misfire after plenum pull

[shuswapz32]

Try the relocate and see what happens. Later on, you can always tackle the 4 hour-ish job to replace the sensor in the stock location. I have mine relocated, and have had no problems.

[solaire]

Got the sensor and harness today. Going to put em in this afternoon and see what happens. I found a broken wire on the EFI harness side of the knock sensor pigtail. I fixed that and I'll attempt to start the car to see if it's fixed. If not I've got parts to do the relocate. The owner took the battery to get me another one since his old one wouldn't hold a charge so I'm kind of stuck until he brings it back. I'll put some jumper cables on it and start the car that way. Not recommended but it'll give me an idea of if it's fixed or not.

[solaire]

Started it with the new sensor put in. It seemed to run better but still felt rough. For some reason I started touching and rechecking coil connectors. #6 was barely attatched, it had backed out. Plugged it in and the car ran smooth. For s*** and giggles i plugged in the old detonation sensor and it still ran smooth so it seems like the broken detonation sensor wire was the main source of my problem along with switching the detonation sensor and cam phaser.

When I get a battery I'll drive the car. For now it idles smooth but idles high when warm. Could just need an adjustment now that it's got new injectors.

Remember for anyone who does a plenum pull the black and green wire goes to the cam phaser and the detonation sensor connector is yellow/black. Both phasers use the same color wires. The other one is plugged into passenger side of the intake so if you're unsure check that one and you'll know what colors to look for.

[t.mcginley.jr]

Good to hear its running smooth now!

Z1 sells a coil pack connector kit for pretty cheap (~$30), you just de-pin your old ones and push them into the new connectors.

http://www.z1motorsports.com/product_in ... ts_id=5001

[solaire]

It is idling high around 1100- 1500 and stumbles and sputters on accel but its smooth if you rev quickly and let out the clutch to rev match on decel. Seems worse under a load. No unusual noises and miss seems worse under 2000 rpm and it struggles to get past 3000 rpm. It does stall occasionally. 1 and 3 are fuel fouled. Coils are dropping a nice blue spark so idk what else to do. What are the odds the piston rings just went out sitting and idling with bad injectors? I may have driven the car 2 miles with the bad injectors? I drove it to work and back and let it idle in the yard a bit diagnosing the problem. Should I look into eliminating the original PTU connectors and straight wiring them?

[t.mcginley.jr]

It is possible, I would do either a compression test or leakdown test to see how healthy the cylinders are. Both testers should be available at any auto parts store for rent (AutoZone, Advanced, NAPA, O'Rielly's, etc.). Compression should be 186-136 for NA and 174-121 for TT. If you do a leak down test (which IMO is easier), cylinder leakage should be 10-15%, anything higher and something is wrong or going wrong (i.e. headgasket, rings, etc.).

Have you already done a boost leak test to see if you can hear any vacuum leaks? Z1 sells the tester for $25-30 I think, you just plug it in where your MAF goes, apply ~5-10psi from a compressor and listen for leaks.

And did we already rule out a bad/dirty MAF and bad/uncalibrated TPS? And/or a bad coolant temp sensor? (Sorry its early and don't feel like reading through all the comments lol)

[t.mcginley.jr]

Well now that I wrote all that I feel dumb, I just saw your post in another thread:

Exept in the case of this car i've replaced injectors and swapped in good coils. Compression on 3 was 0. Leakdown test revealed 81% leakage and the air was whistling out the throttle body so my problem is a bent or damaged intake valve and that's what's killing the other cylinders is the pressure from the combustion chamber being forced back into the intake during driving.

Damn man!

[solaire]

Yea ive been trying to bounce ideas off guys having similar problems. I'm going to do the leak down test again. I may have been just a bit off causing intake valves to be open during test. I had a bore scope in there and the valves looked fine and weird thing is I shined a light down the spark plug hole but couldn't see light with bore scope even with its light turned off so I'm doubting if intake valves are the issue.

[oriZnal]

hey solaire, did u get to the bottom of the problem? im having the same damn issue with my 95 300zx na.

few months back, i replaced all 6 injectors, and it ran fine for a day. next day it threw me a EGR code. I deleted the egr valve, pipes, solenoids and blocked off the vacuum lines and ports. car still runs like its missing.

pulled every ignition coil connectors out while the car was running, only #2 was dead. So i replaced with new, but still same problem. so i pulled the coil with plug, plugged, it was sparking. checked the injectors, all giving me 11~13

ohms. hooked up my modis, and saw the waveform of all 6 injectors and ignition coils, there were all working fine. checked the compression, and they all had 150~155psi. Thought my timing was off, cuz vacuum gauge was showing

lil bit of retard in timing, so took timing cover off, and checked the timing. It was on time of course. While i had it off, i checked to see if the connecting rod was bent on #2. Connecting rod was all the same from 1 2 3 and 4.

got lazy at that point and didnt check 5 and 6.

Checked the o2 sensors and b2 s1 was not responding so i thought ok let me replace it knowing it wasnt the problem, and sure it WASNT the problem haha. i took a step back and checked to see if the plenum was leaking or not

(i've had it done after i replaced the injectors) but SURE was leakin on #2 runner so i was like OK problem fixed!, past saturday i took the plenum off and replaced the gasket. i put it all back together hoping that it'll run like a

champ, but it got WORST!!!! I thought ok, did i f*** up the gasket? did it not seat right? did any of the wires get pinched? and checked my work, but it was perfectly fine, #2 runner wasnt leaking anymore, and no wires pinched

but it was BOGGING!!!!!! by then, i got sooooooooo fed up with the problem. in hand i got, 3 PTU's, 2 MAF's, 3 O2 sensors, 2 TPS', 2 extra coils, i've replaced all of them!!!! ( they are not all new. they were all used) i got 2 300zx's TT

and NA, my co-worker HAD 300zx NA so i had spare parts. WHAT THE F*** can b the problem??? there's no corrosion on connectors. **** one thing i've noticed this past saturday was, if i disconnect 1 vacuum line, just solenoid vacuum,

car actually revs little higher, and runs slightly better, but reguardless, not enough to say ok i fix the problem cuz ITS LEAKING!!!!! HELP ME PLZZZZZZZZ hahahaha ITS SO PISSING ME OFF.

I checked the fuel pressure too, 60 psi. engine codes were all same knock sensor, egr and s***... plz... somebody.... help



edit **** after the plenum was reinstalled, cylinder # 1 2 4 and 6 is not responding... but there's spark, and fuel

[solaire]

I need to run a leakdown test again to know where my compression is going but yours has compression. I'd take a coil off and put it on the intake to see if it's got a good blue spark. PTU connectors can cause spark to get weak, ohm check the wiring from the ptu to #2 coil. Swapping ptu won't help if the sub harness is corroded. Also funny thing did you switch #1 and 2 injector connectors? It is possible. Compare wire colors to a good running car.

[ZL8NING]

So, did you finally put the problem on this car to rest? Did you get to the bottom of this and return the car to the owner? Closure, please.

[solaire]

Did a leakdown test. It's leaking out the intake on TDC #3 compression stroke. I used a borescope and intake valves are open about 1/4" so all that compression is going into the intake killing other cylinders. Also the timing belt makes a flapping noise when you rev the car in neutral. I think the intake VTC sprocket has failed. I'm still stuck with the car but I plan to give it back soon. I don't think I want to mess with the timing belt and VTC sprocket on the car unless I buy it to fix it. He wants $5000 for the car and I"m not goin for that.

We had a conversation about fixing it and he basically said I have to fix the car even if it cost $10,000 (random number) or we're going to court. This whole deal isnt worth the trouble. I havent been payed for my work and everything was in cash with no paper trail or signed legal contract with no witnesses at any time. He can do whatever he wants.

[ZL8NING]

Whoa! What a mess!

[solaire]

Guy ended up picking up the car so I won't get to find out the exact failure. Happy to see it go but not happy about what's getting ready to happen over it tho.

[ZL8NING]

I guess you can't save them all!
Big ups on the effort. Now the owner knows what he is up against when it comes to the 20yr-ish old z32.
I will definitely rely on your posts when I deal with my 93 n/a's sputtering engine.

[solaire]

I talked to the man today. He took it to a local shop that works on euro cars and older imports. They said I didnt have the intake down all the way. That makes no sense because I did it twice so the odds of messing it up are slim and i focused on making sure it was right. I even sprayed carb clean at the gasket on all surfaces after I was done and the car didnt rev. Also i fail to see how a bad intake gasket or gap there could cause no compression on 1 cylinder.

[ZL8NING]

Phew! At least it's out of your hair now!