element303

hi guys. i decided to see if there is someone here who had similar experience and can point me to the right direction. i bought a 300zx as project to rebuild and i drove it pretty much like a grandpa because the shocks are dead. however, i noticed from the start that the engine got really hot (not the water - just the engine itself and the smell of hot oil). i have two issues. #1 is a really rough idle that is WAY too high. i replaced the air flow meter and tried to clean the idle valve without any luck.

but the real issue i have no is that under load i have no power. the engine runs smooth if i barely push the throttle after idle but as soon i press it more than 2-3mm down, it have EXTREME hesitation. this started gradually over a few weeks and got very bad within a day or so. first i noticed that under full throttle it would accelerate very inconsistent. overall not much power for a 222hp engine. it got worst and worst until the point now that i don't even drive it anymore and the only reason it is still possible to drive it is the high torque with low throttle.

i checked for error codes and get 55. im not sure if its coil or injector related because its not just one or two cylinder. it runs smooth or not at all smooth. i heard it could be dirty fuel filter which would explain why it came gradually and i also can smell gas sometimes but i know i have a tiny leak (weirdly only sometimes) in the front where one of the hoses are connected.

any ideas what this could be? it feels like any more and i can't drive it at all anymore. it turns on fine and the isle doesn't drop or turn off ever. only while i drive on load its just nearly impossible to drive. very difficult to get it to drive at all. thank you!

PredatorZ

Quick way to check if you have a vacuum leak, is to pull off the oil filler cap and see if it starts to run ruff, or just stays the same. You could have a bad or corroded connection on a sensor like the Cylinder head temp sensor, or your Throttle Position Switch. many a times its not that the component, but just a bad connection. As these cars get older, the ground becomes suspect, the best thing to do to counter that is to tie your neg battery terminal to the ground on your ECU and to your intake/ plenum, since most your sensors are grounded to the intake. If you don't have a manual, you can download a free version from Xenon, not only do they have manuals, but a great resource of information on common issues like yours.

XenonZ31 Reference

element303

I just see right now I posted in the wrong area. I have the Z32 1990 V6

PredatorZ

most of what I said applies to all the cars, here is the proper link to your FSM

XenonZ32.com

rogerz

heat issue could be your thermostat or a plugged radiator. You don't have an air flow meter you have a Mass Air Flow sensor. why didn't you change the fuel filter if you suspect it. they are only like 10-15 bucks. check your air filter for mouse nests. oil filler cap trick only works really well on an l28 engine.

element303

I didn't get to check it yet (fuel filter). And yes MAF, same sh*t, you know what I mean Air filter is off right now.

I smell gas at all times now when I drive. Also something I didn't mention is that I have no transition from idle to throttle when I drive. Meaning that Im either on engine brake or already 10% throttle. The gas pedal became more and more insensitive the worst that problem got. Also slight misfire or irregular burning in idle but in the small window I can drive it throttle wise, it runs very smooth. If I give more than 2-3mm throttle, it will just misfire and hesitate like crazy.

I already checked all connections to the injectors. They were all corroded so i sanded or scratched them back to the medal and sprayed them with WD40.

Is it possible that the injectors are somehow clocked and they are unable to spray enough gas in the chambers when I use more throttle and I smell the gas because the pressure comes out as some other place instead?

rogerz

why in the ten thousand names of god would you spray wd40 on your injector connectors. you would be better off trying to cure arthritis with it. why check the fuel filter just replace it. if you think the injectors are plugged why would you smell gas? have you ever worked on a car before? can you read the fsm ?

element303

Wd40 to protect the connectors or the metal connections in it from getting corroded again - obviously. Especially living on an island with salt in the air. I find your comment stupid and rude.

Yes I have build Turbo engines but without all the electronic crap those newer cars come with.

element303

ok quick update. its not the fuel filter. it gets fuel but it doesn't burn it. now not at all anymore. i have good idle but as soon i have throttle it misfires like crazy and black smoke comes out. i changed the spark plugs today. no change. if the gas doesn't get burned is it more likely to be the coil or injectors?

86tcoupe

sure sounds as it is very flooded with fuel that needs to be fixed or checked if it is 1st .
by disconnecting the fuel pump and pulling the plugs and have someone crank it while you see if it is spewing fuel out 1 or more cly. BE CAREFUL and Pre-cautious ( like have a fire extingisher and do it outside ) about the spark and fuel ! I would take a cold compression test after it if cleared out .
I usually try running it on carb spray before hooking up the pump again to test.

element303

I don't think its a flooding issue. Its simply not getting burned. So Im leaning slightly towards the coils being dead.