idling,hesitation etc.. solved!

[Keep'emRunning]

My first post :) Great forum!

Own one of the very first G's in the country, late 1998, now almost 200k's on the clock. Been through all the usual astra traumas, fixing them myself when 'experts' couldn't or wanted to charge the equivalent of the national debt.

Had a prob for the last 8 months that no one could solve, poor cold idling, constant hesitation below 1500 revs, kangaroo'ing when moving slow and higher than normal fuel consumption. PITA in sydney traffic!

The cavweb and vaux sites stated egr valve, throttle body clean etc etc.. went through all of them without success. Was close to chucking it on ebay and buying a bland looking jap car as a replacement.

Only when I pulled the plugs last w/end and they were sooty did the penny drop. Rich mixture!

So.. hmm no codes for anything... must be a sensor.. off to the wreckers today to get the lot.

Who can guess? You might be surprised.. I sure was... :)

[DirtyHarry]

good work....a great tool to see whats happening electronically is called opcom. you can buy a cheap chineese rip of it for around $200 delivered.
hook it up to the laptop and you can see what all your sensors are doing, program immobilisers. etc etc.

i have started a habit where every 5-10k i check the sensors and see if they are working correctly.

i had a similar issue with my brothers golf 2.0 mk4. no engine light, until i finally hooked up a vw scan tool and had a look at the output voltages of the O2 sensor. sure enough the sensor was hardly changing. so changed the sensor and after a week or two the long term fuel trim adjusted itself and when i check the plugs last week, they were perfect.

there is also a cheaper and very similar tool called opel-scan...you can buy a chineese copy of it, however when i bought one, it wouldnt work (i think it one of chips on the board was fried). however with this tool i think you can adjust the milage on the dash

[Keep'emRunning]

can't keep you all in suspense..

Was the Temp Sensor :) Even though it was still working, it's resistance curve was way off.

What happens (I guess?) is that the ecu, thinking the engine is cooler than it actually is, richens the mixture up. When the accel is pushed down hard, the motor is probably already overfueled, and adding more fuel sure doesn't help!

Still find it hard to believe though.. I thought the O2 would have taken care of this condition. Will pull the plugs in a week and see how they look, just to be sure.

The cheapest fix ever done on the car, $25 from a wreckers.

Are the ebay scanners any good? What are the realtime readouts on them like? Would beat playing around with a multimeter/cro for sure.

[CNBLU]

I had exactly the same problem but i had the engine light come on, thought it was the o2 sensor so changed both but to no avail, it was the coolant temp sensor! easy fix as i got the part from autovaux for 7 pounds!!