1990 325is. This car has been completely refreshed basically. Timing belt. Cooling system. New harness. New cps. New 02. New intake gaskets and bitch tube o-rings. New exhaust mani gaskets. New valvle cover gasket. This car started out boosted and ran crappy until this maintenance was done. Car still has a rough idle during warmup. Unplug the brand new injector coopant sensor and it idles fine and runs fine. Exhanged the sensor for a new one. Same thing. Car runs fine without it plugged it but with it in runs crappy until warmed up. Tried changing injector harness too. Same thing. What gives?
Announcement
Collapse
No announcement yet.
Temp sensor causing rough idle?
Collapse
X
-
Well thia car ran ok mostly until we got a cold snap. It was intermittent surging and idle issues. Replaced all gaskets because of potential mani gasket leak. Still with everything replaced it cold idle is doodoo. Pull the wire for collant sensor and it runs perfect. Everything....literlly everything has been swapped.
Comment
-
temp sensor is used by the computer to regulate fuel/air mixture during start up. so yes, if the sensor is bad it could possibly be telling the computer that the car is cold, causing it to run rich, which "once at operating temp" would cause it to have a rough idle.Originally posted by unloadedakIt's brand new. I've gripped the shaft a couple times and that's about it.
Comment
-
you got the right sensor?89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
Comment
-
It runs rough, my problem is not the coolant temp sensor...i tested it. It may be the wiring to the dme, u can test the ohms at the dme. I have ordered a ground strap from the oil pan to the frame rail, for my oil sensor light on the system board came on with oil at correct level.
For you i would buy the temp sensor, it cost like 20 from bav auto then go from there. The fact that it runs okay unplugged, to me shows that it give the wrong ohm level to the dme when cold. But that would be easy to test with meter
Comment
-
Originally posted by comitsol View PostIt runs rough, my problem is not the coolant temp sensor...i tested it. It may be the wiring to the dme, u can test the ohms at the dme. I have ordered a ground strap from the oil pan to the frame rail, for my oil sensor light on the system board came on with oil at correct level.
For you i would buy the temp sensor, it cost like 20 from bav auto then go from there. The fact that it runs okay unplugged, to me shows that it give the wrong ohm level to the dme when cold. But that would be easy to test with meter
I've already replaced the temp sensor with a brand new one (twice) same result.
With the sensor plugged in it runs rough at cold start then clears up after its warmed up.
With the sensor unplugged it runs great all the time...
Comment
-
having a rough idle/power loss on startup but once it’s warmed up it’ll idle and drive great. I’ve tried everything else and led myself here. Temp sensor would could cause this right? it’s more so like im not getting the right amount of fuel when cold so i know the temp sensor controls the injectors and ratios and such just up until the o2 sensor warms up then that takes over right ? anyone wanna help explain ?
Comment
-
Originally posted by ScottySbk View Posthaving a rough idle/power loss on startup but once it’s warmed up it’ll idle and drive great. I’ve tried everything else and led myself here. Temp sensor would could cause this right? it’s more so like im not getting the right amount of fuel when cold so i know the temp sensor controls the injectors and ratios and such just up until the o2 sensor warms up then that takes over right ? anyone wanna help explain ?
Comment
-
Originally posted by Lippy View Post
I can't explain how it works, but I just replaced my temp sensors a few weeks ago. Its super simple and they are pretty inexpensive. If they are old it might be worth replacing regardless.
Comment
Comment