New from the Upper Peninsula of Michigan

[arrowhead2001]

Hello everybody, I've been a long time "lurker" and figured I should sign up. I can't even figure out how to express my gratitude to the amount of knowledge on this forum. Anyway, I am the proud owner since May of a 2001 SLE. I got the car for a steal at $2,500 - the upper and lower intake gaskets were changed two months earlier, as well as new front struts, and many other odds and ends. 109,5xxx miles when purchased. Now at 115,9xx, I only have $140 into it since. 2 Ignition coils, spark plugs (autolite iridium), 2 fs oil changes (done myself), alum. cooling elbows, serpentine belt, front valve cover gasket, etc. It's been a great car, especially since most of this is typical 100,000 mile maintenance on these vehicles. I look forward to expanding my knowledge base, and though only 16, hopefully can contribute to the community in some way.

[crash93ssei]

Da Yoopers! Where at in the UP are you? We have one other member in Houghton.

[arrowhead2001]

Sweet! I was hoping there'd be someone! In Harvey, 5 minutes outside Marquette. By the way my name is Darren.

[nos4blood70]

Welcome Darren!

[arrowhead2001]

Thanks, Carl! Ironically enough I bought my car from a Carl. He wanted a truck before winter.. Must've not known the capabilities of these cars lol.

[CMNTMXR57]

"A combination AK-57 uzzie radar lasar triple barrel double scoped heat-seakin shotgun"

From that no good something or other from Ill-in-noise.

[Jfridge92]

Welcome to the forum from another younger member! Well, not so much anymore, but I was 17 when I joined here (about to turn 21 in a few weeks) and it's been a great experience! Everyone is super nice and helpful, and there's so much to learn.

[00Beast]

Welcome Darren!

Dangit Joe, you're young. I just turned 22. Been on here since I was 16. That's really sad....

[arrowhead2001]

Thanks to all. I didn't realize how many people started young on here. Anybody have the intermittent start quality issue? In summer it is vile and unpredictable. It could crank three seconds or fire off right away. In winter when the car is warm it will fire off with the flick of a wrist, but when cold understandibly it takes 3 seconds of cranking every time. I know I'm not really in the correct forum, but while I have your attention. I have done my research on old posts, but nothing *exactly* matches my condition.

[CMNTMXR57]

Heatsoak.

[DJC906]

Welcome! Im in the UP too, Gladstone to be exact, about a hr away lol. Lots of useful info on this site and plenty of helpful people.

[CMNTMXR57]

Happy Rock as we used to call that.

[DJC906]

haha yea, people still call it that

[arrowhead2001]

My mom callls it that. How cool. Did you happen to see that 2003 Aurora for sale in the Copper Country I believe? I wanted it in the worst way. 120k and $3,500. I'd be screwed if the head bolts pulled however. Are there any posts on this heatsoak?

[arrowhead2001]

I searched it lightly. So it's when the engine bay inevitably fills with heat, correct? I have noticed the same extreme power difference between when it's almost 0 degrees F like today and when it's 90 degrees in the summer.

[CMNTMXR57]

For a 50,000 ft view, yes.

And while that does play a part in the performance difference between a 0* day and a 75* day, that aspect is more due to cooler air being more dense. Cooler, more dense air makes more power.

Heat is the performance enemy to the internal combustion engine. Heat, be it high coolant temps and/or high underhood temps increases the potential for pre-ignition (detonation) that can trigger knock sensors to pull timing and decrease power. Catastprophic internal damage can result in really bad situations. Heatsoaked induction components means hotter, less dense intake air is what is being sucked into the engine and results in less power.

Now this is not to be confused with normal engine heat. Having an engine at proper operating temp (proper operating ECT's, combustion chamber temps, etc), with with cool intake plumbing, sucking air in from an isolated point (so as not to suck in hot underhood engine heat), will net the strongest results in addition to proper atmospheric conditions. Typically GM sets their most agressive points in ignition and fueling tables at 57*.

I lost some ~90 lb/ft of torque on Speed Inc.'s DynoJet 248C doing a fresh pull on a cool March morning vs. coming back for a tuning tweak in hot, humid, August. Boosted engines are impacted even more with those temperature changes. Aside from the power loss I mentioned, usually in spring and fall, the car runs like a raped ape. But in August, it just isn't as "strong".

[arrowhead2001]

I understand more now, thanks a lot! How does this affect the car's starting performance, though? Theoretically if it was doing it's job the PCM would make adjustments to the air/fuel mix for consistent starting? Or am I an ignorant rookie?

[CMNTMXR57]

Cold can affect startup too. Fuel is tougher to atomize when cold and then on a fuel injected engine, spraying it against cold head components in the path of the intake path.

However, the PCM goes into Open Loop segment operation, ignoring certain criteria (such as HO2S's, and whatnot), until the catalyst has reached proper operating temps, and then will flip in to Closed Loop segment operation (responding to all it's battery of sensors). When it is in this open loop, especially just after it firing, it'll run at a higher rpm and obviously be running richer.

[00Beast]

I'm guessing some part is being flaky when it's hot. Likely an ignition component, Ignition Control Module or coil pack. My car started instantly in all but the coldest weather.

[arrowhead2001]

Makes sense. It's probably just something small and unimportant. It starts perfect in 10-40 degrees F. Almost can't get my wrist off the starter fast enough haha. I have done 2 coil packs (I know stuff like that you do it all, but I don't have that money to invest in something still working). Could be the third is weird.