• 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!

240 please help me diagnose fault codes after engine swap

autoloclys

Member
Joined
Dec 20, 2016
Location
Boston MA
I just finished swapping a new B230F into my 240 after the last one threw a rod out of both sides of the case. It drives well, but idles rough and consistently turns on the check engine light with codes...

1-1-3 ? Lambda control ? engine running too rich/lean
2-3-2 ? Lambda control ? too lean or too rich at idle

If i clear them they come back after about 10-20 minutes of driving. i'm looking for some help with debugging it.

The new engine is '93 B230F squirter block with a T cam, and my car is a +T (13c) with an intercooler. The old engine ran happily with the same setup and didn't throw any codes.

not sure its related but my boost gauge (volvo triple gauge with no numbers on it) reads less vacuum then i recall it used to at idle, the needle is level at idle and dips (more vacuum) when the engine revs up before climbing up into boost as the load increases. So...air leak on the intake side?

I think i did things right when i put things back together, used new gaskets and such.

What should i be checking to get to the root cause?

my next plan is get some ether and start spraying things on the intake side.
 
Just tried spraying ether on all the connections between the MAF and the head and didn?t find anything. Engine was cold and seemed to be running smooth at idle. So maybe I?ll find something after my drive home?
 
Did it pee oil or antifreeze onto your oxygen sensor?

Before doing anything, clear the codes.

Try looking at the O2 voltage if you can keep it idling enough to warm it up. If it isn't switching, it could be the sensor or its wiring, or something forcing the mixture out of range like the fuel pressure regulator diaphragm has a hole in it or the pumps are not delivering fuel.

Long story short, when I see 113, I grab the multimeter to take a quick look at the oxygen sensor, and as a follow-up, the pressure gauge to look at fuel pressure.
 
Last edited:
Did some googling, but want to confirm i understand the test, with engine running and 02 sensor connected the multimeter to the green wire and ground, if i see moving reading between .1-.9 v the 02 sensor is good, any thing else means the sensor is bad?
 
Did some googling, but want to confirm i understand the test, with engine running and 02 sensor connected the multimeter to the green wire and ground, if i see moving reading between .1-.9 v the 02 sensor is good, any thing else means the sensor is bad?

That's what you should see if everything is working correctly. If you see the sensor voltage cycling, the sensor is working. You can get readings of nearly zero voltage with the sensor not cycling if the mixture is extremely lean, or, nearly 1 volt and not cycling if the mixture is extremely rich. If you see either of those scenarios do something to lean or richen the mixture and see what the voltage reading is after doing so. Inducing a vacuum leak will lean the mixture, pinching off the return line from the fuel pressure regulator will richen the mixture.
 
Did some googling, but want to confirm i understand the test, with engine running and 02 sensor connected the multimeter to the green wire and ground, if i see moving reading between .1-.9 v the 02 sensor is good, any thing else means the sensor is bad?

Not that simple. But if it is switching, you know it and the fuel system are working together at that moment.
 
With codes cleared the O2 sensor seems to be good, it shows reasonable voltages, about .7 when the engine is cold and idling smooth.

I swapped out a spare FPR, and that also didn't change anything, no gas smell in the vacuum line either.

This seems to be tied to the engine being hot. I checked everything on a cold engine and the idle was smooth and it drove well when I left work, about 20 minutes in the vacuum level dropped (less vacuum) whenever i was sitting at idle and the idle got rough/low.

can the IAC get stuck somehow and cause this? i most info i find on bad IAC's is about the idle being too high
 
With codes cleared the O2 sensor seems to be good, it shows reasonable voltages, about .7 when the engine is cold and idling smooth.

I swapped out a spare FPR, and that also didn't change anything, no gas smell in the vacuum line either.

This seems to be tied to the engine being hot. I checked everything on a cold engine and the idle was smooth and it drove well when I left work, about 20 minutes in the vacuum level dropped (less vacuum) whenever i was sitting at idle and the idle got rough/low.

can the IAC get stuck somehow and cause this? i most info i find on bad IAC's is about the idle being too high

CTS plugged in? Wiring in tact?
 
checked everything on my lunch break.

I solve something! but not everything.

o2 signal does oscillate when you use a better meter, seems in range

I ran through the function checks on the OBD box, IAC moves limit to limit.

I did find that the TPS wasnt adjusted right, and wasnt closing when throttle was closed. The sensor checks out and once i put it back on and adjusted it the issue with the idle seems to have gone away. I was thrilled and ran up the highway a couple exits to be sure that all my problems were solved, but after a few mile the check engine light is back, but this time it idles fine and seems to be driving fine.

im going to dig up the check procedure for the ECT sensor and if that tests good pull the IAC and clean it, beyond that Im out of ideas
 
I tried probing the ECT sensor at the ECU connector. I couldn't get a clear reading and have a dumb question. Should i be probing with the ECU connected, from the back side of the connector (with the cover removed), or with the ECU out of the loop and from the front of the connector (where is mates with the ecu)?

Anyway, after that experiment the codes were cleared from unplugging the ECU and did not reoccur on my 50 min drive home.

either the wet weather i was driving in affected things enough to mask whatever underlying issue im having, or is it possible that unplugging the ECU cleared away all the "learning" and now that its re-learning without the TPS issue its happy?

confusing
 
I tried probing the ECT sensor at the ECU connector. I couldn't get a clear reading and have a dumb question. Should i be probing with the ECU connected, from the back side of the connector (with the cover removed), or with the ECU out of the loop and from the front of the connector (where is mates with the ecu)?

Anyway, after that experiment the codes were cleared from unplugging the ECU and did not reoccur on my 50 min drive home.

either the wet weather i was driving in affected things enough to mask whatever underlying issue im having, or is it possible that unplugging the ECU cleared away all the "learning" and now that its re-learning without the TPS issue its happy?

confusing

Youre looking for a response in voltage to temperature, so either way should give you a good reading, but Volvo warns against putting probes in the front of connectors because glyph can bend the contacts and cause intermittent issues.
 
Use needle probes for backprobing.

Only front probe with the proper probe. I got some for $100. Or make test leads using pins from old components and solder on a wire.
 
for the sake of anyone who turns this thread up in a search because they are having similar issues.

its been a week, and the CEL hasn't turned back on since I unplugged the ECU and presumably wiped out whatever "learning" it had stored from driving around with the TPS misaligned.

So in the end it seems that the underlying issue was that the TPS wasn't triggering at closed throttle. Adjusting it so that it did and then wiping the ECU's memory has seemingly solved my problems.
 
Back
Top