Help with a modified B230FT stalling

[yambox142]

Okay folks, I don't usually ask for help here but I have reached the limit of my knowledge.
I have a 1971 142E (not important) with a 2.3 liter B230FT (from a 1993 940) M46 trans swap.
Modifications:
- iPD turbo cam
- TD04-19T ← this is new (still need to truly break it in, boost is set super low)
- Larger intercooler
- Upgraded fuel injectors (newer Bosch design for improved atomization) and fuel pump (high flowing).
- Tuning chip (not the stage 3 chip, where you need the “big greens” and 3 inch MAF)
-Cone filter (brand new)
- 3'' down pipe (running a straight pipe at the moment, haven't gotten to the exhaust yet).
Replaced/Cleaned:
- Distributor cap and rotor
- New oil separation box and all associated hoses.
- MAF cleaned
- New plugs
- Replaced almost every hose in the car
- Throttle body cleaned
- Reset the ECU, more times than I can count.
Diagnostics:
- Smoke test (smoke leak from the throttle body spring and base of dipstick)
- Boost leak test (I only get air from the dip stick, when I pull the dipstick and plug the hole I don't hear air leaking form any other location. When I release my finger from the dipstick a whoosh of air comes out.

My car starts without any issues, idles fine (wideband reads 14.1- 14.5), and feels great when accelerating, BUT when I abruptly take my foot off the gas from acceleration the engine almost stalls, or completely stalls. The car idles fine, it drives so strong I just cannot figure out why it keeps stalling. The next part to be replaced is the “idle air valve.” I feel like I keep replacing parts but I get no closer to solving the problem. My love for this car is starting to turn into resentment.

Any suggestions would be appreciated.

[Swedbrick]

This sounds like a similar issue I encountered with fuel slosh, the pickup loses fuel for a bit and creates an air pocket that stalls your car. Try it with a full tank of fuel, if it goes away, you know where to look;)

After that, lh2.4 has a feature that makes use of your rear axle signal to trigger deceleration, if this wire is left out or the signal is missing high idle after highway driving and odd stalling behaviour can occur

[esmth]

adjust throttle body and TPS switch to spec

https://www.volvoclub.org.uk/faq/Eng...itchAdjustment

When I did my +t i had ridiculous stalling issues like you describe and it was just a mis-adjusted throttle plate / switch. Don't try to wing it, do it right. Trust me haha!

[Harlard]

Originally Posted by esmth

adjust throttle body and TPS switch to spec

https://www.volvoclub.org.uk/faq/Eng...itchAdjustment

When I did my +t i had ridiculous stalling issues like you describe and it was just a mis-adjusted throttle plate / switch. Don't try to wing it, do it right. Trust me haha!

^same

[90volvo]

how far is your Mass Air Flow meter from the turbo. I had similar experience and when I moved the AMM away from the turbo it fixed the problem.

[yambox142]

Originally Posted by esmth

adjust throttle body and TPS switch to spec

https://www.volvoclub.org.uk/faq/Eng...itchAdjustment

When I did my +t i had ridiculous stalling issues like you describe and it was just a mis-adjusted throttle plate / switch. Don't try to wing it, do it right. Trust me haha!

I appreciate this information. I know what I will be doing for Thanksgiving. I hope that I can update that the problem has been fixed.

Cheers

[gsellstr]

This isn't a new issue for many of us. I've been fighting that for a long time, haven't found the magic bullet. My car with a VX cam, no issues at all. With the IPD cam it'll stall. I'm trying to work around it on the tune side, as everything else has already been gone thru.

[Wren]

Check for a hole in your CBV diaphragm.

[yambox142]

Update.
First off, I want to say thanks for all the suggestions. I did everything that was suggested here and I am happy to announce that the stall is no longer. I dialed in the throttle body (it blows my mind how precise this engines need the throttle body to be, and the task of getting the throttle plate / switch just right was not hard, once you read the convoluted instruction ten times). After the throttle plate / switch adjustment the stall mostly went away. When I took apart my CBV cleaned/lubed, things got even better. Finally I received my new Idle Air Control Valve (and associated hoses) and the beast was alive. Thanks again for all the help, I live in Northern Cali and I hope to make some of the Bay Area and Oregon Volvo events, hope to see you guys out there.

Yam