cold start prob

[me217]

hey
my sierra is doing weird stuff on cold starts,
it starts fine for abit at about 1500 or so then after abit it just instantly drops to 900 ish rpm, and its fairly rough then. then after 30 secs or so. it goes back up to 1500 until its warmed up.
i have a 1992 sierra with mpfi 1.6 vitara engine.

me217

[nicbeer]

o2 sensor could be dying. and choke related stuff.

not sure what else on the 16b controls cold starts.

[me217]

is there any way to check what is actually dead/dying.


me217

[lay80n]

The o2 sensor shouldnt affect cold starts, as the ECU will only read from the o2 sensor when the car is at Normal opperating temp. O2 sensors acutally take a short time to warm up and work (time varies, and some o2 sensors are heated so this will vary). The computer uses a coolant temp sensor to check the temp. If it registered cold temp it runs a richer cold start map. Check that your idle control valve is not clogged up as this would cause the problem. Start here, and if you still got problems post up and we can go from there

O2 sensors can be checked, you should see a swing between 0.1 and 0.9 volts when the ecu is running in closed look operation (idle and low load at opperating temp).


Layto....