Rev Issue at Startup

CDsDontBurn

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Over the last month or so, my car has been acting a bit strange on startup. Normally, when the car is started the engine starts and maintains the 2k RPM for about two seconds or so and before dropping down to normal idle RPM, ~900RPM. However, on occasion, instead of the RPMs dropping, they go up to about 3,300RPM and hold there for about 5 seconds before dropping down to normal idle RPMs.

It doesn't always happen, but I've noticed it only happens when the engine is cold. I know that something like this is typical of the IAC vavle, but the one I have in there now is brand new. The only thing I can think of is that the coolant line going to the IAC valve is causing this to happen. The reason why I say this is because when I replaced the IAC valve, I also replaced the coolant line going to it with a generic hose from AutoZone. So, it wasn't molded to the correct shape like the OEM hose from Honda would be. Since it's not molded, the hose kinks a little bit which causes a restriction in coolant flow. That's the only thing I can think of, but I'm not sure if that indeed is the issue.
 

xci.ed6

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I don't think that's your problem, some ppl eliminate the coolant system.

No check engine light?
Also check ecm command, software and output, see quick if the prob is program, ecm, iacv.
 

CDsDontBurn

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I don't know about a CEL. My car's CEL light doesn't work, which is a different issue entirely. However, if I plug in my OBDII scanner, it will detect any present codes (usually random misfire after heat soak issue).
 

CDsDontBurn

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Other things? Like a burnt out CEL light bulb that'll tell me if my CEL is on or not?

The Heat Soak issue is a known issue and it only affects the car after the car has been shut down and attempted to be started up between 15 - 45 minutes after the shut down. The fix requires a new ECU and FPR and is quite spendy because of the new ECU, so I'd rather just deal with that issue because I know how to deal with it.

I'm really just looking for a way to solve this RPM issue at startup.
 

xci.ed6

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I researched that heatsoak thing, my car is doing that. One suggestion was check coolant temp sensor. My ecu reads 63° when ambient temp is ~75°...

12° not bad, but 15% is. I'll check tomorrow how that changes.
 

RichBinAZ

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How is the electrical connection to the IAC valve? Corroded?? Making proper contact?? Slide it in and out of connection a few time, perhaps with a small drop of WD40 on the contact pins for good measure.
 
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