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2G Heater core and fiav delete questions

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jpmxrider489

10+ Year Contributor
2,410
146
Apr 4, 2010
pittsburgh, Pennsylvania
I am working on putting in my new motor and I would like to delete these two things. Reason for deleting the FIAV is because I believe mine is stuck and causes high idle on a cold start. Even after properly adjusting the biss and getting the ISC to correct values in link. The heater core, I dont really have a reason to other than to make more room and a cleaner bay. Also, the car is only a summer car, driven only on nice days, no rain, during the day, and I only put on around 2500 miles a year. The car sees occasional track use but is mostly a weekend car.

Are you guys that delete the heater core, do you have overheating issues? Are there any cons to deleting it other than not having defrosters? I would assume the AC switch would still turn on the other rad fan. Does the heater core act as a second cooling area? Maybe over pressure issues? I wont do this if the risks out weigh the positives. Just want basic motor.

The fiav, I been chasing this issue for a while now. I have read about manually adjusting it with the freeze plug removed but I have bad luck as well. So the cons of this would be just a rough cold start? The drivabilty would remain the same as long as I keep the ISC. I do have v3 full if that matters at all.

With the open nipples/ports, I do not want to weld them. I have heard of people tapping them to plug, looping the lines, or just cap them with a bolt. What would be a more professional method without welding. More of a permanent thing but could be undone if needed? I read somewhere that the nipples on the TB just pull out? I have both block off plates. One that deletes both ISC and FIAV and one that keeps the ISC. Just curious what others are doing. With the block off plate, are you guys replacing the FIAV gasket, sealer, or just bolting it up?
 
Shouldn't have any issues deleting either. Just need to be aware that the first 30sec or so or idling you'll want to modulate the throttle so it'll warm up enough to idle on its own.

If you want a reversible option for the TB coolants lines, just loop them. Otherwise I'd remove them (use a map gas torch to warm the port area, then a pair of pliers to work it back and forth while pulling it out) and then tap them for npt plugs. Then you can always remove the plugs and put npt nipples in place to run hoses.
 
Can’t speak to the heater core issue, but more than a few times in traffic, we’ve cranked the heat and the blower motor to help prevent the engine from getting any hotter. It’s a nice option to have.

As for the fiav and isc, we eliminated the fiav since we didn’t see the advantage of circulating hot water through the throttle body for a summer car. We kept the isc though to prevent surging at idle. We did use a gasket sealer on the block off plate.

We have driven it on as low as a 45* day, and the start up was a little rough running for about 45 seconds, and after that it was fine.
 
Arent you supposed to have a higher idle on cold starts, if the FIAV was stuck open then you would have a high idle when the engine is warmed up since more air is bypassing the throttle plate than should be at that point. I guess it depends on how high the idle is on a cold start.

The FIAV is easy to delete like what ThunderChild said. Its just the issue you are having doesnt sound like a stuck FIAV.
 
Are you also tapping and putting a plug in where the heater cooler lines go to the engine as well? And you think the heater core helps cooling the engine? Just dont know if there are any negatives in my case with deleting the core. The Fiav I will be deleting because I also agree that I dont need the heat going there. With the heater core deleting, you think my mishimoto rad will provide enough cooling?
 
I doubt that the heater core would help cool the car down when the heater is not on. A properly setup radiator with strong fans should not allow our cars to overheat. My setup never comes close to overheating and it has been hitting 98-100 degrees everyday....and I've been tuning during the day too. I kept my heater core because it gets chilly even in Texas, and it feels so good to throw that heater on. For god's sake, I have coilovers, polyurethane bushings throughout the chassis, no a/c and no power steering. Can't I have my heater when it's 35 outside :)? Anyways, get a FIAV BYPASS, not delete, plate and call it a day. I don't even have to touch my throttle when the car is warming up.
 
Maybe I didnt phrase that right. Keeping the heater core wasnt a goal to keep temps down. My temps have always been around 205 and I don't drive in traffic but if I do pulls then come to a red light temps might go to 210 but drop back down. I guess I wasnt looking to delete the core to keeps temps down. I want to delete it just to eliminate that point of failure, and clean it up a bit for more room. I have the stock ac fan, and a spal fan on the opposite side of the radiator since my wastegate is in the way. If deleting it would still keep my temps within range with no change in performance then itll be worth it. I dont want overpressure issues or anything related. So loop or plug? I can say I never turned on the heat to cycle coolant. I do turn on the ac to turn on the other fan. I also do not have ac.

The fiav is a no brainer for me. I have both plates that extremepsi sells. Not sure if that was what you were referring to.
 
Plugs look better, if you are looking to clean things up you arent gaining anything in that department by looping a hose around. You would have an otherwise clean bay and then a random hose looped around. Function over form though I guess.
 
I have a Mishimoto radiator that I recent installed with their slim fans. It runs hotter than the stock radiator with just one stock fan. I put the stock p/s fan back on but haven’t driven it since
From my personal experience, the mishimoto fans cant produce the amount of power the stock fans can. That's is why it is always recommended to keep stock fans when possible. Also, do you still have the factory duct work in place? Seems like when people install a front mount, they remove it. I kept what I could. That plays a big role in it as well. I'm definitely curious about how your cars temp is with the factory fan back in.

I think I'll tap the fiav and heater core. If I don't like the performance I can always go back.
 
I figured I would post a update to this thread. I have capped the fiav and heater core. Deleting the fiav didnt solve the idle surge issue. Motor is new in the car. Throttle body was rebuilt 10k ago. The idle and surge is much better but I am saying it is the isc. This was my 3rd one. Has anyone had luck with the parts store isc for 40 bucks? Or is a OEM the only option for our cars?

Another question. I have a read a discussion from turbosax about looping lines to bypass the thermostat to put less stress on the pump. Is there any proof to this theory? I haven't found much on that topic.
 
You are a 2g so the idle stop switch isn't used as a point for the ECU to know you are not touching the gas but is your TPS adjusted properly by hand, not by using the offset feature in Link? That can have an effect on idle since the ECU uses the 0% as a way to know you don't have your foot on the gas. My 1g would surge if the idle switch wasn't connected (found out one day when the wire decided to "jump" off of the terminal).
 
Idle surge is created by too much air bypassing the throttle plate and when the engine gets to 1500 it cuts the fuel until the rpms come down and then it kicks the fuel back on and then you get this cycle. It could be the ISC, it could be the throttle plate not set right though thats the last thing you should check, vacuum leaks, gasket leaks, injector insulator leaks.

You should check your ISC though, if its the stock orange/brown top then it should see 28-33Ohms when testing the pins 1&2 2&3 4&5 and 4&6 and if you have one of the new black ones that will see around 40Ohms with the same test. If you have an extra set of hands, take the negative off of the battery for 10 seconds and then put it back on, take the ISC out of the throttle body but have it still plugged in, turn the key to the on position. If it does nothing then its bad, Ill try to find the thread I was looking at that shows how the ISC should move. If I remember correctly it moves in towards the motor and then away from it slightly.
 
I have the black top ISC and reads 40. My tps is physically adjusted in link to .63v. I am using the tps offset to fix the wot. My peddle all the way to the floor only goes 96 percent in link. I do have a small boost leak that I will fix but not enough to justify this. I will say, eliminating the fiav cut this issue in half. Injector seals, intake manifold, and tb gaskets are all new. If i were to unplug the isc and then start to car, would this simulate deleting the isc? That would at least tell me if its related to this issue.
 
What about the internal IPS though in the 2g TPS? If that isnt working right you are going to have idle issues. I have a 2g TPS on my 1g and I set it to how the factory says and I have no issues. No trying to get it to a certain voltage like you do with the 1g TPS since the TPS and IPS are separate.

I dont know much about Link though and what it does for all of this when you set it to .63v. It might simulate the IPS based on voltage... i really dont know.

Unplugging the ISC wont simulate a block off of the air passage. As far as I know, even if you delete the ISC you still have to have it plugged in unless there is something in Link for it. That is left to other people that know about Link, wish I could help in that area though.
 
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