easy? I can't find diagrams to test power leads, etc...

ECU? Worked fine initially... anyway to test this?

Relay? I can't figure out which one is the iginition relay. One of the 6 relays under the dash on drivers side? Or, is it the single relay behind the ecu?

What can cause any of these components to just randomly fail? Or, can anyone think of something else that could prevent the ignition from working?

Initially, I had a problem with lots of coolant/water in my oil system, and I think i took care of that.. but, now the car won't start.. Can anyone think of any link between this incident and my current situation regarding the lack of spark?

Car: 95 SEEngine: RB25DET S1


Modified by FriedEGs at 9:30 PM 8/10/2007

[Shocker]

check all your grounds.

[FriedEGs]

all grounds seem to be okay..

the igniter isn't getting voltage at the 2 wire plug just above it.. I turned teh car to "on" and checked for voltage.. and nothing.

The ecu seems to be working if it's allowing the injectors to spray... which they are..

I can't imagine teh Crank Angle Sensor is bad or not working..

Can anyone tell me where the 2 ignition relay's are located? Are they the two that are behind the ECU, or are they on the drivers side by the fuse panel?

[Darius]

For the RB, there is one IGN relay and one ECCS relay by the ECU. Check that you're getting 12V at the appropriate pins on those (refer to your recently acquired wiring diagram).

You can simply check the CAS by taking it off and rotating it with the key in the ON position to see if you can hear the injectors fire.

I would check the ground on the ignitor and the wiring around that first though.

Give us an update when you get a chance too.

[madcowvert]

thats more or less the same thing that happend to me and it was one of the 2 relays that are by the ecu on my rb25.

[craz4240]

Also if you have been cycling the injectors alot make sure you change your oil before you fire the car up....cause theres a chance it could go boom.

[FriedEGs]

UPDATE:

Okay, I ran of series of tests.. basically what Darius suggested.

Eccs Relay harness plug: Voltage good (11.40)Eccs Relay: when voltage applied, ther was 11.40 volts going throughIgnition Relay harness plug: Voltage good (11.40)Ignition Relay: when voltage applied, there was 11.40 volts going throughIgniter: Voltage good (11.73) I checked this by grounding the middle wire of the 7 going into the chip, and power through the 2 wire plug next to the igniter.Coil pack harness: Voltage good (11.73) tested at #1 and 2 cylinders.Crank Angle Sensor: when rotated, fuel injectors fired! (bang included!! What happened? Did the fuel combust on the pistons that were near tdc? Kind of like a diesel?)

(All voltage readings were through the harness, and not through direct battery power or direct ground)

What I have NOT checked. The signal wires on the ignition harnesses. (the 6 pink wires) Also, I have not checked for resistance or continuity between the relay's and the harness for the ECCS and Ign. relay. I have not tested the Coil Packs, either.. I still need to figure out how to test all of these properly.

At this point, I suspect that the ignition sequence signal is not reaching the coilpacks... Or, at least, the coilpacks aren't transmitting the signal for spark down into the plugs.. (plugs are brand new)

[FriedEGs]

Also if you have been cycling the injectors alot make sure you change your oil before you fire the car up....cause theres a chance it could go boom.

can you explain what happens to cause this "boom". Is the fuel combusting on itself in the cylinder, similar to how a diesel would? When I rotated the CAS to test the injectors, I got a loud "bang"... What does changing the oil do? Thanks!

[craz4240]

For one you have been cranking the car and dumping raw fuel into the cylinders thats not getting combusted.....ever light a small puddle of gas on fire and then light a bucket of gas on fire???With the bucket you get almost an explosion where the small puddle just burns.Basically you could lose the motor.

Changing the oil will remove access fuel....or you could if your brave stick a bbq lighter down inside the cylinders lol But I wouldn't suggest that lol Done it before but don't recommend it.

[FriedEGs]

For one you have been cranking the car and dumping raw fuel into the cylinders thats not getting combusted.....ever light a small puddle of gas on fire and then light a bucket of gas on fire???With the bucket you get almost an explosion where the small puddle just burns.Basically you could lose the motor.

Changing the oil will remove access fuel....or you could if your brave stick a bbq lighter down inside the cylinders lol But I wouldn't suggest that lol Done it before but don't recommend it.

pulling the plugs would allow the excess fuel to evaporate... I realize that some fuel may condense to the sides of the cylinders since they are cold...

Are you saying that the fuel vapor is blocked into the crankcase? Or, are you saying the fuel is still liquid and is literally mixed in with the oil now

basically, the car is "flooded" which isn't that big of a deal.. it's not much worse than a car running rich.

[craz4240]

Well all I'm saying is to be safe.....and it is possible you have a bad ecu if the coils aren't getting switched ground.

[FriedEGs]

Well all I'm saying is to be safe.....and it is possible you have a bad ecu if the coils aren't getting switched ground.

Safe from what? You're not explaining what the problem is.. If it's vapor in the crankcase, that can easily be evaporated or vented through the dipstick or throught the crank ventilation line... but, if you're suggesting that the fuel is mixing with the oil, (which is highly unlikely) than, yea, I'd agree that the oil might need to be changed.. I can't think of any other reason to change the oil, unless it's contaminated... and changing teh oil has nothing to do with excess fuel in the cylinders... whether it's a gas or a liquid..

[craz4240]

Man nvm I was trying to help...try your ecu in someone elses car I bet it's screwed.

[FriedEGs]

UPDATE:

Alright, I figured out my ignition problem. I had a toasted relay that was plugged into either the ECCS or Ignition Signal relay.. (most likely the ignition)

Car fired right up!!!

Thanks to everyone that helped out. I learned a lot more about more car's electrical system. Especially, the coilpacks.. I've never had a car with a distributorless system and after studying the FSM to diagnose my ignition system, I learned a lot of new things!

[Jordan_751]

I'm having firing problems out of my s13 rb20. I pulled into the mall one day and it was like someone reached over and shut the key off. My power transistor isn't grounded right and isn't bolted to the block. But I some opinions on what it could be and why the car just died. The car will turn over all day long but won't fire. I even changed out the camshaft positioning sensor. Still nothing, give me a shout out anyone!

[Darius]

I had this same thing happen to me at a car show once. I drove it there without ever having ignition problems. It sat with the hood open for several hours in the sun and wouldn't start when I wanted to leave. Apparently the sun heated up the ignition coil harness which melted the tape adhesive and caused the power to the coils to short to the ground wire. No power=no start. I ended up pulling the harness apart and rewrapping it and it fired right up.

Start by verifying that there is actually switched ON power reaching the coil packs. Then, check the signal wire continuity between each coil and the ignitor. Also check continuity between the other signal wires and ground to make sure the signal is not being interrupted. Next, if those check out, test for continuity between the ignitor and the ECU. Each signal wire should be continuous. Again, check for continuity to ground to make sure nothing is shorting. If all of the wiring checks out normal, try to swap in a known good ignitor.

[Jordan_751]

Alright thank you ill try. I'm just not sure what it is cause it only starts depending on where I put the ignition module (power transistor) on the block. It only starts depending on where I press it against the block. I really think it's something simple but then again I'm not sure. So you think it's the ignition coil??

[Darius]

There are 6 coils, so no I don't think it is any of them since you say it starts occassionally. This sounds like it has a bad connection to the ignitor module (aka power transistor). Check the main coil grounding wire in the coil harness.

[Jordan_751]

Alright but see I also don't have the bracket that you bolt the power transistor to and then bolt to the top of the block. Like I said the car ran just fine and we pulled into the mall and the car died. And all it would do was turn over. I thought It was the camshaft positioning sensor so I replaced it with a new one. Of course I found out that wasn't the problem. But I found the power transistor hanging off the back of the block. And depending where I pressed the metal part on it would start. I really thought it was a ground though. But I'm not sure where to check all grounds??

[Jordan_751]

Alright but see I also don't have the bracket that you bolt the power transistor to and then bolt to the top of the block. Like I said the car ran just fine and we pulled into the mall and the car died. And all it would do was turn over. I thought It was the camshaft positioning sensor so I replaced it with a new one. Of course I found out that wasn't the problem. But I found the power transistor hanging off the back of the block. And depending where I pressed the metal part on it would start. I really thought it was a ground though. But I'm not sure where to check all grounds??

[Darius]

That's why I say check the wiring because something is shorting out. I had my ignitor hanging off the back of the engine for a little while and it made no difference, so you don't need the mounting bracket for it to function properly. It doesn't ground through there if that's what you are asking.

[Jordan_751]

Okay thanks man. Ill see what I can figure out.