Surging/Hesitation While Driving code 1223

[tiger_e30]

Looking for some ideas. 1988 325is rpms are surging only after it warms up and it happens both while I am driving and idling. The stomp test yields code 1223 which is the engine coolant sensors. The check engine light comes on and off but never stays on. I have replaced the air filter, both ECT sensors( blue and brown), 02 sensor. I look over the vaccum hoses but was unable to spot any leaks. After replacing the ECT sensors I still get oscillations in my coolant temp never goes high but it dips low for a second then recovers.

Anyone have this problem? My next course of action is the AFM or give up and bring it to a mechanic to have the smoke test done.

[tiger_e30]

Took my AFM apart and it has some pretty deep groves worn in the carbon. Going to try and bend it tomorrow and see if being on fresh carbon helps

[tiger_e30]

Took my AFM apart and it has some pretty deep groves worn in the carbon. Going to try and bend it tomorrow and see if being on fresh carbon helps

Bent it. Did not go well....... Looking for a AFM from a 325i now

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[tiger_e30]

Bent it. Did not go well....... Looking for a AFM from a 325i now

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Replaced AFM. Still happening. Turned key on and idle control valve vibrated / buzzed. The rpms staying high after I put the car neutral is getting worse. Only idea I have left is replacing vaccum hoses. Anyone have any other ideas?

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[a70droptop]

Build your own smoke tester

Just an FYI ... There are lots of videos on youtube to build your own smoke tester. I did one for under 40 bucks and it works like a champ ...

[tiger_e30]

Just an FYI ... There are lots of videos on youtube to build your own smoke tester. I did one for under 40 bucks and it works like a champ ...

Thanks man. I'm going to check that out. After doing more research I'm leaning towards the c191 plug being my root cause. I'll dig into it tomorrow hopefully

[ahlem]

Try cleaning your coolant temp sensor(s) as well. Check the big rubber elbow between your AFM and Throttle body for any hint of cracks. Clean your idle control valve with carb cleaner, just because it buzzes doesn't mean it's not partially stuck. Did you put in new coolant temp sensors or used ones? I'd also clean all the electrical grounds and the wires at the alternator.

[tiger_e30]

Try cleaning your coolant temp sensor(s) as well. Check the big rubber elbow between your AFM and Throttle body for any hint of cracks. Clean your idle control valve with carb cleaner, just because it buzzes doesn't mean it's not partially stuck. Did you put in new coolant temp sensors or used ones? I'd also clean all the electrical grounds and the wires at the alternator.

Brand new coolant sensors. Since engine temperature will some times go to zero still I am thinking that maybe the c191 is bad and the motronic thinks it just got cold and dumps too much fuel in. But I am going to try everything on your list and check the cps and tps

[tiger_e30]

Disconnected my C191 and found a ton of corrosion. Have to run out and find some contact cleaner but I am optimistic this might fix it my problems

[tiger_e30]

Ordered some needle files after seeing the pins I'm pretty sure this was the problem.

[tiger_e30]

Cleaned the connectors but still getting the error. Going to get a multi meter on both sides and check continuity

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[tiger_e30]

Try cleaning your coolant temp sensor(s) as well. Check the big rubber elbow between your AFM and Throttle body for any hint of cracks. Clean your idle control valve with carb cleaner, just because it buzzes doesn't mean it's not partially stuck. Did you put in new coolant temp sensors or used ones? I'd also clean all the electrical grounds and the wires at the alternator.

Hey man you were right about the icv. I was chasing two issues. The c191 was the root cause of the check engine/ 1223 code and I fixed that by cleaning the pins and a very small amount of lithium grease. Issue two and the cause of my rough idle was the icv. Have to drive it for a couple days but based on this morning it's fixed

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