Z-man91

well i have an all stock 91 Twin Turbo with the exception of the HKS exhaust. and check engine light will come on and off randomly. It seems like if i drive the car hard for a while it'll go off and stay off but if you drive it and don't hit boost for a while it usually comes on. This guy before me put half a tank of regular gas in with a half of premium thinking it would be fine but he was a dumbass anyways... but check engine light never came on before that. It's been a few months and has had premium ever since. what would cause this to come on and off randomly? It's killed the mpg's in this car. and it seems to hesitate when trying to take off.

Lanoi

hesitation huh .. bad injector?

Z-man91

i thought that for a bit but none of the problems happened till he put the regular gas into it. and we've run a lot of injector cleaner through it

KasbeKZ

injector cleaner is not really good for the injectors in the z32. that might be part of your problem. do you still have original injectors? one or more is probably bad or on its way out.

if the check engine light is on, you should have a code. run the codes and tell us what you get. there are a ton of things that could be causing your problem.

Lanoi

when i had my delsol i used injectors cleaner. FCKed it all up after that never used injector cleaner again or recommened it to any else. Try ohm injectors 10-14 above or below will cause to much fuel or too little.

Off topic but is the a How to section or not up yet ?

nismo619

i use lucus fuel system treatment every time i fill up i get excellent MPG . dont listen to these nitwits ! lol

Z-man91

well i don't think it's an injector problem. it all happened when the guy used the lowest grade of pump gas and went on a trip. plus i can't find anywhere to check the codes because the car is obd1.

KasbeKZ

do onboard diagnostics. google search or tt.net search: "codes check ecu" or something like that.

and ruling out injectors for.... absolutely no reason is not.... a well thought out diagnosis. injectors are a completely viable diagnosis right now.

and these nitwits happen to have reliable sources that state the FACT that injector cleaner is NOT good for Z32 injectors, most specifically the early style z32 injectors. i get pretty good mileage too, and i don't put cleaner in.

CanyonCarver

If you check for codes when the CEL is off, you'll usually get a 55, or no errors.

This is usually caused by an o2 sensor that is working intermittently or reacting slowly. This can be observed with a diagnostics software like BlaZt or whatever. You can also verify this by doing the mode II ecu diagnostics. During part of this test you're supposed to observe the ECU LED flash 5 times every 10 seconds. With a slow-reacting o2, it'll take more than 10 seconds to get the 5 flashes.

Some people have been successful with removing the o2's and cleaning off the old carbon deposits and residue. You have to douche the part that is inside of the external tube with the slits or holes.

Otherwise, the o2's may have to be replaced.

Diagnostics here:
http://300zx-twinturbo.com/cgi-bin/m...ault&total=190

Of course I have the newer style injectors, but I've used carb and fuel injector cleaner as part of my regular maintenance for 6 years now without any problems. 157k miles with oem injectors and o2's.