# Car is going wacko!!!



## Denass121 (Sep 16, 2005)

I was driving on the highway yesterday going to work when all of a sudden at around 65mph my RPM's go haywire then drop to 0 and car totally shuts off. I still have battery power but it then wouldnt start. Like it wasnt getting gas. I let it sit for a min, then tried to start it up and it started right up, i got about 30 feet and shit started all over again. I called AAA and had it tow'd to my mechanic. He took it out for a test drive and said everything was fine and he had it up to 90 mph. Today i go to work, same deal went wacko at around 60-65 mph soon as i got on freeway and rpm's went crazy. I dunno what the hell it could be, i'm guessing ECU? Seems like some kind of electrical problem. ANy help is appreciated.

84 NA 300z


----------



## Denass121 (Sep 16, 2005)

No one knows huh?


----------



## JAMESZ (Mar 12, 2004)

A battery cable could be loose. Need more info...

What do you mean the RPMs went crazy? If the car is in gear and at a constant speed the rpms will not change.


----------



## Zen31ZR (Mar 24, 2004)

The tach might go nuts if its an electrical problem. Kinda sounds like a bad ground connection or a shorting power wire. Who knows, there might be a smalll vibration at 60-65 mph that causes it to happen, that may not be there at 90 mph. A smart mechanic would test the car at all speeds, not just *fast*...... Tell him to go at around the speed you are getting these problems and see what happens.


----------



## Madmaxfl (Oct 22, 2005)

How long has it been since you changed the fuel filter. Symptoms indicate this could be a problem.


----------



## Denass121 (Sep 16, 2005)

I last had a tune up in September and "supposedly" the fuel filter was changed. I'm gonna take it to the shop tomorrow. My girlfriend's borther is a mechanic and said it could be the fuel pump, i just dont understand why the RPM's would fluctuate at around 60-65 unless like he said above its a shortage. I might be wrong but doesn't the car shift into 4th gear at around that speed? At 65 i sit around 2500 RPM's. Its wierd, it's fine till i get going then engine cuts off like its getting no gas, cant start it right up right after it dies either. I gotta wait like 30 seconds. The RPM's don't go higher either, they drop, then go back up a little then drop again, then back up a little then down to 0 and engine is off.


----------



## Zen31ZR (Mar 24, 2004)

Fuel pumps don't generally cause problems like that, they either work or they don't. I'd say that possibly its an ECU or a distributor problem. In any case, it's highly likely that it may be an electrical problem. If it is a fuel pump problem, it sounds like the relay is overheating. That may, again, indicate some sort of short in the system.


----------



## WhymyZ (Dec 27, 2005)

Denass121 said:


> I was driving on the highway yesterday going to work when all of a sudden at around 65mph my RPM's go haywire then drop to 0 and car totally shuts off. I still have battery power but it then wouldnt start. Like it wasnt getting gas. I let it sit for a min, then tried to start it up and it started right up, i got about 30 feet and shit started all over again. I called AAA and had it tow'd to my mechanic. He took it out for a test drive and said everything was fine and he had it up to 90 mph. Today i go to work, same deal went wacko at around 60-65 mph soon as i got on freeway and rpm's went crazy. I dunno what the hell it could be, i'm guessing ECU? Seems like some kind of electrical problem. ANy help is appreciated.
> 
> 84 NA 300z


We are experiencing the same problems with ours. Cold weather and the car is a dream.


----------



## Denass121 (Sep 16, 2005)

If you figure it out let me know. I took the car to my mechanic. Hopefully they figure out the problem.


----------



## WhymyZ (Dec 27, 2005)

*Found something that might help you*

After reading the Haynes manual and reading several other messages I pulled the passenger side kick panel off of the demonic beast. The ECCS self dianosis was a major help. Hopefully the ECU (that is what everything is pointing towards) is alot cheaper than the mass air flow sensor that I was told would effect the car more at start up than after driving. The manual is pointing in the direction of one of the load signalcircuits( a/c power steering or radiator fan being OPENED? or the ECU is malfunctioning. Hope this helps and if it does please let us know.


----------



## Denass121 (Sep 16, 2005)

Cat converter was the problem. $404.00 to replace it. :O( I would tell him to put a striaght pipe on it but i don't think i could get through inspection with that.


----------



## Zen31ZR (Mar 24, 2004)

Converter has absolutely nothing to do with the problem you were having. Not to mention its fairly obvious if the converter were totally clogged your mechanic would not have been able to get the car up to 90 mph....... I had an 90 Mustang with the 302, 225 Hp, and when the cat was clogged the car has problems getting to 60 mph.... No way the cat is not going to cost $400. No place I went to around here could get cat installation up that high, even if I got a stainless 4" high-flow cat.
I smell a rat.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Zen31ZR said:


> I smell a rat.


haha one of my buddies fired up his MR2 the other day and after a speed run we pull over and smelt something burning..........mmmm rats nest on turbo housing


----------



## Denass121 (Sep 16, 2005)

Well the day i took it in to the shop i couldnt get the car passed 45, and the smoking got worse. I dunno what else to do, kind of stuck in a hard place, i need my car to get to and from work. If it doesn't fix the problem then they will just have to fix it again but for free lol cuz i aint paying. Luckily the guy fixing it lives across the street from me, so if anything goes wrong i know where to find him heh. I'm prolly getting ripped off but not like i can do anythign else.


----------



## ICP Sux0rZ! (Jan 10, 2005)

u coulda bout a running old skool VW bug for what u paid for that cat and used that until u got the Z back up



mmm VW back up cars rule


----------



## Denass121 (Sep 16, 2005)

lol true, i'm sure i'm paying for the labor more than the part, i live in jersey, everything is a rip off


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> Well the day i took it in to the shop i couldnt get the car passed 45, and the smoking got worse. I dunno what else to do, kind of stuck in a hard place, i need my car to get to and from work. If it doesn't fix the problem then they will just have to fix it again but for free lol cuz i aint paying. Luckily the guy fixing it lives across the street from me, so if anything goes wrong i know where to find him heh. I'm prolly getting ripped off but not like i can do anythign else.


So its smoking? You didn't mention that before....... If that cat is clogged, there is another problem. Emissions equipment is expected to and required by law to last 100,000 miles. If it has not, there is another problem. Cats don't clog up for no reason. The typical reason is, that the engine has been running too rich for a very long time. Cats clog up because they get too hot and melt inside, caused by running too rich.


----------



## Spongerider (Nov 18, 2002)

Denass121 said:


> Well the day i took it in to the shop i couldnt get the car passed 45, and the smoking got worse. I dunno what else to do, kind of stuck in a hard place, i need my car to get to and from work. If it doesn't fix the problem then they will just have to fix it again but for free lol cuz i aint paying. Luckily the guy fixing it lives across the street from me, so if anything goes wrong i know where to find him heh. I'm prolly getting ripped off but not like i can do anythign else.


One way to test if the cat is bad is taking off the cat and running the car on the street. If your problem goes away then it's the cat.


----------



## Denass121 (Sep 16, 2005)

Yeah the car does run really rich, i thought it was fixed though after i got a tune up, the cat was smoking on the day i took it to the shop, exactly how you said , it was melting and smelt bad. Now if i get it replaced is it gonna happen all over again? The car is at 107,000 miles. So i guess it did last 100k miles.


----------



## ICP Sux0rZ! (Jan 10, 2005)

something is causing your ecu to see a lean exhaust code, i'd have ur 02 sensor replaced

but the only way to melt a cat is to either have the plugs wires messed up or be running to lean


----------



## ICP Sux0rZ! (Jan 10, 2005)

Zen31ZR said:


> So its smoking? You didn't mention that before....... If that cat is clogged, there is another problem. Emissions equipment is expected to and required by law to last 100,000 miles. If it has not, there is another problem. Cats don't clog up for no reason. The typical reason is, that the engine has been running too rich for a very long time. Cats clog up because they get too hot and melt inside, caused by running too rich.


*cough* lean is hotter *cough*


----------



## Denass121 (Sep 16, 2005)

My 02 sensor was replaced when i got a tuneup.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Denass121 said:


> My 02 sensor was replaced when i got a tuneup.


might be a bad sensor, jsut cause they replace it doesn't mean it works, the connectors for it might be dirty and its sending bad signals


----------



## Denass121 (Sep 16, 2005)

Well is the Cat gonna last for a while or is it gonna burn up again right away? Cuz i won't be able to get the 02 replaced for another cpl weeks. This Cat is gonna break my pockets after its done. I'm gonna get my Thermostat replaced as well. I'm tired of driving with gloves and a wool hat.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Denass121 said:


> Well is the Cat gonna last for a while or is it gonna burn up again right away? Cuz i won't be able to get the 02 replaced for another cpl weeks. This Cat is gonna break my pockets after its done. I'm gonna get my Thermostat replaced as well. I'm tired of driving with gloves and a wool hat.


it wont die right away, just drive slow and dont beat on the motor


----------



## Denass121 (Sep 16, 2005)

ICP Sux0rZ! said:


> it wont die right away, just drive slow and dont beat on the motor


Since the Cat was clogged, do you think my engine power has been restricted for a while? I just got this car in June, it runs great but i'm wondering if it wasn't running to its potential all this time cuz of this Cat.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Denass121 said:


> Since the Cat was clogged, do you think my engine power has been restricted for a while? I just got this car in June, it runs great but i'm wondering if it wasn't running to its potential all this time cuz of this Cat.


could be.....


----------



## Zen31ZR (Mar 24, 2004)

ICP Sux0rZ! said:


> *cough* lean is hotter *cough*


*cough* unburnt fuel causes the cat to overheat *cough* As in *Rich Condition*. Or possibly a lean misfire, which will still cause much unburnt fuel to be passed to the cat. In either case, the cat is attempting to ingest and burn far more raw fuel than it was ever designed to.


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> Yeah the car does run really rich, i thought it was fixed though after i got a tune up, the cat was smoking on the day i took it to the shop, exactly how you said , it was melting and smelt bad. Now if i get it replaced is it gonna happen all over again? The car is at 107,000 miles. So i guess it did last 100k miles.


If the engine was running properly, I've seen cats last to 300,000-400,000 miles. Basically the cat should be good for the life of the vehicle, if the engine is kept in proper tune. I used the 100K as an example. And yes, unless you get the initial problem fixed, the one that caused this in the first place, it *will* happen again.


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> I'm gonna get my Thermostat replaced as well. I'm tired of driving with gloves and a wool hat.


I think this is possibly the cause of your problem right there. If the engine never warms up, it will constantly run rich. The ECU thinks the engine is not warm, as in like it just was started, and so is making the injectors spray a lot more fuel than they need to.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Zen31ZR said:


> *cough* unburnt fuel causes the cat to overheat *cough* As in *Rich Condition*. Or possibly a lean misfire, which will still cause much unburnt fuel to be passed to the cat. In either case, the cat is attempting to ingest and burn far more raw fuel than it was ever designed to.


*cough* i know *cough* i took a class that dealt only with the emissions of a motor vehicle, i forgot about the unburnt fuel, thanks dad


----------



## Zen31ZR (Mar 24, 2004)

ICP Sux0rZ! said:


> *cough* i know *cough* i took a class that dealt only with the emissions of a motor vehicle, i forgot about the unburnt fuel, thanks dad


You're welcome, sonny.


----------



## Denass121 (Sep 16, 2005)

So when i replace the thermostat the ECU will recognize the engine temp and regulate the fuel injection? I'm learning guys. You guys are awsome teachers. :O)


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> So when i replace the thermostat the ECU will recognize the engine temp and regulate the fuel injection? I'm learning guys. You guys are awsome teachers. :O)


The early model ECU in these cars doesn't recognize engine temp so much, as the differences between how efficiently the engine runs warm vs cold. O2 sensor readings are different, there's more blowby when the engine is cold, so air intake readings are different etc etc. The ECU is seeing the engine as being cold by these readings and is reacting accordingly. Without the thermostat engine temperature probably isn't even reaching 150 degrees, so the ECU is basically stuck in warmup mode, making the engine run rich (cold engines require more fuel to run, as a lot of it re condenses in the intake runners and isn't useable for combustion. The unburnt fuel also washes down the cylinder walls, removing the oil film and causing excessive wear) because it sees the engine as being cold, even though you may have driven it for an hour. Typical engine warm-up is 5 minutes tops under driving loads, maybe 10 minutes idling. The catalytic converter can handle the load of unburnt fuel for that period of time and burns off the excess when its completely warm, but can't for the equivalent of hours at a time..... Your gas mileage has probably dropped like a rock as well, and at this point engine wear is high, There's also probably a lot of gas in your oil, and gasoline isn't the greatest lubricant...


----------



## Denass121 (Sep 16, 2005)

Damn, i'm gonna have to get that thermostat changed ASAP, plus a Oil change. Since ive had this car since June and since it was hot out the car would get warmed up pretty well *halfway point* or a little less. Soon as it got cold out it wouldn't even get close to being as warm as it should. After i get the CAT and Thermostat changed is there anything else i should do?


----------



## ICP Sux0rZ! (Jan 10, 2005)

Denass121 said:


> Damn, i'm gonna have to get that thermostat changed ASAP, plus a Oil change. Since ive had this car since June and since it was hot out the car would get warmed up pretty well *halfway point* or a little less. Soon as it got cold out it wouldn't even get close to being as warm as it should. After i get the CAT and Thermostat changed is there anything else i should do?


stop spending money save some, get an old bug use that as a DD and take the Z to a nissan or Z shop and have them diagnos it


----------



## Denass121 (Sep 16, 2005)

I hope your kidding lol. I'm not driving a damn BUG hehe If anything i'll keep driving my grandfathers truck. I can get a guy i know to put the thermostat in for me for a 30 pack of beer lol I'm thinking about selling it for around 4k after everything is done and getting a later model w/turbo. I really want leather seats too and a stick shift. The car only has 107k miles on it, paint isnt bad, few rust spots on wheel wells. Carpet is stained alot though in the back but i got a friend who does car carpets who could get them out easily. Outside color is black,inside tan. Pretty clean under the hood too. I bought it for 1k off my sis's boy friend cuz they moved. So far ive put 1k into it. When i throw it up for sale i'll let you guys know before hand and put some pics and more info up.


----------



## chillow (Aug 18, 2004)

GOod luck selling it for 4000.


----------



## Denass121 (Sep 16, 2005)

After everything is done, it'll be worth 4000. I was offered 3000 when i first got it.


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> Damn, i'm gonna have to get that thermostat changed ASAP, plus a Oil change. Since ive had this car since June and since it was hot out the car would get warmed up pretty well *halfway point* or a little less. Soon as it got cold out it wouldn't even get close to being as warm as it should. After i get the CAT and Thermostat changed is there anything else i should do?


I'm assuming you've gotten a comprehensive tune-up done? Plugs, wires, cap, rotor, air filter, thermostat (obviously not done), radiator flush, oil change, trans fluid/oil change, new battery. At that age the car is, this should all be done at least once a year (except the battery and T-stat), no longer then every 2 years. Hopefully you change the oil more than once a year.......


----------



## Zen31ZR (Mar 24, 2004)

Denass121 said:


> After everything is done, it'll be worth 4000. I was offered 3000 when i first got it.


Don't expect to recover much money from doing general maintenance. My 85 Turbo was right about $3000 when I bought her, at 167,000 miles. 5-spd and turbo, it was worth a touch more than yours, I think. And it was in perfect running condition with almost no issues beyond minor neglect. Depends on where you live, and how good a shape the car is in, but don't expect to get more more than $3000, maybe a bit less. If you want to see my car, look in the gallery under my name.


----------



## ICP Sux0rZ! (Jan 10, 2005)

Zen31ZR said:


> Don't expect to recover much money from doing general maintenance. My 85 Turbo was right about $3000 when I bought her, at 167,000 miles. 5-spd and turbo, it was worth a touch more than yours, I think. And it was in perfect running condition with almost no issues beyond minor neglect. Depends on where you live, and how good a shape the car is in, but don't expect to get more more than $3000, maybe a bit less. If you want to see my car, look in the gallery under my name.


RIP Zens Z


----------



## chillow (Aug 18, 2004)

plus his is a non T. good luck in your car though sometimes they can give you a hard time but there easy to work on. im pretty sure you wont be gettin 4000, or even 3000.


----------



## ICP Sux0rZ! (Jan 10, 2005)

$5 says he gets around $1000-2000 MAYBE $2500


----------

