No spark? Only sometimes...

[oes]

1992 nissan 240sx ka24de-t w/ AEM EMS

Well I just got the car running finally. We were able to fire it up for the first time. Had it running for around 15minutes @ 2000rpms to do the cam seating. Right around 15minutes of running, the car dies on its own, we try to recrank it, and it wouldnt. Check for spark, no spark? Swap out coils with my other one and try to fire it up, no dice. We let it sit for a few mins and try once more and it fires up. After messing with some stuff we try again and it wont crank. We call it a day.

Few days later I go out and try to fire it up with no success. Decide to slap the battery charger on it and try. Fires up first time with charger running. Turn it off because I noticed a fuel leak. After fixing the leak, try to start it up again, it wont fire. Not getting spark again. Let it sit for awhile, fire it right up and let it run for about 10 minutes, then it starts to lose RPMs and then just dies. No more spark again!

Figured it might be a problem with the alternator so I take it out and take it to Autozone to get tested. Fails all tests (I dont trust their machine) but I buy a new one anyway. Replaced the alt and noticed the power/charge wire on the alt was ghetto rigged so I redo the wire and add a new connector. Try to start it up with new alt and no go again. Put the charger on it for about 45mins @ 12volt/2amp and try again, still no fire or spark.

I used a meter to test the voltage on the battery directly, was reading about 12.45volts. Noticed the EMS was reading 11.65 battery voltage with key on and when I was trying to crank it would drop down to 8-9volts. I have no idea what is going on. Any help?

[WDRacing]

Well obviously you have a power drain. It also sounds like the battery is bad. If the battery is bad, it won't take a charge. It makes it hard for even a charger to start it. I had the same issue when my 240 sat, swapped the battery, good to go. Try swapping in a known good battery. Then measure the current coming from the alternator. Once the car is started, remove the negative terminal from the battery, the car should stay on.

WD

[oes]

I should have mentioned, this is a brand new battery. Gonna look over all my grounds and make sure they are all there tomorrow. Maybe even add some more?

[WDRacing]

Damn...I was hoping for an easy fix

[oes]

You arent the only one

[1995240sxSE]

Damn...I was hoping for an easy fix

where on earth do those exist? At least in nissan land!

[DammitBobby]

Voltage across the battery should not drop below 10 volts when trying to start the car. Actually if it is around 10 volts you either have bad starter or battery. Since you replaced the battery, altenater and the connectors I would recharge the battery and place volt meter across the battery and see what voltage you have at idle. You should read around 14 to 14.5 volts at idle. If you do not read at least 14 volts either the battery, altenator or the connections are bad. By the way I had a brand new battery from Autozone not hold charge. I have since swap to an Optima battery to solve my battery issues. One good thing about Autozone is you can upgrade your battery and they will give you full credit if you have problems with the new one. A fully charge battery should get you 20 to 30 minutes of driving if you need to take it to Autozone to have them check your system.

[oes]

Guess i should have given some info on my build. This is the first time the car has even ran. I just finished putting the motor in and doing everything for the first time about a week ago.

When I checked the battery itself (car ON but not started up) it read 12.45volts. I cannot get the car itself fired up because I am not able to get spark all the time.

If the starter was bad, would that keep me from getting spark? Its weird though, sometimes I will get spark and sometimes i wont. I think mainly when the car has sat for awhile, I can crank it but if it dies and i try again within an hour it wont fire up. I am gonna go try again now, its been sitting for about 18 hours.

[oes]

OK tried to crank it this morning. First couple times it would spin over, but not fire. It was hesitant at first (on key turn it would pause before it would try to spin it over). Hooked the charge up to it and tried again, same thing. After a few more minutes i tried again, this time all it would do is click. Would not even spin the motor over.

Battery is reading 12.45 volts stillPower to alt is 12.30voltsPower to Coil is 12voltsPower to starter is 12.31volts

Anyone?

[halnfl]

I would remove the battery and take it to Autozone(or where you purchased it) let them charge it and test it to see if the battery is any good. Also check your cable from the battery to the starter. If your charging cable was bad, your starter cable lead could also be bad(check the resistance with a dvom). I work in a body shop alot of cars batteries take a dump from sitting 2 to 3 weeks, and believe it or not I'm about 1 out of 5 for bad batteries even though they are new.

[C-Kwik]

How do you know it's getting no spark?

[oes]

I am gonna go start checking over everything that is related to the battery/starter now.

If it makes any difference: the battery was relocated to the rear.

I added the ground from the head to the firewall (10gauge wire) just now, still no turn over.

I was looking at the FSM, double checking all the grounds. All the listed grounds for the engine harness are in place. But the one ground on the lower harness I could not account for?



From what I see there is no ground for the lower harness.

I know its not getting any spark because I took the coil wire to the distributor and held it to a body ground while trying to crank it, no arcs.
Modified by oes at 12:04 PM 2/18/2007

[DammitBobby]

To check spark you will need the wire from the distributer and spark plug. Ground the spark plug to the frame and then turn it over.

I would fix your known problem first. Something is causing the system not to charge or the battery is not holding charge. I wouldn`t waste anymore time checking for spark. Resolving the first issue probably fix the 2nd issue.

[WDRacing]

Big difference between volts showing and cold cranking amps. You have a battery issue no doubt about it. It you had a spark issue, then the motor would turn over all day with no spark. The not turning over is purely between the battery and starter.

WD

[oes]

Well the not cranking issue just started today. It would spin over all day long until today.

[WDRacing]

You don't have a MSD ignition do you? Fiznat had issues with the EMS and the MSD coild getting fried.

[oes]

Nope, stock ignition

[halnfl]

make a short ground wire and remove one of the bolts holding the starter on and ground that cable from the starter directly to a known good ground and let us know what happens.

[C-Kwik]

I know its not getting any spark because I took the coil wire to the distributor and held it to a body ground while trying to crank it, no arcs.

Just to be clear, did you hold it near or actually against (in contact with) the body ground?

I'd probably try again with a spark plug grounded as DammitBobby suggests. Or, the way I check for spark is to just hook up a timing light and see if the light blinks with the trigger pulled while I am trying to crank the motor.

And as DammitBobby suggests as well, resolve the battery issue. Though, you would probably need to in order to even troubleshoot the rest of it. Test the voltage with a voltmeter as you are trying to crank the motor. Getting 12 volts means crap if you can't get enough amperage. Perhaps try to jumpstart it using another car that is running if you can. Get someone to rev up the other vehicle while you try to start yours. I've never had great experiences with simple battery chargers for jumping a car.

[oes]

I am gonna take all of these replies in to consideration tomorrow when I go back to messing with it. I took a few days off from it so I wouldnt wanna burn it to the ground

[DammitBobby]

Yea sounds like a good idea. It helps to walk away from something you have been working with no success to clear your mind and frustrations. Believe it or not sometimes in my sleep I will come up with solutions to problems that I am having.

Good luck!!

[oes]

Ordered a new starter, will be here tomorrow and I will have it in to see if that is my cranking issue.

[oes]

Replaced the starter and it started right up. Cut it off and on a few times after running it for several minutes to be sure. It fires before one full revolution even. Makes me happy, hope it stays.

[eazye2000]

Hey, glad to see that everything worked out. I wish some of my issues were as simple as a starter swap! LoL

[halnfl]

Good to hear that was all it was. Had a friend who did a battery relocation and he didn't have any good grounds and was having alot of problems for a while, so sounds like all is well.

[oes]

Uh, well, I put the starter in friday, it worked great like I said above. Well I disconnected the battery and went on with my weekend. I didnt touch it all weekend, and went out there Monday and tried to fire it up. Nothing but spinning over. Didnt wanna kill my new starter so i gave it minutes between trying.

Still nothing, pulled the 1st wire and used a sparkplug and grounded it. Spark is there (this was while connected to battery charger at 2amps), just not firing?

Set the charger to 12volt/10amps for 15minutes and then tried again. No go. Took the charger off and tried without it, still nothing. I disconnected my laptop from the EMS and let it sit for a few minutes. Came back, tried again and it fired right up and died. Few mins go by, crank it again and it started up and idled. I drove it for a second and turned it off and started it right back up.

Im so lost.

[C-Kwik]

If you have a timing light, try checking for spark by using a timing light instead. The inside of a combustion chamber has much more going on, including higher pressure and resistance and perhaps poor a/f mixtures that can affect the spark. It would tell you if you are at least getting spark under the conditions you need it to.

[DammitBobby]

I think at this point we need to get some more info.

1. I would recommend a fuel pressure gauge which you can get cheap and fitting for under 30 bucks. This will determine if we have the correct fuel pressure.

2. Next I would take out each spark plug to look for signs of injector leakage.

3. I would check for vacuum leaks and boost leaks. Again cheap diy tester can be made to check for this problem.

4. My other thought is to put back the stock injectors and ECU. Test and see if it will start and run properly. That way we can narrow it down to an Faulty EMS program and injectors or look somewhere else.

[oes]

Will try the timing light again.

1. I am running a FuelLab regulator with gauge and is set to around 44psi last time i checked.

2. How can you check for injector leakage?

3. Will check this out too.

4. Cannot use stock injectors and ecu, I am running MAP and do not have any of the stock stuff. I built this car from scratch, i didnt have a car that was in one piece.

[WDRacing]

Are you using sidefeed or top feed injectors? Sidefeeds can leak, top feeds won't. Thye will fail open sometimes, but I have NEVER seen one fail.

For a leak down test you crimp the fuel return line with a vise grip and rag. Just tight enough to retrict the flow from returning to the tank. The fuel pressure on the gauge should stay at 44 or whatever psi for quite awhile before draining back to the tank. If it loses pressure quickly, chances are you have a leaky injector.

The motor will almost always start though, unless you have like 3 injectors leaking. Did you swap plugs yet? If not they are probably fouled pretty good by now. Check and replace those as nessasary. Before you start the motor this next time, pull the fuel pump fuse and crank it over a few times. This will evacuate any residual fuel inside the cylinders. Put the fuse back in and try to fire it up. Also, check for spark on ALL of the cylinders.

You have to hate troubleshooting a motor built from scratch with a full standalone. Have you talked to Chris or Ivan from AMS? I'll direct them here.

WD