1990 Volvo 760 Turbo low idle/stalling Topic is solved

[keatoro]

Cheers to the redblock connoisseurs,

I’ve been having a long term issue that I wanted some advice on.

1990 760 Turbo wagon 280k

Car always runs and drive, stalls occasionally at lights or while parked, starts back up immediately. Never dies under load. recently it needed a jump to start which led to alternator suspicion.
Today I’ve tested the alternator and found it’s only reading 12.50-12.80 while idling so I’m going to replace it.
Now that may solve the stalling issue but I’m starting to think there are two separate issues.

The car also does not spike RPM to 1500 on start up like every other 740 turbo I’ve driven. Very weak idle that stays around 500-600. Almost seems like it’s the reason for the stalling.
No codes on the LH2.4
I’ve checked ignition and replaced ICM, swapped IAC, ECU, MAF, checked for vacuum leaks. No change in low idle...

Current suspects: temp sensors, cold start injectors, clogged cat?

A lifelong Volvo mechanic told me the 760 turbos from 1990 are a bit of a unicorn year and are closer to the 960 than 740 turbo. He said the ECUs from this era 1990-91 had known low idle issues so I was hoping that would be the fix. But no cigar.

Anyone brain storm anything else up that I’m missing?

Glad I have an 850 at times like this lol

Thanks gentlemen

[lummert]

Idle switch on the throttle body? And your friend is correct that your 1990 760 Turbo is closer to a 960 Turbo just as the 1991-92 940 SE is a 960 Turbo.

[abscate]

Get the battery on a charger so that’s it is at 100% SOC before chasing down esoterica. Electronics hate saggy voltages and a compromised ignition will give you lots of demons and angels to chase

[keatoro]

After replacing the alternator all of my gremlins have gone. Idle is back up to a healthy 700 rpm. Good advice!

Cleaned/adjusted the throttle body, and now the car is running better than ever.

Thank you all!