Guys -I am inclined to test the injectors for any foul play. Have looked into the service manual - but perhaps can benefit from someone'e experience on this board.
What steps are needed to test the resistance?
Just use the connector harnesses (whatever else it is called - the ones that are mounted on or near the power transtistor area on each bank) for the resistance to be b/w 10-14 ohms?
My ECU code is saying 55, but the idle is very rough and lots of vibration.
Thanks
How to Check for bad injectors?
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Q451990
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ECU won't indicate injector failure (on pre-OBDII models at least). You're right on the ohm test. The connector you're looking for is on the right side of the engine bay near where the throttle cable cams bolt on to the plenum. Trace the wires back from the #1 and #2 injectors to figure out the wiring... I can't remember it right now...
If you're looking for a completely dead injector, a check of each exhaust tube on the manifold will tell you which one is out - it'll be the cold one. A non-contact infrared thermometer works great for that...
Heath
If you're looking for a completely dead injector, a check of each exhaust tube on the manifold will tell you which one is out - it'll be the cold one. A non-contact infrared thermometer works great for that...
Heath
If you have a consult run on the engine the dealer can tell which cylinder is giving you trouble. Had one where the injector had a cracked nozzle and was not properly atomizing the gas. Did not discover it until removal of course. Did not test bad for resistance, and could not tell from outside. Just knew the cylinder had a lean miss at idle. Try this??? its only an $85 consult and can eliminate a ton of guess work.
Doug - I wish I had known it before. Now it is too late - the plenum is off and the car is in my garage.
Well - I keep my fingers crossed when I start the car the next time.
I think we should have best practices for these common tasks. And one of the best practices should be to always do a consult before removing the plenum to make sure if something not otherwise identifiable needs to be fixed (like you said - resitance check would not reveal this...). I think anyone knowing what is involved in doing the plenum most likely would gladly spare the 80-100 bucks for the fear of removing the plenum again the next day.
Thanks
Well - I keep my fingers crossed when I start the car the next time.
I think we should have best practices for these common tasks. And one of the best practices should be to always do a consult before removing the plenum to make sure if something not otherwise identifiable needs to be fixed (like you said - resitance check would not reveal this...). I think anyone knowing what is involved in doing the plenum most likely would gladly spare the 80-100 bucks for the fear of removing the plenum again the next day.
Thanks
Look very closely at the tips of your injectors prior to re-install. Look for any cracks, chips etc... If there is a crack, replace the injector. Get new F.I. O-rings for the re-install, and coat them with vasoline. When you re-intsall push them straight in, and don't twist them!!! I accidentally pinched an o-ring twisting it in once and it puffed large plumes of gas enriched exhaust!!!! If you do have any suspicious injectoprs, put them into the #1 or 2 cylinder.
Q45 Injectors replace all or none?
I am getting a rough idle, so I took my car to my local shop for diagnostic. They said my #3 injector was at 24 ohms. The next day I took the car to Infiniti for diagnostic and they said both the #1 and #3 injectors were over 24 ohm and need replacing.
My question is, is my only repair option to replace the injectors, and if it is should I replace all eight? Can a cleaning help the bad injectors?
Any information will be appreciated.
My question is, is my only repair option to replace the injectors, and if it is should I replace all eight? Can a cleaning help the bad injectors?
Any information will be appreciated.
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Professor_Mike
- Posts: 96
- Joined: Wed May 01, 2002 2:19 pm
Are you saying that I could replace just two injectors and probably have no trouble?
My car '94 Q has 81K miles on it and I live in Phoenix, AZ where they say we have bad gas. Is it likely that the other injectors will fail shortly, or can this be predicted? Given the miles and where I live, do these factors impact the life of my injectors and the likelyhood of future failures? Thanks.
My car '94 Q has 81K miles on it and I live in Phoenix, AZ where they say we have bad gas. Is it likely that the other injectors will fail shortly, or can this be predicted? Given the miles and where I live, do these factors impact the life of my injectors and the likelyhood of future failures? Thanks.
Just to add to your worries: I am currently doing my plenum job on 92Q. All 8 injectors were replaced 20K miles ago and #4 failed within 20K miles.
When I took all the others out, one of the injectors were showing a little bit higher that the other (13.9 as opposed to nice 12.5 or 12.6 for the others - but still within the safe range of 10-14 ohms).
I sent all to a local fuel injection bench cleaning shop - just to be sure. The one that was showing 13.9 jumped to 26.9 after the load test (at the fuel injection facility). Had I not done it, I would have just reassembled with a soon to go faulty injector - back to square zero.
So, in order to be really sure, you may want to send the injectors for bench cleaning and have them perform the coil test under load conditions for any anomalies. I paid $125 for the 7 injectors to be cleaned in Phoenix, AZ. The guy came out and picked and dropped the injectors within 24 hours from my work place.
Now when I put my injectors back in, I may just enjoy a little bit more piece of mind - still no guarantees.
Goodluck
When I took all the others out, one of the injectors were showing a little bit higher that the other (13.9 as opposed to nice 12.5 or 12.6 for the others - but still within the safe range of 10-14 ohms).
I sent all to a local fuel injection bench cleaning shop - just to be sure. The one that was showing 13.9 jumped to 26.9 after the load test (at the fuel injection facility). Had I not done it, I would have just reassembled with a soon to go faulty injector - back to square zero.
So, in order to be really sure, you may want to send the injectors for bench cleaning and have them perform the coil test under load conditions for any anomalies. I paid $125 for the 7 injectors to be cleaned in Phoenix, AZ. The guy came out and picked and dropped the injectors within 24 hours from my work place.
Now when I put my injectors back in, I may just enjoy a little bit more piece of mind - still no guarantees.
Goodluck
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Shows the importance of a hot and cold resistance test plus a current flow test.
Some injection cleaners check the 100% duty cycle to confirm the 370cc flow...........this can overheat the Q injectors [especially if old] as they are never open more than 55% of the possible time under any conditions. What you really want to know is 55% [11 millisecs] and the idle [2.2 millisecs] open flow.
But then as in heart disease a stress test is good if it doesn't kill you or your injector.
Sending them out of state assumes that the viscosity of the test fluid is the same as your local gasoline. It varies a lot by emission formulation.Racers run into this all the time as race fuel [103+ octane] is different, it doesn't matter much with a Carb but injectors are very sensitive!
They are going crazy trying to make direct injection work with US junk fuels.....they are having to make each injector independently controlled to correct for clogs and wear and this means a pressure sensor for each cylinder.
With thousands of codes possible and each thing [sensors] checking it self twice sometimes 3 times you'll need a PHD in Computer Programming to just check [diagnose] out a car by 2006.Members might as well get ODB2 scanners and start working with them on post 95 cars, its only going to get worse every year!
Some injection cleaners check the 100% duty cycle to confirm the 370cc flow...........this can overheat the Q injectors [especially if old] as they are never open more than 55% of the possible time under any conditions. What you really want to know is 55% [11 millisecs] and the idle [2.2 millisecs] open flow.
But then as in heart disease a stress test is good if it doesn't kill you or your injector.
Sending them out of state assumes that the viscosity of the test fluid is the same as your local gasoline. It varies a lot by emission formulation.Racers run into this all the time as race fuel [103+ octane] is different, it doesn't matter much with a Carb but injectors are very sensitive!
They are going crazy trying to make direct injection work with US junk fuels.....they are having to make each injector independently controlled to correct for clogs and wear and this means a pressure sensor for each cylinder.
With thousands of codes possible and each thing [sensors] checking it self twice sometimes 3 times you'll need a PHD in Computer Programming to just check [diagnose] out a car by 2006.Members might as well get ODB2 scanners and start working with them on post 95 cars, its only going to get worse every year!