Oxygen sensor and \"G Signal\"?

Adam_NAclubman · Postby **Adam_NAclubman** » Thu Sep 06, 2007 5:51 pm

Went for an afternoon drive in the hills, after 10 minutes or so the engine seemed to be running flat at low revs, then from about 4200rpm it would jump and run at full power. I thought this seemed quite strange so made it repeat itself a bit, then while I was engine braking down a hill to a stop sign the exhaust sounded a bit funny, louder and rougher than normal. I thought maybe I'd finally killed the new muffler. When I was stationary I gave it a bit of a rev in neutral and it was popping near the redline sort of like when you get an air leak in the exhaust and it ignites unburnt fuel.

It wouldnt idle properly, dropping to a roughish 500rpm (possibly less).

Drove slowly back to town, stopped at the supermarket as its on my way home anyway, lifted the bonnet while the engine was running and the filter's idle sucking noise seemed different, not sure how to explain it, but different to usual. After I'd done my shopping the car seemed fine for the first two minutes, full power as normal, but then it started feeling flat with the sharp increase from 4200rpm.

I was thinking maybe the airflow meter or something could have died, or there could be a leak in the inlet tract, but it does seem to be doing everything I'd expect from a belt thats jumped?

Any takers? 1994 NA8, stock BP with pod, exhaust, 14 degrees timing or whatever everyone reccomends to set it to (I cant remember)

16bit · Postby **16bit** » Thu Sep 06, 2007 6:21 pm

could it be an o2 sensor?

Uncle Arthur · Postby **Uncle Arthur** » Thu Sep 06, 2007 8:30 pm

Check your leads

jules · Postby **jules** » Fri Sep 07, 2007 10:47 am

Leads, plugs, coils?
Look at the simpler things first.

Jules

JBT · Postby **JBT** » Fri Sep 07, 2007 11:00 am

If the timing belt has jumped a tooth it would be consistently off song and not keep changing.

Try ignition (leads/plugs) first IMHO.

Adam_NAclubman · Postby **Adam_NAclubman** » Fri Sep 07, 2007 2:19 pm

Ran the diagnostic codes

Codes said \"G signal\" (which I have no idea wtf that is), and \"O2 sensor - output not changing\"

Is oxygen sensor do-able at home without lying on the floor, or is it mechanic/exhaust shop time?

jules · Postby **jules** » Fri Sep 07, 2007 4:44 pm

Piece of piss. Bolted in, lead plugged into the back of the engine.
Make sure you spray plenty of WD-40 on the sensor thread the night before. It will probably be rusted into the exhaust.

Jules

Fatty · Postby **Fatty** » Fri Sep 07, 2007 5:20 pm

jules wrote:Piece of piss. Bolted in, lead plugged into the back of the engine.
Make sure you spray plenty of WD-40 on the sensor thread the night before. It will probably be rusted into the exhaust.

Jules

agreed 100%

Adam_NAclubman · Postby **Adam_NAclubman** » Fri Sep 07, 2007 5:28 pm

Where is the cheapest place to buy one?

And does anyone have any idea what the G signal is?

Juffa · Postby **Juffa** » Fri Sep 07, 2007 5:33 pm

Adam_NAclubman wrote:
And does anyone have any idea what the G signal is?

I was directed to read about this in a womans magazine as I was deemed to be lacking expertise in this paricular area, but not sure how this is relevant to your particular problem.

J

JBT · Postby **JBT** » Fri Sep 07, 2007 5:34 pm

SuperMazdaKart · Postby **SuperMazdaKart** » Fri Sep 07, 2007 5:35 pm

my NA6 one costed me $80 i think (rrp something like $110) at Motor Traders on South Rd near Castle Plaza. said i got quoted from mx5 forum/mx5 club sa at $70 & they brought the price down to near it :lol:

Russellb · Postby **Russellb** » Fri Sep 07, 2007 8:18 pm

G signal is the cam postion sensor
When G signal is lost the 2 injectors are are drop and limp home mode is aplied ( spelling bad too much beer sorry )
this is what is said in the manual

To me it sounds like the CAS is on it way out

I had this with My NA8 on an after market computer . sometime it would just stop dead
then let sit for a whilke and it would restart. after a week it stoped dead

hope this helps