Have been fighting this issue for a while now and I have some odd circumstances around it to try and figure out as I want my daily driver to be driveable before winter.

Car will be really hard to start taking at least 10-20 seconds to go with a lot of backfiring and a rich fuel smell. Once started it drives and idles perfectly and pulls really nice.

This just started happening this last month or so. The car has been gone through this year to replace a lot of out of spec sensors.

I have replaced in the last 2 years.
JWT Ecu (just for fun)
MAF (out of spec)
Front CPS
Side CPS (on side of transmission)
Camshaft position sensor (was soaked in oil and specced out wrong)
Alternator (stupid autozone one failed and got a new on on warranty)
Starter (because of this issue my oem nissan 10 tooth was replaced with a napa rebuilt)
Just put in a new clutch (oem nissan) about a month before this started happening.
Put in 4 gauge ground wires to the starter and alternator to try and make sure it wasn't bad grounds causing this.
Also put on a new ground to battery cable as the old one was corroded.

Some of the things I noticed/bother me. Car is running at like 13.0 volts when on which makes me think the alternator or charging system is off.

Car gives me a CPS sensor code although the other posts I have read that this is a result of the problem as it reads the correct voltage and ohm's out fine.

Running out of ideas here and part of me just wants to light this thing on fire and go and replace it as I need it to run before winter.

 

Bad CPS will lead cause the problem you're having, when my T-Ring was off, I had the exact same problem... Car isn't timing the sparks right not burning up all of the fuel...

Have you replaced the harness to the front CPS? Could help....

Since we're on the issue of poor ignition, coil packs? Done anything about those? Spark Plugs?

Can't speak much on the battery charging issue, sorry.

 

Have not replaced the harness to the CPS, I have replaced the sensor. Will have to go back and check to see what it is seeing voltage wise.

Spark plugs were replaced as they looked black/rich. Coil packs work fine once on etc so I haven't seen a need to check them.


I did have my flywheel machined. Is it possible something happened with the timing ring?

 

sounds like bad timing

 

Very possible.

Take out the flywheel inspection plate and take a look see from both angles, take out the fuel pump fuse (under the steering wheel fuse box) and the EMA fuses 1 and 2 (Under the hood on the right side), and crank away, look at the teeth on the trigger ring (what the CPS reads), the ring should be straight and not bent missing any teeth.

 

have u tried adding a ground from negative battery terminal to the tranny housing.

This has been documented many times on the org. Anytime u separate the tranny from the engine, u must completely clean mating surfaces or u will have grounding issues/hard starts.

 

Will do, will also try putting a ground to the bellhousing although I think I have an 8 gauge one already.

 

i used 4awg for all my grounds.

8awg should be cool, but idk definitively. The wire for the ckps is only 12awg or 16awg.

 

Hard starting and overly rich could be ECT.

 

Yeah had that happen on my 300zx. But this one is showing the proper temps in Nistune when I hook up my consult cable to the car.

I was able to pull the viewing area and the timing ring is there. Bugs were chewing me up alive so waiting until I can finish the Z and get this in the garage to take a real look at it. Just need to confirm that the damn thing is getting a signal from the timing ring.

 

when replacing the clutch, did you thoroughly clean the mating surfaces before bolting everything back up?

test coil packs
check fuel filter

 

Did not clean the mating surfaces. Never knew it was that big of an issue as every other job I have done it hasn't been. I ran a ground to the body and to the transmission to try and account for this.

Might just pull the damn transmission again and do that if it comes down to it.

 

in most cases, add a ground wire from the neg battery terminal to tranny bolt will cure hard starts. In extreme cases i have hrd of ppl pulling the tranny to clean mating surfaces

 

Either that or add grounds... Silly nissan... To this day they still only have 3 grounding points on most of their vehicles...

 

if you're running on 13 volts then your alternator might be going out. I know mine went out this morning so I get to stay home today(drive to work is too far to make it to work on just battery) and take it apart and go get my 4th alternator for my car this month! autozone SUCKS.

 

This is what ultimately happened to me... i have tested every single wire in my engine bay and all my sensors, have added multiple ground wires and have gone through many starters trying to figure out what the f happened to my car. i have come to the conclusion that my hard start, and yours because it is identical to mine, is due to an improper ground of the mating surfaces.

my tranny is leaking and needs to be tended to so im waiting until i have to to r&r mine. if you end up unbolting and cleaning, PLEASE post your hard start results.

once i find an lsd i'll post my results. good luck

 

honestly you probably have the issue with sanding down the bellhousing on the trans. This seems like what was happening to me. It was crank and crank, make crazy popping noises out of my exhaust then finally start with a big cloud of fuel coming out my exhaust

 

sounds like my daily ritual, hahaha

taking my car in to the tranny shop on monday to get a leak checked, let's hope they can fix it for cheap!

 

Well spent yesterday pulling the transmission and I found this.




Cleaned it up with a dremel and put her all back together about 4 hours later. She starts up on the first turn now. Also cleaned up the engine block where the ground meets the engine block and that was all corroded also. I still maintained the extra grounds I had setup. Now to spend some time getting all of those plastic undertrays to fit underneath her again. Lots of drilling and zipties will be required. Oh how I love Chicago salt.



Only highlight of this being broken most of the summer is I was driving my fun car.

 

Glad to see you fixed it. I was going crazy when this was happening. Looks like your axle seal was leaking did you replace that? btw nice Z any mods?

 

I replaced the axle seals about a year ago. If they are leaking again I didn't notice and didn't have access to the parts anyways. At this point I just need the damn thing to hold together for at least a year. Car has 193k miles and has been through 8 years of being parked outside in harsh chicago winters. Autocrossed it this summer before all of the stupid stuff happened with the starting.

Z is more modified than I would have hoped. Hoping to hit 400-410hp this spring on pump gas with stock turbos. Just a fun cruiser for now. Looking for a project Datsun when I get some garage space.