1998 q45 Injector Test

[ChefJwill]

Hello and thank you to all of you who contribute to this website. It has been a life saver for me with all the great info. I found a link to doing the ohm test for the injectors but I'm having trouble locating the injector connector on my 1998 Q. I'm fairly sure from all the info that I've read up to this point that I have at least one injector that is bad. Unfortunately that one injector is one of those under the plenum. The number 1 cylinder has a spark plug with a black electrode all the others are white. Also I have a strong fuel smell from the exhaust and terrible gas mileage at about 16 mpg highway. I replaced the coil with an aftermarket brand and now suddenly I have a TCS Off Slip light on. Anyway help with advice on how to locate the connector and how to deal with the TCS lights please.

[elwesso]

Welcome to NICO Chef!

Injector failures are almost unheard of on the 2nd gens, so I would suspect much more highly that the coil pack is bad. Did you replace the plug along with the coil? If the plug was black you probably fouled it bad enough that you need to replace it before it will start firing properly.

IN answer to your question though, go to www.nicoclub.com/FSM and go to the EL.pdf, page EL-437. The 2nd gen has 2 connectors for the injectors, for the drivers side it's connector F101/F22 and the passenger side is F106/F26.. They're on the front side of the engine on each bank.

[ChefJwill]

Thanks Elwesso for the quick response.... I hope your right... I knew better than to just replace that coil pack without replacing the plug. Also I just downloaded the FSM for the 98. Thanks again.

[Q451990]

If the plug looked that way when you replaced the coil, it may just need to be cleaned. They can be fouled beyond being able to spark. Ideally you would use a sand bag style spark plug cleaner, or just replace it - but I've gotten away with an old tooth brush and some gasoline or brake parts cleaner too.

Heath

[ChefJwill]

I thought i had lucked out but nope. I replaced the plug but i still have a problem. I really think it is an injector. The test for injectors on this site doesnt work for my car. As elwesso said there are two connectors and there are 5 pins in each one. Anybody know how to test a 98's injectors?

[elwesso]

You should still be able to do the same thing or at least the same idea. Basically the way the wiring works is that they're all fed the (+) side of the battery from a common wire.. In the case of the 1st gens, all 8 injectors share the same common power line. The way the injectors are triggered is by the ECU instantaneously grounding them. Since you want to measure resistance across the two terminals of the injectors, you put the positive lead of the multimeter on the positive terminal of the battery, which in turn becomes the positive terminal on the injector. You then put the negative terminal on the terminal side of the connectors I outlined.

In the FSM, if you check out EC-484 in the 1998 FSM that gives a little more accurate description of doing it that way. Resistance you measure should be about 12 ohms. Looking at the wiring diagram you might have to turn the key on to measure the resistance. I would try it with the key off first, then if you don't get a result turn the key on and see if it works.

There are 2 other ways you can see if the injectors are working...

Most OBDII scanners should be able to turn of injectors or spark on a per-cylinder basis, so that'd be the easiest way. See which cylinder is causing the issue.

Another way if you really think it's the injectors is to get a long handled screw driver or something like that, and with the engine running put one end on the injector, and the other end up to your ear. You should be able to hear a very distinct, rhythmic clicking. Put it on every single one, and if you have an injector bad you will DEFINITELY be able to tell which one is bad.

going full circle, it's most common on Y33's that the coils can fail intermittently and the only sure-fire way to fix the coil packs is to replace all (8) of them.

[ChefJwill]

Man you guys are the best. Like you said they would my injectors tested good OHMS wise. One question about that though if I have an injector sticking open will the OHMS be off? Also here is some info on testing the 98 injectors. Connecting to the positive terminal of the battery didn't work but there is another way to test without removing the injector.

First view the diagram that I have attached so that you will know which pins belong to which injector. Notice that the connectors for the 98 have other pins in the connector. 5 on the drivers side and 7 on the passenger side. To test each injector connect the positive lead of your multimeter in the ohms setting to the + pin and the negative will be connected to the corresponding pin for the injector. Might be a slight variance due to testing through the wires but its is fairly precise. 10 - 14 ohms is the range.

Now I guess I will buy two coils and play duck duck goose with them until I eliminate which ones are bad. (replace one on each bank and see if I find improvement. If so that coil was bad. If no improvement I move to another coil and place the previous one back where it belongs)

[elwesso]

The pictures didn't show up, Chef. Feel free to email them to me and I can post them for you.

Us G50 guys are more than familiar with injectors, and if they ohm test properly 9.999/10 times they're OK. I've heard of one instance where they allegedly ohmed correctly, but I'm still kind of skeptical because details were sketchy.

Good luck with coil roulette, normally most people give up and replace all (8). If it were my car, I'd probably replace all (8) and then try and determine out of my old set which ones were good for spares.

[ChefJwill]

Thanks elwesso...... I didn't see an email address for you but I'm assuming if I add aol.com to your aim screen name that will be your email, right?

#OAN I found a test for the coil packs in the 98 FSM.... It's really easy which kind of makes me wonder if I'm missing something. According to the test you just OHM the first two pins and if you get any reading of 0 the coil should be replaced. If this works than no more roulette. Also if this works I might not mind spending $35 bucks for a used one since I can test it before I even pay for it. If one of you gurus have time to review the component test and give your opinion on its viability I would appreciate it. ec-375 1998 Q45 FSM

[elwesso]

my contact info is on www.q45.org... [email protected]

I think the problem with that test is that sometimes coils fail intermittently, or sometimes the issues only show up when the car is hot, so sometimes those ohm tests may not truly indicate if a coil is bad.. It certainly can't hurt to try and if you find one that's for sure bad that's a step in the right direction. Historically this isn't a very good test because of the former fact.

I wouldn't buy a used coil for this car, knowing what kind of problems people have with them. Maybe if you could get a set of 8 for under $50 or something, you might find a few good ones.

[ChefJwill]

Makes sense Wes..... I knew there was something too easy about that test. Oh well $750 for coils it is... Thanks though. Sending that picture now....

[elwesso]

Chef... I got this info from someone who emailed me a couple months ago, I think this will help you out:

Q had a long standing problem with a misfire. I got lots of suggestions on
resolving this online in multiple forums and from Infiniti mechanics. Worked
through them all. In the end my diagnosis pointed to coil(s). But, diagnostic codes
couldn't pinpoint the cylinder(s) misfiring, so it was trial and error swapping with
a new coil trying to find the bad coil(s). Then I found out the OEM coils had been
superseded with a new part number because of an intermittent-misfire-when-hot
problem. This convinced me that I probably had multiple bad coils and my single coil
swapping approach was not going to work out. The Infiniti and Nissan mechanics I
know told me that the OEM and cheaper aftermarket coils tend to misfire when they
get hot (especially as they age), so I should stick with Hitachi coils on this car.
Dealer price was $120 each and they couldn't confirm whether they'd be Hitachi until
they were ordered and arrived--plus, I had to prepay. Found an online source
(PartsGeek.com) with the right Hitachi part number where I could order just the
bodies for $60, and reuse the original wires. At that price I gave up the coil
swapping experiment and replaced them all. Engine runs smooth again. Was hoping
this might help improve Q's MPG. It's only been 60 days of driving with all new
coils, so limited data, but mileage seems to be up to 15-16. Still well below what
Q use to get.

[elwesso]

Here's the picture that you sent me. I had AutoCAD open so I took the liberty of making something a little bit more clear



Also, since you're a chef, you might appreciate this...... Not sure if you're a Gordon Ramsay fan, but....