Hey guys,
first post on here as I just bought a 1991 300zx NA 2+2 the other week. I bought it and the cats were bad so when I went to get it smogged, the mechanic told me it was basically dumping out fuel from the exhaust it was so rich. He installed new cats (previous owner was responsible for smog) and it seems to run a bit better but I still don't get full power sometimes and my gas milage is terrible. (Approximately 8-10mpg city)
I will be checking the O2 sensors tomorrow with the ECU but is there any other thing I should check? Some friends recommended checking the vacuum lines but I'm not too sure on how I'd go about doing that.
Any help would be greatly appreciated!
Thanks,
Max
91 300ZX na 2+2 misfire and terrible gas milage
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maxlkauker
- Posts: 4
- Joined: Sun Jul 19, 2015 4:03 pm
- Car: 1991 NISSAN 300ZX Z32
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DCaff300ZX
- Posts: 4202
- Joined: Sun Jun 14, 2009 8:18 am
- Car: .
1993 CRP TT- Modified - Location: Tacoma, Washington
Re: 91 300ZX na 2+2 misfire and terrible gas milage
Welcome to Nico!
If you are handy as a mechanic, in addition to your O2 test you will want to check over all of the various vacuum lines for cracked hoses and/or missing/removed ones.
Other possibilities for your emissions failure is fuel injectors which being the old style are well on their way to ethanol and electrolysis death, as well as possibly/probably having corroded connectors. These are hard to check and would need a mechanic with Nissan experience, looking for green connector corrosion and also testing the injectors with an ohm meter to be within spec resistance.
A good emissions shop should be able to handle these duties although a Nissan or Z specialist is best.
Good Luck!
If you are handy as a mechanic, in addition to your O2 test you will want to check over all of the various vacuum lines for cracked hoses and/or missing/removed ones.
Other possibilities for your emissions failure is fuel injectors which being the old style are well on their way to ethanol and electrolysis death, as well as possibly/probably having corroded connectors. These are hard to check and would need a mechanic with Nissan experience, looking for green connector corrosion and also testing the injectors with an ohm meter to be within spec resistance.
A good emissions shop should be able to handle these duties although a Nissan or Z specialist is best.
Good Luck!
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maxlkauker
- Posts: 4
- Joined: Sun Jul 19, 2015 4:03 pm
- Car: 1991 NISSAN 300ZX Z32
Re: 91 300ZX na 2+2 misfire and terrible gas milage
Thanks for the reply! I was expecting a notification email when someone replied but I guess not. Oops, my bad 
The 02 sensor test passed and now I have some new problems. I am getting code 32 and 34. Knock sensor and EGR system. I heard that EGR problems can be simply from clogged lines but I don't know how I'd go about cleaning them. I took a look into the engine bay and I tried to spray carb cleaner around some of the vacuum lines that I saw. The hardest part about this was finding the lines! I only found 2 or 3 lines to spray and those ones I did, didn't raise the engines idle at all.
The engine is starting to get worse it seems. I have had numerous stalls when coasting to a stop and starting from first is incredibly hard from having so little power.
I did a seafoam treatment to the engine and I felt a huge power increase on the top end but it did little to the low end hesitation.
I looked and the plugs in the car were the BKRGES and not the recommended PFR6B-11 plugs. I have 6 new PFR6B-11 plugs on the way to see if that helps anything.
I'm thinking of getting a Nissan technician to look over the car and see what he/she says If i don't make progress soon.
Any help would be greatly appreciated.
The 02 sensor test passed and now I have some new problems. I am getting code 32 and 34. Knock sensor and EGR system. I heard that EGR problems can be simply from clogged lines but I don't know how I'd go about cleaning them. I took a look into the engine bay and I tried to spray carb cleaner around some of the vacuum lines that I saw. The hardest part about this was finding the lines! I only found 2 or 3 lines to spray and those ones I did, didn't raise the engines idle at all.
The engine is starting to get worse it seems. I have had numerous stalls when coasting to a stop and starting from first is incredibly hard from having so little power.
I did a seafoam treatment to the engine and I felt a huge power increase on the top end but it did little to the low end hesitation.
I looked and the plugs in the car were the BKRGES and not the recommended PFR6B-11 plugs. I have 6 new PFR6B-11 plugs on the way to see if that helps anything.
I'm thinking of getting a Nissan technician to look over the car and see what he/she says If i don't make progress soon.
Any help would be greatly appreciated.
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diplomat 1
- Posts: 40
- Joined: Thu Mar 20, 2014 7:19 pm
Re: 91 300ZX na 2+2 misfire and terrible gas milage
If you don't mind me asking how did u test the O2 out?
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maxlkauker
- Posts: 4
- Joined: Sun Jul 19, 2015 4:03 pm
- Car: 1991 NISSAN 300ZX Z32
Re: 91 300ZX na 2+2 misfire and terrible gas milage
I used the ECU to check them via this guide: http://www.nicoclub.com/archives/nissan ... ostic.html
--Update with the car--
The car has a terribly hard time idling now. It will idle if I rev it and slowly bring down the throttle but if I rev it and let go of the pedal it will forsure die.
I replaced the plugs hoping that it would help and nothing.
I looked at the EGR and I unplugged the vacuum hose going to it and I didn't feel any suction from weather side of the hose, nor did it alter the engines idle whatsoever. Could a faulty EGR cause my hesitation and idle hunting?
P.S. just cleaned my MAF too.
--Update with the car--
The car has a terribly hard time idling now. It will idle if I rev it and slowly bring down the throttle but if I rev it and let go of the pedal it will forsure die.
I replaced the plugs hoping that it would help and nothing.
I looked at the EGR and I unplugged the vacuum hose going to it and I didn't feel any suction from weather side of the hose, nor did it alter the engines idle whatsoever. Could a faulty EGR cause my hesitation and idle hunting?
P.S. just cleaned my MAF too.
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valliheart
- Posts: 1
- Joined: Thu Aug 06, 2015 5:23 pm
- Car: 1991 Z32 2+2
Re: 91 300ZX na 2+2 misfire and terrible gas milage
I have the exact same car, same symptoms, but my code is coming up as Fuel Injectors. I am so Not looking forward to that. I've found a place online that only rebuilds the injectors ($179), but you have to pull them, send them in, wait a couple of days for their side, more sending... Getting back to stuff is not what I excel at.
Grrr
Grrr
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maxlkauker
- Posts: 4
- Joined: Sun Jul 19, 2015 4:03 pm
- Car: 1991 NISSAN 300ZX Z32
Re: 91 300ZX na 2+2 misfire and terrible gas milage
Update:
I pulled 2 more codes today. 13 and 45
The 13 I think is from today when I took off the connector and I must not have seated it properly, not too worried about that one.
45. I guess I gotta pull the plenum to fix that one. So here's the question. Do I need to buy a new injector or can I just fix the leak with a new o-ring in there?
I pulled 2 more codes today. 13 and 45
The 13 I think is from today when I took off the connector and I must not have seated it properly, not too worried about that one.
45. I guess I gotta pull the plenum to fix that one. So here's the question. Do I need to buy a new injector or can I just fix the leak with a new o-ring in there?