SaffronC70
Jun 11th, 2006, 18:48
Hi peeps
Thought I would share my findings :)
Just for history; I have had a bad idle since I have had the car, fluctuating +/- 100 rpm, occasional hesitation and stalling. The car has had 3 ETMs each resulting in the same idle result.
I have discovered the root cause for this fault: a failed non-return valve on the EVAP system (pollution control).
This was allowing a direct air leak at idle from the inlet piping to the manifold.
Testing involves "sucking and seeing" lol; remove the pipe from the inlet tube and you should be able to suck, but not blow.
To remedy this, I inserted an extra non-return valve (as I am on a budget and didn't fancy paying £48 + vat from Volvo). The OEM valves also acts as a reducer, hence my reason for keeping it.
Results are SOLID IDLE (glourious to me as this has been a pain in 2 years ownership and £££s), better braking power (due to increased manifold vacuum under engine braking) and I have already seen a marked improvement in MPG (I used to see 230 to a tank normal driving. After running the tank dry from half a tank with the fixed leak, I am seeing 260 :) I'll report back how many miles from a full tank!)
Hope this helps some peeps and it's really quick to check out.
Chris
Thought I would share my findings :)
Just for history; I have had a bad idle since I have had the car, fluctuating +/- 100 rpm, occasional hesitation and stalling. The car has had 3 ETMs each resulting in the same idle result.
I have discovered the root cause for this fault: a failed non-return valve on the EVAP system (pollution control).
This was allowing a direct air leak at idle from the inlet piping to the manifold.
Testing involves "sucking and seeing" lol; remove the pipe from the inlet tube and you should be able to suck, but not blow.
To remedy this, I inserted an extra non-return valve (as I am on a budget and didn't fancy paying £48 + vat from Volvo). The OEM valves also acts as a reducer, hence my reason for keeping it.
Results are SOLID IDLE (glourious to me as this has been a pain in 2 years ownership and £££s), better braking power (due to increased manifold vacuum under engine braking) and I have already seen a marked improvement in MPG (I used to see 230 to a tank normal driving. After running the tank dry from half a tank with the fixed leak, I am seeing 260 :) I'll report back how many miles from a full tank!)
Hope this helps some peeps and it's really quick to check out.
Chris