Hi! I am new to this forum and I really need someone's advice. So I have a 1993 Volvo 940 Rex Regina system mixed with Bosch. Anyways, I am having trouble with my car in the mornings. This started about a week ago and this is what happens:
So I turn the car on and all is well. However after 2 minutes of getting warm the car starts to act weird. The idle starts to go up and down, up and down, up and down, and it starts to sound like a cammed muscles car 🤣. It's pretty annoying. It also idles up to 1,000 rpms and sometimes goes up to 1,500 then back down and starts to go up and down up and down. However after getting 1/4 warm it settles down and goes back to normal. Car drives well and doesn't act strange when completely warm. I want to figure out what's going on before it get worse.
I have changed:
Vacuum lines
Pcv lines
Fuel pressure regulator
Cleaned IAC and even got a buddy to let me test his.
I've changed pretty much everything to do with vacuum lines. I even sprayed around with starter fluid to see if there were leaks somewhere.
I cleaned my MAF
Does anyone have any suggestions?? I literally running out of hope. This car has been in my family since 93 and would like to keep it that way.
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It may be still the MAF sensor--cleaning it rarely helps. It could be the Coolant Temperature Sensor.
Turn the car off when this is going on, unplug the MAF, see if there is any diff. once plugged back in and running.

 

 

Goldenblock here!!! Its your throttle position sensor... Check to make sure you hear a click upon opening/closing as you manually open throttle. It may need adjusting or replacing!! Oss

I also have regina bosch hybrid 1989 740 gl

 

Clean the throttle body?

 

It does click. I had a buddy of mine readjust the throttle body but no help.

 

It throws a 233 code and 223 sometimes. I wondering if it is the IAC but that is rare. I adjust throttle body and even cracked open the TPS. I found one of the metal things that makes the tps click bent a little for some odd reason but I bent it back. I reassembled it back together however, it did not make a difference. Next thing I did with my volvo friend that is a mechanic is, we decided to try to put the hoses on the IAC all backwards and it seems to have fixed the "cammed" idling however, it started making the alternator make sounds, very odd. I honestly dont know what is happening with this car. Another thing that is happening now is the throttle seems to be sticking at 1,500 rpms when driving. if you are around 40 mph the rpms goes down but then goes back up to 1,500 and stays there. Essentially, feels like the car is driving itself. So now I have issues with idling and rpms getting stuck at 1,500 rpms. If you have the car all warmed up also and rev it passed 2,000 rpms the car will get stuck at 2,000 as well. Any clue? Guessing it could be TPS? Should I replace idle air control and temp sensor?

 

the 'TPS' is just a microswitch, closed if the throttle is fully at idle, it enables the idle control circuit. some cars also have a microswitch for full throttle, this is less important