• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

B230ft swap idle issue

brickb!tch

Member
Joined
May 8, 2020
Hello! I have recently completed a b230ft swap on a 1992 244 and am having some strange problems. The engine is from my old 1991 940 t. I took the engine and trans out, did every gasket I could think of, as well as the accumulator mod. Both cars use LH2.4 so I used the 240 harness which was in great shape. After starting her up and driving around the block a few times the cel came on and gave me a code for the iac 223. The strange thing is that this code stayed on always while the engine was in the 940 as well, even after swapping 2 different bench tested valves. I came to the assumption that it must have been the wiring harness in the 940, as it was a train wreck. The 240 doesn’t idle well and exhibits the same hiccuping idle and increasing Rpms in park and neutral that the donor 940 did. I did the obd test and could hear the valve functioning .

Here are things I have checked:
Smoke tested for vacuum leaks
A few different Iac valves
Unplugging iac, car acts the same
Unplugged maf, the idle went very high and I had no throttle control
Checked timing
Tried 2 different NA ECUs (only ones I have access to) and the car would barely keep running


And here are some engine specs:
15g
Blue hi z injectors from a s70
Compression is 160-165 across all 4
Vacuum at idle is around 13-16 at 6000ft elevation
Ngk copper plugs gapped to .028
Egr deleted
Ac deleted

The one commonality between the two cara that keeps popping in my head is the 560 ecu from the 940.

Anyone have an idea of where I should go next? Thanks
 
Have you set the base idle? Either clamp shut the IAC hose or ground the test plug and use the thumb screw on the throttle body to set idle to around 700rpm with a fully warmed engine. Make sure the TPS switch is working too.
 
I just measured tps and everything checks out perfectly. I will try the base isle adjustment, but I don?t see how it would affect he hiccuping / rough idle.
 
Did you cut your tps wide open wire that turbo cars ecu's don't have or like to have? If you don't cut that wire in the tps and use a NA harness with an older 5xx ECU it will cause the car to flood out if you floor it click the tps to the full open position.

<iframe width="560" height="315" src="https://www.youtube.com/embed/0cbr--8QJio" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


Is your speed sensor hooked up and getting to the ECU from the rear end and then to the dash and from the dash to the ECU? If not that will mess with idle. You should get a code for that if it isn't.
 
I will cut the wot wire. Yes the speedometer is functioning. I bought a later year turbo ecu and am going to try that
 
All of my Volvo?s idle around the same on the boost gauge. I live at a very high elevation, so 16 inhg pretty much equals 19 or 20.
 
UPDATE: Feel pretty dumb but during a compression check I realized that one of my spark plugs was not gapped to .028. Bought new spark plugs and re-gapped them and it purrs like a kitten. One of those incidents of going down a rabbit hole for no real reason. The IAC still persists even though it's idling well now, so I will try out a new ECU.
 
Back
Top