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Is a 1992 240 3.1 fuel system +T possible?

Slurp544

Slurp544

New member
Joined
Apr 10, 2024
Location
Kentucky
I bought a 92 240 5 speed with a 3.1 fuel system and at the time I knew verry little about volvos and working on cars in general so I thought it would be a good project car to start on. Recently I've been trying to do a +T conversion and so far it's been giving me alot of trouble.

Me and a buddy pulled the engine, changed the seals, put all new gaskets on with a VX turbo cam from IPD. We get the engine back in the car and it doesn't run (of course) so after a few weeks of trouble shooting the list so far is

- New tps sensor
- New O2 sensor
- New spark plugs
- I'm using the ecu and ezk off of the donor car we got the turbo from (1993 940T)
- No vaccum leaks
- Good fuel pressure

My issue currently is I can start the car and it will idle perfectly as long as the MAF is unplugged and it can rev as long as you do it slowly, trying to quickly rev it will result in it bogging down and dying. Whenever the MAF is plugged in it hardly starts and when I do get it started, it idles horribly and pressing down on the gas halfway will cause it to loose all power (what I'm thinking is a fuel cutoff idk). There is also no cutoff when the MAF is unplugged.

However whenever I switch out the ecu to the original 240 one the opposite happens, the car will idle perfectly with the MAF plugged in and it can rev fine. When you try to drive the car like this though there is absolutely no power and immediatey wants to die while in gear even if it's barely rolling with the clutch hardly let out, its like trying to drive while starting in 5th gear.

I recently just discovered that I have a 4 pin 3.1 MAF and fuel system on my car. I've already ordered a new one just to test but untill it arrives I'm wondering if there is anything different with the MAF that causes a +T conversion not to be possible. I would just assume it's a faulty or broken MAF except for the fact that before the +T conversion the car ran perfectly fine.

Any thoughts on what's wrong?
 
You need to add the connector and 016 hot wire mass air sensor for the LH2.4 ecu to read the data from the mass air sensor correctly. You can use the mass air sensor and connector from the donor turbo car. You will have to add a wire for the burn off function on the LH2.4 mass air sensor. The mass air sensors between LH3.1 and LH2.4 are not compatible.
 
So your saying to try to splice the connectors and add a wire to it? If so where does the burn off wire connect too? Or would it be easier to just use a 2.4 wiring harness?
 
My '92 240 5spd was +T'd a long time ago by the previous owner of the car. He used computers from a donor 940 turbo, used the -016 AMM/MAF from the 940. Extended the wires for the MAF to move it to the other side of the engine bay (pre-turbo, like a turbo car would have had). He used the injectors from the 940 turbo so he added the resistor pack, but you can also use injectors from an 850 Turbo or similar later volvo and you don't need resistors, so no changes to injector wiring needed. The throttle body was swapped since the TPS is different, and I think one of the wires gets cut, as it's not used.

I think there's an old thread around here somewhere detailing the wiring changes needed. I don't think swapping the entire engine harness would be easier, but that's just my opinion.

My car has been quite reliable. I bought it with around 132k miles on it, with the turbo already added. It currently has around 255k miles.
 
2manyturbos said:
Realistically, it takes approximately three hours to swap the harness. Much less if you’ve done it before.
Click to expand...
First try for me was probably 2 hours. I did my research and didn’t have to pull the intake, like some do.
 
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