I just like threads with funky names.. sue me.. or is that sew me? sugh me? huh..

I have a couple few small issues I can't wrap my brain around.. you'uns here have mostly proven to be purt' smart.. you're welcome to skool my old ****, and I won't mind..

I have a goodhood with sizable scoop hanging out above my front quarter panels.. it feeds into a true by golly cold air box which is sealed against it.. it doesn't really shove air in there, but it certainly remains at a higher pressure, and the entire system is insulated from box to TB.. I've seen as much as a 40 degree difference in ambient air temp and intake air temp..



So- two things..

I get a 1282 'engine too cold for too long' code almost on a weekly basis.. when it flips, the PCM opens loop and mileage tanks. it happens more when it's cold.. there is more than a correlation between the IAT sensor and the code, (running an a-g; it's in the hat)- meaning, that code triggers when it's cold outside... period..

So, the engine struggles to maintain a/f @ 14.7.. it fluctuates on the rich side.. I figure this is because it's dumping, figuring it's colder, and confusing itself thoroughly between IAT, engine coolant temp, and o2's..

I'm seriously considering moving that IAT to a warm spot.. like, a really warm spot.. outside of the hat, laying or dangling above the tiny plenum area of the a-g.. outside of the air stream, though.

Before I do this, I'm wondering, how much will it lean me out? I know the IAT can advance or retard spark as much as 1.5* either direction, but I've no clue how much it can account for a/f.. I mean, that's it's primary purpose, no? air mass, right? it figures along with the MAP about the mass of air, no?

what can be gained by moving it? Mileage? A few free pings? Massive melted holes in the pistons? I'm curious.. what are your thoughts?

another subject somewhat related:

vacuum..

I pull 17~19 inches at idle.. when I goose it from a roll, I bury it.. all the way to the needle, and a slow rise.. yeah, I know, under load.. cruising at any given speed with the engine 'planed' off I hold around 16", so long as that speed is under 60mph or so.. anything above 60mph and the vacuum drops related to forward speed.. I've searched and searched, and studied as much info as I can get my hands on.. what I think is happening is the ram air is actually working... your thoughts on that? the engine 'planed off' at 75mph, and my vacuum is around 10~11".. is it possible that the ram air is pressing into the intake enough to cause that? when I abruptly drop throttle, it drops to 25~28", and then recovers to just shy of 20"..

does this question make sense?

thanks..

I love winded posts, don't you?

 

What temp thermostat do you have in there?

I wonder if the PCM EXPECTS higher air temps, simple because of where it THINKS the IAT sensor is......

 

I've got a 180.. and SCT tuned for it..

 

Then it really shouldn't be doing that...... Have you chatted with Hemifever about this? (I seem to remember something along those lines happening.... that WAS you, wasn't it?)((Alzheimers......))

 

Hey Drew, I take in a lot of what you say on your "adventures", as I'm trying to learn as much as I can. Reason being, I am a pretty competent mechanic. I do all my own work, have for 17-18 years. I went to school for Autobody and am ASE Cert. for Paint and Body, so I know that. But when it come to this type of technical "stuff", I am at a complete F*CKING loss.

Basically, what I'm saying, is that I am learning and trying to comprehend all this, but it ain't easy.

Keep it up.

 

I emailed Sean last night on this. Here is his response, and what I had asked.


-----Original Message-----

I checked the codes, the CEL was on from prior emmisions, but I got a P1281 code also. Searching, I found it's "engine too cold for too long" and the recommended fix is to replace the stat. I have the 180* stat you reccommed with your tunes. I boiled it before install to verify it works correctly. When I had a 180* prior to this I never got a code. The truck heats up to operating temp in the same time as it did before. Now, I am assuming your tunes are programmed to run with a 180* stat, correct?


Hemifever's response:

The tunes have a timing curve for a cooler motor, it doesn't coordinate the actual 180 stat. Winter time it can sometimes kick off this code. Sometimes the cheaper priced stat's will do that. It needs a bleeder hole if there isn't one in there. I don't hear much problem with the Jet tstats but the $5 Stants often do

 

Yep, just saw that post in your thread. Was gonna link to it here, but, you just made that unnecessary. Thanks. Interesting to know though.

 

i bought a humdinger $25 180* stat for that rig, and it was bad out of the box..

i bought another humdinger, something like $20, and it wouldn't fit in the port of the air gap.. it was a barrel style, not an exposed spring type..

i got pissed and bought one from Summit with a couple other goodies.. I don't recall it being top of the line, but it wasn't bargain basement.. I can't recall the brand, because there were several I went through in a short period..

the issue is absolutely IAT related.. according to my software via obdii, the only gaudy number is air intake temperature.. I get that code with the coolant temperature reading anywhere from 180* to 190*.. It only happens when there is a substantial gap between ambient air and IAT reported temperature..

I've put a new IAT on there- same thing..

there has got to be a software alteration that will correct this, no?

 

That would be something Hemifever would have to address. Not sure just how complicated that may be......

If my supposition that the PCM EXPECTS relatively high temps from the IAT, because of where it is located, simply moving it further downstream may solve the problem. A couple folks have drilled into the TB adapter, and mounted it there..... I don't hear of them having the same problem....... (but, they may be just because they don't post about it here.... who knows.)