EVAP Purge solenoid cleaning/maintenance?

[Jdmspoonitr]

Okay so I've had this problem for a while and now researching how to fix it. Randomly, it would seem during hot days/track days I will get a super rough idle after starting the car. It's to the point where the car will lope at really low idle and shut itself off.

If I drive the car about a block it goes away and all is well. But it's annoying and I'd rather just fix it. If possible I'd like to not remove all the EVAP stuff since I live in California.

Anyone have experience cleaning the solenoid?

TIA,

Ken

[aklackner]

Are you running an s300 by chance? Basically due to the differences between obd1 and obd2 system use of the obd1 ecu causes the charcoal canister to vent (on hot days) to the IM and causes cold starts to be rough.

If you still want to run evap system what I did was run a throttle body with the upper vacuum nipple and move the bypass solenoid vacuum line to that nipple as with OBD1. This allows venting of the evap system but prevents venting of the canister into the IM at start since there isn't airflow through the TB to generate the vacuum to open the canister vent. The canister will basically only be vented at near full throttle.

[aw614]

Are you running an s300 by chance? Basically due to the differences between obd1 and obd2 system use of the obd1 ecu causes the charcoal canister to vent (on hot days) to the IM and causes cold starts to be rough.

If you still want to run evap system what I did was run a throttle body with the upper vacuum nipple and move the bypass solenoid vacuum line to that nipple as with OBD1. This allows venting of the evap system but prevents venting of the canister into the IM at start since there isn't airflow through the TB to generate the vacuum to open the canister vent. The canister will basically only be vented at near full throttle.

Which throttle bodies have that additional vacuum nipple? I'm assuming obd1 gsr and aftermarket ones?

In my case with s300 I was running with the EVAP inverted and it seems to work, but I do wonder if that was the cause of my occasional cold starts that I could never pinpoint. My tuner mentioned that could also be the cause, although putting a new fuel pump on my car seemed to have made starts a lot better.

[aklackner]

The 98+ JDM TB had it, since its evap system was more similar to obd1. These use to be pretty easy to find and is what I've used. To limit explanations during inspections I cut the upper nipple off, re-drilled, and tapped the hole. Now I can either insert a npt threaded plug or nipple depending what my current needs are.
https://www.icbmotorsport.com/jdmindc2thbo.html

Otherwise the Edelbrock aftermarket TB is Carb legal, has that upper nipple, and is over-bored to 65mm.
https://www.jegs.com/i/Edelbrock/350/47 ... xEQAvD_BwE

With any throttle body replacement, make sure you have a good (preferably OEM) TPS and it's adjusted properly. I highly recommend checking sensor resistance over the whole range with a voltmeter to make sure resistance is progressive, dead spots can cause issues.

[aw614]

I just got a JDM ITR intake manifold and TB on a local deal,it looks like it has the top nipple for the EVAP. I am guessing you'll need to cap the intake manifold port for the EVAP if I move the hose to the TB instead?

[aklackner]

I didn’t think the JDM IM had an evap nipple? I do cap the nipple on my USDM IM when I have evap routed through TB nipple.

[aw614]

I should have mentioned that, I was going to put the TB on a USDM intake manifold, thanks that clears it.