Need help with Z32 300ZX please!

[StigZXTT]

Hello everyone,
I just joined Nico, so I'm just learning how to use it and post and things like that, very happy to be a member though! I'm very sorry to have to start off on here with a problem I'm having with my Z32 300ZX, but I have quite few questions that I need help with.

I have a 1990 300ZX that I just very recently finished converting to a twin-turbo. After about 2 weeks of driving I noticed that it started safety boosting. So just before last weekend, I ran the codes and found the dreaded code 34 for the detonation sensor. So my question for that is, what are your guy's thoughts on relocating the det sensor to a spot on the upper plenum? I really don't want to have to have my mechanic tear the engine apart or remove it for that matter to change it if it's viable to relocate it. The other code I got at the time was 13 for coolant temp sensor, and given we put on a brand new engine harness before dropping the motor in, I'm guessing the connectors are clean, so I'm guessing just go ahead and change the sensor?

The last thing is, after I ran the codes on the ecu, when I would try to start it up, I turned the key, all the required lights came on on the dash, but the starter wouldn't go for a second or 2, then the starter would go and it fired right up, and it hasn't failed to start since then, it's just paused every time before the starter did anything. I ran codes again today, pulled 13 and 34 (was kind of expecting that, although over the weekend it ran absolutely perfect, full boost, no weirdly high idle or anything), but also pulled code 11 for the CAS. What are some symptoms of a bad CAS? Is the slow to react starter one of them or could that be a failing starter relay or something to do with the PTU possibly? My TT engine has the older style PTU I'm pretty sure. If it's the CAS I should be able to use the one off of my '90 n/a motor right? My TT motor is as far as I know a '92.

Any and all help and tips are greatly appreciated! And I'm glad to finally be a part of the NICO club!

[BigTDogg (MA)]

Welcome to Nicoclub!

1) Bypass the sensor, IMHO. I'd search for det sensor bypass if I were you. I'll check myself later and if I can find a link I'll post it. Relocating doesn't do anything, especially since it's most likely the harness that's bad.

2) Check for corrosion on the sensor connector (on the sensor itself) before swapping it out. They may just need to be hit with a wire brush to be cleaned up.

3) You can swap a 90-93 CAS without issue. IIRC, 94 or 95 is when they changed the connector. I'd suspect your starter relay before the CAS issue.

11* Camshaft Angle Sensor circuit (CAS) Either 1° or 120° signal is not entered for the first few seconds of engine cranking.
Either 1° or 120° signal is not input often enough while the engine speed is higher then the specified RPM. Harness and connector (if harness and connector are OK, CAS might be bad)

from here

[StigZXTT]

Eh, I'm don't really want to bypass it because I'd like to have a fail safe sorta thing in case it really detonates. My TT motor has a completely brand new engine harness, so I could just change the detonation harness, plug it in to the detonation sensor plug in the engine harness and relocate it then right?

As far as the other sensors go, I've got to think my mechanic cleaned all the connectors on the sensors themselves, as I said the harness is brand new, so the connectors on the wiring is all good. But I'll definitely check them before replacing.

Also I cleared my codes yesterday and drove it for about 30 miles, appeared to run fine, I'm going to check codes again in a little bit. The CAS currently in the engine looks pretty old and ragged, so I'm glad I have a working one in my old engine if it needs to be changed.

I'm definitely goin to further investigate the starter relay, thankfully those are cheap to buy and easy to change.

[StigZXTT]

Ok just checked the ecu codes again, only got 11 and 13 now. But I suspect I could have an intermittent det sensor issue (ie it's beginning to fail or its sub-harness is bad), I'll be looking out for any safety boost when I go drive it later tonight.

[BigTDogg (MA)]

I said to bypass it because mounting on the plenum doesn't do anything. Unless you were to mount it to a bolt holding the upper plenum to the lower plenum, and even then the effectiveness of the sensor is greatly compromised. You can relocate it if it makes you feel better, but it's not really doing anything at that point.

Here's a link to rebuilding/cleaning the CAS

[StigZXTT]

I do see your point, and that was where I was thinking of mounting it. Anyways this would probably be temporary until I had a much more serious reason to open up the engine, and then I'd just put it in the factory location.
Thanks for the link though btw.

[BigTDogg (MA)]

No prob, glad to help. If you weren't in Cali you could eliminate your EGR and mount it back there. But unless you know someone at inspection time me thinks that wouldn't work so hot for smog.

To remove the lower plenum you need to remove the timing belt as well, so when your 60K or 120K is due, that's a good time to plan it.

[StigZXTT]

Yes I would like to be able to get rid of it, but CA emissions laws suck a**. Lol. You gotta have a carb sticker displayed for any mod besides like a cat-back exhaust, oh well. I'll probably plan to do it with a 120K, we did the 60K during the TT swap, unless I decide to upgrade some fueling stuff when I decide to get a JWT ecu, then I'll change it earlier. Good thing I'm going to put premium octane gas in every time. Thanks for your help man!