Achieva starting hard after warm

[CAT Wrench]

This seems strange...my 2.4 Quad '94 Achieva starts great when you first start it cold. It will run great all day as long as you do not shut it down. With engine still at operating temp or even slightly warm, the engine cranks but will not start unless you press accelerator to the floor. The engine then starts but is revving high & pulses. After about 10 seconds you can back down on the accelerator & it then runs great again. In the time of restarting it does put out a lot of black exhaust but clears in about 10 seconds & runs great until shut down again. I replaced the engine coolant temp sensor but this did not help. Had to install a water pump & t-stat...what a design mistake that is...This car seems to be high maint. Any suggestions would be appreciated!!!

[95OldsHO]

There was no 2.4 in 94, either the car is 96 or newer, or is a 94 with a 2.3 motor. Unless someone swapped the 2.4 into the 94 chassis.

I would say possibly the O2 sensor, or the throttle position sensor could be bad, you can test them with a multimeter. Also could be the ignition coils and/or module, the module can be tested at most Autozones among some other places.

If it is a 2.4 motor try taking the car to an Autozone or someplace that can scan for codes on your OBD2 system, can also buy a scanner yourself. If its a 2.3 they wont be able to get codes for you because the system is OBD1(1.5).

Also wanted to mention that the engine cover that says 2.4 can fit on the 2.3 motor and vice versa, if someone put it on there it can confuse the hell out of the person trying to diagnose the problem of the vehicle, so first identify what engine you have for sure. One easy way should be the power steering pump- the 2.4(and 2.3's in 95)has the pump mounted directly on the motor, it runs off of the intake cam.. the 2.3 design runs off of the intake cam but uses a pulley on the end of the cam and on the pwr. steering pump.

From what you said about the design of the waterpump it sounds like you have the 2.4, the 2.3 pump is a little easier to replace though still no fun.

Hope that helps get you started.