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Discussion Starter #1
Okay, so Doris has got about 3k miles with the new engine and so far I'm loving it. But there are a few things that bugged me, and really showed up out in Moab. I've got some theories on these things, but I thought it would be helpful to have some other people thinking on this stuff.

#1: At extreme angles, the idle shoots way up to like 1500+ RPM. I have noticed it mostly going up steep ledges, but it seems like it has done it other times on the trail. This never happens off the trail. The truck can tilt backwards, and it's fine for about 30 seconds. But if I don't quite make it up a ledge or something, and end up sitting there for a minute, the idle shoots up to the point that I can barely hold the truck back with the brakes. (It's an automatic). Even after I level out, it takes about another 30 seconds for the idle to return to normal. Obviously, this is a big problem. If I had a manual transmission, I could care less. But I don't like having to kill the brake pedal just to make the truck stay put. And god forbid I have to put the truck in reverse!

My theories:

* The EVAP canister is somehow putting excess fuel vapor into the intake when the truck tilts back. This could be related to problem #2...

**Faulty IAC... But that wouldn't explain why it only does it titled back.

What I have ruled out:

* Sticky throttle. I have verified that the throttle returns to the idle position, and that it is in the idle position when this occurs.

** A symptom of overheating. (See problem #3) At first I thought they were related somehow, but since then I have seen my coolant temp be exactly 189, and the truck still did the high idle thing.

#2: A reoccurring CEL (about every 250 miles) P0441: Evaporative Emission Control System Incorrect Purge Flow. According to the internet:

"This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is contolled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set."

To try and fix this, I tightened hose clamps and ensured that there are no leaks in the system. Still the light comes on, although less frequently.

Like it said above, it could be the gas cap, or the purge solenoid. Or maybe I don't have something routed correctly. Here's what I don't know:

That said there was a purge solenoid AND a vacuum switch. I was under the impression that the purge solenoid and the vaccuum switch were the same thing. Or at least integrated somehow. Am I completely missing a component here? What else could it be?

#3: Overheating/High IAT. Specifically when going slowly up a long steep hill climb. I wasn't aware this was a problem until I went to Moab where ambient temperatures and humidity (or lack there of) intensified the problem. Since then, I have been keeping a very close eye on my coolant temps, and I have seen the temperatures rise to 205 or more when climbing a hill back in Colorado. The difference is that in Colorado, the temps go right back down in no time. In addition, my exhaust gets extremely hot, and tends to bake the sheet metal of the cab which makes it an oven in there. Granted, I have zero insulation in the cab... but still it gets pretty ridiculous. Now cooling is a fairly simple thing, so this one isn't so complicated.

I did a study today on intake air temps. After letting Doris idle for approximately 15 minutes, I plugged into my OBD2 port to check on things. I did notice that the cab was fairly hot as usual when I began. The coolant temp however was only 190. I found the intake air temp to be 126 degrees with an ambient air temperature of 82. I knew that these cheap "cold air intakes" were really "hot air intakes", but DAMN! 44 degrees difference is quite a lot. Granted, the engine had been idling, so there wasn't any airflow through the engine bay.

I began by popping the hood to allow more air into the bay. This changed the IAT very little. Then I tried to pack ice around the filter and manifold. This helped a little, but with those temps it was water fairly quickly. Then I rotated my filter to be sticking up out of the bay, into cooler air. Doing this alone, the IAT dropped down to about 105 degrees. Then I wrapped a damp paper towel around the filter, and came back in about 5 minutes. At that point, the temperature had dropped to a very respectable 88 degrees at the lowest. I also noted that the cab seemed cooler, and the exhaust was cool enough to actually touch! The coolant temp went as low as 187. Keep in mind this is only at idle, so that may not be the case while driving.

In conclusion, I think that intake air temps have a lot to do with combustion, exhaust and coolant temps. If I can lower the intake temperatures, the radiator won't have to try and shed nearly as much heat from the engine.

So...how do I do a cold air intake on Doris? After looking into it, I think the best way is to take it outside of the engine bay all together. That engine bay is tiny, and with that 3.4 taking up so much room, it gets to be an oven in there. I would put in a factory air box if I had the room... but I don't! Another hood scoop or like a ram air thing would be cool. But I think that's a little beyond my budget and fabricating scope. I considered throwing the filter into the cab... but again, there's no space... And I don't really want to hear air being sucked in all the time.

So as much as I don't necessarily want to.. a snorkel might be in order? I'm not a big fan of the look of them, but maybe I can piece something together that is decent looking? I was thinking that maybe a Humvee style snorkel that only goes above the hood a little would be better than the safari style that goes all the way to the roof.

Obviously other options would be a better radiator, a bigger fan, etc. But I'm not convinced that I need that yet.

Your thoughts?
 

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Discussion Starter #2
BTW, Sorry for the novel! I'll try to be more quick and to the point next time.
 

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I have the same re-occurring problem as you with #2. However i've had it even since i still had the toyota tank in the truck. With the ford tank i was able to drive to AZ, wheel AZ for the week, and then on the trip back (first 10 mile leg) it came on again, and has continued to come on randomly since (as it did with the old tank).

A buddy of mine thats a tech at Mountain States hooked it up to the OBD2 port and either i have a faulty pump or sensor within the system, or it's because it has been "modified". I started pricing some of the replacement sensors, and the pump in the charcoal canister and it gets too pricey to do a process of elimination on it.... long story short, i gave up on it and now i just pull the ecu fuse while i'm pumping gas whenever it comes on. If you gather any good info on it, post it up!

As for the cold air intake, get creative but dont place the filter in the wheel well. Even with my OEM intake setup, i suck water in driving down the highway when it rains (no splash shields) and i need to change it up. Also, it sounds ghetto but PVC will do you better than that aluminum intake thing. Obviously, metal will heat soak quicker than plastic. The sticky aluminum heat flashing wrapped around it will also help keep the cool air in, and hot air out. Just scope out the engine bay and see what you can do, even if you have to cut a hole on the apron (inner fender) to get the intake tube out; do it. It wont hurt the structure or compromise the integrity of the body at all.
 

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Problem #1
It may have something to do with the fuel tank being much higher than the evap canister and it can't drain properly.

Problem #3
Take out the right headlight like a 60's muscle car and run a fresh air pipe to the intake. :xrocker:
 

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#3: go to the firewall and pull cooler air from the cowl area... it'll be out of water levels too. Smokey Yunick did that to his early Camaros and kicked ass in the early Trans-Am and Nascar (IIRC) races:

http://www.highdefforum.com/car-forum/115098-trivia-game-muscle-cars-1962-1972-a-46.html

third pic down; also a lot of cool info there.

I've done this with a few of my 73-79/80 GM trucks in the past and it's worked great for anti-water applications.

Bring that ol' broad on by, we'll think of something.
>>Dan
 

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I've noticed my IAT being pretty high as well. I need to setup the ambient temp gauge on my sgii so I can see the difference. The other day when it was 80-sh out, my IAT was way above 100. It was higher at highway speeds and at stops, but if I was going slower (between 20 and 50) it would cool off a little.

I've been knocking around the same ideas about pulling air in from outside the bay. I have an air damn that came with my intake setup, I came to the conclusion that I'm going to trim that to fit and drill a hole in to pull in air out of the wheel well (I still have fender liners so I shouldn't have the same problems as Nate, but I think I have an idea for a splash shield if I do.

I got nothing for you on #1 and 2. Evap stuff confuses me, and that's the biggest part of my decision to transfer all the stock evap shit in it's factory configuration to the 85. I have no idea what all controls the idle on these motors, and of all the reading I've done, I haven't seen it mentioned very much if at all (unlike the 22r motors where it's very well documented).
 

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Discussion Starter #9
Well I think I figured one thing out. A week ago, I drove up Rist Canyon when it was about 87 degrees. By the time I was at the top, my coolant temp was about 212. Today I drove the same route at 63 degrees with a slight sprinkle. I didn't have my laptop but I'm sure the IAT was much better than normal. This time, my coolant temp gauge didn't move at all from what should be about 190. So in my opinion, that's proof that the overheating has to do with high IAT.

I'll just have to see if I can piece a cold air thing together in the next couple of days.

In other news I tried to make my truck do the high idle thing. I pulled up on top of a big rock and just sat and waited. And of course that time it didn't do it. Although I did notice a slight increase in idle as soon as I shifted into reverse... very strange. I also remembered that my truck did this coming down Moab Rim both times. So it's not isolated to going up a hill. It seems almost like it's a random thing that occurs while in low gear.

I had another theory on that, actually: The computer monitors 2 speed sensors. One of them is in the transmission, and one of them is at the back of the transfer case. From the factory, auto transmissions have an input signal into the computer to let it know that the transfer case is in low gear. I do not have this. I wonder if the computer is getting extremely confused with the speed sensor readings that it is getting from the second sensor when it is in low gear, and there is no input telling it should be in low gear. And somehow that makes the computer decide to start increasing idle? Okay, maybe not.... but to be honest I'm out of ideas. :dunno:

My CEL hasn't come on for awhile.... but I'm sure it will.
 

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I know most people dont like the snorkle look but if you fab up something nice and make it draw from that and only that rather then just an add on to the factory box you will get cooler air while driving. The other positive is you will made your intake longer giving you more tq. It will rob a small amount of your higher RPM power but i think that you will make up for it by the lower IAT and the air it will catch on the highway. You could also do a water to air type intercooler. I know its for FI cars but if you wanna get it lower then you could do it and just run dry ice in it. Header wrap to help keeping bay temps down may help too. bigger or more fans...Just a few ideas for ya. I need to work on this too. My K&N has a shield that really doesnt do anything. It would be nice to get temps down all over in my truck.
 

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FWIW, I watched my IAT and coolant temp last weekend. I saw the IAT spike during the log slow climbs where I was lugging the motor pretty good (1k rpm). The coolant temp stayed right at 190*, even dropped to 184-ish occasionally. I stopped and popped the hood so the intake could pull cool air, and the IAT did not drop right away, tho the intake manifold was pretty warm to the touch.

I'm thinking that the IAT is not reporting the temp of the air at the MAF but some sensor in the manifold itself.

Moving to CAI (snorkle, whatever), might not actually solve that particular problem.

I was also thinking that perhaps our x-over pipes might be playing a part in the IAT.
 

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Just FYI, I'm fighting a cooling issues with my 3.4 swap. My truck is supposed to run at 170°. Last summer running in town it would run at 190°, while loaded or towing I could get it to 220° really easy.

The first issue I found was an ineffective fan clutch. I searched online and found that the green clutch would engauge sooner. This repair seems to keep my temperatures around 200° now, though I'm still worried.

My second issue. I have a new radiator, a Performance Radiator unit. it was supposed to be a high efficency radiator but it seems to lack any real cooling ability. It is one of those single core aluminum radiators. measurements now indicate it is only equal to a 2 core units. I will be going to a 3 core.

Throughout the last year i have had a cold air intake and under hood open filter. There was no change in the cooling ability of the engine with either system. While colder air is better for timing advance I don't think it is your root cause.
 

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Discussion Starter #13
Interesting stuff, Brian. You may very well be right. Did you happen to take any data on the IAT from from the 2 different filters? Also I was hoping you would have some theories on number 1 and 2. :D. Number 3 I'm sure I can solve with enough time and money. But those 2 I have no idea.

I'm sure that increasing the cooling capacity of the whole system would solve the problem. But it also seems to me that I wasn't having these issues until it was hot enough outside to be getting IATs of 125 or more. My theory is the cooling system only has so much capacity to shed heat from the engine. But when you keep feeding more and more heat into the engine, it may exceed the capacity of the radiator. So I wanted to try lowering IAT anyway because it can't be good to be pulling air that hot regardless of coolant temps. That may or may not bring it back to where it needs to be. If it doesn't then absolutely I need a bigger radiator or a bigger fan of some sort.

Doug, your cooling system is probably more efficient than mine is. I have a used 3.0L radiator that still occasionally has a seed floating around in it... Damn squirrels... And I have a 16" electric fan with a 12" fan motor. All this cramped in an engine bay that holds heat like an oven. I don't doubt that yours stays cool and mine doesn't. Did I just identify the problem? Maybe... But it was working fine before. So I just want to get back to that.

As for the cold air thing, I think I might just relocate my battery and try to stuff an airbox in that corner. I didn't want to do that before because I just wanted to keep moving on the swap and get it running. My original plan was to do an airbox though. It just got to the point that it was too difficult and time consuming to make it work.
 

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With a factory airbox piped to fenderwell I was running 115° after 30 minutes of driving. With a open air element I get to about 125° on average. So not a big deal in my case.
 

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Is that IAT? or coolant?
IAT. Intake air temperature is also measured at the airflowmeter, it looked like there was some confusion earlier in this thread.

My coolant temps go from 170° on cooler days all the way up to 200° on hotter days. If the load is increased (towing) it can easily overheat (230°).

I run a TRD thermostat.

As you can tell by my numbers I'm right on the cooling threshold of my current cooling system. Also, my gauge doesn't move from 170°-215°
 

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the 1st 2 issues your feeling, I'd have to check the vehicle out for that. do you have a way to watch short and long term fuel trims?
 

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IAT. Intake air temperature is also measured at the airflowmeter, it looked like there was some confusion earlier in this thread.
So it is at the MAF (aka AFM if I remember right). That's odd. I know my IAT was up around 90, I have an open air element and opened the hood to see what difference it made. The engine bay temps were pretty low (weather outside was 60-ish, temps in the bay were maybe 70-ish, IAT stayed up around 85. The only thing that was that warm was the intake plenum. That's what made me think the IAT wasn't being read at the MAF.
 
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