e30 Hard to start when warmed up and running rich

[jaydeep]

I have 1988 325is. When car is warmed up its hard to start also running rich. I can smell gas in the exhaust.
So far I have checked.
1) coolant temp switch (When car was cold reading was 250 ohm and 100 when warmed up)
2) Oxygen sensor

Please help

UPDATE

I checked fuel pressor at fuel rail and after fpr. Both is showing 70 psi. What is wrong. I took these reading when car was just started.

[jlevie]

You looked at the wrong temperature sensor. Those readings are appropriate for the sensor that drives the gauge. At 20C the ECT sensor should be 2500 ohms. Unless you happen to have a mixed gas flow bench all you can say about an O2 sensor is that it is doing something. You can't tell if it is operating correctly. The O2 sensor is a scheduled maintenance item with a replacement interval of 100k. If of that or greater age, replace it.

That said the gas smell in the exhaust could be fuel from misfires, which will cause hard starts, and the most common causes of those are intake leaks, aged ignition wires/distributor cap/rotor, aged/wrong plugs, or fuel system problems.The first actions should be a smoke test of the intake and repair of the leaks it reveals, new ignition wires/distributor cap/rotor, new O2 sensor, a fresh set of NGK ZGR5A plugs, a valve adjustment and a check of rail fuel pressure. That may be all that is needed, but the next step from there is to have the injectors cleaned and flow tested.

[jaydeep]

You looked at the wrong temperature sensor. Those readings are appropriate for the sensor that drives the gauge. At 20C the ECT sensor should be 2500 ohms. Unless you happen to have a mixed gas flow bench all you can say about an O2 sensor is that it is doing something. You can't tell if it is operating correctly. The O2 sensor is a scheduled maintenance item with a replacement interval of 100k. If of that or greater age, replace it.

That said the gas smell in the exhaust could be fuel from misfires, which will cause hard starts, and the most common causes of those are intake leaks, aged ignition wires/distributor cap/rotor, aged/wrong plugs, or fuel system problems.The first actions should be a smoke test of the intake and repair of the leaks it reveals, new ignition wires/distributor cap/rotor, new O2 sensor, a fresh set of NGK ZGR5A plugs, a valve adjustment and a check of rail fuel pressure. That may be all that is needed, but the next step from there is to have the injectors cleaned and flow tested.

There is brown and blue temp sensor. Readings are from brown sensor. I thought blue is for temp gage.
Is there any other temp sensor I need to test?

[jlevie]

The brown sensor is for the gauge, the blue sensor is for the DME. On a Motroninc 1.1 0r 1.3 system the blue sensor is the only one that matters for temperature related adjustment to fuel delivery.

[jaydeep]

I took reading from blue plug when car was warming up and got 400 ohm.