A quick question. My 1989 m20b25 is idling low and very unstable for a while when starting cold. When i disconnect the ICV plug, nothing happens. Doesnt even change a bit. The ICV buzzes when the ignition is on. Tested the ICV with a multimeter and getting the correct ohm readings.
I've read some similar problems online and a few people have been talking about a faulty DME. To be honest I'm unsure what the DME actually is even after reading the wiki. Is it in the ECU?
I'm having the same issues as I did with my 2.0 engine which i swapped out last year. I am using the same ECU as the 2.0 but with a chip. Could it be something faulty with the ECU?
Thanks!
ICV
Moderator: martauto
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Brianmoooore
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Nothing should happen to the idle speed of a M20 when the ICV is unplugged, unless the load on the engine changes. I.e. Switch on the headlamps, and the revs. will then drop slightly.
DME = ECU. What is the type number on it?
DME = ECU. What is the type number on it?
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Rhyse30
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Nothing should happen? Right ok. I think I've misunderstood what the ICV actually does.
The ECU is 172. But with a speedtouch b25 mild chip. I've heard of the 380 ECU failing and affecting idle? Could this happen to the 172? I'm just thinking this as I'm having the same problems I had with my old 2.0 engine. The only parts I kept from the 2.0 is the ICV and ECU. Everything else was swapped engine wise. I suppose it's just a coincidence and need to keep searching.
Blue temp sensor reads as it should. 95% of the problem goes away when the engine starts to warm up. Still slight hessitation on acceleration but not that noticable.
Sprayed wd40 around the intake with no change. Injector refurb and intake manifold gaskets is next I think.
The ECU is 172. But with a speedtouch b25 mild chip. I've heard of the 380 ECU failing and affecting idle? Could this happen to the 172? I'm just thinking this as I'm having the same problems I had with my old 2.0 engine. The only parts I kept from the 2.0 is the ICV and ECU. Everything else was swapped engine wise. I suppose it's just a coincidence and need to keep searching.
Blue temp sensor reads as it should. 95% of the problem goes away when the engine starts to warm up. Still slight hessitation on acceleration but not that noticable.
Sprayed wd40 around the intake with no change. Injector refurb and intake manifold gaskets is next I think.
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Brianmoooore
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It's only the later 380 ECU that has the fragile idle control circuitry.
Have you checked that the TPS idle switch is working and adjusted properly?
Have you checked that the TPS idle switch is working and adjusted properly?
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Rhyse30
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Yes, TPS is working as it states in the wiki.
Could it be that my fuel pump is in the way out?
Could it be that my fuel pump is in the way out?
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Brianmoooore
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Unlikely that the fuel pump would cause this problem.
Injector refurb would be a good idea, even it it only ends up eliminating them as the cause of the problem.
Injector refurb would be a good idea, even it it only ends up eliminating them as the cause of the problem.
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Rhyse30
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No idea when the last time, or if at all the injectors have been looked at so it can only be a good thing
Thanks Brian. Any other causes come to mind please let me know. It's bedn driving me mad for the last 6 months!
Thanks Brian. Any other causes come to mind please let me know. It's bedn driving me mad for the last 6 months!