I have a 1996 Dodge Caravan with 2.5l 4-cylinder motor. 130k miles. The engine runs fine except at idle. The motor sometimes dies when I come to a stop. I pulled off a vacuum plug and the motor ran a little better, but as soon as I put the plug back on, the motor shuddered a little then it stalls out.
I checked vacuum with a guage, it seemed normal. 15-16 units on the guage. I looked at air filter and it appears okay.
I cleaned throttle body with cleaner.
I ran a scan test with an OBDII code reader, it says the downstream O2 sensor is bad, code: PO140, no activity. I read where the downstream sensor doesn't affect idle, but if the upstream O2 sensor is bad, it could affect idle.
#1 205 210
#2 210 225
#3 210 220
#4 210 220
wet test done after squirting small amount of 30-wt. Motor oil in cylinders, compressions taken with all plugs removed. Mininum 4 cranks. Pressure is holding at those numbers on all cylinders.
Haynes manual for 4-cylinder specs are showing between 170-225 psi as acceptable.
Based on those readings, I would say the cylinder head, piston rings and engine bores are good. The car appears to have good acceralation although there are no steep hills in area to test a load.
Should I be looking at replacing the Idle Air Control(IAC) valve?
have the same problem?
Thursday, May 3rd, 2007 AT 6:28 PM