What Are These Spark Plugs Telling Me?

[goody90q45]

The 90Q that I bought a couple of weeks ago is having a tough time getting out of it's own way so I thought I'd check the plugs today.

The PO installed a junkyard fuel rail last year and said his engine troubles only got worse. The rail currently has a dead #5 injector and #4 is ohming at 18.0. The other 6 are within range but I'm not sure which injectors were bad on the previous fuel rail and the PO had no clue.

Other than being the wrong plugs (these are NGK PFR5B11, they should be PFR5G11) what does the condition of each plug tell me. Could these be the reason I can barely hit 50mph? Are they fouled enough to not fire?

A short history- > I've swapped in a fuel pump, FPCU and a new fuel filter. No improvement. > The only ECU code is 54- (or is it 51?)- open injector circuit> Steady idle RPM at 750> All connections were green with corrosion. Have cleaned as many as I could reach without removing the plenum, yet.

I'm a spark plug newb. Thanks for the help.

[qship96]

#5 & 6 look oil/carbon fouled-are they wet and oily feeling, or dry and dusty feeling like powdery? Definitly something not operating correctly in those two cylinders{no spark,fuel or oil getting into combustion chambers thru worn valve seals or piston rings}

[3Q Jay]

you gotta get over this plenum paralysis and just DO IT (j/k).

like qship said= 5 and 6 don't look good. now, why?i'd change #5 injector since you know that's bad, but for #6.....well, do a compression check while the plugs are out.

is there stumbling or bogging, or backfiring or any symptoms other than poor power?

how does timing look?

[maxnix]

you gotta get over this plenum paralysis and just DO IT

No, really. You have to have a good baseline to start, and a clean plenum, TB, injectors and the right plugs will sure eliminate a lot of wrong guesses.

Like is it the plugs or the injectors?

Can't wait to see a picture of the lower runners.
Modified by maxnix at 6:10 AM 2/26/2008

[Q451990]

5 and 6 both look exactly like my plugs looked after my injector failures. They very well may be fouled enough to prevent them from firing. In both instances, I had to pull the corresponding spark plug for cleaning after replacing the injector due to the fouling. So my guess is that you have one plug that corresponds with the bad injector you know about - and the other one is fouled for another reason... Remember that an injector can still fail to work while ohming OK.

Heath

[goody90q45]

#5 & 6 look oil/carbon fouled-are they wet and oily feeling, or dry and dusty feeling like powdery?

All the plug ends are dry and dusty. There's no oil but I'll be doing the compression checks after work today.

No, really. You have to have a good baseline to start, and a clean plenum, TB, injectors and the right plugs will sure eliminate a lot of worng guesses.

I'm trying to be systematic in finding the problems. I really thought it was the fuel system at first but I've eliminated that as an issue. Now I'm on to compression tests today and I might as well put new plugs in since they're out and are the wrong ones. Plenum removal and intake path cleaning is next. I've got a fishbone chart on my office wall at home and am crossing the bones off one at a time. Fuel delivery is all go. Compression bone is yellow and on hold until verified. I should be ready for a flight test by Friday.

you gotta get over this plenum paralysis and just DO IT (j/k).

I'm working my way up to it. I have nightmares that I'm a Lilliputian at the bottom of a pit, chained to a KS, and can't see light because of all the hoses to find my way out. Saturday's the day.

....is there stumbling or bogging, or backfiring or any symptoms other than poor power? how does timing look?

There's no backfiring but I would call it a 50/50 combination of stumbling and bogging. I got my laptop stolen in a home burglary a few weeks ago so I don't have NDS to easily check the timing. Once I get the plugs back in the engine should run well enough to get some meaninful data from NDS. I'm hoping that one of the two locals with laptops/NDS will have a few minutes this weekend to do a scan.

I'd like to have it running well enough with new plugs to drive to AAA and pay registration and tranfer title on Friday morning. I guess the remaining questions I have are:> what is the difference between the B and G ratings on the plugs?> Will the two fouled plugs and/or the wrong plugs (B vs. G) cause the bogging engine.

Thanks for all your inputs so far.

[RAP]

NDS ? And Laptops? Can you elaborate on this please? I would like to know more. Thanks

Jack

[96Qowner]

For RAP - Nissan Data Scan threads:

GROUP BUY: USB CONSULT!

USB consult too long - lets talk software

[ScottJackson]

How 'bout that thar MAF? Or maybe you sucked a plastic bag into the air intake.

[lino]

This may be of some use to you:

http://www.ngksparkplugs.com/t...2.asp

http://www.4secondsflat.com/Sp....html

[AlabamaDan]

I think they're saying "Change me! Change me!" JK. I'm not familiar with what the inspection of a used plug tells the mechanic either and I'm interested to learn. However, I think there's a difference in what a 10k plug can say vs a 100k plug.

[3Q Jay]

fishbones and fault trees....right on goody!

don't forget that the NDS will assume your base timing is set to 15°BTDC and just show you the delta from there. so you need to check timing with a light.

[goody90q45]

NDS ? And Laptops? Can you elaborate on this please? I would like to know more. Thanks Jack

NDS= Nissan Data Scan software and consult cable made by Blazt. They're one of our sponsors and you'll see their banner on the right side of your screen. The cable plugs into the unused gray connector in the passenger compartment fuse box. If you already own a laptop and have an extra $135 to blow it's a fun toy.

How 'bout that thar MAF? Or maybe you sucked a plastic bag into the air intake.

I'm not getting the stalling, fluctuating idle or black smoke that you'd expect with a bad MAF. The engine idles steady at 750 rpm and no MAF ECU code. I did clean it though.

This may be of some use to you

Good stuff Lino. I've bookmarked them both. Thanks for doing my surfing for me.

I think they're saying "Change me! Change me!" JK. I'm not familiar with what the inspection of a used plug tells the mechanic either and I'm interested to learn. However, I think there's a difference in what a 10k plug can say vs a 100k plug.

I'll know tonight. Compression checked OK in all the cylinders and the new plugs are in. I'll finish up later today.

fishbones and fault trees....right on goody!

Trying to follow a logical path eliminating one bone at a time. Maybe I'll turn it into a checklist some day.

[AlabamaDan]

Trying to follow a logical path eliminating one bone at a time. Maybe I'll turn it into a checklist some day.

That checklist might be a great asset to us - really.

[mxr662]

Need progress report.

[goody90q45]

Need progress report.

I put the new plugs in and got enough improvement in acceleration that I was able to drive it to work and get the fuel tank to empty. Filled with a fresh 1/2 tank of Chevron premium and no real improvement. It looks like the real problem is going to be the one dead injector and the one dying injector.

The plenum comes off tomorrow morning and I'll be changing out two injectors and checking hoses. Andy I'm ready to take you up on your offer of hoses. If you're available for a bit on Saturday let me know.

[qship96]

If you plan on keeping the car a few years or more, might as well have EVERY hose on hand along with knockers and harness, plenum gaskets{8}, throttlebody and aac gaskets,etc and do the complete job so you wont have to touch it again for 100K miles.If the plenum has never been off,most of the hoses will split,crack, or already be soo stiff you will need to replace once they are touched.Have plenty of aspirin before and after the procedure, as it will ease the backache!!!

[goody90q45]

Need progress report.

Starting at 8:30 this morning (Saturday) I removed the plenum from my 90 Q. Not too bad a job if you have the right tools, are organized and have a good memory. I've got two of the three covered.

Once I got that last hose (in the rear in front of IAC) to release its grip and I was able to remove the plenum I immediately saw that #5 injector was unplugged. That explains the open injector circuit ECU code and a lot of the engine miss and bogging. FI #4 was ohming at 17+ so I changed it also. The harness connectors as well as the FI pins were covered in heavy green corrosion so they got a good scrubbing and coating of dielectric grease. Finally, the plenum had a crack in one of the legs from being overtorqued and I happened to have a clean spare on hand.

After a midday trip to the stealership to get IAC, TB and EGR gaskets which they didn't have, I came home and found the ones I knew I had but couldn't find earlier. Wasted trip. I'll clean the TB and EGR (both filthy) in the morning and finish the reassembly. I should have it running before lunch.

I just did a quick in-and-out under the plenum today without replacing anything else since I just want to get this car up and running before I invest any real time or money into it. If I decide to keep it a lot of deferred maintenance will be taken care of in the near future. For now I'm just getting pleasure out of bringing it back from the dead (it was towed to my home by the PO when I bought it) and doing it for zero $$ since I've had all the parts needed so far. I think the issues I mentioned above and corrected today should make it run a lot better when I fire her up tomorrow.

[maxnix]

Having spare new gaskets on hand, pulleys, etc. is worth a fortune when you need them on the weekend.

Hope you restore it.
Modified by maxnix at 4:35 AM 3/6/2008

[mxr662]

Goody came over tonight with his new Q. Dead miss that did not seem to go away under acceleration. Power balance results below. Also when using OBD Scan Tech to to shut off cylinders 6 and 8 there was no decline in RPM. No picture but with the 02 sensors on the scope the right hand one stayed low all the time.

[3Q Jay]

6 and 8 are on the right bank, but the O2 may just be indicating that it is sensing full rich from unburned fuel coing out of 6 and/or 8.

i usually run the scan tech multiple times, and in gear to get some loading. you can also force a higher rpm--try about 1250.

i'd pull 6 and 8 plugs (again) and look for wet this time.

EDIT: just looked at original picture again and it looks like #8 was wet before too. Try coil packs (I'm sure Mike has a spare boatload), and maybe the actual harness from ignitor to coil paks.

[goody90q45]

....I'd pull 6 and 8 plugs (again) and look for wet this time.

EDIT: just looked at original picture again and it looks like #8 was wet before too. Try coil packs (I'm sure Mike has a spare boatload), and maybe the actual harness from ignitor to coil paks.

Andy had a good (=simple) idea to narrow down the problem. Tonight after work I'm going to unplug #5, #6 and #8 coil packs one at a time and plug in a spare coil with spark plug in it to see if I'm getting spark (to ground). If I get spark I know it's an injector problem and not a bad coil/harness/plug. I'm fortunate to have spare coils so it will take just a few minutes to check.

I never gave an update after the plenum removal. After putting in new plugs and seeing some improvement (not as much as I thought I'd get) I removed the plenum Saturday and replaced #4 injector, cleaned up all the corrosion on the connections, and made sure that all 8 injector connections were secure since the connector had come loose on #5 FI. I put it all back together and got more improvement in the acceleration but the engine was still missing and lacked acceleration.

In the middle of all this Andy got in touch with me and offered to do a power balance (PB) test. The results were very conclusive. The PB takes about 2 minutes and the results are automatically summarized on the page Andy posted. After the test, Scan Tech lets you shut down one or two cylinders at a time. When #6 and #8 were shut down individually there was no change in idle. Shutting down each of the other cylinders one at a time made the engine miss bad. Scan Tech also lets you shut down 2 cylinders at a time and when we did #6 and #8 together there was absolutely no change in idle.

I've got to add that with every small repair or cleaning that I've done there's been some improvement. Cleaning corrosion off the connectors has given the biggest gains. She would barely go 25 mph when I test drove her on day one and now I can easily keep up with the flow of traffic on surface streets and the freeway.

Andy was very gracious to offer his services and last night's PB test was the data that I'd been looking for. It really narrowed down the problem and I think we both learned a lot from it. Thanks for your time.

[AlabamaDan]

This is like a soap opera for Q buffs. Que the music...

Will Goody's New Q fire on all cylinders?

What will new coils tell us?

Will NICO ever see pictures of this 90Q?

Tune in next time to As Goody's Q turns...

:lol

[jonseyq45]

Just a thought.

Have you checked the plug gap before installing the plugs. This simple thing gets over looked a lot. As the ignitions have improved, plug gap has increased. Larger gap = higher voltage needed to cross the gap (good thing). I may be preaching to the choir, but sometime we over look the obvious. The other possible source of a problems is the high voltage connector from the coil to the plug. Over time and being subjected to heat it can break down slowly and lower the voltage at the plug.

Well that my 2 bits on this countinuing saga

Jonesy out...

[Haitian_King]

Uh. Sorry to bother anyone, but I'm in need of plugs before Tuesday mroning. Sparkplugs.com shows only the PFR5B-11 and Mike says that they need to be PFR5G-11.

What should I do? I'm going to Infiniti of Maple Shade tomorrow, but I'm afraid that they might not be in stock. Is this something that they normally keep on hand? Or would I have to go to Autozone/ABC Auto?

Sorry guys, I've been searching but I'm just trying to cover all the bases here.

[goody90q45]

Uh. Sorry to bother anyone, but I'm in need of plugs before Tuesday mroning. Sparkplugs.com shows only the PFR5B-11 and Mike says that they need to be PFR5G-11.

I went back to Q45.org and looked again and I found the same discrepency. In Wes's How to Install Plugs he calls out a G plug, but in the thread about gapping plugs Tech calls out the B plug. Maybe someone (Brian) knows the difference. I just changed my plugs switching from B to G and there was little change so I'm going to guess that either will work fine.

Just a thought. Have you checked the plug gap before installing the plugs.....Jonesy out...

I didn't check any of the plugs as I installed them but they were in an eight pack sealed package with individual sleeves and should have been pre-gapped to 1.1mm. But you are correct that anything could have happenedbetween the manufacturer and my purchase.

This is like a soap opera for Q buffs. Que the music...Will Goody's New Q fire on all cylinders? What will new coils tell us? Will NICO ever see pictures of this 90Q? Tune in next time to As Goody's Q turns... :lol

I missed these couple of posts and realized that I hadn't given an update for a while.

After determining that the #6 and #8 cylinders were not functioning, and knowing that I had spark to each of the 2 plugs, I decided to take her to my local shop and get a fuel rail flush for $120. Other options would have been to 1) install a used injector in #8, or 2) remove the fuel rail and send to Deatschwerks for rehab.

I've only got one injector left so I didn't want to chance removing one with the plenum on nor did I want to remove the plenum again to remove the fuel rail. As it turns out the injector flush yielded no improvement and now I'm weighing these 2 options again. In the meantime I've gotten NDS reinstalled on my laptop, thanks to quick response from Blazt, and was able to verify that #6 and #8 are still plugged.

At this point I've decided to replace #8 FI without removing the plenum. It's my last injector. After this I should be running on 7 cylinders instead of 6 and should see a definate improvement. If replacing #8 works then I won't feel so bad about removing the plenum a 2nd time to replace #6 FI. In the meantime I'll also recheck the gap on the 2 sparks plugs.

[maxnix]

Maybe someone (Brian) knows the difference.

Detailed on the NGK data code sheet I sent you.

[Haitian_King]

Detailed on the NGK data code sheet I sent you.

I now understand the code. But which plug would be ideal? The Copper core ground electrode? Or the "Special Design"?

What's the "Special" design? Is there an increased benefit to the different firing end construction?

[maxnix]

MA-15 of the 1995 FSM specifies the PFRG series as the VH45DE was optimized for operation with this plug.

[Haitian_King]

MA-15 of the 1995 FSM specifies the PFRG series as the VH45DE was optimized for operation with this plug.

Alright. Thank you!

G it is! If only the damn parts department at IOMS was open today. Or at least have a price list on the site.