Injector problem
#1
Injector problem
98 xj8 217k. It either wont start or it will barely start and then die. Battery and spark are fine. Good fuel pressure at the rail. The injectors do not click. The noid light looks to flash correctly when I turn it over. I got the injectors bench tested and I heard them all click like they should.
I thought that if the noid light works, and the injectors bench test good, then they should work. I cant figure out why they are not clicking.
I thought that if the noid light works, and the injectors bench test good, then they should work. I cant figure out why they are not clicking.
#2
#3
#4
#5
A little over 40psi. The pressure is about the same after 5 minutes.
The injectors are not doing anything. I had 1 injector pulled out, but still hooked up to the harness. The harness for the next injector had a noid light in it. When I turn it over the noid light blinks, but the injector does not click or do anything.
But the same injectors click and function when bench tested.
The injectors are not doing anything. I had 1 injector pulled out, but still hooked up to the harness. The harness for the next injector had a noid light in it. When I turn it over the noid light blinks, but the injector does not click or do anything.
But the same injectors click and function when bench tested.
#6
#7
Trending Topics
#8
#9
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,520
Received 12,952 Likes
on
6,470 Posts
98 xj8 217k. It either wont start or it will barely start and then die. Battery and spark are fine. Good fuel pressure at the rail. The injectors do not click. The noid light looks to flash correctly when I turn it over. I got the injectors bench tested and I heard them all click like they should.
I thought that if the noid light works, and the injectors bench test good, then they should work. I cant figure out why they are not clicking.
I thought that if the noid light works, and the injectors bench test good, then they should work. I cant figure out why they are not clicking.
If you're connecting your noid light to the two terminals of an injector connector and it lights okay but an injector won't fire, that is mysterious.
Cheers,
Don
#10
#11
#12
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,520
Received 12,952 Likes
on
6,470 Posts
PM me your email address and I will send you the X308 electrical manual so we can discuss a few possibilities.
Cheers,
Don
#13
Seeing a small voltage drop on an operating injector is normal due to the VOM not being able to track the rapid ground/open pulse from the ECM but battery voltage while cranking would be good information. A weak battery is capable of rotating the engine at a voltage below the level required by the electronics, about 10v.
Last edited by test point; 03-14-2014 at 03:05 AM.
The following 2 users liked this post by test point:
rocklandjag (03-14-2014),
sparkenzap (03-14-2014)
#14
Yeah, the term "voltage" refers to "potential difference". So, for the the ten volt measurement to have meaning, you must define across which two points you read the voltage. From the control lead to ground, the measurement is affected by the injector pulse width, as tespoint pointed out. If it was truly across the connector for the injector, that would indicate an injector that is motly on, which I doubt. If it was from the power connection of the injector to ground, it is probably just the cranking voltage drop. The correct tool for inspecting the injector voltage is an oscilloscope, since it is a pulse, and the measurement would be best across the two injector terminals.
In fact, the injector circuit apparently uses the supply voltage in the pulse calculation algorithm to adjust the pulse length to accont for voltage variations affecting the injector pull in time.
In fact, the injector circuit apparently uses the supply voltage in the pulse calculation algorithm to adjust the pulse length to accont for voltage variations affecting the injector pull in time.
Last edited by sparkenzap; 03-14-2014 at 06:37 AM.
The following users liked this post:
test point (03-14-2014)
#15
#16
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,520
Received 12,952 Likes
on
6,470 Posts
xkrmaxer, have you measured the voltage at the battery terminals while cranking, and if so, does it dip as low as 10-11V? That could definitely be the source of or a contributor to your issues.
Don
#17
Thanks for the ideas guys. Don, I have been using the x308 electrical guide. Spark, I don't have a oscilloscope. I have been using a multimeter and a noid light, so I am a little limited.
Test point, I cleaned up the ems bulkhead ground. It looked fine before I touched it and cleaning did not make a difference. I am going to clean up the rest of the easily accessible grounds.
It will probably be a few days before I can get a second person to crank it while I take the measurements. I reread my post about the voltage, and I see I was a little unclear. The noid light was plugged into the 2 terminals of the harness, but with the multimeter I was putting the positive lead on the power terminal of the harness and I was just grounding the negative lead.
When I get a helper, I will get all of the voltage numbers with the key in the on position and while cranking. I will also remove the fuel pump relay and one of the injectors and make a video of the injector (removed but still plugged into the harness), next to a noid light plugged into the next harness while cranking.
Thanks again guys, hopefully I can have those voltage numbers by Monday.
Test point, I cleaned up the ems bulkhead ground. It looked fine before I touched it and cleaning did not make a difference. I am going to clean up the rest of the easily accessible grounds.
It will probably be a few days before I can get a second person to crank it while I take the measurements. I reread my post about the voltage, and I see I was a little unclear. The noid light was plugged into the 2 terminals of the harness, but with the multimeter I was putting the positive lead on the power terminal of the harness and I was just grounding the negative lead.
When I get a helper, I will get all of the voltage numbers with the key in the on position and while cranking. I will also remove the fuel pump relay and one of the injectors and make a video of the injector (removed but still plugged into the harness), next to a noid light plugged into the next harness while cranking.
Thanks again guys, hopefully I can have those voltage numbers by Monday.
#18
#19
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,520
Received 12,952 Likes
on
6,470 Posts
Just for clarity, is the engine ground strap on the right side of the block when facing the rear of the car, or on the right side when sitting in the driver's seat?
Thanks,
Don
#20