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Cylinder #1 Dropping Completely

SkudR33

By SkudR33,
in Engines & Forced Induction

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GTSBoy
GTSBoy

Injector loom, but not ignitor. Seeing as the ignitor is on a whole other loom for a whole other part of the fuel-go-bang system.

SkudR33
SkudR33

Hey guys, Been trying to troubleshoot this issue which occurred one day while I was driving the car during the stinking 35+ degree hot weather. My 1st cylinder is not firing at all. Some days it s

..::R33GTS-T::..
..::R33GTS-T::..

id defiantly give it a go, worst case after you pull everything out is that It works, then you know the injectors wont be the issue.. my old pulsar was misfiring on 1st cylinder, replaced leads, plug

SkudR33 Proficient

SkudR33

Posted
  • Author
Posted

I started off by pushing the positive probe into the back of the plug in the ecu. Managed to wedge it in so that it touches the terminal. Then earthed the other end on the chassis.

I think it made it easier because the microtech ecu has roomy plugs... The only other way to do it is to strip the wires, but you gotta try do that without destroying them.

Shoujiki Proficient

Shoujiki

Posted
Posted

A good way to probe the back of any terminal or connector is to insert a small pin into the back of the wire terminal first, and then probe that pin with your meter. Helps to get a good solid connection into the wire (for accuracy, especially in this situation, where 0.5v can mean a pass or fail) and also doesn't damage the wiring or terminal from trying to jam a big probe in there.

SkudR33 Proficient

SkudR33

Posted
  • Author
Posted
A good way to probe the back of any terminal or connector is to insert a small pin into the back of the wire terminal first, and then probe that pin with your meter. Helps to get a good solid connection into the wire (for accuracy, especially in this situation, where 0.5v can mean a pass or fail) and also doesn't damage the wiring or terminal from trying to jam a big probe in there.

Yeh - I wish I had read this post before I attempted it myself :P. Luckily the plugs for my ecu have a large enough gap to fit my probes.

  • 1 month later...
lismo Community Regular

lismo

Posted
Posted

Hi all,

First of all i'd like to say sorry about the long story.....

I am now having the exact same issue. Cylinder 1 is not firing at all. Was fine one day and just completely dropped out the next day. I must say though occasionally on start up it would run rough like it was dropping a cylinder but within 30 seconds would pick up and run completely fine.

Im running an apexi pfc ecu.

So far we've eliminated spark plugs, splitfire coils, coil wiring harness and harness plugs. Tested the injector as in, it was wetting the plug but not igniting the fuel. Placed coil slightly away from sparkplug and we could see it sparking the top of the sparkplug but its not igniting inside the cylinder. It has been compression tested and its all good there although cylinder 1 is slightly wet with oil....

My injectors are 570cc sard and are about 5 years old and the splitfire coils are same age.

I dont actually use my skyline very much so it sits in a garage as i use my daily most of the time. So i let the rego lapse for about 2 months and in that time i didnt even start the skyline. Ive never had a problem like this before where it hasnt been an obvious issue.

Once registered and i took it for a drive around for the day it split the radiator bleed valve hose but the car didnt get too hot as i realised something was wrong as soon as it happened, i replaced the hose, filled coolant up and drove away with no issues. I started the car 3 days later and thats when it dropped the first cylinder and we've been just testing and eliminating with no success so far. Thought i'd mention what happened with the car in the lead up to the cylinder not firing.

Next step we were going for was to get a test module (black box at back of engine on top of coil cover)

I was also told to check the crank angle sensor but they are expensive things to buy for testing if thats not the issue.

Thought i'd read the sau threads as ive fixed many issues myself from people posting on this awesome site!

Skud33 does this sound like the exact problem you were having with your skyline?

Like not igniting the fuel in cylinder but sparking from the coil to the top of the sparkplug?

I did read that you checked your injector voltage and that was the problem but how did you check them?

Does it need to be checked through the ecu?

I wont be doing this myself, i will be asking my mechanic to test it for me.

Did you end up just replacing the one injector?

Thankyou so much to anyone taking the time to read my post and respond

: ) liz

  • Like 1
  • 2 weeks later...
  • 1 month later...
Ryno Experienced

Ryno

Posted
Posted

I'm also currently dealing with this problem of #1 cylinder not firing on my RB25.

As I have a wideband permanently wired in, I was quickly able to diagnose that the #1 injector was not squirting fuel. I initially thought the injector was clogged so cleaned it and reinstalled and a week or so later the problem resurfaced. I then figured the injector was on it's way out and ordered a new Nismo 555cc from Japan.

After driving to work on 5 cylinders for the last two weeks, with the car sounding like a poxy WRX, I installed the new injector only to find it is still not firing on that cylinder.

I have found the problem, as I connected a mutimeter to #1 then #2 injector plags and found that #1 is only getting 7.5 volts and #2 is getting 11.5 volts. Any idea what would cause this?

My next step will be to pull the injector loom apart and look for anything dodgy there.

SkudR33 Proficient

SkudR33

Posted
  • Author
Posted

I'm also currently dealing with this problem of #1 cylinder not firing on my RB25.

As I have a wideband permanently wired in, I was quickly able to diagnose that the #1 injector was not squirting fuel. I initially thought the injector was clogged so cleaned it and reinstalled and a week or so later the problem resurfaced. I then figured the injector was on it's way out and ordered a new Nismo 555cc from Japan.

After driving to work on 5 cylinders for the last two weeks, with the car sounding like a poxy WRX, I installed the new injector only to find it is still not firing on that cylinder.

I have found the problem, as I connected a mutimeter to #1 then #2 injector plags and found that #1 is only getting 7.5 volts and #2 is getting 11.5 volts. Any idea what would cause this?

My next step will be to pull the injector loom apart and look for anything dodgy there.

Run your multimeter across the metal pins in the injector where the loom plugs in and check resistance - it should be roughly 12ohms. If you get a resistance of 12 ohms, this will confirm your injector is not faulty... Other thing I'd check is the voltage for that first injector at the ECU. It might be breaking down somewhere along the loom? Or check for continuity in the loom.

If you need anymore help let me know :)

Ryno Experienced

Ryno

Posted
Posted

Cool, I've ordered a new injector loom (from "Wiring Specialties" in the states) so hopefully that fixes the issue.

In the mean time, I'll check for any obvious problems with my old loom (continuity, grime in plug etc). As driving around on 5 is killing me!

Ryno Experienced

Ryno

Posted
Posted

I've fixed the problem, and the solution was so simple I feel rather foolish...

I checked all the plugs and continuity of both the injector loom and from the ECU to the injector plug (for the injector loom). All tested good, however when I unplugged the ECU I noticed the end of the ECU plug wasn't quite flush with the housing on the ECU.

Cylinder #1's ground is right at the end of the plug (pin out 101) and so is a switched 12v power (pinout 109) - which I imagine powers the injectors. When I looked inside the plug I noticed both pinout's 101 and 109 had a slightly splayed female connection. So I closed the connection back up, bolted the ECU plug back together and the problem is fixed.

I guess over time the plug worked it's way loose at that end and #1 cylinder was the first to drop offline when the connection became dodgy.

SkudR33 Proficient

SkudR33

Posted
  • Author
Posted

I've fixed the problem, and the solution was so simple I feel rather foolish...

I checked all the plugs and continuity of both the injector loom and from the ECU to the injector plug (for the injector loom). All tested good, however when I unplugged the ECU I noticed the end of the ECU plug wasn't quite flush with the housing on the ECU.

Cylinder #1's ground is right at the end of the plug (pin out 101) and so is a switched 12v power (pinout 109) - which I imagine powers the injectors. When I looked inside the plug I noticed both pinout's 101 and 109 had a slightly splayed female connection. So I closed the connection back up, bolted the ECU plug back together and the problem is fixed.

I guess over time the plug worked it's way loose at that end and #1 cylinder was the first to drop offline when the connection became dodgy.

Good news :) glad I could help...

  • 1 year later...

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