cold highway driving [96 2.2L]

During the summer my car runs perfectly fine in terms of heat. Doesn't overheat, doesn't underheat. (eh?)

Come winter if I hop on the highway the car's temp gauge drops to the 'C' and cold air comes out the heater vents. Driving around town under 40-50mph is fine, but any higher and my temperature drops dramatically.

What I have done so far:
1) replaced thermostat
2) replaced coolant sensor
3) replaced water pump
4) flushed radiator w/ dex-cool

What else can it be & what could I possbily do to diagnose this!?

The thermostat will prevent the engine cooling too much by closing when temp in in eng. drops. When you get cold air blowing at a lower rpm like when you leave the highway tell me there is air in the cooling system, sometimes you need to remove the rad cap or tank cap idle eng in driveway and wait for it to come to temp to open the thermostat then it will (burp) bubble out the air in the system. Your thermostat should always keep eng. to temp. no matter what the air temp is. When fluid is low in system it wil go the route of least resistance around the block and bypass the lines to the heater core.

Hmm, I have plenty of fluid. I don't think it's an air pocket, simply because I just had the system flushed and I'd bet they did it right. That and I've had the coolant changed a number of times for several replacements and stuff.

I think I'll also grab a high-end thermostat and hopefully install that tonight... I'll keep you posted.

Also, I should add that I have had the car overheat several times on me before. (water-pump) Someone suggested that I might have done actual damage to the engine. What type of damage could I have done?

check your OIL cap for a mayo like substance on the inside, if so water in you combustion chamber with busted headgasket or water jackets. Also pull out the oil dipstick and (i know it's dirty but trust me- you cant do this with gloves) rub some oil between your fingers. If it's gritty this is metal filings meaning that a rebuild may be on the cards and if it's smooth you're ok. Also look for the crankcase breather on your intake (rubber hose about 1" in diam putting air into intake.) if this blows a lot of air out you may be suffering with blow-by which means that you have worns bores/rings or both. Also the head may need skimming/planing if it's over heated this does up the compression ratio though so that's a good thing (except with a turbo-detonation more likely!!)

After replacing my thermostat with 180 degree one, new coolant hose & waterpump on my 96 2.2 Cav, my car's temp gauge drops to low end of the "range" (the white line above C and below the red) when driving on highway . For street driving, the needle is always at the center.

Never understand why GM places the thermostat on the opposite end from coolant inlet/coolant temperature sensor on our Cav... So in theory if my thermostat opens at 180 degree, the hot coolant travels thru the radiator and is cooled down (cool winter+high speed), the temperature sensor is measuring the coolant returning from the radiator.

Thanks a ton for the info noshun... but unfortunately I need some clarification :)

1) What does the crankcase breather look like & where is it?
2) Approximately how much would it cost to repair worn bores/rings?
3) How much for a skimming/planning?


Langning:

I believe the cavalier takes a 197 degree thermostat. That's what I have at the moment. Does it really make a difference though if the engine is already cold?

Thanks a ton for the info noshun... but unfortunately I need some clarification :)

1) What does the crankcase breather look like & where is it?
2) Approximately how much would it cost to repair worn bores/rings?
3) How much for a skimming/planning?


Langning:

I believe the cavalier takes a 197 degree thermostat. That's what I have at the moment. Does it really make a difference though if the engine is already cold?


1) basically on the intake if you strill have the stock plastic one there will be a 1" diam black rubber hose right at the intake plenum, best thing to do is to remove your whole intake assembly and after you have undone the clips etc the breather will be the thing that is stopping you from removing it completely, however this just pushes on and pulls off.

2) this is basically a bebuild. So not cheap and if you want to tune then you might want to upgrade these parts which really isn't cheap. and it's not cheap for oem pystons, rings boring etc this is a complete strip-down job. This was purely for 'Worst Case Scenario' reasons not to scare you.and unless you are particularly attache dto the car or really don't want to sell it then it may be best to get a new car before anythin drastic goes wrong. Would suck for the buyer if it is bad but at least it's not you. I'm also not suggesting you sell your car this is merely a last resort kind of thing.

3) Planing isn't particularly cheap but it does involve stripping the head down. This is a hell of a lot cheaper if you can strip the head from the motor and just take it to a shop to be done then letting them take it out. If you took it out yourself which you shouldn't do if your not entirely confident then I would hazard a guess at a couple hundred. I've not been in north America long (English) so don't know of anyone to recommend yet.

Checked you profile, saw you were in Ohio. Seing as I'm in Toronto I have been recommended a place and you are not too far away so it may be worth checking their site, they cater for american customers all the time and really know their stuff www.rsmracing.com check that out should give you a good idea although the prices will be for a different head etc and you just have to send yours to get the core charge refunded. It may even be worth calling them.

Remember also that I am just providing advice to try help out. It's ultimately your choice what to do.

Hmm well...

Perhaps we should exhaust all cheaper parts first. Is there any chance that it's the IAT sensor? Or any sensor potentially?

Also I think I should mention that my fan doesn't come on when the engine gets hot (though the fuse & relay all work) and I have a small exhaust leak at the bottom end of the exhaust manifold. Gonna replace the gasket weather permitting.

your best bet is to check everything because even doing the cheap stuff is frustrating when it doesn't work and the money adds up it was mainly to let you know if it's serious problem or not.

I'd fix the exhaust asap as you are losing power and economy at the moment.

The fan may just be down to the fan switch which is in the cooling system and tells the fan when it need tom cut-in this isn't very much at all but just change it when the engine is cold as coolant will come out of the hole.

Driving around town under 40-50mph is fine, but any higher and my temperature drops dramatically.

I normally drive 75mph on highway and this morning I intentionally drove around 60-65mpg and the temperature gauge stayed just shy of middle. When I sped past 70mpg and that is when my needle started to drop slowly. The only difference is that my needle doesn't go to C and dramatically...

I saw a Cav with "leather front grill cover" yesterday. Can you use something like that to block off the wind and keep your engine from cooling down at high speed driving?

Yeah I contemplated that. But, if i sit in traffic for a while the engine will hit middle. So if i had a slab of cardboard there, it might heat up too much. Thus doing more harm than good.

Yeah I contemplated that. But, if i sit in traffic for a while the engine will hit middle. So if i had a slab of cardboard there, it might heat up too much. Thus doing more harm than good.

If you are sitting on traffic, the fan will kick on when the tempature is high enough... Looked at the list of things you replaced, I hope your fan is working :)

Read post #9 :)

If you are going to cover the rad only partially cover it. this will help if you're ok at 60-65 but not higher. Card works well and is cheap. It doesn't show either so itr doesn't look stupid like the covers. Check that fan swith it'll be under $20 for a new one and all it does is screw in so you'll need a socket or wrench. I just realised that my prev post wasn't too clear, coolant will come out of the whole that the fan switch is in regardless of eng temp so that's whay I said don't do it hot as it will be under pressure and it could scald you.

stop just replacing parts... feel your heater hoses.. are they hot at operating temp,,, it could be as simple as a pluged hose.... finding a cooling system problem is pretty easy.. find it, not just replacing everything....

Well if there was an obstruction, the garage that did my radiator flush would have told me. I asked if they found anything wrong in the process and they said, "No".

So I guess that narrows it down, if not a little.

You obviously feel it's not the cooling sytem and if it's getting hot tand then fan isn't cutting in there is something wront. You said everything else works would def say fan switch!!!


Merry Xmas by the way.

It's not the hot i'm worried about, it's the cold. :)

Let's summarize:
- 3 thermostats, same results
- pump has been replaced
- coolant system flushed
- no air pockets
- apparently no blown head-gasket

Got my car back from the garage. Brand new thermostat & inspected thoroughly and I still have the same problem. Mechanic was completely stumped. So he got a GM certified friend from a local Chevy dealership, and he was also stumped.

Now I've done some research of my own, and I've come to the conclusion that it may very well be a blown head gasket. Normally it's difficult to tell if your car is blowing smoke or vapor from the cold. One day here, it got up to 60 and I found it was still smoking. The more i revved, the more it smoked. So it appears there is coolant burning up in the engine.

So why? And is it just the head gasket or maybe worn rings?

well if you blew your head gasket an have been driving it around not knowing cause of the cold - you could of dont more damage then ya think - if you have a good buddy that is a good mechanic have him pull the valve cover an check the gasket an he is qualified enough have him pop the valve head off if the head gasket is blow an check to see if the cylinders are shinny or black - shinny is good black is bad means your rings are shot an or you might have a crack..... let us know whats up - good luck

Is it using water/coolant? I know you are convinced it isn't the hoses but there my be a blockage.

If your not losing coolant, and upon an oil change you dont notice coolant in your oil, or vice/versa its not a head gasket. I have a 97 with this exact problem, above 60mph, and upon hard acceleration temp drops to ice cold, and lack of warmth from the heater confirms this. I have it narrowed down for you to one possible problem. Since you replaced the stat a couple of times, and the rubber gasket, and flushed and burped the system, than the only possible thing it could be is the PCM. The onboard computer has a glitch causing a variety of sensors to act inappropriately causing your run cold condition. It is not a heater core since you have warmth until temp drops at given speed, it is not a radiator problem or clogged hose, since you dont have overheat issues. AS I said I have the exact same condition, only I dont want to drop 200 plus to pull and replace my PCM since the car runs perfect until you exceed 60 MPH.

If your not losing coolant, and upon an oil change you dont notice coolant in your oil, or vice/versa its not a head gasket. I have a 97 with this exact problem, above 60mph, and upon hard acceleration temp drops to ice cold, and lack of warmth from the heater confirms this. I have it narrowed down for you to one possible problem. Since you replaced the stat a couple of times, and the rubber gasket, and flushed and burped the system, than the only possible thing it could be is the PCM. The onboard computer has a glitch causing a variety of sensors to act inappropriately causing your run cold condition. It is not a heater core since you have warmth until temp drops at given speed, it is not a radiator problem or clogged hose, since you dont have overheat issues. AS I said I have the exact same condition, only I dont want to drop 200 plus to pull and replace my PCM since the car runs perfect until you exceed 60 MPH.

Could it not be a block in a heater core hos so that when the coolant is hot, the heat is getting through but not when the edge is taken off. Replacing the PCmis a little expensive. But you could trey it using a buddies tremporarily or one from a junkyard.

That's an awfully odd recurring problem for a PCM. Doesn't sound too likely to me. Also I've read that blown head gaskets will do one thing for one car, and another for another car.

My coolant has been pressure tested and the coolant system flushed. What else could I do to check for a blockage?

Could it be at highway speeds the headgasket is what is losing pressure!???

are you getting HOT air when the temp gauge drops? or does it get colder with the drop of the temp gauge? Once again if you had a blockage of any kind the temp of your engine would increase, not decrease (basic science). If your heat remains hot, you have a condition known as vapor lock, or a large air pocket, the system needs to be bleed of air. eg. the temp sensor on the outlflow of your block cannot read air temperature, its just like sonar, it must be completely free of atmosphere to register correctly, thus without the presence of coolant on the outflow returning to the radiator your temp gauge drops like a rock because there is nothing for it to measure. which can cause a variety of different problems; which the PCM measures and compensates for. this is why I stated It is HIGHLY LIKELY if the afformentioned conditions are not present it will likely be a defective PCM. Remember the recall for corroded PCMS and that cheap ass rubber they put around the computer, if you didnt get it repaired ASAP your computer could have succumbed to the elements. unfortunately you cannot just swap out PCMs, as they are EEPROM flashed to your specific VIN. Napa sells them for 115 USD dealer charges 85 bucks to flash in car ( must be in car). The other problem is with this condition, the computer will start to throw all kinds of codes, due to the lean nature of running the computer sees necessary to run the car ( as cold ) so the car will usually also act as if the problem were an Downstream O2 sensor ( the one at the catalytic convertor). you know sluggish, jittery, crap for gas mileage etc. Happy hunting Jason.

Heat drops with the thermostat. Sorry, didn't think about the blockage/heat issue.

Where is the PCM located so I may inspect it?

Heat drops with the thermostat. Sorry, didn't think about the blockage/heat issue.

Where is the PCM located so I may inspect it?
unfortunately you wont be able to tell anything about the PCM by inspecting it, it is the cavaliers onboard computer, on 97's it's located in front of the passenger side front wheelwell. THis may be the same on 96, best way to find out is through a Chilton manual. if so remove the screws holding the inner wheel house get a trouble light and shine into opening behind fender voilet your crappily located onboard vehicle computer. However as I said, this is a pretty expensive; cant return it if it doesnt fix the problem; part. And it must be EEPROM flashed by the dealer, you should try to eliminate any other possibilities before pursuing this avenue. My suggestion is start with a vacuum pump, get an adaptor and remove your temperature sensor and vacuum two volumes worth of coolant through your system, the other end of the vacuum to your overflow bottle, to avoid introducing more air into the system as to rule out vapor lock. Or utiliize any other point post engine block (return line) that may be easy for you to access. I recall someone stating you should run the car with the cap off of the coolant overflow to burp the system, however this will not work because of the fact it is a closed system, the system needs to have the cap on to develop pressure to work properly. KEEP THIS IN MIND, THE CAR SHOULD BE OFF AND RELATIVELY COOL BEFORE PERFORMING THIS PROCEDURE. ALWAYS ABOVE ALL BE SAFE.

Hmm well...

I believe I'll have the car back in the shop. That or do it myself. One way or another, I'm going to determine if I have a blown head gasket and such... I'll post back my results.

bird why do you keep going back to the head gasket? earlier in this post you stated you had the cooling system pressure tested. This would have determined whether your head gasket was smoked. Go to Autozone, rent the cooling system pressure tester, pull your spark plugs, pressurize system, let it sit for about an hour, and if you have dexcool coming out of any of the spark plug holes you have a blown head gasket. I am willing to bet you either have a defective PCM, or one or a series of defective sensors causing the PCM to stay in open loop mode. A cheap fix might be to have a dealership reset your EEPROM 85 bucks, or see if they can pull any hard codes that might help narrow your search.

Well if I have a warped head gasket, perhaps upon accelleration and pressure increase, the head gasket bends and lets coolant into the valves. Possible??? After all... I can see no other reason why I would have white smoke.

I'm not so sure about the PCM. That's still $85 for a somewhat wild-guess.

If it were senor(s) screwing up, how would I diagnose that? Which ones? MAP? IAT?

well generally blown head gaskets will cause white smoke, you are correct about that; however blown head gaskets will also cause a boat load of other problems, which you are not describing as having. Also because this is a pressurized system you would be able to pull your spark plugs upon immediate shutoff of engine and see coolant in the combustion chamber, since the pressure doesnt magically go away without popping off the radiator cap( DONT DO THIS BECAUSE YOULL MESS UP THE PLUG THREADS, AS THE HEAD IS ALUMINUM). The way you can tell this is let the car sit off for 15 minutes after having run it for an half hour. If when you start it back up again you have a cloud of smoke like your fucking Houdini performing a disappearing act, than its a head gasket. If your car is a high mileage car I am guessing you are burning off oil more rapidly than a new car since the oil rings are bound to be worn, and the valve guides, and seals are leaking oil into the combustion chamber as well, THIS DOES CAUSE WHITE SMOKE. Not to mention the fact that you would need to be dumping an awful lot of coolant in the combustion chamber to drop 150 degrees within seconds, and it would be noticable with coolant level, and with that said you would have a great deal more trouble than just no heat. What is the condition of your upper hose ( connects on front of block on the drivers side of car?) It is possible this hose is collapsing, and although your coolant indicator states otherwise(remember the sensor can only read fluid not atmospere), the engine is actually overheating and you have no heat because there is no coolant in the heater core because the hot coolant returned to the bottle through the thermostat, and new coolant cannot be sucked into the engine because of the hose.

as for the sensors, test each one individually by getting the specific values they produce upon run, and testing them with a digital multimeter(some produce resistance, some send voltage). some national auto parts stores do this for free (MURRAYs etc.) values available in a chiltons manual Im sure. I would check all startup sensors O2, O2s, MAP, temp sender, any sensor which could cause a rich running condition by tricking the PCM into staying in open loop mode. The other way is with a really good scan tool, which most amateur mechanics dont bother to purchase because of the expense. I dont know man, as I said my car does the same damn thing, and every time I replace what I believe the problem to be it takes a little less to get the temp to drop to ice cold and its not exactly warm in chicago. IN summation what Ive changed to try to correct the problem. temp sender, upstream O2, crank sensor, map sensor, knock sensor, CAI sensor, EGR, multiple relays, back flush heater core, new radiator, 5 different stats, H2O pump, heater core return/bypass pipe, upper and lower hoses, system flush. any guesses? thank god I dont do this for a living anymore

The upper radiator hose is brand-new. Had to replace after it sprung a leak :)

I can't think of one, but could there be a reason the engine got cold if it was an air/fuel mixture problem?

Sensors I'll test:
MAP
O2
Crank
Knock
CAI
EGR
IAT

I've already replaced the temp sensor, nothing wrong with the old one either. Also, there appears to be multiple temp/air sensors I'll consider. Seeinz how I certainly don't have this problem during the summer!

Perhaps the cooling system is loosing pressure through the head gasket? Through the exhaust? Is anything like that possible?

Perhaps the cooling system is loosing pressure through the head gasket? Through the exhaust? Is anything like that possible?
I went upon a suggestion from a friend of mine who suggested a small crack near the water inlet on the head gasket could cause exhaust gas fumes to leak into the coolant system, without losing any coolant causing a constant airlock condition. So I worked on the car all night last night, and changed every top end gasket on the car (head gasket all the way up) result: same condition as before. So I really doubt its your head gasket. I am going to change the heater core hoses today, as they are so malleable with the age of the car maybe they are collapsing with the small amount of vacuum this system produces. I am moving away from the possibility of sensor (s), as I think about this more the amount of fuel required to produce a rich enough condition to be the cause of symptoms would definitely show up as an MIL. There is no question the computer is reacting to the low temperatures causing the car to run rich, but I doubt the computer is the cause. summation save your money, because if you cant change your head gasket yourself its gonna cost you about 600 bucks. Are all of the hoses new on your car, which ones have you replaced?

I replaced both heater hoses today and decided to purchase yet another thermostat and seal (number six) part numbers at napa for the hoses 11703, and 11704 30 bucks worth of parts after countless hours worth of BS. Problem solved. It would be hard to believe it was the thermostat as six defective stats right out of the box would be pushing it so I do believe it was the hose from the heater core to the water inlet that was collapsing during operation. I certainly hope this solves your problem too. Jason.

Just ordered a nice digital multi-meter... also I'll be purchasing a good thermostat and the new heater hoses over the weekend.

Also, where are the coolant fan resisitors???

Just ordered a nice digital multi-meter... also I'll be purchasing a good thermostat and the new heater hoses over the weekend.

Also, where are the coolant fan resisitors???

I dont quite follow your question. do you want the blower motor resistor? As the underhood cooling fan runs off of a relay that is activated after the PCM senses conditions from a variety of sensors which warrants its activation. I hope this answers your question. The blower motor resistor is a ceramic circuit board directly behind the blower motor in the passenger compartment which has a fixed resistance for each of the 4 speeds on your heater switch. The cooling fan is sharp contrast is an ON/OFF only, the only resistance circuits that may come into play ( and Im not entirely certain of this ) is if your car is equipped with A/C as the fan needs to blow faster to keep up with the heat produced at the condensor.

Someone told me that there was 2 resistors for the coolant fan. I can't find that anywhere, so I'm assuming it's wrong.

Well, I've got my multimeter, and so far the IAC and ECT sensors check out fine. I've bought a new upper radiator hose and I cleaned out my coolant reservoir. Geez, sludge/sand came out of that thing! That has prompted me to replace a few other hoses like the heater hoses.

BTW, anyone know a good way to get off those stupid tension clamps??? I can't get this one because the metal tabs are facing the frame so there's very little room to work with.

Someone told me that there was 2 resistors for the coolant fan. I can't find that anywhere, so I'm assuming it's wrong.

Well, I've got my multimeter, and so far the IAC and ECT sensors check out fine. I've bought a new upper radiator hose and I cleaned out my coolant reservoir. Geez, sludge/sand came out of that thing! That has prompted me to replace a few other hoses like the heater hoses.

BTW, anyone know a good way to get off those stupid tension clamps??? I can't get this one because the metal tabs are facing the frame so there's very little room to work with.

If you're replacing that pipe cut it and then go from the side and use a flat-head screwdriver!

Wow... took me like an hour to get that bastard hose off!

Anyways, I replaced the upper rad hose and checked the thermostat. I checked the thermostat by getting a pot of boiling water going to see if it opened. It did. Poured some cold water on, and it closed right up. But, I need to get the 180 tstat instead of the 195. It's too hot!

Speaking of hot, how does the cooling fan know to come on? Is it how hot the radiator gets or is it the ECT sensor? Just wondering if a lower tstat would do the trick.

Next, I flushed the system with Prestone Super Flush. But, as you can see from this thread (http://www.automotiveforums.com/vbulletin/showthread.php?p=2798847), I have another problem before I can continue.

Another question, what size heater hoses do I need and about how much? I know little about this particular area.

both the hoses are 3/4" but they have a couple of 90 degree bends that are near impossible to duplicate, and would probably only occlude and cause the exact same condition you are trying to correct. save yourself the aggravation go to napa and pick up the part numbers listed in my previous post. Oh, and if you have a floor jack and a set of jack stands those hoses are alot easier to get to from below with a pair of channel locks.

Bah. Yeah yer right... I just don't like getting under a ton 1/2 of steel!

Looks like the next few days will be warmer here, allowing me to work a bit easier. I'll hopefully have the system completely flushed, new tstat & hoses by Monday.

Bah. Yeah yer right... I just don't like getting under a ton 1/2 of steel!

Looks like the next few days will be warmer here, allowing me to work a bit easier. I'll hopefully have the system completely flushed, new tstat & hoses by Monday.

Using jack stands if you possition properly i.e not on the floorpan or rocker panels etc then there is an extremely small chance of the car falling unless it's unbalanced or the wheels aren't locked and chocked!

Apparently all the work I did to the car did absolutely nothing. I put in a new 180F thermostat & gasket, replaced the upper & lower rad hoses, heater hoses and checked the IAT & ECT sensors. Oh and the fan works now, but rarely needs to come on. So now I'm exploring other options! Next on my list: MAP, IAC, EGR, PCV ect. What about freeze plugs? Do they have anything to do with pressure? The more I think about it the more I believe it's an air/compression issue, so I'll be tearing into the intake here in the next few days.


http://www.ezautoshopper.com/pcv-valve.jpg
Does this PCV valve look like it's supposed to be on my 96 2.2L engine? Notice some of the oil all around that hole? Not sure how that got there. It does make a rattle sound though, which is good.


http://www.ezautoshopper.com/air-intake.jpg
A) Crankcase breather? (looks like I'll be tearing into this)
B) MAP sensor?
C) ummm?
D) IAC sensor?

bump

Ok... was driving around yesterday and I stopped at Denny's. Came back out and my coolant light came on. I checked and it was coming from the front left of the car. So i got a buddy to take me up to walmart so I can grab some coolant & water.

I discovered that I have a bad leak from either the over-flow hose from the reservoir (the only one I didn't replace!) or the radiator. It appears to be a pinhole leak.

This could be causing my cold highway driving, so I'll advise!

This might be something as simple as a bad vacuum/air mixing problem with the heating/cooling system. Even though the dash settings indicate heat mode, the controls may not be activating the heat/outside air mixing controls. I suggest you closely scrutinize any vacuum lines that control the lot. Something as simple as a pinched or split hose could cause major aches. You might hear the hissing as the lines do their thing; but the lines may be sucking outside air and doing no good. Vacuum lines can be notorious for "faking it"...lol
Have somebody in the know do a complete vacuum/air-control inspection before you go replacing any more parts. This whole problem seems way too complicated when the KISS rule oughta have been applied.

Tookie

Wouldn't I have a major loss of power if it were a pressure problem though? And my coolant is actually cold after the highway! So it's not a sensor problem.

And no... simple doesn't seem to do it :)

Well it does seem you've done most of the complicated stuff already, and still no joy. If the coolant is still cold in the rad then it appears likely there is no exchange tween the rad and block. A complete back flush might work, or bad water pump, or blocked hose could be the culprit, providing the thermostat really is workin. Find yourself a thermostat with built in failsafe.
As for loss of power, I'm actually referring to the controls that move the flaps that mix cold air with warm. The ones that reside in the firewall/heater area. The assembly might be stuck in cold air mode. That shouldn't affect engine power at all really; but it will afftect inside temps in most cases.
I still think its something simple you've overlooked; or failed to recognize.

Tookie

chevelle 69 was right, partially. He went to NAPA and bought hoses and a thermostat.
as it turnes out it was a thermostat. It is the BRAND of thermostat you are using. Did you buy a "MOTORAD" thermostat? I did and had the exact same problem all of you had. ITs not a speed issue though, its a RPM issue. If you dont believe me then drop your car into a lower gear and drive it at over say......... 2600 rps (that is where my heat drops signifigantly). This happened to me even in first gear if I tried it. Anyways, I went to NAPA and bought a thermostat from them . Turns out the spring is probably about twice as stong. Only allowing it to open when its actually supposed to. So anyways, I slapped this new NAPA thermostat in and problem solved. Instantly.

Hope this solves all your guys problems.

Peace!

Oh, I never wrapped this up... I was using Duralast themostats from AutoZone. Turns out they were all (6 of them) defective, but only in my car :)

I went to NAPA and got a stanton t-stat and now the car runs beautifully now. Oddly enough, the fan works fine now too.

check for codes

check for codes

Umm... it works fine like I said. Let this thread die!