knock sensors, injector analysis, confused!

[mobiusinfinitus]

2 month owner of 94 q45t w,165k.Mostly if not all original, cleaned MAF, ohmed injectors at connector: 1 8.4 ohms,2 29,3 12,4 54, 5 open,6 13 ,7 12, 8 12. Car ran great up until a few days ago, when idle became rough and fuel economy deteriorated along with performance, mostly in the low end. Fairly recent water pump replacement, 1-2 yrs? Obviously some serious issues that need to be addressed, but can I do further harm by limited local driving other than increased emissions, poor fuel economy,etc. Service manual is on the way along with owners man. and warranty manual. already have owners man but has'nt helped much. Anyone have some injectors that could be workable? Plenum removal seems imminent, so what else should be replaced as long as I'm in there? Mechanically competent, but new to Q's. Must admit the complexity is slightly intimidating as I'm used to working on High-output 4's w sidedraught webers, race cams, headers, high compression pistons, etc. Most recent was 1976 Lancia montecarlo, 2-seat mid-engine pocket rocket. anyway, am i in over my head with this Q, or will I adjust. Also, my inspection mechanic failed to tighten the center cap on the bbs wheel, so now I have only 3! Any leads? Was going to do some suspension mods, but feel that it is more important to deal w/ the mechanical issues at this time. All was unanticipated as the car ran so well, till the cel and ecu problems reared their ugly heads. I live in Columbia, Mo and it is a daily driver, so I need any constructive input that can be gleaned from all this apparent expertise available through this forum. I will bend over backwards to reciprocate in any way that I can. Am new now, but a quick learner and a poor but generous individual. DIY is the only way I see to afford a machine like this, and I am prepared to put in the time and effort it takes unless I just acquired a total moneypit, in which I will sell and patiently await for something similar to come along. Does open injector indicate a possible wiring problem between harness and #5 injector or could it read as such? I'll try to be more succint and to the point in future correspondence, but am a bit flustered at this point.Thanks guys, and I'm sure you will find me a positive addition to your 'family'.Sincerely,Dennis Ray3415 Wakefield Dr.

[Jesda]

Sorry, my friend. A pet peeve of mine is when long posts lack paragraph divisions. Allow me...

2 month owner of 94 q45t w,165k.Mostly if not all original, cleaned MAF, ohmed injectors at connector: 1 8.4 ohms,2 29,3 12,4 54, 5 open,6 13 ,7 12, 8 12. Car ran great up until a few days ago, when idle became rough and fuel economy deteriorated along with performance, mostly in the low end.

Fairly recent water pump replacement, 1-2 yrs?

Obviously some serious issues that need to be addressed, but can I do further harm by limited local driving other than increased emissions, poor fuel economy,etc. Service manual is on the way along with owners man. and warranty manual. already have owners man but has'nt helped much.

Anyone have some injectors that could be workable? Plenum removal seems imminent, so what else should be replaced as long as I'm in there? Mechanically competent, but new to Q's. Must admit the complexity is slightly intimidating as I'm used to working on High-output 4's w sidedraught webers, race cams, headers, high compression pistons, etc. Most recent was 1976 Lancia montecarlo, 2-seat mid-engine pocket rocket. anyway, am i in over my head with this Q, or will I adjust.

Also, my inspection mechanic failed to tighten the center cap on the bbs wheel, so now I have only 3! Any leads? Was going to do some suspension mods, but feel that it is more important to deal w/ the mechanical issues at this time.

All was unanticipated as the car ran so well, till the cel and ecu problems reared their ugly heads. I live in Columbia, Mo and it is a daily driver, so I need any constructive input that can be gleaned from all this apparent expertise available through this forum. I will bend over backwards to reciprocate in any way that I can. Am new now, but a quick learner and a poor but generous individual.

DIY is the only way I see to afford a machine like this, and I am prepared to put in the time and effort it takes unless I just acquired a total moneypit, in which I will sell and patiently await for something similar to come along.

Does open injector indicate a possible wiring problem between harness and #5 injector or could it read as such? I'll try to be more succint and to the point in future correspondence, but am a bit flustered at this point.

Thanks guys, and I'm sure you will find me a positive addition to your 'family'.Sincerely,Dennis Ray3415 Wakefield Dr.

Welcome to NICO.

To me, it definitely sounds like injector replacement is due. 1, 2, 8, and 7 can be done without plenum removal. The rest require at least partially removing or lifting it. The extra injectors I have unfortunately are for 90-93. Its not too hard to DIY. Just remember to thoroughly depressurize the fuel rail and insert the injectors straight in -- no twisting! #5 sounds like a bad harness connector, but it could also be bad coils in the injector.

If youre replacing at least a couple injectors under the plenum, its a good idea to buy a new harness from Infiniti of Scottsdale (everythinginfiniti.com).

If you need a hand with the injectors, swing by my place in St Louis. Just bring me some steaks and a bucket of potato salad.

Otherwise, its not too terrible of a DIY job. More tedious than it is complex.

[maxnix]

Might tell us what you have done, but certainly under plenum hoses and knock sensors at that mileage a must. Do you have the dealer performed service history?

Sorry, my friend. A pet peeve of mine is when long posts lack paragraph divisions. Allow me...

Well, at least it wasn't all caps!

[96Qowner]

I'm curious about the gasoline you've been using. Ever since reading about that episode in Wisconsin last year, where detergents weren't being added to the gas, and injectors began to clog up all over the area, causing repeated expensive replacements for dozens of owners, I've been more careful about the quality of fuel I put in the Q.

You said it was running fine, and then suddenly very poorly, and now you have more than one injector that isn't working properly.

Did you recently change gas stations? What brand do you usually buy?

[mobiusinfinitus]

Thanks for the reply. I have been running premium unleaded from Breaktime (MFA). No doubt almost any consumer grade gas is marginal at best, but I don't see how that could cause one injector to read open at the connector. Of course, it is number 5, making it next to impossible to ohm direct w/o taking off the plenum. I assume I have a bad connection in the harness somewhere, but don't really know. Wouldn't bad gas just cause the injectors to clog prematurely? Don't see how that could cause them to have an open circuit. Sorry I haven't responded earlier, but work overnights and haven't been online. Thanks again for everyones offers and input, but I don't see any way to isolate the problem without pulling the plenum. Not a pleasant task!

[Jesda]

I'm familiar with the Breaktime stations in Columbia, and I avoid them. I know you guys have QT. Use QT instead. Thats all I use when I'm there.

Q45Tech has a post explaining this better than I can. Basically, the injectors get stuck open then it damages the electrical coils, or something.

[mobiusinfinitus]

I'm not familiar with QT stations in Columbia, but that doesn't mean they aren't here. Wouldn't an open line to #5 injector be more indicative of a wiring harness short, or can injectors become so clogged as to create a short circuit? My quandry is why so sudden of a change in performance. It runs at speed o.k., but at idle, it can be pretty rough and uneven, but has never stalled. Safe to drive for short distances, or should I let it sit until problem is rectified. Thanks for all your advice and I'm sure I'll get it figured out with all your help.

[Jesda]

A bad harness could result in an open circuit, but so could bad coils. When my injectors went bad, they happened pretty suddenly. They were fine, then suddenly at a stoplight my idle got unbearably rough.

Youre safe to drive all over the country, but its a nuisance that adversely affects fuel economy and power.