astra h squealing+ oxygen sensor problem

**martand** · 1st April, 2010, 10:09 PM

hi again guys! im afraid i need some help again, our lasses astra has developed a problem, the engine revs up and down on tickover and makes an awful squealing noise. ive got a fault code po138 o2 sensor signal fault, and the fuel system is in constant open loop . now and again it can be overcome by a few revs but smokes pretty bad . the engine is a 1.6 z16xep any ideas guys thanks!

**oldford** · 2nd April, 2010, 08:09 AM

P0138 is not the fault you are looking for. This is the sensor after the cat, which has no influence on fueling or ignition.
Carefully check the inlet and exhaust manifolds for leaks. Check all hoses around the inlet manifold for leaks.
Can you read live data in EOBD? Then post Long Term Fuel Trim and Oxygen sensor signals at idle and 3000 rpm.

**hackerabcd** · 2nd April, 2010, 10:00 AM

with engine running is it hard to remove the oil cap ? if so you will have to replace the rocker cover

**Albanais** · 2nd April, 2010, 04:22 PM

Originally Posted by hackerabcd

with engine running is it hard to remove the oil cap ? if so you will have to replace the rocker cover

Take a brake pads cleaning spray and spray all over the inlet manifold pipes, if the revs will rise up you have already resolve your problem

**dafdiagnos** · 2nd April, 2010, 06:25 PM

as with the posts above, it sounds like a leak on the inlet side which will throw out the lambda & fueling

**martand** · 2nd April, 2010, 06:53 PM

thanks for your intrest guys! i will find time in the morning to plug on to the car and get the readings, i see what you mean by intake problems causing it to hunt for fuel .

**martand** · 3rd April, 2010, 05:17 PM

i used auto enginuity to take these readings here goes! got fault code p0130-04 o2 sensor range performance bank 1 sensor 1. at start up cold both o2 sensors reading 99.06 fuel system in closed loop. at 3000 rpm o2 sensor 1 at constant 1.24 v sensor 2 at 0.76v fuel trim sensor 1 was 0.00 fuel trim sensor 2 was 99.06 at idle fuel trim sensor 1 was 99.06 sensor 2 was 0.08 the squealing has stopped so the car is being used , but ive got a crecorder on it.

**oldford** · 3rd April, 2010, 05:44 PM

The fuel trims you describe are the short term fuel trims.
99% here isn't 99%, but it's a special case where the value is 0xff and means NOT USED.
The interesting value is the LONG term fuel trim (Pid 7).
See: OBD-II PIDs - Wikipedia, the free encyclopedia

**martand** · 3rd April, 2010, 09:32 PM

sorry! yes you did ask for long term results i will leave the recorder on for a couple of days then let you know then thanks!

**martand** · 4th April, 2010, 08:10 PM

the readings from the data recorder are long term fuel trim bank 1 minimum 0 max 6.25

**oldford** · 5th April, 2010, 08:43 AM

That's well within limits.
Is the car in closed loop or open loop? Because this in total contradiction with black smoke coming from the exhaust.
What signal do you get from the oxygen sensors?
Are there fault codes present at the time?

**kev50** · 5th April, 2010, 10:00 AM

Make sure the exhaust isnt blocked and the cranhshaft pulley hasnt slipped altering the timing both very common problems.

**martand** · 5th April, 2010, 08:24 PM

the fault code present is po130 -04 oxygen sensor range performance bank 1 the fuel system is in closed loop, and oxygen sensor 1 reads 1.24 volt sensor 2 reads 0.76 at 3000 rpm . the black smoke stopped when the squealing did

**oldford** · 6th April, 2010, 08:06 AM

Oxygen sensor 1 is far out. Should not be more than 0.95 Volt. Either some short circuit on Oxygen sensor signal or sensor defect OR the engine is realy that rich.
What's the map sensor reading at engine off, engine idle and engine at 3000 rpm.
Whats the Oxygen sensor 1 signal with engine cold and NOT running (just before starting it the first time).

With this fault code the Closed loop control is disabled. So you need to fix this before anything else.