Fuel Injector Test

[Sned]

I've been a reader for many months and recently joined NICOclub. Thanks for all your posts as I have worked on my car for the first time because of your help.zeropost?cmd=newtopic&id=177#

I have a 1994 Q with 45K original miles (driven in TX for 38,000 mi and KS 1,000 mi) in mint condition (I will post pics and more when I figure it all out) with the exception of the very rough idle, low performance and steering wheel shaking. I live in CA and the car has been receiving CA lousy gas for about 8 months. I believe I've read all your posts regarding the subject. I'm not tech savvy and I've done the following:1. Cleaned the MAF and even swapped out with my 1991 Q (205,000 miles)2. Added fuel system cleaner several times including BK44. These seem to help temporarily.3. Alignment and tire rotation (I had done).

I had Aamco run a free computer diagnostic and they found that the injectors had a communication problem.I've bought an ohm meter and tested the pins. When I test the male pins I don't get any signal on any of them. When I test the female pins, I get about a 14 read but that's coming from the battery so they are going to read correctly right?

I feel a little out of my league here guys. I'm a veteran Q owner since '94 but a very novice do it your selfer.

I'm scheduled to do an injector cleaning with a MotorVac system that will cost me $140 along with an oil change for $42.

Any help is appreciated. Thank you.Dave

[Q451990]

Welcome to NICO!

The test instructions that you have probably read here were written for the 90-93 Q45, which are on an "always on" circuit from the battery. The 1994 revision included making the injector circuit switched.

So you can do one of two things... run the same test with your ignition switch in the on position (but with the engine not running) - or test the injectors through both sides of the hearness. This eliminates getting a reading through the battery and should be more accurate - but requires unplugging the harness that feeds 12V + to the injectors. You can read up on those pinouts in your factory service manual. If you don't have it - you can view it here.

I would cancel the flush until you complete the ohm test. Flushing an electrically dead injector is pointless.

Good luck!

Heath

[Sned]

Thanks to Mike Goodwin and Old School for your help so far!

In addition to the above post information I've performed the following:

I've put in two bottles of RedLine and driven for two hours on the highway. Although the ride was smooth, performance is still lacking and still a very shaky idle.

The OBD computer kicked out on Injectors 2 and 6.I ohm tested the harness and all of them read approx 21 except for 3 and 6 which would not give me a reading at all.I tested the following injectors without removing the plenum: 1, 4, 8 were good and 2 was bad.I listened via a stethascope to all injectors and they were all ticking to the same beat.

The mechanic I'm working with is recommending a pulse test and thinking of checking the spark plugs.

Any suggestions would be greatly appreciated.

Thanks,Dave

[Infinitiguy19]

Better off finding someone with a Nissan Consult (Dealer, 300ZX specialty shop, Nissan shop....) And have them run a Power Balance test, Have them do that a couple of times and then average the results.

There are also multiple variables with which you can run a power balance test if your a perfectionist like Q45tech. Do a search for "power balance".

[Q45man1]

David - I just sent you an email. I'm pretty close to where you live. I have a consult laptop and I can help you performed a diagnostic test.

Also I've been going to this shop in Van Nuys area. Owners are former Infiniti master techs. Talk to William at http://www.carzoneautorepair.com.

They are an excellent shop.

[Q451990]

I would certainly take Q45man1 on his offer!

[Sned]

Thanks Paul and Q45man1,

I forgot to mention I've had two consults run and both showed "51 Fuel Injector Circuit". Does this mean s51? And if so, isn't that telling me that it's #1 or #2 fuel injectors based on FI Schematic? If that is indeed the case, and if the #6 FI is bad then wouldn't it throw a code of 56 Fuel Injector Circuit as well?

While the car was idling, one at a time I pulled the wires off of both #1 and #2. #1 significant rpm drop and with #2 FI, no change which obviously tells me that it isn't contributing anything to the engine. I also had no reading with #2.

I think I will see Q45man1's shop tomorrow and will run this by them. Does anybody know what would cause the FI's to ohm read over 20 except for 2? I used the 'battery to pin' test posted by Wes.

I also read an old string here on someone having the transmission pan dropped and cleaned and the rough idle went away.

Your input is greatly appreciated!

Dave

[goody90q45]

......I ohm tested the harness and all of them read approx 21 except for 3 and 6 which would not give me a reading at all.I tested the following injectors without removing the plenum: 1, 4, 8 were good and 2 was bad.

Something is not quite right with your readings if #2 is reading good at the connector but not good directly on the injector. As for #3 and #6 where you're getting no reading, check the connector at the fuel injector to make sure they're plugged in securely. If the reading is correct this is the cause of the bad idle and 51 code.

The 21 reading on all the other injectors at the main connector (should be 10-14) is probably the result of a warm engine, low battery in your voltmeter, or a lot of corrosion on the connectors. What's important is they're all the same so you're looking for the ones that are out of family. Drop by Radio Shack and get a new battery and a 10 ohm resistor ($2) and measure it against your meter. It should read 10.0-10.5 ohms resistance.

Save your money and the drive to Van Nuys and let Percy show you the ropes. I've met him and he's very knowledgeable and a really nice person. You'll learn more from Percy in an hour than you would reading NICO posts for a month. He'll be able to do a version of a power balance test through his laptop that will hone in on the bad injectors. Do you golf? We met at the 9 hole course on Sepulveda in El Segundo.

BTW- Code 51 isn't telling you connector s51 (or s56) or that any particular injector is bad. It's saying that something is wrong in the injector circuit (all 8) and you've got to go one step further to isolate the bad one(s)- normally accomplished with a power balance test by turning off one injector at a time.

[Q45man1]

Mike - Thanks for the nice words.

David - Thanks for calling me last night. I've spoken with the owner of the shop that you are coming today.

They can run a full diagnostic tests using their real Consult. Please let William know that you are coming for sure.

[Sned]

Thanks to Percy (Q45man1) for putting me in touch with Carzone in Van Nuys, CA. William and Donald were great. They are both master Infiniti technicians.

They hooked up the car to a Nissan Consult II and performed a power balance (Thanks Mike) isolated each injector and confirmed #2 and #6 were bad.

Cost:Consult II reading, FreeRemanufactured GB OE replacement injector, $93 (their cost)Install of #2, $40 (I know I could have done it myself but am glad I didn't. Gave them some biz and William showed me the trick to do it. WD 40, place and twist in.)Consult II reading again, Free

William is a true lover of the Q (owns a '94 as well) and was with Miller Infiniti since '93 and started his own shop last year. Very clean shop which was great as I had my 20 month old daughter with me.

I'm going to see a friend in Phoenix today and have ordered a GB FI for $40 ($18.32 core charge) and will install with my friend for the cost of some beer.

My friend Darren has rebuilt normal cars but I have never even changed my own oil. I am undertaking this because of the confidence I have from of all the great guys in this forum and Darren.

Please advise as to any pitfalls we can avoid. Thanks again.

BTW: My Q is already riding smoother and I squeaked the tires on takeoff for the first time since owning it. I actually thought the '94 started out in 2nd gear vs. my '91 in 1st because of the poor performance out of the gate.

[Sned]

Thanks Paul for the power balance test suggestion:)

[maxnix]

Remanufactured GB OE replacement injector, $93 (their cost)

One must learn that there is no way to "remanufacture" a used injector. At best it means they are used and hopefully cleaned ones. Why no one on the board uses them when a plenum job is involved.

[qship96]

I am confused, the shop diagnosed 2 bad injectors and you only had them replace 1 of them? Why not both and be done with it?

[Sned]

I did not know that they can't be remanufactured. I have read someone here uses "used" injectors.

I wish I would have posted sooner. I've already ordered the used so I'll give it a shot due to finances. They are warranteed for a year and 12,000 miles. If anything happens sooner, finances are changing quickly and I can adapt at that time so must roll the dice now.

How have the used fared in replacement not involving the plenum?

Thanks.

[Sned]

We couldn't find another reman injector on Saturday.

[maxnix]

How have the used fared in replacement not involving the plenum?

Used is used. Who knows what the previous fuel system maintenance regimen was?

[Sned]

I get that used is used. The difference is $100 savings per FI.

I'm in California with lousy gas, the feeling I've gotten on the forum is that they are going to go bad anyway, including new ones, which is why I decided to go with used. Chances sound pretty good that the "new" ones that came with the car will fail so as long as the used outlasts those, I'm good.

[CINNALOCKS]

Not to bash you... just to inform you.

When those go bad and they will..................try deatschwerks.comIt is a sponsor and for a few more bucks you could have had a new injector.

One more thing, if you drive one and really like it, show it some respect and learn how to spell it. Infiniti not Infinity.

[Q451990]

You're correct in that all of the OEM injectors, used, new, or otherwise will fail at some point. We have not been able to verify that Nissan ever made any rolling changes to the injector design that will prevent failures of the new ones.

I did a great deal of research on BWD branded injectors and installed them in my Q. Their tolerances don't appear to be as tight as the factory ones, from the one test we ran - but they are touted to be capable of withstanding ethanol laced fuel. Check out my thread on all of this...

zerothread?id=347484

Heath

[goody90q45]

Cost:Consult II reading, FreeRemanufactured GB OE replacement injector, $93 (their cost)Install of #2, $40 (I know I could have done it myself but am glad I didn't. Gave them some biz and William showed me the trick to do it. WD 40, place and twist in.)Consult II reading again, Free

It sounds like you found a good mechanic. He changed the easy injector for you but the replacement of #6 FI is going to involve removing the plenum. As good as your shop is they're still going to have to charge 6-8 hours labor at $100+/hr to stay afloat.

If money's tight and your mechanic buddy is worth his salt the two of you should have no problem removing the plenum. It's not rocket science. Since your Q came from the other side of the Rockies be prepared for some hose replacement while the intake is off. Between now and then do lots of reading in the Q forums and print up some articles so you're prepared. Lots of people have done it with no issues, minimal hose replacement and posted some great tips to make it easier for the next member to take on the challenge.

"Remanufactured" means they've been sent to Deatschwerks (or equivalent) and been sonically cleaned, ohm tested and flow tested. If you've sent an entire fuel rail with 8 injectors they'll put them back in the rail with new o-rings and then pressure check the rail for leaks. Other than a new pintle cap nothing has been replaced or disassembled.

It's always a crap shoot buying used injectors but removing the plenum and getting it back together in 3 hours gives you something to brag about. Plan ahead and buy a fuel rail with injectors from another member or ebay ($100-$150), send them to Deatschwerks for cleaning ($15/ea) and you'll be set to go plus have a few to sell.

[CINNALOCKS]

I was just wondering Goody, why he would want to buy used ones and go through all the trouble of finding a used rail, getting it shipped, doing the work under the hood for three hours only to have the number three injector fail and have to repeat the process.

My suggestion was that he just buy buy a set of new ones already matched. Price per unit is roughly $105.00 from Deatschwerks. A little more expensive on the front end, but a much better move on the back end.

[goody90q45]

If you're mechanically inclined with a clear memory (not foggy like mine) and have good tools, pulling the plenum isn't difficult and the job can be finished in just a few hours. It's a cost tradeoff and $$ is tight with a lot of people right now.

When I owned the 94Q (darn I miss that car) I was able to buy a rail with 8 injectors and have them all cleaned and tested for cheaper than buying one new injector at IOS discount. I used 3 of them in the 94Q with no problems and sold the other 5 with no complaints from the buyers to get my money back.
Modified by goody90q45 at 7:33 AM 2/20/2010

[Q45tech]

Often it is much easier and safer to replace the entire bank of 4 injectors due to flow balnce issues and the ability of ecu/o2 to [trim] adjust flow between banks [at least at idle and cruise rpm].

Over the years I've collected a few sets of rails with good early injectors from chain guide destroyed engines...........knowing that they would and will become handy in future.

Things one learns in having the same vehicle for 20 years.

Coming up on 2 years [March 1] when E10 came to ATL Metro. So far it has cost me 4 injectors 2 per bank/rail.

Since the AMG was acquired I have split my annual mileage so the Q rarely sees more than 5-6k per year now.