Another Dead Fuel Injector In The 90Q

[goody90q45]

All was well until after work on Wednesday when I started the Q and the CEL came on. I knew right away that another fuel injector had died.The bad thing is that this FI (#5) had ohmed at 13.3 up until the last time I checked it two weeks ago. I had one FI left and was able to change it out last night and put everything back together this morning. The Q is running great again and I have a couple more used injectors coming from one of our trusted sellers.

I bought this Q for $500 in February and the PO had just put in a junkyard fuel rail and was having major problems. I pulled the plenum and replaced #4 FI which was dead, put it back together to find out that #6 and #8 were plugged even after a fuel rail flush. Pulled the plenum a second time and replaced these two. Things were going good for a couple of months but about 3 weeks ago #7 FI died overnight so I pulled the plenum a 3rd time. The 4th pull of the plenum was today to replace #5 FI.

The odds are with me if another FI decides to roll over dead. The 3 original FI's that haven't been changed are #1, #2 and #3 and two of them can be changed without pulling the plenum. Maybe the Infiniti gods will curse another injector but show mercy on me and let it be #1 or #2. I am getting very good at plenum R&R and can do it in about 3 1/2 hours. Not bad for a car repair noob who could barely change his own oil until I bought the Q and joined NICO 3 years ago.

[Haitian_King]

All was well until after work on Wednesday when I started the Q and the CEL came on. I knew right away that another fuel injector had died.The bad thing is that this FI (#5) had ohmed at 13.3 up until the last time I checked it two weeks ago. I had one FI left and was able to change it out last night and put everything back together this morning. The Q is running great again and I have a couple more used injectors coming from one of our trusted sellers.

I bought this Q for $500 in February and the PO had just put in a junkyard fuel rail and was having major problems. I pulled the plenum and replaced #4 FI which was dead, put it back together to find out that #6 and #8 were plugged even after a fuel rail flush. Pulled the plenum a second time and replaced these two. Things were going good for a couple of months but about 3 weeks ago #7 FI died overnight so I pulled the plenum a 3rd time. The 4th pull of the plenum was today to replace #5 FI.

The odds are with me if another FI decides to roll over dead. The 3 original FI's that haven't been changed are #1, #2 and #3 and two of them can be changed without pulling the plenum. Maybe the Infiniti gods will curse another injector but show mercy on me and let it be #1 or #2. I am getting very good at plenum R&R and can do it in about 3 1/2 hours. Not bad for a car repair noob who could barely change his own oil until I bought the Q and joined NICO 3 years ago.

Lol. Good to hear that you might catch a break!

I'm having injector issues of my own, however they're a little strange. I wish they were as straightforward as yours.

I don't know if you remember, but several months ago, (March I believe) I got my chain guides done, hoses and plugs changed, and valve covers resealed at Van Meter Auto. At the time, I was having issues with a rough idle that I attributed to an injector failure. Keith confirmed it with a power balance test which showed that the #7 injector was the culprit. It ran fine upon start up, but after the engine reached temp, that's when the injector failure was noticeable and there was a visible rough idle.

I made plans to get more spare injectors and get as many as I could replaced. I figured if the #7 was on its way out, others would be soon to follow. I began to experience slight power loss (I guess that's the best way to put it.) during load. It felt like it wouldn't want to accelerate in proportion to the pressure applied to the pedal.

The weird part is, it seems that the problem has sorted itself out. For the last month or two, the rough idle has disappeared and the Q now purrs at idle. I was so used to bouncing up and down that now at red lights, I have to make sure that the engine is still on. That's how smoothly it idles now.

I'm doing WOT runs sometimes 2-3 times a day and it's running beautifully.

To the best of my knowledge (which isn't much, lol), injector issues generally don't resolve themselves do they? I mean it went from a "put-put" to silky smooth with no intervention on my part. Unless there is an anonymous Q ninja that replaced the injector, I don't know how it happened. I'll have another PB test to see if everything is ok. Strange.

The only issues I'm having now are an annoying ATF leak, (Small, but I'd rather it was non existant), squealing brakes (which will be done on Tuesday) and a strange ticking noise that I hear at idle and full stop. I don't recall hearing it before the magical injector resolution though. I'm assuming it's the work of a very patient assassin or my lifters. I've read the fix on HLA noise, so I'll be checking that out. I'm almost due for another oil change so hopefully, that will go away.

Sorry to intrude on your post Mike, I just wanted to share my own injector experiences.

[Q451990]

HK,

Have you ohm tested your injectors? I bet there's one (or more) reading very high. I have had mine "self heal" a couple of times, but the ohm readings rise rapidly... I'm guessing a bad solder joint that's rebonding itself - definitely some sort of intermittant electrical issue internal to the injector windings.

Heath

[Haitian_King]

HK,

Have you ohm tested your injectors? I bet there's one (or more) reading very high. I have had mine "self heal" a couple of times, but the ohm readings rise rapidly... I'm guessing a bad solder joint that's rebonding itself - definitely some sort of intermittant electrical issue internal to the injector windings.

Heath

No. I haven't ohm tested. It's one of those things that I've been meaning to have done, but every time I'm in the mall, I forget to stop by Radio Shack and get a voltmeter. It's really frustrating because as of late, I'm spending 40+ hours in the mall.(New job.)

I'll definitely try to stop in tomorrow.

[OnTheRoadAgain]

Quote »Lol. Good to hear that you might catch a break!

I'm having injector issues of my own, however they're a little strange. I wish they were as straightforward as yours.

I don't know if you remember, but several months ago, (March I believe) I got my chain guides done, hoses and plugs changed, and valve covers resealed at Van Meter Auto. At the time, I was having issues with a rough idle that I attributed to an injector failure. Keith confirmed it with a power balance test which showed that the #7 injector was the culprit. It ran fine upon start up, but after the engine reached temp, that's when the injector failure was noticeable and there was a visible rough idle.

I made plans to get more spare injectors and get as many as I could replaced. I figured if the #7 was on its way out, others would be soon to follow. I began to experience slight power loss (I guess that's the best way to put it.) during load. It felt like it wouldn't want to accelerate in proportion to the pressure applied to the pedal.

The weird part is, it seems that the problem has sorted itself out. For the last month or two, the rough idle has disappeared and the Q now purrs at idle. I was so used to bouncing up and down that now at red lights, I have to make sure that the engine is still on. That's how smoothly it idles now.

I'm doing WOT runs sometimes 2-3 times a day and it's running beautifully.

To the best of my knowledge (which isn't much, lol), injector issues generally don't resolve themselves do they? I mean it went from a "put-put" to silky smooth with no intervention on my part. Unless there is an anonymous Q ninja that replaced the injector, I don't know how it happened. I'll have another PB test to see if everything is ok. Strange.

The only issues I'm having now are an annoying ATF leak, (Small, but I'd rather it was non existant), squealing brakes (which will be done on Tuesday) and a strange ticking noise that I hear at idle and full stop. I don't recall hearing it before the magical injector resolution though. I'm assuming it's the work of a very patient assassin or my lifters. I've read the fix on HLA noise, so I'll be checking that out. I'm almost due for another oil change so hopefully, that will go away.

Sorry to intrude on your post Mike, I just wanted to share my own injector experiences.[/quote]Quote »The weird part is, it seems that the problem has sorted itself out. For the last month or two, the rough idle has disappeared and the Q now purrs at idle. I was so used to bouncing up and down that now at red lights, I have to make sure that the engine is still on. That's how smoothly it idles now.[/quote]the same thing happened to me... I was using regular gas..... never any ping or spark knock..... ran BG, Lucas and Techron thru the tank, still had the miss.... then after reading about how the ethanol reduces the octane, I thought i better run hi test, never thinking it was going to make any difference in performance. After 3 tanks of hi test, a long run 200 miles, the miss is gone, came back for a day or two and is gone for several weeks now;

tech said it was definately an injector, and I too was deciding how to fix it, all or one etc...

I've also started talking NICE to the car, let a couple of friends drive it.... maybe the car is HAPPY now?

[texasoil]

THe quality specifications for 'regular' gasoline do not require enough detergent to keep the Q45 injectors and intake valves clean enough for a smooth idle. If you regularly use a 'clean-up' or 'drive your engine clean' gasoline--they WILL clean it up and keep it clean. Knock on wood--both of my Q-ships (92 & 94a's) are silky smooth at this time, even at very low no-load idle. Be sure and clean the EGR valve seat and passage to ensure no leak there--it only takes a minisucle amount of air/exhaust recycle in-leakage to screw up the idle. Of course, and vacuum hose leakage between the MAF and the intake valves will do the same damage.

[Q45tech]

"after reading about how the ethanol reduces the octane"................

Ethanol has a higer octane index [both M&R] than any pump gasoline. What ethanol does is allow junky [octane] gasoline to be up graded[ label on pump] to meet the old 87-89-91 labels.

[Q45tech]

The Temperature Coefficient of Copper (near room temperature) is +0.393 percent per degree C. This means if the temperature increases 1°C the resistance will increase 0.393%.

So a 10C [18F] increase would change 12.8000 ohms to 13.303 ohms.Critical to measure injector temperatures [with ACCURATE IR gun] when comparing resistance changes.

The question is what is the copper coil temperature running idle in 100F ambient.............160F???.

To know for sure you need to disco injector 1 or 2 and measure resistance running with hood closed at max heat.

Luckily the ecu trims open time in milliseconds based on coolant temperature to correct for changes in injector .

[Haitian_King]

This is probably why my Q ran fine cold during the first PB test, but after it warmed up, the second PB test showed #7 as the culprit.

[Q45tech]

The Power Balance test on the Consult requires 174F minimum coolant temperature.

Competent testers KNOW to do 3 PB test in a row and average the results.

Deposits on the intake valves can create variations from test to test ........why fuel system cleaners tend to improve results.

[Haitian_King]

The Power Balance test on the Consult requires 174F minimum coolant temperature.

Competent testers KNOW to do 3 PB test in a row and average the results.

Deposits on the intake valves can create variations from test to test ........why fuel system cleaners tend to improve results.

Unless in my case 6 were done and I was printed out the average of both. Oh well.

My tests were performed by a tech recommended by the president of your fan club.