Melted IAC

[Pookapotamus]

So anyone that knows my jeep knows that my hood is pretty religious, http://img.tapatalk.com/d/14/07/24/7etyjybu.jpg
That being said, I have been having idle issues lately, and stumbling under light acceleration (the odd time I don't have the pedal to the floor to hear the exhaust whistle) so in have been thinking IAC and tonight I decided to have a look at it.
First thing I noticed was I could not even touch my fuel rail after mort sat for 15 mins with all three fans on to cool him down. Pulled the IAC and it was clean but a light tug on it and it came right apart. http://img.tapatalk.com/d/14/07/24/vasureze.jpg

So... Apparently my under hood temps are still pretty high, I have a stainless borla header, with the late model intake (also way too hot to touch) gauges say I'm running around 100f.

I don't want to wrap the header because I have heard that doing a water crossing the wrap can hold water and crack the header. Is this true or not?

Is it possible to wrap the fuel rail? Would this be a problem in winter?

Is there some spray on insulation you could get for the intake?

Is a custom heat shield in my future?

Any advice???

[4.3LXJ]

Custom heat shield might be the ticket. They do make one for that intake to insulate the fuel rail and get rid of the #3 miss the late models have. I made a heat shield for my exhaust out of a double layered cookie sheet. Works great and easy to work with

[Pookapotamus]

What about the wrap Steve? Have you used it?

[4.3LXJ]

Yes I have. It accelerates corrosion when wet, so I took it off

[Pookapotamus]

Even with a stainless header?

[4.3LXJ]

Not sure on that. But stainless does corrode too with heat and exhaust gasses. I really think one of the most effective wraps would be with multiple layers of aluminum foil and a couple of hose clamps to keep it in place.

[gary63]

you might try eastwood's 2k ceramic underhood high temp.paint or there Hi-Temp internal exhaust coating w/extension tube.

[Pookapotamus]

Thanks Gary I'll look into that!

[Carves]

Rusted out an expensive, replacement set of headers on an old 1000cc suzuki years ago ... thanks to the myth that header wrap is good idea.

Didnt take long either.



Just as a thought, and as a test

... slap some magnetic vehicle decal material over your front vents ... in case they are reducing flow past the manifold.

Shouldnt be an issue really tho - as the front vents will usually draw air from most spots in the engine bay.

[Pookapotamus]

I borrowed a laser thermometer from work, now I can at least see what temps I'm running. Go from there. Awesome advice carves! Still stalled 5 times this morning, did not seem to stumble too much though.

[Pookapotamus]

So the new IAC did nothing!!!

Fuel rail temp when I got home was average, 95*c intake temp avg was around 110*c, header temp at head was 120*c and at the collector 270*c.

Methinks that with all the venting I have in the hood it's pulling all that heat up around the intake and rail, where as a stock hood will allow the heat to be pulled down and out. At least at any sort of speed.

So...I'm thinking of wrapping the intake and cutting the fins between the ports to allow as much heat as possible to escape, and wrapping the fuel rail. And maybe add a heat shield between the block and header.

Opinions?

[gary63]

what I have done to help the heat soke is wrap half of the fuel rail the bottom and lift the top open so air can get around and heat can go around the rail and not heat it up. now I'm working on trying to wrap the bottom half of the intake to see if it can make it any cooler.

[Pookapotamus]

Number 6http://img.tapatalk.com/d/14/07/26/5a4etu7e.jpg

Number 4http://img.tapatalk.com/d/14/07/26/enezu5ur.jpg

[4.3LXJ]

Looks like that might be running a wee bit warm. You burning oil Dana?

[Pookapotamus]

Yes, 4,5 and 6 ports have oil in them.

[Pookapotamus]

http://img.tapatalk.com/d/14/07/27/na3a7asy.jpg

What is that sensor down there???

[Pookapotamus]

Ok so if I am over heating my plugs, do I run a hotter plug or a colder one, electrodes are fine but the ceramic holding them are burnt up.

Also I was running a bosh iridium, is this really benifitting me or not. Should I just run a standard ngk as I have a mad coil but still have to run a distributer.

[4.3LXJ]

You should run a colder one

[Pookapotamus]

Does that mean it can take more heat?

[4.3LXJ]

No, it means that the tip of the plug will be closer to the end of the threads. By drawing the spark farther in, the speed and temp of the combustion is reduced. Also I asked about the oil consumption, because I see a lot of ash deposits there. You also might need to run racing oil to reduce that

[Pookapotamus]

Number 4 and 6 cylinder have leaky valve seals, they've leaked from day one, always planned on doing them just never got around to it!

Thanks Steve that was exactly the info I was looking for for the plugs!

[slvmart]

I was going to comment on all the crude on the plugs, but I see that 4.3LXJ already has.


You should run a colder one

Just FYI ! from : http://www.carcraft.com/techarticles/spark_plugs_tips/

Heat Range

Controlling the operating temperature of the plug’s firing tip is the single most important factor in spark plug design. “Heat range” is the relative temperature of the spark plug’s core nose, and it is determined by the length and diameter of the insulator tip, as well as the ability of the plug to transfer heat into the cooling system. A “cold” plug transfers heat rapidly from its firing end into the cooling system and is used to avoid core nose heat saturation where combustion-chamber or cylinder-head temperatures are relatively high. A “hot” plug has a slower heat transfer rate and is used to avoid fouling under relatively low chamber or head temperatures. What’s confusing is that a “hotter” (higher performance level) engine requires a colder plug because more power equals higher cylinder temperatures.

Critical factors affecting heat range include:

• Air/fuel mixture: Lean air/fuel ratios raise cylinder-head temperatures, requiring a colder plug. Rich air/fuel ratios require a hotter plug to prevent fouling. Mixtures that cause the plugs to read lean may contribute to pre-ignition or detonation. If not running an electronic engine management system, it pays to tune slightly on the rich side to avoid detonation.

• Spark advance: Ignition timing has one of the greatest effects on plug temperatures. It becomes more critical as compression ratios increase. More timing raises combustion temperatures, calling for colder plugs.

• Compression ratio: Increasing the mechanical compression ratio raises cylinder pressure, resulting in higher cylinder temperature. The higher the compression ratio, the colder the spark plug needs to be. According to Champion Spark Plugs, for normally aspirated, gasoline-fueled engines, a good rule of thumb is to go about one heat range colder for each full point in compression ratio increase from 9:1 through about 12.5:1, and two heat ranges colder for each point increase between 12.5:1 and 14.5:1. Beyond 14.5:1, 3-4 heat range reductions per point may be needed.

• Gasoline quality: With musclecar-era leaded gas, the lead is attracted to the hotter (core-nose) part of the plug, causing glazing. The spark runs down the core nose instead of jumping the gap. Going to a slightly colder plug helps prevent lead-glazing. However, with today’s cleaner-burning oxygenated unleaded gas, an equivalent engine needs to run plugs about 1-2 heat ranges hotter than originally specified (many plug manufacturers have revised their catalogs accordingly).

• Methanol: Methanol has a higher octane level compared to gasoline (allowing an increased compression ratio), contains 50 percent oxygen by mass (requiring a much richer air/fuel ratio), and has a reduced latent heat of evaporation (which cools the incoming air/fuel charge and allows a denser mixture). The net effect is to require a plug that’s at least one step colder than normal for an equivalent gasoline-fueled application.

• Nitrous oxide: N2O raises cylinder temperatures and may require a plug 1-2 heat ranges colder. Lower output street systems may get by with standard heat ranges if nitrous use is held under 10 seconds.

• Supercharging/turbocharging: With increased pressure and temperature in the chamber, two or more heat ranges colder may be needed. Extreme high-boost race-only applications may need a surface-gap plug.

• Sustained acceleration: Prolonged acceleration or high-speed driving raises temperatures and calls for colder plugs.

• Elevation: Leaning the mixture and advancing the timing can partially compensate for lost power and efficiency caused by increasing elevation. Spark plug heat ranges should stay the same as at sea level unless racing above 3,000 feet, where one step hotter usually suffices.

[4.3LXJ]

Just a note to add to that. When passing smog, particularly the hydrocarbon part, hotter plugs will result in cleaner burning engines

[Pookapotamus]

Thanks slvmart! That helps clear thing up! I will be heading to the parts store for colder plugs!

Good thing I don't have to pass smog up here!