BrickBoard Archives
The files contained in this listing have been automatically archived from the active forums. Because the vast majority of posts are now in one place, this archive is considered legacy. You should use the SEARCH feature OR choose your topic and select date tabs within the forum you choose.
Knock sensors[ALL/1998] posted by Frederick Wezeman on
Monday, 22 December 1997, at 2:01 p.m.
What's the purpose of replacing a knock sensor(s) if one consistently uses 93 octane fuel in an 850? Isn't the purpose of the sensor to detect knock and advance the timing? But if you use high octane fuel that doesn't cause knocking, why pay the service bandit $300 to replace the sensor? My "check engine" light coded for the knock sensor, now it has gone off (after approximately 1000 miles after diagnosis of the faulty sensor). Does this mean that the sensor is back in business or is the panel light coded to remain lit for only a period of time?
Re: Knock sensors[ALL/1998] posted by Patric on
Monday, 22 December 1997, at 9:58 p.m.
Why ask your question, if you think your tech. is a bandit.
Yoy had a problem and you got an answer.
Re: Knock sensors[ALL/1998] posted by Ira Blumberg on
Tuesday, 23 December 1997, at 10:26 a.m.
I am not sure about Volvo engine controls, but on Mitsubishi 2.0L turbo engines, the knock sensor is very important. The ECU continuously advances the timing until it detects slight knock and then backs off a bit. The ECU uses this algorithm up to an advance appropriate for about 110 octane. Thus, you always get better performance if you use better gas. A bad knock sensor will either cause terrible performance (if it registers a false positive), will endanger your engine with excessive advance (if it fails to register knock when present), or will cause your ECU to go into limp mode (again terrible performance) if failure is detected.
I would suggest replacing the sensor if it is bad. You could purchase one from a discount mail order place or even order one used.
--Ira
Re: Knock sensors[ALL/1998] posted by Mark Klein on
Sunday, 28 December 1997, at 12:47 a.m.
There was an update for knock sensors on some of the older 850s. Check with your dealer. Even if your car is out of warranty, Volvo may help with the cost of this repair.
Re: Knock sensors[ALL/1998] posted by abe crombie on
Sunday, 28 December 1997, at 11:41 a.m.
What year and model is your 850, turbo or non-turbo. The knock sensor can't be checked by any meter or gauge only by relying on the computer's fault code which doesn't tell you whether it's a bad electrical or in fact a truly defective knock sensor. The high price is partly a result of difficult access to the knock sensors.
Re: Knock sensors[ALL/1998] posted by Bret Bodas on
Sunday, 28 December 1997, at 3:27 p.m.
The update is for 94 Turbo models. The problem they have is corrosion at the terminals, and the terminals moving at the knock sensor connector, causing poor connections. The update is quite inexpensive, about $45.00 the last time I checked. It does take about 2 to 3 hours to update the harness (need to remove the intake manifold) and replace the sensors, hence the high cost. I've never seen a car with this repair trigger the check engine light again, so it does work. Good Luck