86WS6

iTrader: (1)

Hi Y'all. We have owned this 86 TA since 2006. It currently has 32K actual miles on it and is mostly a garage baby. It is a stock WS6 car with the 305 TPI. When I bought the car it had a single electric cooling fan, and would overheat at the drop of a hat. I bought a factory dual fan set-up and a new three flu brass radiator. It helped a lot. I added a temp switch and relays that turned on both fans at 190 F, keeping the factory setup so that the AC would turn on the fans, and in case the aftermarket switch failed the factory switch would turn on the fans at 232 F. The car ran fine in all conditions except when climbing a steep mountain grade, in which case it would do OK for about 10 miles then puke out it's coolent. The temps would climb into the 240F range. Pulling off at an overlook and letting it idle before it puked would allow it to cool back down to the 200 range fairly quickly. The engine would run rough for a while mimicking a vapor lock.
People told me that it wasn't acutally overheating. I was told that the OE guages are not accurate. No doubt, however the car would stall and it sure acted like an overheated car.

Since we live in the mountains and the car was basically useless to us with this problem, i broke down and decided to deveate from stock and install a really good radiator. I bought the highest capicity Champion aluminum radiator with twin Spal high CFM fans. Installed a new 195F t stat, and new temp switch that switches the fans on at 195F. I used the fan wire from the factory system to trigger the fans also. Guess what. It runs 195F on hot days and cold days, with and without the AC on, climbing a mountain, idling, or barreling down the interstate. Sounds like the problem was solved, except for the fact that everytime we climb the mountian to the top of the pass the car runs fine until we slow down at the top, then the engine stalls.

it starts right back up, but won't stay running at idle. If I put it in neutral and rev it to 1000 RPM it will stay running, however as soon as it returns to idle it shuts off again. After decending back down the mountain for a mile or two it's running normally again. It's not altitude, as the mountain is only 6500 feet tall. Any ideas are appreciated.

OrangeBird

iTrader: (1)

6500 feet is plenty enough to cause issues in a car that can't sense altitude, and properly compensate the fuel/air mixture to accommodate it.

Now, your car really can't sense it's altitude per se, instead what it does sense is barometric pressure, of which the standard measurement is 29.92 inches of mercury at sea level. As you go higher up the mountain the atmospheric pressure gets lesser, (having lesser oxygen) and your ECM's "baro" sensor is supposed to react to that, letting the ecm "know" that it's operating in a lower pressure (oxygen) environment, and to adjust the mixture accordingly. Is the baro sensor plugged in, and is there nothing blocking it's port that's supposed to be open to the air? (sometimes people mistakenly put a vacuum hose on it, cause it looks kinda like a MAP sensor that actually does have a hose connected to it).

I have seen sensors fail that don't trigger the check engine light, so it could be that even if the light isn't presently on......

Tom 400 CFI

While some of that description of operation is right, I don't agree with all of it, and definitely not as it relates to stalling and elevation.

I live at 7100' elevation, and have owned an '83 CFI car (MAP) and currently own an '89 'Vette (MAF) and a '92 'Vette (MAP). None of these cars have idling/stalling issues at all. I've lived in Telluride and used to drive my car to work (Tel ski), where I'd park it in the Mtn Ops lot, at 10,000' elevation (see pic). No idling or stalling at all.






The OP's car is a MAF car; it doesn't have a MAP/BARO sensor.
*I* would be checking the function of the IAC, and I'd check the minimum air....then do a data stream on a Mtn drive and see what looks awry when it's stalling.


There is a Click & Clack episode where a woman calls in w/a volvo that dies above 4000'. Exactly 4000'. She knows the elevation, she can reproduce it at that point, the car runs below that point, won't run above it. The brothers mused on it for a bit, didn't really know why or what the problem was, but concluded that Volvo's aren't know for reliability and it's a good thing they didn't use that engine in an airplane!

86WS6

iTrader: (1)

I forgot to mention that when the car is acting up, pulling over, shifting into neutral and maintaining the RPM around 1000 to keep the engine from stalling results in the problem disappearing after a few minutes.