rough idle, running rich

[nissans13240sx]

ok i have a 91 240sx with the redtop SR motor in it. I just finished the swap a couple of months ago and havent really driven it to much because of this problem. when i do drive it it runs fine until it warms up then the crazy idleing begines. Also when driving it, it stutters on light acceleration. while it is idling like **** it just clouds black smoke out the back. I did search on here and am thinking it has to do with either my MAFS, my o2, or my TPS. My o2 is brand new but is from a blacktop because stock wouldnt fit my turbo outlet. My TPS reads 4.045 volts at WOT, and i belive it is supposed to be at 4.5 not sure if this is a problem or not. I do have my BOV recircualted and i have checked multiple times for boost and vac leaks. oh and my vac gauge when it is idleing is only at 10, when it should be at 20.. I know i just wrote alot but your help would be appreciated. thanks

I check the ECU for codes as well i got code 55 which i believe is running normal so im guessing its the o2 sensor or MAFS... how do i test the mafs?
Modified by nissans13240sx at 2:41 PM 10/13/2006

[da40]

try running the bov normaly instead of recirculated

[nissans13240sx]

i did have it venting instead of recirculating... a lot of ppl told me that it will run rich if its not circulated thats why i went back to having it circulated. thanks for the suggestion though.

[nissans13240sx]

bump... anyone?

[Blown240sx]

02

[nissans13240sx]

thats what i was thinking. Do you think i gotta use the stock o2?? thanks for the reply

[wildacexxx]

its not your o2. its your water temp sensor. the one that goes to the ecu not the small one that goes to your cluster. my friend had that problem too. when car warms up it ran crappy.

[nissans13240sx]

ok, wouldnt a coolent temp sensor throw a code though??? And where is this sensor located at, How do i test it? thanks for the suggestion

[skillzilla]

Most sensors like that wont throw a code. Ive had bad knock sensors that didnt even throw codes.

Sounds like a temp sensor to me as well, or an O2 possibly. Both would make it run rich once it was warmed up.

[nissans13240sx]

ok so where is the temp sensor at? right by the thermostate housing? And is this sensor the same as the US sr20de sensor,... if not where can i get one at? thanks

[masterteque]

This problem is most likely the temp sensor like everyone else has already said. It is usually a red plug connector that is located kinda near the throttle body. If you straight on at the throttle body you'll see it. It is below it off to the right. You can get a replacement from the Nissan dealer and order it for a 91-94 SE-R. The new one will probably be a blue connector but that is o.k. If that doesn't fix it, I would go after the O2 sensor. You can check this with a multimeter if you have one....If you need to replace that order it for a 1988 Nissan 300zx turbo car. The connector will need to be repinned but it is very easy...Let me know if you need me to tell you how to check the O2....

[Cyberkreig]

rough idle, running rich

yup. You definatly own an sr20.

[nissans13240sx]

yup. You definatly own an sr20.

Haha tell me about it... I know that the o2 sensor itself is good because its brand new. I am using a 95 TT 300zx sensor same as the blacktop sensor.... I am thinking this maybe the problem becuase they are 2 differnt kinds of sensors. I have the stock sensor but i need to get an adapter to make it fit in my turbo outlet. im going to replace the coolant temp sensor though to probably. wouldnt a bad coolant temp sensor give me a false reading on the gauge though??? My gauge works fine. thanks for the replys

[masterteque]

Your gauge sensor and your ect sensor are two different sensors. The problem with ect sensor is that is telling the ecu the wrong input. What happens is when the car is warmed up the sensor is telling the ecu it is cold. This in turn makes it too rich. This especially affects the vehicle when sitting at idle because it really loads up the car with fuel. You then take off and it runs like ****....I am pretty sure the O2 sensor you are using is wrong also.....!988 300zx....It should be like $100 from the dealer

[nissans13240sx]

oh see... I was told the 95 TT was the same as the blacktop o2 sensor... but never the less im switching it back to the stock one. i just got the coolant temp sensor. we actually had one in stock at the dealership i work at, so i will be putting that in today most likely.

[nissans13240sx]

ok i replaced the coolant temp sensor... wasnt the problem, it runs good at cold idle as soon as it warms up the black smoke starts. So im almost positive its the o2 sensor now because until it is heated up its in open loop. and when it heats up switches to closed loop it starts running rich. its not getting the right signal im guessing. If anyone wants to corrct me please do, but for not im going to try that.

[oki_bum]

If your looking for a blacktop O2, the 1987 200sx 1.8L Turbo model one would work. Bought a Bosch one from autozone for $60 or less...

[masterteque]

Like I had said before, you will need to buy an O2 sensor for a 1988 300zx turbo model......

[nissans13240sx]

ok but arent the o2 sensors 2 differnt types redtop and blacktop. what i did was i spent 15 bucks and got an adapter for my redtop o2 sensor from megan racing. so i hope that works.