Help Nissan Mechanic

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

Hey

The Car: 1989 240sx

The Problem: Poor fuel economy.

The explanation: Ok so the engine was rebuilt about 5 months ago and everything seemed peachy until about 3 tanks ago. before that i got about 500 kilometers per tank (310 miles). Now I get 400 if im lucky. during the rebuild i put in new plugs new wires new O2 sensor. Cleaned intake and 32psi in tires. new thermostat as well. The only thing that i can think that may be a bit iffy is the tank is pressurized when i take off the gas cap after driving for a bit. (i think my breather doesnt work). But that shouldnt have an effect on it i think. During the rebuild i cleaned the injectors and fuel rail (there was a little of garbage in injector #1). when i cleaned out the injects, silly me didnt put in new seals.

But can you please give me some other common problems that i may have.

Thanks

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

do you have a check engine light in this car? if so go to the faq on codes and how to retrieve them pull them and post back your results

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

no there isnt a check engine light in the '89 unfortunatly

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

there still is a cpu(ecm) and i would think you could still retrive codes. I assume by your distance measurement your car is a canada model. even so you should still have a ecm try locating it and perform the code retrieval process to determin if a code has been stored. as far as fuel milage goes a bad connection(corrosion build up) in your coolant temp sensor connector can cause rich fuel mixture. also a inacurate reading from the airflow meter can cause a rich condition. small vaccum leaks can fool the ecm and cause it to richen up as well. give all these things a good look over and see if ya find something. but the codes if any are stored is the most important thing you could do first.

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

ok thanks i will check that out very soon.

i have chiltons manuel so that will tell me

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

the chiltons manuals from experiance are not very good on the ecm stuff. here is a link that is pretty thurough

http://www.240sx.org/faq/index.html

go to the link labeled engine code reading(sohc)

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

Hey

well i went to the cpu and i ended up with code 33, witch is Exhaust gas O2 sensor circuit. So everything should be ok when i replace it, but what i dont understand is why did the sensor die so fast? it was only 5 months old.

Thanks

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

quality of the part plays a factor. was it a factory part or after market? also if coolant manages to run thru the engine and hits the o2 it can take it out. If it were to be hit bysomething when its hot could cause a it to break internally. check to make sure the o2 connections are all good before you jump in and just replace it.

Post by **dima** » Sat Oct 18, 2003 5:10 am

make shure you have good ground on your O2 sensor. If not use condactive grease.

Post by **deftdrummer** » Sat Oct 18, 2003 5:10 am

what is this code for?? where exactly is the exhaust O2 sensor circuit located and how do i replace it? where are the parts for sale??

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

o2 sensor is located in the exahust usually on the manifold or in the header pipe off the manifold. it is the only electrical component screwed into the exhaust system. could have 1 to 4 wires going to it.

Post by **deftdrummer** » Sat Oct 18, 2003 5:10 am

im thinking about getting the hotshot header in the near future. Is it worth it to replace the O2 sensor now or wait until I get my header and install it then on a brand new header? that makes more sense to me as its brand new parts with brand new parts. Will my check engine light go off then? I also remember reading that it will go on or (stay on) because of "primary catylatic converter failure" as the first cat is removed by the hotshot header. However, i have a spot for the second cat that is just fake so i guess i could put one there and still be emissions legal. Only problem is there's no sensor for that cat so i think my light is doomed to stay on forever!

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

the cat has 0 effect on the o2 for your car. you only have 1 o2 and it is pre cat. only obdII cars have an o2 after the cat. obdII started in 96. before you install the header make sure it has an EO# with it. Their will be paper work which supports this and you will need this paper work any time you have a smog performed or the shop will most likely send you to the refferee. If the header you are buying is labeled "for off road use only" it does not have an EO# and will not pass the visual portion of the smog check. if you are eliminating the pre cat and you have no other cat on the car with a substrait it will most likely fail the tail pipe portion of the test as well. so you definitly will need to install a new cat. If you get me the part# and manufacture of the header i can look up on the state web site for approved modifications and see if it listed for your car. Smog tech's have to use this site it was one of the excersizes I had to go through in class before i got my state smog license.

Post by **deftdrummer** » Sat Oct 18, 2003 5:10 am

ok well its a hotshot header for S14 part #NS3010 By the way, i think we have some miscommunication here. I know the 02 seosor has nothing to do with the cat, but what im saying is that this hotshot header ELIMINATES the first cat alltogether. My car is a California car and therefore only has 1 real cat near the engine and a fake one in the middle of the car. My thinking is this:

Eliminate cat #1 near engine with hotshot headerReplace fake cat with real cat in middle of car

the result: still get check engine light because "primary cat failure" because its non existant anymore. However, i should still pass smog. I didn't know about that paperwork stuff though, it would be great if you could check for me although im pretty sure its 50 state legal

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

you wont get a cat code since your car is obdI. cat codes came with obd II.

I will check your part# against the data base

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

ok I looked up the approved headers for your 240 and also visited hotshots website and looked up your header. the header you want does not have an EO# meaning it is not approved. It also says on their site that it is intended for off road use. which means it is not street legal. During my visit to the state page I found that only the 1995-1998 240sx are approved for a header and it is only a greddy header. I searched their site and found it. so here is the link to the only CA smog approved header.

http://www.greddy.com/products/headers_frame.htm

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

Hey

I just wanted to say thanks for your advice, i got my problem solved by buying a bosch O2 sensor and now im getting my 550 KM per tank.

Post by **NISTECH** » Sat Oct 18, 2003 5:10 am

no problem . glad to hear you got it fixed:D what brand o2 was it you put in 5 months ago?

Post by **simonlazarski** » Sat Oct 18, 2003 5:10 am

It didnt say what brand it was, but i recal it was a generic one.

a cheapo one from a car parts store

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