H3 Alpha Sluggish All of the Sudden.

[LagunaH1]

I recall reading that GM had issued a TSB about the H3 when in hot environments. If I recall correctly (don't recall if this was applicable to I5's and / or V8's) it had to do with the location of the air intake. Under certain circumstances the air taken in by the engine would be hot enough to cause the engine to run hotter / reduce power / feel sluggish

 

[f5moab]

Never heard of that bulletin and just did a search and found nothing. The air intake on the H3 is between the outer and inner fender and not from inside the engine compartment (stock intake). Air does warm up moving through the system. Biggest concern is during hot engine shut down, when all the hot components in the engine compartment (exhaust manifolds, pumps, engine block, etc.) soak the cooling system which with the engine off is not circulating coolant; therefore the engine/heads get hotter than hell.

An overly hot heat soaked engine can affect the injector pintle clearances; especially if the injector(s) are the least bit dirty. I know it sounds like an old saying, but run a can of Techron through the fuel system and see if that helps. The PCM or ECM should pick up that issue with injectors, but not all the time. Especially if all 8 injectors are acting up.

The other problem is the design of the H3 with the V8...when it was first released, there was a lot of concern about how hot the V8 ran with the small radiator, while be packed tightly into an engine compartment. (Hunner can remember my concern when NEO and I rescued him on Hunner Switchback on Kane Creek. Yes, we call it that, :giggle: and every time I drive down it, I think of that white Alphas sitting off to the side.)

If you consider the same basic engine is used in the full size P/U trucks and on my Silverado, I can probably sit on each inner fender and place my legs between the engine and the inner fenders, and there is about a foot from the front of the engine to the radiator to allow for more airflow around the engine. In addition, the radiator on a P/U has a larger capacity of 2.6 quarts.

 

[LagunaH1]

Yeah, I'm not at all sure where I read this, but anyhow.... Heat and H3 Alpha's does tend to go together

 

[4speedfunk]

You might try a thinner coolant-to-water ratio. Crazy as it sounds...coolant de-rates the heat transfer abilities of the system. A very common problem is that service monkeys will top off a system with 100% coolant, and they never check the actual mix. This can result in a lop-sided ratio, and make your car overheat. It also effects the heater core in the winter time, and if the ratio is far enough out of whack...you won't get any heat! The water is what transfers the heat...the coolant does not. I know GM recommends a 50/50 Dexcool mix but, that is way out in left field for most high performance applications. Drag racers run just enough coolant to prevent boiling....probably around 20/80. This keeps the cooling capacity where it needs to be, prevents boiling, and still gives plenty of lubrication and corrosion resistance inside the system. Freeze protection is not a concern with drag racers, so they can get away with the 20/80. Boil-over protection and lubrication will be fine at 20/80...I've ran this for 30 years without issues (with green and orange). But depending on your geographical location, you may have to increase that ratio for winter time. Freeze protection will always be the driving force when selecting the ratio and I can only assume that GM has settled on 50/50 as an idiot-proof solution for their vehicles. "There...that should prevent freeze-ups at the south pole!"

You can check your mixture with a $3 hydrometer, available at any auto parts store. The little thing will have a series of balls that floats inside a glass tube, and it will tell you the mixture. The only real concern (here in the midwest) is that you keep enough ratio to prevent freezing in the dead of winter. I run just enough mixture to protect me down to -10F degrees, (I think around 30/70). Any more than that is just extra coolant (which ain't cheap), and it lowers the cooling capacity of the system.

This will no doubt stir up a bunch of net-opinions (worse than welding cast iron!)...so get ready. I'm not trying to re-write any books, just stating my experience. For $3 its a no-brainer. Who knows?...maybe some dufus filled it up with straight coolant.

 

[Sethmark]

Here's what I've learned. Apparently GM retards the timing substantially after 212°. That's why I'm getting no throttle. I live in the south...it's hot it's humid and I'm running a lot of errands. I realize that the engine management is important, but will a superchips type product work to eliminate this problem?

They're product is based on adjusting timing, right?

 

[LagunaH1]

My 2 cents would be that I wouldn't want to mess with this as it probably (I'm speculating) is part of the engine protection system. Things like this are the way they are for a reason.

1st Edit: I imagine (again, I'm speculating) that this is done deliberately to prevent the engine from getting much hotter than it already is.

2nd Edit: In other threads there are mentions that H3's that were sold in other countries such as Australia and in the middle east came factory equipped with extra e-fans.

 

[Sethmark]

Where's the fun in that?

 

[Best4x4]

You've also got to remember the clutch fan is going to enage at slower speeds and sitting at a stop light. Until it disengages you will feel some lag.