Swapped motor, no spark on just 2 cylinders
Swapped motor, no spark on just 2 cylinders
Back in July my motor decided to take a dump with 230k on it. Got another motor finally put in this past weekend and the damn thing wont run right. For some reason Im not getting spark on cylinders 2 and 3. I am getting fuel to all cylinders.
Ive checked the obvious...coil packs, plugs, crank and cam sensors, MAF...still nothing.
I also checked the wiring harness for the coil packs. I was getting the 13v supply voltage but nothing on the signal wires on 2 and 3. Checked continuity and got nothing for those 2 cylinders, so I figured I somehow damaged the harness moving it out of the way while swapping the motor.
So I made my own harness and ran new signal wires from the ecu straight to each coil pack. Made no change.
Then I thought that maybe the ecu was bad, so I borrowed another one and put it in. Made no change.
Im at a loss here. Am I missing something?
CLIFFS:
1) Motor gets replaced and only 4 cylinders are getting spark. Nothing on cylinders 2 or 3.
2) The obvious have been checked, swapped, or replaced...plugs, coil packs, crank and cam sensors, MAF.
3) No continuity in signal wires from ecu to coil packs...new signal wires run.
4) New ecu swapped in, still no change.
Any ideas?
Ive checked the obvious...coil packs, plugs, crank and cam sensors, MAF...still nothing.
I also checked the wiring harness for the coil packs. I was getting the 13v supply voltage but nothing on the signal wires on 2 and 3. Checked continuity and got nothing for those 2 cylinders, so I figured I somehow damaged the harness moving it out of the way while swapping the motor.
So I made my own harness and ran new signal wires from the ecu straight to each coil pack. Made no change.
Then I thought that maybe the ecu was bad, so I borrowed another one and put it in. Made no change.
Im at a loss here. Am I missing something?
CLIFFS:
1) Motor gets replaced and only 4 cylinders are getting spark. Nothing on cylinders 2 or 3.
2) The obvious have been checked, swapped, or replaced...plugs, coil packs, crank and cam sensors, MAF.
3) No continuity in signal wires from ecu to coil packs...new signal wires run.
4) New ecu swapped in, still no change.
Any ideas?
Jarrod, did you check the pins in the ECU harness? Check to make sure they're not hollowed out, and not getting a good connection. Same goes to the pins inside the coil pack plugs.
Also, have you tried plugging in a coil pack, putting the plug in the end, touching the plug to ground and seeing if it sparks then?
Are you getting no spark, or weak spark?
Also, have you tried plugging in a coil pack, putting the plug in the end, touching the plug to ground and seeing if it sparks then?
Are you getting no spark, or weak spark?
He has replaced the crankshaft position and the reference sensor, from what I read elsewhere. The flywheel wouldn't affect that, but if the signal is getting disrupted for either sensor, due to a bad gear/teeth, or a bad wire, it could cause an issue like this. However, I wouldn't usually expect it to cause zero spark, on two cylinders (and only two, no more, no less) all the time.
Jarrod, did you check the pins in the ECU harness? Check to make sure they're not hollowed out, and not getting a good connection. Same goes to the pins inside the coil pack plugs.
Also, have you tried plugging in a coil pack, putting the plug in the end, touching the plug to ground and seeing if it sparks then?
Are you getting no spark, or weak spark?
Also, have you tried plugging in a coil pack, putting the plug in the end, touching the plug to ground and seeing if it sparks then?
Are you getting no spark, or weak spark?
He has replaced the crankshaft position and the reference sensor, from what I read elsewhere. The flywheel wouldn't affect that, but if the signal is getting disrupted for either sensor, due to a bad gear/teeth, or a bad wire, it could cause an issue like this. However, I wouldn't usually expect it to cause zero spark, on two cylinders (and only two, no more, no less) all the time.
no bad teeth on the FW. the whole motor was out and the FW put on, it would have been an obvious catch. not to mention missing teeth would effect start up and more random missfires...
yes we tried the spark plug trick... works on the other cylinders but not 2 & 3... using different coil packs and everything.
everything obvious has been checked so far and as stated above, also swapped with others to make sure they were good.
another cliff note:
when you disconnect one of the coils from a cylinder that sounds like it has a slight nock, the nock goes away... detonation maybe? ecu is trying to adjuct too much because of the other missfires? <--- thats my guess on that.
just thought id throw that out there in case someone gets a "dr house" moment!
edit: looks like i repeated some of the same stuff. but yeah. weve frigin thought of a ton of stuff...
yes we tried the spark plug trick... works on the other cylinders but not 2 & 3... using different coil packs and everything.
everything obvious has been checked so far and as stated above, also swapped with others to make sure they were good.
another cliff note:
when you disconnect one of the coils from a cylinder that sounds like it has a slight nock, the nock goes away... detonation maybe? ecu is trying to adjuct too much because of the other missfires? <--- thats my guess on that.
just thought id throw that out there in case someone gets a "dr house" moment!
edit: looks like i repeated some of the same stuff. but yeah. weve frigin thought of a ton of stuff...
no bad teeth on the FW. the whole motor was out and the FW put on, it would have been an obvious catch. not to mention missing teeth would effect start up and more random missfires...
yes we tried the spark plug trick... works on the other cylinders but not 2 & 3... using different coil packs and everything.
everything obvious has been checked so far and as stated above, also swapped with others to make sure they were good.
another cliff note:
when you disconnect one of the coils from a cylinder that sounds like it has a slight nock, the nock goes away... detonation maybe? ecu is trying to adjuct too much because of the other missfires? <--- thats my guess on that.
just thought id throw that out there in case someone gets a "dr house" moment!
edit: looks like i repeated some of the same stuff. but yeah. weve frigin thought of a ton of stuff...
yes we tried the spark plug trick... works on the other cylinders but not 2 & 3... using different coil packs and everything.
everything obvious has been checked so far and as stated above, also swapped with others to make sure they were good.
another cliff note:
when you disconnect one of the coils from a cylinder that sounds like it has a slight nock, the nock goes away... detonation maybe? ecu is trying to adjuct too much because of the other missfires? <--- thats my guess on that.
just thought id throw that out there in case someone gets a "dr house" moment!
edit: looks like i repeated some of the same stuff. but yeah. weve frigin thought of a ton of stuff...
Member who somehow became The President of The SE-L Club
iTrader: (19)
Joined: Jun 2001
Posts: 16,024
Your timing chain is off a tooth, what if any work was done to the motor?
Vehicle: 1996 Nissan Maxima. VQ30DE
Symptom: Misfires. No spark from the coils for cylinders No. 2 and No. 3. The cam timing is off a tooth.
The problem began with a leaking water pump. After the water pump was replaced, ignition coils No. 2 and No. 3 did not fire.
This Nissan's engine is equipped with a distributorless ignition system (DIS), with a separate power transistor mounted with each one of the six coils. This gives each cylinder one coil and one power transistor. A separate signal from the powertrain control module (PCM) to the base of each of the power transistors turns the power transistors on and off. The power transistors pulse coil negative to ground, based on those signals from the computer.
The technician verified that the signals from the PCM to the base of the power transistors for the other four working cylinders were good. He found no signal from the PCM to the base of the power transistors for cylinders No. 2 and No. 3 at the power transistors. The harness was checked for opens and shorts between the computer and those two coils' power transistors. The signals at the PCM were checked as well. The technician tried running new wires between the PCM and the power transistors, and also tried new coil/power transistor assemblies for those two cylinders, as well as a used PCM. There were still no signals from the PCM to the base of those two power transistors. The camshaft position sensor (phase) and crankshaft position sensor (reference) signals were both scope-checked and had nice, consistent sine wave type patterns with proper amplitude for both signals.
Since the problem occurred right after the water pump was replaced, I wondered if the camshaft and crankshaft position sensor signals were out of phase with each other, since the timing chain must be taken off to replace the water pump. This engine has a main timing chain and two camshaft timing chains. The camshaft timing chains go around the smaller intake and exhaust camshaft sprockets. The main timing chain goes around the crankshaft sprocket, and then up around two larger camshaft sprockets that mount on the end of the intake camshafts, outside of the smaller intake camshaft sprockets that the camshaft timing chains go around. The main timing chain is the one that needs to be removed to replace the water pump.
When I asked the technician to check the engine mechanical cam timing, he found the timing chain was off one tooth. He corrected the cam timing and the two coils started firing once again.
So if you get a couple of coils with no spark and there are no signals to the base of their power transistors, make sure the timing chain is not off a tooth.
Symptom: Misfires. No spark from the coils for cylinders No. 2 and No. 3. The cam timing is off a tooth.
The problem began with a leaking water pump. After the water pump was replaced, ignition coils No. 2 and No. 3 did not fire.
This Nissan's engine is equipped with a distributorless ignition system (DIS), with a separate power transistor mounted with each one of the six coils. This gives each cylinder one coil and one power transistor. A separate signal from the powertrain control module (PCM) to the base of each of the power transistors turns the power transistors on and off. The power transistors pulse coil negative to ground, based on those signals from the computer.
The technician verified that the signals from the PCM to the base of the power transistors for the other four working cylinders were good. He found no signal from the PCM to the base of the power transistors for cylinders No. 2 and No. 3 at the power transistors. The harness was checked for opens and shorts between the computer and those two coils' power transistors. The signals at the PCM were checked as well. The technician tried running new wires between the PCM and the power transistors, and also tried new coil/power transistor assemblies for those two cylinders, as well as a used PCM. There were still no signals from the PCM to the base of those two power transistors. The camshaft position sensor (phase) and crankshaft position sensor (reference) signals were both scope-checked and had nice, consistent sine wave type patterns with proper amplitude for both signals.
Since the problem occurred right after the water pump was replaced, I wondered if the camshaft and crankshaft position sensor signals were out of phase with each other, since the timing chain must be taken off to replace the water pump. This engine has a main timing chain and two camshaft timing chains. The camshaft timing chains go around the smaller intake and exhaust camshaft sprockets. The main timing chain goes around the crankshaft sprocket, and then up around two larger camshaft sprockets that mount on the end of the intake camshafts, outside of the smaller intake camshaft sprockets that the camshaft timing chains go around. The main timing chain is the one that needs to be removed to replace the water pump.
When I asked the technician to check the engine mechanical cam timing, he found the timing chain was off one tooth. He corrected the cam timing and the two coils started firing once again.
So if you get a couple of coils with no spark and there are no signals to the base of their power transistors, make sure the timing chain is not off a tooth.
Crap. I was afraid of that. A friend brought that up last night. Yes, the water pump was changed prior to me taking possession of the motor. I installed another one as preventative maintenance while I had the timing cover off...timing cover had a hairline crack in it so I swapped mine over.
Very interesting! Good catch there. Hopefully you've found your answer, I know its been bugging you. Even though its not the answer you wanted.
On a side note: I have run into way too many issues with ECU plugs getting damaged just from plugging and unplugging. Not typical with our cars, the plugs are built properly, and the pins are sturdy, but its always an option.
On a side note: I have run into way too many issues with ECU plugs getting damaged just from plugging and unplugging. Not typical with our cars, the plugs are built properly, and the pins are sturdy, but its always an option.
Junior Member
Joined: Oct 2010
Posts: 20
From: Phx, Arizona
this could be the anser to my problems aswell. car ran perfect. changed the water pump and then drove the car for a few days and bam died. wouldnt start up any more it kinda back fired onceor twice, than i had no spark on none of the coils. im guessing this could be my issue aswell?
this could be the anser to my problems aswell. car ran perfect. changed the water pump and then drove the car for a few days and bam died. wouldnt start up any more it kinda back fired onceor twice, than i had no spark on none of the coils. im guessing this could be my issue aswell?
over all though... i can say one thing!
*in the discovery channel monster garage voice*
DONNNNNEEEE!
details from the owner to follow!
Very interesting! Good catch there. Hopefully you've found your answer, I know its been bugging you. Even though its not the answer you wanted.
On a side note: I have run into way too many issues with ECU plugs getting damaged just from plugging and unplugging. Not typical with our cars, the plugs are built properly, and the pins are sturdy, but its always an option.
On a side note: I have run into way too many issues with ECU plugs getting damaged just from plugging and unplugging. Not typical with our cars, the plugs are built properly, and the pins are sturdy, but its always an option.
this could be the anser to my problems aswell. car ran perfect. changed the water pump and then drove the car for a few days and bam died. wouldnt start up any more it kinda back fired onceor twice, than i had no spark on none of the coils. im guessing this could be my issue aswell?
this is not the same issue. if your car was running fine for a few days it was something else. not saying that its not timing related but this wasnt your issue. i will say though, that the water pump was changed on the motor before he got it. we believe the problem arose from that.
over all though... i can say one thing!
*in the discovery channel monster garage voice*
DONNNNNEEEE!
details from the owner to follow!
over all though... i can say one thing!
*in the discovery channel monster garage voice*
DONNNNNEEEE!
details from the owner to follow!
Junior Member
Joined: Oct 2010
Posts: 20
From: Phx, Arizona
it could probobly be a combo of both. i did replace the crank sensor with a new one after the issue happened. i noticed a big drop in performance after the water pump change. before i took it to the track it ran 15.4 and after the swap which was like maybe 2 weeks after i couldnt get it under 16s i was like wtf. i even had ks code when i ran the 15.4 and i replaced the ks with the WP to and bam. the only reason i thought it was the timing was because once it died on me when i tried to turn it on again it ran for a couple block than turned off again and i tried to turn her over again and it like back fired a couple times. belts are easier to work with ive never really dealt with chains before. one thing does make sense though the timing could be off and it also can be the CPS. i believe they have 2 right? i only replaced the one on the top of the flywheel area ima have to do some wrench work. ive been trying to find some diagrams but ima have to go get a book
If you are looking for the other crank sensor, it is at the harmonic balancer. Look to the right of the oil filter.
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