Long story short, i ordered a chip with a basemap for my stock d16y8 from phearable. When i received it there was a paper with basic information and recommendations, one was aimed toward Obd2 cars which stated to unplug the evap purge solenoid(s). Firstly, im pretty sure my car only has the one solenoid on the fuel rail, or am i missing another?
Secondly, wouldn't the unplugging of the purge solenoid not allow the vapors to escape thus allowing the tank to become pressurized? If so what would i have to do to relive the pressure?

Thanks in advance.

 

What car and trim? What mods besides chip?

 

It's a 98 EX, only mods are the usual useless mods, CAI and header. Only reason i really got it was because my knock sensor broke and i already had a socketed p28, so i just ordered the chip to get rid of my CEL, plus it'll give me room for improvement later on.

 

Coupe or sedan?

The OBD1 P28 ECU should no look for EVAP sensors, so I don't understand the point of unplugging them.

 

Its a coupe.

I thought so to which is why i didn't initially unplug it but i was getting random rough starts. When i finally decided to unplug it, i noticed much better start ups

I emailed phearable about it but i'm awaiting a response.

 

...

 

Looked at that diagram several times before but didn't really help me...

 

Generally 3 EVAP related sensors: fuel rail, top of the charcoal canister, and one at the fuel tank.

 

So should i unplug all three?

 

I would assume it's only the one on the fuel rail but I'd wait for the response. Post it when they respond.

 

Here was the initial situation...

Hello,

I recently ordered a chip with a basemap for my d16y8 which is for the most part completely stock, the only issue is that it randomly has a rough start either when cold or at operating temperature, but once it fires up, runs fine with no issues. The car is mechanically in outstanding shape, never had this issue with the stock ECU. Any recommendations?


Your vehicle is obd2 which means you are using an obd2 to obd1 ecu
jumper harness.
When using an obd2 to obd1 jumper harness you some times need to unplug
the evap purge solenoids and charcol canister to resolve the issues you
are experiencing.

Thank You,
Phearable.net Sales

What about the corresponding vacuum lines? Do those stay put? Wouldn't the unpluging of the purge solenoid stop the fumes from being relieved into the intake manifold thus allowing the fuel tank to become pressured putting more strain on the fuel pump?


That is correct, the tank can become pressurized.
Most of our customers atmospherically vent the vacuum lines.
As mentioned before, it is a common issue with obd2 to obd1 converted vehicles.

Thank You,
Phearable.net Sales

 

I'm not sure why the one on the fuel rail would matter. OBD1 had an intake mounted evap purge solenoid too (the ECU wont throw a code for it though) I'm not saying it doesn't, I just don't understand why it would.

 

My thoughts as well, as many others, but it indeed was the cause of the rough and prolonged start ups, there was one occasion where i tried starting up the car and it just would not at all, it smelled very rich, i then unplugged the solenoid on the fuel rail and started up just fine.