1990 Volvo 240 rough Idle on start
 

Hello All,

I am hoping to find some help here about an issue I am having with my 1990 240 DL.
The car will idle rough when you first start it, it seems to be worse the colder it gets. After running the car for a few minutes, the idle gets better but if I try to drive the car right away it will stall. Here are the parts I replaced hoping to fix the issue:

1- New NGK spark plugs
2 - New Bosch Oxygen sensor
3- New Temp sensor (FCP EURO)
4 - Idle control switch (Aftermarket)
5 - New injectors (Refurbished and tested)
6 - New Alternator and Battery (The old one wasn’t charging)
7 - My mechanic checked the cold start injector and engine compression and says it is good.
8 - New MAF by Delphi
9 - Checked for vacuum leaks with a smoke machine and found one leak which is now fixed.

My mechanic also checked the fuel pressure and says that is fine, I want to check that myself since the only thing left for me to replace is the fuel pump.

not on the list: cap + rotor

was the idle air control valve cleaned and tested? when you remove them, you should have a pair of new IAC hoses on hand because the old ones likely will crack. you clean it with throttle body cleaner spray, then test it by repeatedly applying 12V to the pins, and verifying that it opens/closes briskly and without sticking.

also verify that the 'new' idle throttle switch actually opens/closes with the throttle, by using a ohm (or continuity) meter

if the contacts at the top of the underside of the cap are
corroded, the cap has hairline cracks, and or if the rotor shows wear or burned marks on it

here is an example of a badly burned rotor that came from my car, and the engine still ran!!

https://volvoforums.com/g/picture/7897572

if there's a surpression disk inside your distributor, its probably overdue for replacement, too... this is a plastic insulator disk across the top of the distributor, under the rotor, they too acquire carbon buildup and start encouraging arcing

Thanks, @silvermine! I checked it this morning, I think it is good since the contact and the overall condition looks good. Now the CE light is illuminated, when I pulled the codes, I got 232, 133, and 231.

@pierce - It has not been long since I cleaned the idle control valve, I think it was tested by a mechanic but I will pull it out and test it again with a 12v source. Hopefully, this will fix my 232, 133, and 231 codes. Thanks for the tip.