what makes TBI's sluggish in the summer heat

[oldred95]

Right on cue my truck has become a dog once again. Its always become a turd come summer when its a consistant 90+ degrees in the heat of the day. Its like anything under 20% throttle and it doesn't even want to move. Also my gas mileage seems to get worse. Is it just a lack of being in a proper state of tune as far as fueling VS ambient and intake air temp or is it something more? It always seemed to me like the TBI's took a huge hit in the summer months but the vortec 350's and Gen III engines don't seem to be bothered by it much.

[91chevZ71]

I am noticing the same thing. not that bad, but a definite difference from winter. heat sucks

I'm sure it's about 100 things from the engine to tranny to diff to you name it

[cancritter]

not a good time for a heated intake :O)

[91chevZ71]

dude, you aren't kidding.

[1realZ71]

On my 91 the heat door on the underside of the intake neck wasn't closing once up to temp.I took the tube off that fed it from the mani. and put a rubber pipe cap over the heat door.It helped so might try it and see if it helps you.

[91chevZ71]

I think I'm gonna fab up some ducting to get cooler air to the TB tomorrow. dryer hose, something like that

[rainman318]

not a good time for a heated intake :O)

He acted like I was crazy when I asked him about that heated adapter

[oldred95]

not a good time for a heated intake :O)
Yea considering there is not coolant circulating through it unless the heater is on. Further more, the stock intakes entire floor is heated by a continuous flow of hot engine coolant. Even more so, it runs within a few degrees of the same temp winter and summer. Stop being an idiot.

[rainman318]

Ease up its a joke.

[HaulnA$$]

Right on cue my truck has become a dog once again. Its always become a turd come summer when its a consistant 90+ degrees in the heat of the day. Its like anything under 20% throttle and it doesn't even want to move. Also my gas mileage seems to get worse. Is it just a lack of being in a proper state of tune as far as fueling VS ambient and intake air temp or is it something more? It always seemed to me like the TBI's took a huge hit in the summer months but the vortec 350's and Gen III engines don't seem to be bothered by it much.It is more than just the tune. Even the best possible tune cannot replace lost HP due to thin hot air. It is just plain physics. The summer blend gasolines don't help either. JMHO

[cancritter]

seen a part on power hr or what ever...some folks by ceramic paint and coat the bottom sides of thier intakes to keep heat away from tbi or carb above...thought that was pretty snazzy idea
as for your heating prob REd seen you trying to heat your intake awhile back so have no idea what silly thing you did...figured you did so it only stands to reason to mention it...just tryin to help ya out son..my mistake

[91chevZ71]

although the engine runs relatively at the same coolant temp between winter and summer, the air is much hotter in summer (less dense, we knew that already). I have excellent performance and cold IAT readings up to the thermostat opening even on hot days like today, then after 180 deg opening performance drops a little (makes sense, rad heat). Not dropping like WTF but dropping off a tad. Yes, the % IAT has on fueling isn't that much (ADJUSTABLE), but it makes a noticeable difference. Also, I think the wet-flow goes through some serious changes in hot vs cold environments. Saturated air retains heat (hot or cold) better than non saturated. I'm getting all of this from my meterology classes. I think it would apply somewhat, sharpshoot the hell out of me if I'm off

[90C350]

I guess i have a little different issue!! I have trouble's tuning in the winter but summer is pretty good. I also run an Air-gap manifold so that helps in the summer and not in the winter. Need more heat in the winter-heat riser etc. Otherwise its pretty good in the summer

[91chevZ71]

makes sense, you prolly need a truckload of AE in winter

[95nProgress]

A phenolic TBI spacer does wonders to decrease the hot TBI boggyness.

Brian

[90C350]

Yes I do need a fair amount of Ae during the colder months. AS well as a fair amount just during the summer for the first 10min of driving and then its good!! Just need 2 chips basically. I really need to get the new ebl and an iat sensor set up and that would make life alot easier!! LOL $$$$$

[91chevZ71]

the "Flash EBL" is in the mail...ETA 3 days. IAT helps. I have mine set up dry right now. Get that IAT.

Yeah, I am impressed with the spacer. Just got it on today, great results. I'll check on the dyno in a couple days.

[hornsfan10609]

On my 91 the heat door on the underside of the intake neck wasn't closing once up to temp.I took the tube off that fed it from the mani. and put a rubber pipe cap over the heat door.It helped so might try it and see if it helps you.
I took out the spring for the pre-heater duct, and taped it so it's always open. When it is cold out, (In Central Texas, that's for about two weeks) hot air still leaks through, so it will work a little, but I figured when it is hot, having the intake fully open vs. probably closed all the time will help the engine breathe better.

[BigWheelinBubba]

I took my hood seal off (at the cowl) to reduce underhood temps.. it seems to work. Anyone else try this?

[oldred95]

I took my hood seal off (at the cowl) to reduce underhood temps.. it seems to work. Anyone else try this?
I've done it but never noticed much difference. I might try it again just for chits and giggles though.

[hornsfan10609]

I also took off the cowl to hood seal, but decided to put it back on after about a month. Didn't notice a difference at all.

[383 silverado]

A cooler running engine improves performance by increasing the mass air flow rate of intake air and by reducing the engine's tendency to detonate.
Reduces the temperature of both the incoming air/fuel mixture and the surfaces of the combustion chamber allowing the engine to safely develop more horsepower.
Available in 160? F opening temperatures (Factory thermostat is 195? F).

http://www.lmperformance.com/6756/24.html

[Tbi-MAX]

i have never noticed this problem, but i do know the TBI likes lots of air, and in the other 3 cooler seasons, be brutal... i guess its how i have a tb spacer, cause, if i barely touch my pedal, the big burb is gone.. and i mean, my blades barely have to be open... i mean, i should make a video of the tb for better explanation..

old red, check for any intake leaks around the manifold or such.. also try a tb spacer, and a 160 degree stat... just tune for it.

now i got rid of my CAI setup 2 days ago... what a time, cause it was 102 yesterday.. i have a open element filter now.. and i noticed no loss over the CAI setup, actually it felt better! and sounds better too, slugish, far from it.... winter time, i bet it will add lots of fun too..