97 4.6 auto mild upgrades

[97teebs]

It has a pro comp all aluminum intake and a cone filter on it. Every so often the idle will jump up to 1500 then drop back to normal. IAC, MAF, TPS all seem to be fine no vacuum leaks other than I get a purge selniod code which I believe is the vac line at the tank but that's been there a few years and I get a lean condition (gutted cats) which has also been there for years. Anyone got any other ideas?

 

[KevinVarnes]

Idle jumps like it goes to 1500 and stays there for a while or goes up for a second and then comes back down?

 

[MadMikeyL]

Gutted cats shouldn’t cause a lean code. A disconnected EVAP purge line could cause a lean condition and a corresponding idle surge since it is expecting a certain amount of fuel vapor to come through the EVAP line when purging, and with the line disconnected, it will instead suck air. Maybe start by unplugging the purge solenoid. That will stop it from opening, and if your idle surge and lean condition goes away, then you know what the problem is. If they stay, I would start looking into a vacuum leak, or a dirty/faulty MAF, or possibly bad O2 sensors.

 

[97teebs]

Idle jumps like it goes to 1500 and stays there for a while or goes up for a second and then comes back down?

Goes there and back down to normal but not like a bad tps where it's up down up down mostly stays normal then out of nowhere goes up to 1500 and back to normal but doesn't go right back up it maybe a day or so before it goes up again some trips it doesn't do it at all

 

[97teebs]

Gutted cats shouldn’t cause a lean code. A disconnected EVAP purge line could cause a lean condition and a corresponding idle surge since it is expecting a certain amount of fuel vapor to come through the EVAP line when purging, and with the line disconnected, it will instead suck air. Maybe start by unplugging the purge solenoid. That will stop it from opening, and if your idle surge and lean condition goes away, then you know what the problem is. If they stay, I would start looking into a vacuum leak, or a dirty/faulty MAF, or possibly bad O2 sensors.

02s are relatively new last few years not to say it's impossible they are bad just wouldn't think it's been long enough. But I'll try unplugging the purge selniod