850AWD start/idle problem - need help to diagnose
#1
12-05-2007, 12:09 PM
850AWD start/idle problem - need help to diagnose
Hello,
I have 1997 Volvo 850 AWD B5254T engine at 217,000 km, standard transmission.
Recently the following 2 problems appeared:
1. After a sudden emergency stop, the RPM drops to 550- 600 RPM and then is shoots up to 950rpms and after that it stabilizes. It happens at any weather conditions with any quantity of gas in the tank and only if the engine is at normal operational temperature;
2. The cold engine start is different compared to before – the last 3 – 4 days ( it is -18C here in Alberta, Canada) after I start the engine (no block heater on my car), the first 2 – 3 seconds the engine shakes like the RPM is too low or some of the cylinders is not working properly and after that the engine works fine.
Can you, please, advise if the 2 problems are related and what can be done to fix them?
Here is what I did so far:
1. No codes or frozen frames at this time on my OBDII reader;
2. New synthetic 5W30 oil and Man 917 filter;
3. New spark plugs BOSH;
4. Ignition wires and distributor cap are on 17,000 km;
5. Idle air valve and throttle body are cleaned a week ago (new gasket for the throttle body);
6. New air and fuel filter;
7. New vacuum lines - most of them;
8. Cleaned the intake air hose between the turbo and the MAF sensor;
9. Cleaned the MAF sensor (it is a hot film type and it was not dirty);
10. The MAF reads 3.7 to 3.9 g/s at idle (slightly fluctuating) - MAF is not the reason - i installed a brodn new one and the result was the same.
11. RPM at idle runs at 840 (fluctuates from time to time to 810 rpm);
12. PCV was cleaned 25,000 km ago;
13. O2S – the front one runs when driving between 100 to 790 v. (up and down – not very fast – a second between the peak and the drop value);
14. The rear O2S is having a smaller amplitude of the fluctuation;
Any suggestions if this is fuel delivery problem or ignition problem or something else?
Regards,
Ivo
I have 1997 Volvo 850 AWD B5254T engine at 217,000 km, standard transmission.
Recently the following 2 problems appeared:
1. After a sudden emergency stop, the RPM drops to 550- 600 RPM and then is shoots up to 950rpms and after that it stabilizes. It happens at any weather conditions with any quantity of gas in the tank and only if the engine is at normal operational temperature;
2. The cold engine start is different compared to before – the last 3 – 4 days ( it is -18C here in Alberta, Canada) after I start the engine (no block heater on my car), the first 2 – 3 seconds the engine shakes like the RPM is too low or some of the cylinders is not working properly and after that the engine works fine.
Can you, please, advise if the 2 problems are related and what can be done to fix them?
Here is what I did so far:
1. No codes or frozen frames at this time on my OBDII reader;
2. New synthetic 5W30 oil and Man 917 filter;
3. New spark plugs BOSH;
4. Ignition wires and distributor cap are on 17,000 km;
5. Idle air valve and throttle body are cleaned a week ago (new gasket for the throttle body);
6. New air and fuel filter;
7. New vacuum lines - most of them;
8. Cleaned the intake air hose between the turbo and the MAF sensor;
9. Cleaned the MAF sensor (it is a hot film type and it was not dirty);
10. The MAF reads 3.7 to 3.9 g/s at idle (slightly fluctuating) - MAF is not the reason - i installed a brodn new one and the result was the same.
11. RPM at idle runs at 840 (fluctuates from time to time to 810 rpm);
12. PCV was cleaned 25,000 km ago;
13. O2S – the front one runs when driving between 100 to 790 v. (up and down – not very fast – a second between the peak and the drop value);
14. The rear O2S is having a smaller amplitude of the fluctuation;
Any suggestions if this is fuel delivery problem or ignition problem or something else?
Regards,
Ivo
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