Hi to everyone, i have a rover 214 spi 1991. when the car its cold the idle works nornaly,after a while when begin to warm the idle is unstable.i check the fuel filter new,vacuum leaks,pump pressure,relay,all sensors work ok it checked with mems plug and with multimeter.i change spring to the brush of the distributor,the antiflash sheld its broken i dont know if that affect the idle.stepper at 30 in the 92 celcius.i check the servo when i press the brake affect the iddle but as servo works ok.some times times after driving the rpm stick at 1500 rpm but goes to 900 after.

Have a look at this thread: https://rover200.org.uk/forums/topic/16491

the kpa its between 36-44.the car looses power or run ok radomly.i didnt find something strange at csv file.can i find if the ecu have problem with the mems cable?

The MAP reading on idle should be around 32 to 35 kPa. It should rise if you open the throttle. The other parameter than can affect the idle speed is the coolant temperature. If the coolant temperature sensor is faulty, it might be telling the ECU intermittently that the engine is colder than it is and it compensates accordingly, raising the engine revs. What diagnostic are you using? The RoverMEMS App shows the coolant temperature graphically. As the engine warms up from cold, this should be a smooth curve going up to about 90 degC. If it's not smooth or has periods showing 60 degC, then the sensor is faulty. I've had that problem with my 1990 214 SPi.

One other thing. I think these earlier cars have a throttle switch which tells the ECU your foot is off the accelerator and it then enters the idle routine. It's possible this switch is intermittent so the ECU sometimes thinks it shouldn't be idling. The later cars didn't have this, but instead take a reading from the Throttle Position Sensor. Also while the car is idling, try turning on headlights, rear screen heater etc. The RPM should remain roughly constant as the ECU compensates by setting the stepper motor.

all the sensors are ok. the temperature increase normal. i use the rover mems app.the csv measurements seems ok.when start works ok after a while the idle is unstable.when begin to drive have missfires and then works perfect.when i slow down the rpm remain at 1500 1600 for a while and then goes to 900 rpm.with 36-44 kpa maybe i have air leak but i check all the vacuum hoses and is ok .can you tell me the yellow hose from air intake goes to the air filter and then where goes? where is the spot of the end of the vacuum hose?

The yellow vacuum tube goes to a thermac switch (valve) in the air filter box. There should be another
(probably red) coming from the other side of that vacuum switch, then going to a nipple on the inlet
manifold. The vacuum from that switch operates an actuator at the air inlet, to draw warmed air from
over the exhaust manifold, when the ambient air is cold.

i cant find that spot.can you tell me where is exactly?the inlet manifold have 2 vacuum hoses.one goes to the oil trap in the air filter and then to the ecu. the other goes to the carbon canister.is that the reason for the increaae kpa and the unstable idle?or something else to fix it?

That reminds me. About three years ago I had some work done on the engine by a garage. Not long after, I started getting unstable idle. I took it back to the mechanic, a former Rover mechanic, and he immediately went to the vacuum tubes coming off the inlet manifold, one to the this air divert valve (the yellow tube) and the other to the MAP. One of these was loose or fallen off. Problem fixed. Because the ECU is in a feedback loop it may well compensate for the air leak but wouldn't normally have to. Worth checking all the vacuum pipes are in good condition including the feed to the servo and for any other leaks round the manifold.

i replace all the vacuum hoses and tight them.mine dont go to the divert valve but to the carbon canister.the spi mini have the connection that you told me.i try to find where is the spot after the divert valve to connect it. do you know where is?the servo work ok, but when i push the brake at iddle the rpm and the kpa get lower.any thoughts?