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Old 08-26-2019, 09:45 PM   #1
autoloclys
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Default please help me diagnose fault codes after engine swap

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.
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Old 08-26-2019, 10:17 PM   #2
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Did it pee oil or antifreeze onto your oxygen sensor?
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Old 08-27-2019, 06:05 AM   #3
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Not that I know. You mean when the old motor died? No it blew out the sides of the block but the head didn’t get damaged
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Old 08-27-2019, 12:41 PM   #4
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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?
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Old 08-27-2019, 01:05 PM   #5
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Originally Posted by 2turbotoys View Post
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.
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Old 08-27-2019, 02:03 PM   #6
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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?
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Old 08-27-2019, 02:21 PM   #7
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Originally Posted by autoloclys View Post
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.
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Old 08-27-2019, 02:22 PM   #8
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Quote:
Originally Posted by autoloclys View Post
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.
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Old 08-27-2019, 07:00 PM   #9
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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
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Old 08-27-2019, 08:15 PM   #10
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Quote:
Originally Posted by autoloclys View Post
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?
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I didn't think there was anything to the whole 7/9 thing, but I have to say that my 745T is the only Volvo I've owned that blew up and self-immolated.
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Old 08-27-2019, 08:45 PM   #11
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O2 voltage should oscillate.
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Old 08-28-2019, 01:43 PM   #12
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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
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Old 08-28-2019, 04:23 PM   #13
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You probably have an air leak. I use a smoke machine.
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Old 08-28-2019, 08:45 PM   #14
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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
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Old 08-28-2019, 09:43 PM   #15
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Quote:
Originally Posted by autoloclys View Post
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.
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Old 08-29-2019, 02:41 AM   #16
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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.
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Old 09-05-2019, 09:02 PM   #17
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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.
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