Hey guys,

       back again to solve another mystery on my 1977 280z California spec coupe. So in short my number 1 cylinder doesn't fire (I have no idea how long it has been like this). Or if it does it is extremely weak.  Anyways, the reason I know this is that when I pull the spark plug wire the engine idle does not change noticeably.  Also the idle is slightly rough and will surge if I have it anywhere lower than 1000rpm, as well as the car doesn't like full throttle under load. I have also disconnected the fuel injector and that made no change at idle. Disconnected any other cylinder causes the idle to drop very noticeably. 

So, here are the tests I have run thus far.

First I checked for spark in a number of ways. 

• I pulled the #1 plug and had it zap the valve cover by cranking the engine over. worked fine, spark looked strong.
• I swapped plug wires just for the heck of it between #1 and #2. No change. Dead cylinder did not follow the wire
• I swapped spark plugs from cylinder #1 to #2 and vice versa. The dead cylinder did not follow the plug. Always dead on cylinder #1.

Next checked compression

• Even between #1 and #2 at 150psi. Didn't bother with the rest.
• Pulled valve cover and turned over motor. Valves opening and closing as should. The wipe pattern on the rockers looked very good.

Next I went to the fuel injector. Which is where I get confused.

• I listened for injector noise with a screwdriver. I swear I heard a 'tick tick tick' like all the others. However, I still heard that noise when disconnected. Possibly the sound from another injector is carrying through the fuel rail.
• Tested injector for ohms. It passed matching all other injectors.
• Next I checked the connector. It was fudged up, but I would get 12v with ignition on. Measured with a multimeter with  1 pin in the injector connector and the other pin in the injector connector and going to a ground on the intake manifold. Thus is is getting current. 
  • Just to be safe I rewired a new connector on. Tested perfect.
• Removed #1 fuel injector 
  • Tested with 12v batt very briefly to see if the solenoid would actuate. It did.
  • it also was not clogged and would spray fuel.
• Checked fuel rail for fuel coming out of #1 injector rail port. Worked perfect with starter signal disconnected and fuel pump on. So no clogs there. Gas looked crystal clear.
• Replaced #1 fuel injector
  • At this point might as well try. It did not help.
• Disconnected both #1 and #2 injectors while car was running. RPM dropped
  • Swapped #2 injector plug to #1 injector. No change in rpm.
  • Swapped #1 injector plug to #2 injector. It improved rpm.
    • however I did this test many times, and sometimes the rpm would not climb. It is not consistant.

So, what the heck is going on here. Is it possible that the ECM is for whatever reason not alternating the ground for cylinder #1? Or is it possible that the #1 injector is firing but angled somehow and completely missing the spark plug. I would like to emphasize that during this process I would check plug #1 consistently and I never noticed it really appear wet. As well as it appearance never changed in general. All the other cylinders have more carbon on them as they are running a bit rich right now. 

Any suggestions are welcomed, thank you!

 

 

 

Edited April 1, 20222 yr by ckurtz2

Well honestly, I'd consider swapping back to the original cam just to make sure you have the rest of the bugs worked out. I didn't know you had the original cam as an option.

If you can get it to run right (under all conditions) with the original cam, then maybe toss the aftermarket one in and see what happens. In other words... Baseline it running well with the OEM and then put in the high lift? At least that way you'll be able to separate cam issues from other issues.

Cam swaps aren't that bad of a job. Just don't drop the timing chain and it's no big deal.

27 minutes ago, Captain Obvious said:

Well honestly, I'd consider swapping back to the original cam just to make sure you have the rest of the bugs worked out. I didn't know you had the original cam as an option.

If you can get it to run right (under all conditions) with the original cam, then maybe toss the aftermarket one in and see what happens. In other words... Baseline it running well with the OEM and then put in the high lift? At least that way you'll be able to separate cam issues from other issues.

Cam swaps aren't that bad of a job. Just don't drop the timing chain and it's no big deal.

Sounds exactly like my journey 15 or so years ago.  I was right where @ckurtz2 is at and I too swapped the original cam back in just to be sure the rest of the EFI was operating correctly.  It immediately ran great and I never looked back.  The cam went into my other Z which I sold last fall.  If I wanted to get more performance now, I'd ditch the L Jet and go with something better.  SU's are getting dumb expensive, so I'd likely go triple Webers or stand alone EFI.  The reality is that I'm pretty immune to power, so I'll likely live with the low power I have.  I've spent the last 27+ years working on performance cars and no matter what power they make, you get used to it after a while.  The last one I worked on was the GT500 at 760HP.  No amount of power I put in the Datsun will make it feel fast after the Shelby, so I won't bother.

Yes, so the original cam is an option, but only because its cheaper than going to a new EFI system (I am ruling out Fast EFI cause it doesn't have that much tuneability). The entire reason I upgraded cams is because I messed up my cam oiler and it destroyed my original cam. The comp cam and original cam were around the same price when switching to an internal oiling cam so I chose the comp cam.

So it isn't really readily available to swap to the original:( online looks like it would set me back several hundred dollars. Unless you guys know where to get a cheap one I really would rather not.

Interesting Jeff. If I could go back in time and go the original cam I probably would now. That Shelby sounds sweet. Anyways, I know the power hunger haha. Long story short I drove a friends a Warrior 302 and stick shift hellcat a lot in highschool. Lots of fun, but almost too fast as to where I would get into "criminal" territory real quick. 

Edited April 9, 20222 yr by ckurtz2

14 minutes ago, ckurtz2 said:

The entire reason I upgraded cams is because I messed up my cam oiler and it destroyed my original cam.

Interesting Jeff. If I could go back in time and go the original cam I probably would now. That Shelby sounds sweet. Anyways, I know the power hunger haha. Long story short I drove a friends a Warrior 302 and stick shift hellcat a lot in highschool. Lots of fun, but almost too fast as to where I would get into "criminal" territory real quick. 

Do you have a N47 head with a spray bar?  If so, that's a pretty rare, but not unheard of.  I have a very early N47 in my car with a factory spray bar.  I've thrown away a bunch of stock cams.  I might even have a spare from a ZX motor that's internally oiled.  I can look around and see what it is.  If you want it, I can give it to a co-worker who lives in South Tempe.

Here is video of me driving a GT350R with "only" 526HP on a race track with a journalist in the passenger seat.  

 

Yes, my N47 originally had just the spray bar, interesting that it is considered rare for my car. Now I am running an internally oiled cam with the spray bar too. If the ZX cam would work I would love to put it to good use! Just set a price. I will see what this weekend brings about when it's at the shop if I end up throwing in the bag on the cam, or if a solution comes along.

That video is badass, the car sounds so good. The track itself looks really fun too.

 

4 minutes ago, ckurtz2 said:

Yes, my N47 originally had just the spray bar, interesting that it is considered rare for my car. Now I am running an internally oiled cam with the spray bar too. If the ZX cam would work I would love to put it to good use! Just set a price. I will see what this weekend brings about when it's at the shop if I end up throwing in the bag on the cam, or if a solution comes along.

That video is badass, the car sounds so good. The track itself looks really fun too.

 

If my ZX cam is good, it's yours.  

The spray bar went away with the introduction of the N47, yet there are a few with that combination.  I might even have a set of block off plates.  It's been so long, I can't remember for sure.

Yes, the GT350R engine sounds incredible at it's 8250 RPM redline.  In that video, I purposely didn't upshift in several places around the track where a higher gear would be faster, but it was more fun to scream it.  That day was close to 100F and we ran the cars all day like that.  Grattan Raceway is a fun track.  I prefer others around the country, but every track is unique and is special in its own way. 

@Jeff G 78

Just saw this. Well, thank you!

Were u able to see if it was good? That's awesome, I love the sound of Ford V8s. The high revving gt350s make it all the better:) 

2 hours ago, ckurtz2 said:

@Jeff G 78

Just saw this. Well, thank you!

Were u able to see if it was good? That's awesome, I love the sound of Ford V8s. The high revving gt350s make it all the better:) 

I haven't gotten to look for it yet.  I might have time tomorrow.  I can't remember where I stored it.  I saw it after the move to AZ, I just haven't seen it lately.  I'm sure it's somewhere that made sense at the time.  🙂

 

On 4/8/2022 at 9:32 PM, ckurtz2 said:

 Now I am running an internally oiled cam with the spray bar too.

Uh no, you're not. You're running an internally oiled cam. The spray bar is there but right now it's just acting as a block-off for the two oil ports that feed it. 

30 minutes ago, cgsheen1 said:

Uh no, you're not. You're running an internally oiled cam. The spray bar is there but right now it's just acting as a block-off for the two oil ports that feed it. 

This makes sense. Lol I just saw the external oiler knowing the cam was internally oiled and figured they were both putting in work. I stand corrected🙃

My early n47 had both. I never saw them actually putting out oil but it had terrible oil pressure on the gauge so I thought they were both working. Never considered the spray bar was used for block off. 9/76 build date.

 

Not really clear what cgsheen1 meant.  The cam towers have to have the ports for the spray bar.  If you run spray bar cam towers and a spray bar then oil will flow to the spray bar.  The cam towers have the passages.

As I understand things, but I haven't actually seen it, only read about it, the cam will accept oil from the cam towers if it is drilled for it.  So if you put a drilled camshaft in a spray bar head you'll get oil traveling both ways.

Can't find anything on carpartsmanual because Nissan considers the cam towers as part of the head.  You can't buy them separately.