Issues with my 90 NA Z

[Rastadori]

So I just got check engine light and received these two lights

11: crank angle sensor circuit
32*: EGR function

Ive never messed with any of these things and never heard of how to attempt to fix them. My question is, how hard is it and cost to replace parts? Would you recommend i do it myself? the only things I ever done to my Z myself has been spark plugs, filters, fuel pump.

[DCaff300ZX]

Quite possibly these two are popping up due to corrosion of their connectors (common), or a broken lead or scorched harness wires (EGR). The CAS connector is easy to check, the big connector on the round silver "cap" on the right front of the motor. Remove it carefully and if it has green crud in it, that's your issue- clean it well with contact cleaner and toothpicks/rags, and reassemble using di-electric grease.
If this is the case, you will need to inspect the EGR connector and harness, which commonly gets corroded as well as scorched and brittle back there, and is a good idea to replace with an upgraded harness from Z1 or CZP or Specialty Z.
Finding corrosion also means that many of the rest of your engine connectors will have the same problem, and be ready to cause you a code and/or driveability issue...so spend some time checking them all out.
Downloading the osm here for testing procedures and diagrams, etc. is also a must for DIY work on your old Z32...Good Luck!

[Rastadori]

I turned on the car today and the light went off on its own. I'm going to assume its really dirty and tbh my engine bay is disgusting, I have no idea how to properly clean it.

[z.Leinbach]

I'd get some good quality degreaser. And a pressure washer. And have some compressed air

[rgregoryb]

Pressure washer and 300zx, bad idea

[Rastadori]

I still haven't cleaned it but a new issue came up Sorry guys but lets see if you guys can help

a few months ago my car would stall in and die out, it would crank but not start for a few minutes. I was told by people here to check out the fuel pump since its pointing in that direction. my gauge didnt work either to read fuel. I replace the pump with an OEM one and the whole unit. My gauge works now and car runs. My issue now is, whenever I run the car in high revs. lets say 4000rpm and higher, the car will try to stall again. sometimes it catches itself when i let go of the gas and wont stall, but sometimes it stalls completely and i have to pull out to the side. usually with my old fuel pump id have to wait forever for it to cool down, this time, i just turn the key completely off, wait 20 seconds, hear the pump and it turns on again. so I have a feeling that my new issue with fuel at high RPMs is not with my fuel pump. any idea of what it may be? I haven't done anything to this car besides fuel pump/filters/spark plugs and oil. Maybe bad injectors?

as of right now i can drive the car, but i never try to have fun with it since i cant really get past 3500rpms until the car dies. sometimes i hit 4500-5000 and its fine, other times it doesnt. its a hit/miss type of thing.

[elecfus]

dont clean it. it's a really really bad idea. Z32's get really hot. so hot that they basically burn up all the wiring. I've replaced injector wiring nowhere near the turbos that had turned completely brown. made reworking the wiring ever so incredibly fun with no color codes to go off. not to mention the connectors get so brittle with the heat that changing an injector, if you can get at it, means finding then rewiring a new connector on everything you disconnect to the get the plenum off as they disintegrate in your hands.

your car is cutting out at high revs and the idiot lights are coming on randomly. think what is happening at high revs. the engine is vibrating more, shaking the wiring, maybe even kicking back a fair bit when you punch the throttle if your engine mounts arnt in good condition. all of this moves the wiring around. now they did a good job over at nissan but they never expected anyone to still be driving these beasts around on the road with the original wiring harness 20 years later. Dcaff has the simple solution. you might be able to find a corroded ground wire or replace a bad wire here or there for now, which might seem like the easy way out but electrical problems are going to start cropping up and you're going to want to deal with that before you need to do any other work on it. a dodgy connection can fry components and some of those components arn't cheap. I like to think of it like how you should disconnect your battery before doing any electrical work. we all know this is a good way to avoid frying things. only right now, your wiring harness is randomly disconnecting and connecting components with the battery connected on a constant basis.

As for the EGR, the light will come on if the ECU senses a bad fuel burn it cant correct. it's not a light for the EGR valve but rather for the exhaust gasses the car is emitting. A Z32, like most cars are programmed to not start if there is a fault in the crank angle sensor circuit. In the old days the distributor was geared to a cam or the crank and this is how it knew when to fire, as the distributor turned in time with the engine. the crank angle sensor lets the ECU know when to fire and when to rain fuel as one of its many inputs. fix what's going wrong with the CAS and the EGR light will go away.

[Rastadori]

dont clean it. it's a really really bad idea. Z32's get really hot. so hot that they basically burn up all the wiring. I've replaced injector wiring nowhere near the turbos that had turned completely brown. made reworking the wiring ever so incredibly fun with no color codes to go off. not to mention the connectors get so brittle with the heat that changing an injector, if you can get at it, means finding then rewiring a new connector on everything you disconnect to the get the plenum off as they disintegrate in your hands.

your car is cutting out at high revs and the idiot lights are coming on randomly. think what is happening at high revs. the engine is vibrating more, shaking the wiring, maybe even kicking back a fair bit when you punch the throttle if your engine mounts arnt in good condition. all of this moves the wiring around. now they did a good job over at nissan but they never expected anyone to still be driving these beasts around on the road with the original wiring harness 20 years later. Dcaff has the simple solution. you might be able to find a corroded ground wire or replace a bad wire here or there for now, which might seem like the easy way out but electrical problems are going to start cropping up and you're going to want to deal with that before you need to do any other work on it. a dodgy connection can fry components and some of those components arn't cheap. I like to think of it like how you should disconnect your battery before doing any electrical work. we all know this is a good way to avoid frying things. only right now, your wiring harness is randomly disconnecting and connecting components with the battery connected on a constant basis.

As for the EGR, the light will come on if the ECU senses a bad fuel burn it cant correct. it's not a light for the EGR valve but rather for the exhaust gasses the car is emitting. A Z32, like most cars are programmed to not start if there is a fault in the crank angle sensor circuit. In the old days the distributor was geared to a cam or the crank and this is how it knew when to fire, as the distributor turned in time with the engine. the crank angle sensor lets the ECU know when to fire and when to rain fuel as one of its many inputs. fix what's going wrong with the CAS and the EGR light will go away.

Thank you for a very detailed explanation. So first things first, I will check my CAS to make sure the wires look like they are in proper shape. If everything looks good and still get the code, I may replace it as I can get the part for 70 bucks, rather not risk it and replace it with a fully working one. So I will tackle that first for sure. Thank you, I'd like to rev to 5k+ every now and then

[elecfus]

make sure you get the full unit not just the sensor module. things like distributors and CAS units tend to fail due to the worn bearings generating heat that cooks the sensor. i'm pretty sure you need a timing light to install them as well. it's also far cheaper to buy the Mitsubishi Lancer EVO TPS plug than it is to buy the z32 CAS plug if you decide it warrants replacing.

[Rastadori]

Alright so i started the car and then i was checking to see if everything was fine. The moment i touched with my finger the connector to the cass. The plug, the car turned off. So im assuming its not my cass but the connector or something? I dont see any dirty corrosion or anything

[elecfus]

you can disassemble the connector to check it more thoroughly. remove the retaining clip on the back. gently push the wires towards the pin side just enough so the barb isnt catching through the plug then use a pin or small tool to depress the retaining barb on the pin then gently pull the wire out. it should come out smoothly if you depressed the pin properly with no resistance. careful the barbs are sensitive and if you fold it over it can snap off then the pin wont sit right again. take photos for reference to color codes of the wire positions.



better illustration of pin barbs but the z32 connector only has one of them, not one on both sides.


clean the connectors with phosphoric acid. also called battery terminal cleaner or rust/lime/scale remover in home cleaning products.

[Rastadori]

oh wow. I hope i can do this. This seems a bit advance for a newb like me. Thank you, will try this tomorrow morning

[Rastadori]

Okay. Cleaned it out, car was running, drove it for a bit and revved it hard as hell. 5k rpm like all day. drove it i want to say for 100 miles, all good. ill get a more update in a day or two

also, since its "fixed" at least imo since it doesn't stall and i can rev all i want and when i touched the sensor, do I have to hard reset the codes on ECU?