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LH 2.4. AFR stuck at approximately 14.5 – Volvo 940 B230FK

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Emil2001

New member
Joined
Sep 27, 2025
I have a 1996 Volvo 940 B230FK, recently rebuilt with a VX cam, Siemens Deka 630cc injectors, fuel/ignition chip, do88 intercooler, Holset HX30, 3 MAF, Walbro GSS 342 pump, and EGR delete.

I suspect that it might be the MAF sensor, since I had to solder some connections when converting it to 3-inch. Has anyone experienced something similar and possibly know how I can test the MAF sensor? I’ve got a new one on the way, but it won’t arrive until next week.
It runs fine at idle and while cruising, but it seems like the AFR is stuck at around 14.5. I’ve checked the fuel pressure and it’s at 3 bar and follows the manifold pressure 1:1, checked the trigger sensor on the flywheel, fuel pump relay, TPS, and also disconnected the lambda to see if that made any difference during load— it didn’t.

All suggestions or tips are appreciated.
 
redblockpowered said:
Can you provide a little more detail? Is it never leaving that AFR, even with the oxygen sensor unplugged?

Any fault codes?
Click to expand...
I forgot to mention that it also doesn’t start right away. I have to turn the key several times until I hear the pump, and only then will it start. I checked the fault codes now and didn’t get any blinking on fuel until I had turned the key several times and heard the pump (same as i have to do for it to start). Could it be the chip? I’ll switch back to the original chip and test. There was no fault codes both fuel and ignition had 1-1-1.

EDIT: changed the chips and the car now starts normally, not sure about the afr because of the current chip is made for original maf size, but i think the chip is the reason for the afr not going down.
 
Last edited:
Emil2001 said:
I forgot to mention that it also doesn’t start right away. I have to turn the key several times until I hear the pump, and only then will it start. I checked the fault codes now and didn’t get any blinking on fuel until I had turned the key several times and heard the pump (same as i have to do for it to start). Could it be the chip? I’ll switch back to the original chip and test. There was no fault codes both fuel and ignition had 1-1-1.

EDIT: changed the chips and the car now starts normally, not sure about the afr because of the current chip is made for original maf size, but i think the chip is the reason for the afr not going down.
Click to expand...
Agreed - sounds like it's in the tune. You might be able to drive the car around enough to see if it acts differently (be VERY careful).
 
Sort of sounds like an issue with the AFR gauge to me. They tend to default to 14.7 when they're not yet getting a signal from the sensor (usually while the sensor is heating up).
 
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