Assist please in finding this phantom problem

[bytemyfsb]

Ok, a month ago I purchased a 1990 Z32 N/A in semi rough condition for a steal of a price. I finally fixed the window regulator (project from hell) and now I want to resume finding this phantom problem the car has.

Problem in detail:

The car seems to seriously lack some go i.e. while in first gear at 4K RPM and I punch the throttle, the car only mildly accelerates. Now I have ridden in another Z32 N/A and it has MUCH more giddy-up as mine. I know something is amiss somewhere, but I have yet to hit the correct problem. No check engine lights since I've had the car and the light does come on with the key in ACC position, so I know its not burnt out.

After sitting for a long period (at least 8 hours), the car starts very hard and doesn't want to run right (runs rough and stumbles if I punch the accelerator). After the car warms up, it will start up and run decent, but still has a tough time. When out on the highway running 65 and I drop to 3rd and punch it, the response is very lax and frankly pathetic, but no backfire or definite stumble, the car just isn't there power wise.

I will try to post a trouble shoot video in the next couple days to aid in this process. In the mean time, please shoot me some ideas of where to look and what I might replace to conquer this demon.

Pics also coming soon.

Thanks,

Markus

[SlidewaysZ]

i have this same problem with my 90 n/a.

[bytemyfsb]

Ok after more road trials I can add a few more symptoms. While driving 70, I came up on a turn faster than expected so I got on the breaks pretty good and clutched the car only to have it die on me. It started right back up with no problem. So coming back to town I tried the same scenario, getting on the breaks, and clutching the car to have it die again. I repeat this 2 more times and the car now catches itself and idles correctly while coasting. The last two trials, the car responded as I felt it should; come down from 3K rpm while clutching it, RPM dipped to 800ish RPM and idled perfect.

Also while having a friend drive the car I noticed something strange sounding when we pulled up to the house, when he got on gas, I could hear a hissing sound, so I had him repeat this several times and I can definitely hear a hissing, so I am thinking a possible vacuum leak.

Would a vacuum leak cause some of the problems that I have listed here?

Any input is appreciated.

Thanks again!

[tmeyer29]

vacumm leak would definatly do this...My mustang had a very similar problem..I tested it by spraying carb cleaner around the vacumm lines and when The rpms surged up a little I new thats where it was. The hose was simply not connected. I connected it and it felt like a new car.

[evildky]

first things first, gett the codes read!

[bytemyfsb]

I have a Consult cable and software to interface with the ECU and I have pulled the codes today. The only code is a Code 33 (Don't remember the exact wording) Front EGR Temp something, this is a stored code and not a current code. I also went ahead and did a power balance test and each cylinder test resulted in the car running rougher, which I assume means air, fuel, and spark are getting to all cylinders.

I have replaced the spark plug boots as a few of them were cracked. I also had a local mechanic change the plugs for me and do a compression test (owed me a favor). He said all the cylinders were within 4 pounds of each other (I didn't ask him what normal compression was however).

Also I have ran IACV and AAC tests, each came out good (the car dipped in idle speed when the test was conducted).

I am still fairly certain I am looking at a vacuum problem. Another 300Zx owner told me maybe to look to the PCV valves. Does this sound like a good lead? I know enough to be dangerous with engines, so I want to get as many opinions as I can.

Thanks!

Edit: Code 33 Translate to Heated Oxygen sensor according to a couple of web sites. Keep in mind that this is also a STORED code and isn't current.

[Ill give u a head start]

i

Ok after more road trials I can add a few more symptoms. While driving 70, I came up on a turn faster than expected so I got on the breaks pretty good and clutched the car only to have it die on me. It started right back up with no problem. So coming back to town I tried the same scenario, getting on the breaks, and clutching the car to have it die again. I repeat this 2 more times and the car now catches itself and idles correctly while coasting. The last two trials, the car responded as I felt it should; come down from 3K rpm while clutching it, RPM dipped to 800ish RPM and idled perfect.

Also while having a friend drive the car I noticed something strange sounding when we pulled up to the house, when he got on gas, I could hear a hissing sound, so I had him repeat this several times and I can definitely hear a hissing, so I am thinking a possible vacuum leak.

Would a vacuum leak cause some of the problems that I have listed here?

Any input is appreciated.

Thanks again!

The problem with the stalling is fuel related. I had the same exact problem with my previous Z32. the car would die on me in the exact same way u described. I took it to a nissan dealer and they found that all fuel injectors had high resistance and all needed to be replaced. by the way my engine light didnt come on either.

Weird this morning on my way to school in my current Z my car stalled on me when i braked suddenly with the clutch pushed down to to avoid hitting debris on the road. The car started right back up with no problem. im sure its the fuel injectors once again.i dont know alot about cars but i have experienced alot of problems with the 300zx seeing as ive owned a few of them and have pretty much experienced every common problem out there. The fuel injectors are a very common problem on the 300zx.u might wanna have ur wiring harness checked out too

im not really too worried about my stall today as i need a new motor neways becuz of a rod knock.

btw the brand new long block from nissan comes with new injectors right