check engine light/idle flucuation/stall but auto restarts

[dudewtf]

ok so i fixed my car by replacing my MAF sensor. the car ran perfect for two weeks until we had huge storm with heavy rain and wind, drove it to work once in that weather.

as i drove home that night the weather was fine(no rain) i was at a stop light and as the light turned green i pressed the gas but my car did not move, i hit the brake and tried again and it worked.


instance 2:
two days later i drove my zx to work(about 7 miles) and when ever i stopped at a traffic light the RPM's would drop danger low at the little line right after zero.

then the RPMs kicked back up to 1k then back to danger low and so on till the car just shut off like i had turned the key off, it didnt stall just shut off.

so i restarted the engine and the car started up like nothing happened for about 1 min then it repeated. the RPMs dropped danger low then kicked up to 600rpm then down to 300rpm then the check engine came on.

instance 3:
started the car again 6 hours later and the car seemed fine but the rpms are totally different. the car used to idle at 1500rpm on a cold startup and idle down to 1k-800 when warm in PARK. once put into R or Drive they dropped to 700?

now the car starts up at 1200 and almost instantly goes down to 700 - 600rpm and when put in R or Drive will drop down to what i think is 500rpm or lower.

the car is also a little shakey now. not to bad but noticeable


anyone have any imput as to wtf happened to my baby?

also anyone know the correct rpms for a 1990 NA?

thanks!

[es.biggs]

Pull ECU trouble codes...the check engine light is on so the ECU definitely has at least one code stored. Just search for the proper procedure it's been covered a lot and it's easy.

Get very familiar with this thing - the FSM. It shows you how to diagnose and repair everything on the car. It takes a while to find things in it but it's a priceless resource. It has specs such as, the correct idle speed for a 1990 NA automatic like your car. I can't remember exactly where it should be but 700-800 is a healthy target. The FSM has the exact speed it should be at.

Once you pull codes, that will make it a lot easier to figure out what's going on in there.

[dudewtf]

yeah i was going to pull the codes today but the check engine light turned off but instance 3 was still happening without the check engine light on.

can i still check for codes that would be related to this issue?

oh yeah also a few times the car tried to shut off but automatically restarted itself. maybe its f*** low jacked haha.

[es.biggs]

You can still pull codes bud

[A Paratroopers 300zx]

Well, the idle problems lead me to believe that the IACV system isn't functioning properly. May just be dirty. The purpose of the system is to provide an air bypass for the intake tract on a cold start so that the car can have a faster idle to get everything up to operating temps. Take a look at this: http://s95014253.onlinehome.us/63104/157335.html And definitely pull codes as stated above.

[dudewtf]

yeh i cleaned the aicv a few weeks ago when i replaced my coils,sparks and MAF sensor. ill clean it again on friday. now i have another problem. my oil psi gauge is reading 60 psi on startup and 30 psi when warmed.


before it would show 60 on start and 10-15 or 15-20 psi when warmed up.

freeway at speeds of 65mph @ 2100-2400rpm it reads 60 and above

street speed of 25 - 35 mph @ 2000 -2500RPM it reads 30-40 psi.

(sorry for double post. im gonna keep this issue to my own thread)

so i have a list of possible issues.

-spun rod bearing?
-bad oil filter
-bad oil pump or clogged hose
-oil leak
-blown head gasket

also when i gas it to semi fast either with no load or driving it shoots up past 90psi super fast

can high psi cause damage to my engine?

thanks again!!

[es.biggs]

If you are worried about your oil pressure you need to check it with a real gauge/oil pressure tester.

The stock sending units are known to be so inaccurate its a joke.