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Discussion Starter · #1 ·
New plugs and #2 is firing, pulled the injector and cleaned, then swapped #1 and #2 injectors, problem still on #2. Checked voltage and I'm getting a constant 12 volts at the connection to the injector. (Side note: I don't really understand how that works if it is open all the time, but checked #1 and it is the same. Meter never blinks so I'm assuming it has 12 v constant) Just installed the head, It was checked for cracks and surfaced, valves are not bent, I have not checked compression but no reason to believe it is low. It smokes like it's on fire but obviously only 1 of 4 cycles. Strong fuel smell also. I can't understand why if it is firing and is getting fuel in the cyl. it still has a dead miss. Your thoughts are appreciated.
 

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Sounds like the #2 injector either has a leaky o-ring or is stuck open, and either one will cause flooding of the cylinder. Is the #2 plug wet?

(Side note: I don't really understand how that works if it is open all the time, but checked #1 and it is the same. Meter never blinks so I'm assuming it has 12 v constant)
Port injectors have 12V power on one side of the coil at all times and the ECM grounds the other side of the coil to fire it. They're basically glorified solenoids, no rocket science required. Your meter will average the voltage on the ECM side, so it will only read a little lower than the supply voltage because the injector spends most of its time inactive. For that reason, meters are not a good tool for injector diagnosis, a Noid Light will serve you better. However, #2's problem is most likely mechanical and not electrical, so even a Noid Light won't help with that.
 

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Do a compression and leak down test, could have stuck rings on #2 or a valve out of adjustment, either can cause a dead miss and the leak down test will tell you where the issue is, pop the oil cap, block throttle open and listen at tb, oil cap and exhaust for sounds of air escaping.
 

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New plugs and #2 is firing, pulled the injector and cleaned, then swapped #1 and #2 injectors, problem still on #2. Checked voltage and I'm getting a constant 12 volts at the connection to the injector. (Side note: I don't really understand how that works if it is open all the time, but checked #1 and it is the same. Meter never blinks so I'm assuming it has 12 v constant) Just installed the head, It was checked for cracks and surfaced, valves are not bent, I have not checked compression but no reason to believe it is low. It smokes like it's on fire but obviously only 1 of 4 cycles. Strong fuel smell also. I can't understand why if it is firing and is getting fuel in the cyl. it still has a dead miss. Your thoughts are appreciated.
What symptoms do you get that show you the problem is with Cylinder #2?

Also, the check for injectors also includes testing the resistance. They should be 12 to 14 Ohms, I believe.
 

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New plugs and #2 is firing, pulled the injector and cleaned, then swapped #1 and #2 injectors, problem still on #2. Checked voltage and I'm getting a constant 12 volts at the connection to the injector. (Side note: I don't really understand how that works if it is open all the time, but checked #1 and it is the same. Meter never blinks so I'm assuming it has 12 v constant) Just installed the head, It was checked for cracks and surfaced, valves are not bent, I have not checked compression but no reason to believe it is low. It smokes like it's on fire but obviously only 1 of 4 cycles. Strong fuel smell also. I can't understand why if it is firing and is getting fuel in the cyl. it still has a dead miss. Your thoughts are appreciated.
If you're getting good spark on #2 and you also swapped #1 and #2 injectors; and still having a dead #2 cylinder, then the #2 signal wire is probably shorted to ground so the injector is not being pulsed but staying constantly open. Unplug the harness at the ECU and at the injector then check for a short to ground of the #2 signal wire. If it's OK, then the ECU is probably bad.
 

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Discussion Starter · #8 ·
Try swapping the spark plug (and then spark plug wire) for #1 and #2. Even if new, you might have a bad spark plug (or spark plug wire).
Swapped the plug wires already and no change. Haven't swapped the plugs, but I'll try it. Haven't had time to mess with it last couple of days. Maybe tonight for awhile. Thanks.
 

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Discussion Starter · #9 ·
If you're getting good spark on #2 and you also swapped #1 and #2 injectors; and still having a dead #2 cylinder, then the #2 signal wire is probably shorted to ground so the injector is not being pulsed but staying constantly open. Unplug the harness at the ECU and at the injector then check for a short to ground of the #2 signal wire. If it's OK, then the ECU is probably bad.
Yes. That makes sense and seams to be more in line with the issues i'm having. I have a manual so I'll try to pin down the wire at the ECU connector. No pun intended.
 

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Update: I have not been able to determine which wire to check at the ECU, but my son changes oil for Nissan and a mechanic from there came over this week to help troubleshoot. I told him everything I had done and in his experience, he suggested the EGR valve. I didn't really understand how a faulty EGR would only affect only one cyl. but he said he had seen it so I pulled it. And it was faulty. I changed it with no difference. Still a solid miss. I'm going to keep trying to locate the wire at the ECU but, from what i can see all the wiring looks to be in it's place.

I feel I should tell more about the vehicle. I held back on the first post because I didn't want to write a book about something someone could point me to quickly, I'll still try to summarize. About 4 yrs ago I bought the truck. Shadetree mechanic had been working on it. (Engine parts missing, bolts missing, stripped, etc.) I bought it for me and my son to rebuild for his first vehicle, (I know I'm cheap.) He drove it awhile and we sold it to our neighbor who drove it on the interstate daily and it ran hot. Parked in his yard for two years and did not run. A couple months ago I repurchased. Found blown head gasket. Reworked the head. Installed and found a miss on #2 cyl. The blow gasket explains the EGR valve faulty because of the water it was spitting out. Also water in the crankcase. Oil was extremely milky. Obviously, I changed before testing after the head replacement and will change again. In original post i said I have not checked the compression, but don't feel it's necessary.
Lastly, very strong smell of fuel when it cranks. like raw fuel almost. Thanks for any help team. I appreciate it. I really don't want to pull the dash to look for a shorted wire that is not actually there.
 

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Update: I have not been able to determine which wire to check at the ECU, but my son changes oil for Nissan and a mechanic from there came over this week to help troubleshoot. I told him everything I had done and in his experience, he suggested the EGR valve. I didn't really understand how a faulty EGR would only affect only one cyl. but he said he had seen it so I pulled it. And it was faulty. I changed it with no difference. Still a solid miss. I'm going to keep trying to locate the wire at the ECU but, from what i can see all the wiring looks to be in it's place.

I feel I should tell more about the vehicle. I held back on the first post because I didn't want to write a book about something someone could point me to quickly, I'll still try to summarize. About 4 yrs ago I bought the truck. Shadetree mechanic had been working on it. (Engine parts missing, bolts missing, stripped, etc.) I bought it for me and my son to rebuild for his first vehicle, (I know I'm cheap.) He drove it awhile and we sold it to our neighbor who drove it on the interstate daily and it ran hot. Parked in his yard for two years and did not run. A couple months ago I repurchased. Found blown head gasket. Reworked the head. Installed and found a miss on #2 cyl. The blow gasket explains the EGR valve faulty because of the water it was spitting out. Also water in the crankcase. Oil was extremely milky. Obviously, I changed before testing after the head replacement and will change again. In original post i said I have not checked the compression, but don't feel it's necessary.
Lastly, very strong smell of fuel when it cranks. like raw fuel almost. Thanks for any help team. I appreciate it. I really don't want to pull the dash to look for a shorted wire that is not actually there.
If you smell fuel, then you need to check the resistance on the injectors.

What year is this Hardbody?
 

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Pull the #2 injector clip, turn key to on and find the pin with power, then turn key off, grab a test light, connect clip to batt + and touch the probe to the pin that didnt have power, I the light illuminates you have a shorted ground circut that's opening the injector. No light turn key to on, touch that pin again, if it illuminates the injector driver for #2 is shorted. No light, crank engine while touching that pin and the light should flash, if no flash either the wire is broken of the injector driver is.
If everything checks good the next step is a compression and compression leak down test.
 

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Discussion Starter · #15 ·
For the 1997, here is the section on the Engine Control System:


You mentioned wanting to know how to check the pin outs. That starts on EC-83 "ECM Terminals and Reference Values"
Thank you very much. I will check soon. Thanks for the specific information. I'll post back when I find something.
 

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Discussion Starter · #16 ·
Pull the #2 injector clip, turn key to on and find the pin with power, then turn key off, grab a test light, connect clip to batt and touch the probe to the pin that didnt have power, I the light illuminates you have a shorted ground circut that's opening the injector. No light turn key to on, touch that pin again, if it illuminates the injector driver for #2 is shorted. No light, crank engine while touching that pin and the light should flash, if no flash either the wire is broken of the injector driver is.
If everything checks good the next step is a compression and compression leak down test.
No light turn key to on, touch that pin again, if it illuminates the injector driver for #2 is shorted.
Finally getting back around to this truck again. The above is the situation I have. You statement is the injector driver is bad. Is this the ECM or is there another part that I might could actually buy new.
 

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The injector driver is an N-channel transistor (usually a MOSFET) inside the ECM, the ECM uses it to drive ground to the injector coil and not power. The injector coil will have power at all times but ground only when the ECM fires it. That's why the light should only pulse while cranking. If it's on constantly, either the wire from the injector to the ECM has a ground short or the transistor is melted short (common with all MOSFETS, the MO stands for Metal Oxide).
 

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Discussion Starter · #18 ·
No light turn key to on, touch that pin again, if it illuminates the injector driver for #2 is shorted.
Finally getting back around to this truck again. The above is the situation I have. You statement is the injector driver is bad. Is this the ECM or is there another part that I might could actually buy new.
Fixed!!! Repaired!!! Problem Solved!!!
After taking your advice and your troubleshooting methods I concluded that the #2 had 12v to the opposite side of the connector that the other three had. This led me to farther trace the wiring harness back and it did not look right. I found that after I installed the head I had incorrectly switched the #2 fuel injector wire with a sensor beside the carburetor. I changed these two wires and it now runs perfect. Thank you so much for your detailed troubleshooting help. Your help, with some mechanical knowledge of my own and I got my problem solved, Thanks again,.
 
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