Strange Stalling Problem

[alaskaloyale]

My car just broke down again today, 1988 GL, fuel injected, 5-speed dual-range. Earlier in the day, my belt came loose and caused the car to overheat since the water pump wasn't turning. I caught it pretty quickly and the engine never reached red, but was elevated for a while. It was running just fine after that for a few hours, with no unusual symptoms.

 

Then when I was driving home, the car began to stall out under load pretty badly. It would idle just fine, and would Rev up normally in neutral until hitting 3000rpm, and it would abruptly stall back down to 1000rpm. Under load this happened at much lower engine speeds, making the car almost undriveable. What do you think would cause this? Fuel delivery issue? Distributor? Timing Belt?

[ruparts]

hi, 

  symtom is a lot like a restricted flow through the fuel filter,   cheap , you might try it and see if that does some good,  the diagnostic check connectors need to be unplugged for normal running or the ignition advance will not function.   on FI  cars the coolent temp sensor can cause a variety of problems , and  look for anything you might have done by accident while putting another belt back on.

[SS_Subi]

First thing I would check would be the area you were working in to re-install the water pump belt… Did you bump something loose, unplug something, or possibly break a connector?  If you didn't overheat the engine badly and it was running fine before you replaced the belt chances are your issue is going to be there.  

 

Other questions… Is the engine misfiring at all when idling? Is the engine popping from the intake or backfiring? Is the engine holding a regular temp now? Even though the engine didn't get into the red did you lose any coolant?

[alaskaloyale]

The engine does not seem to be popping from the intake or backfiring. Even when it stalls out, it doesn't seem to misfire, just kind of dies and then starts back up once the RPM drops. I did lose some coolant, because the line to my overflow tank was broken, so when it started to overheat some steam and liquid was able to escape that way. The engine is holding regular temp with no problem now. I'll take a good hard look at the front of the engine, but since I was just messing with the belt up front I don't think I could have messed up anything important. It's -40 degrees outside right now though, so I could believe just about anything breaking. Things get pretty brittle when it's that cold out. I'm towing it to my friend's garage tonight and I'll let you guys know what we find.

[Gloyale]

MAybe the IAC hose got cracked or dislodged?

 

That or some other vac or unmetered air leak/s

[alaskaloyale]

How do I test the Coolant Temperature Sensor? They are about $90 around here from NAPA, so I'd like to somehow confirm the problem before replacing it.

 

I'll take a good look at all the vacuum hoses, would not be surprised if one of them cracked, I had one break a month or so ago that I replaced, and the other ones all look pretty old.

[SS_Subi]

The coolant temp sensor can be checked with a multimeter taking an ohm resistance reading.  You'll take one reading cold and one reading at normal operating temp.  I don't have the specs off hand but I can get them if you need them.

[alaskaloyale]

If you could find the specs that would be fantastic. Fired up the car today, and it seemed to run normally, although I didn't have a chance to give it a real test drive, just drove it up onto the trailer to tow it home. It's possible that something just iced up in the engine and was messing things up, I'll know for sure tomorrow when I get a good look at it. -40 degrees does strange things to cars.

[SS_Subi]

Yeah cold temps can do some crazy things...

 

Ok… Here are the specs I was able to dig up.

Resistance should be 7-11.5 kilo-ohms at approximately 14F

Resistance should be 2-3 kilo-ohms at approximately 68F

Resistance should be 700-1000 ohms at approximately 122F

 

Now… Seeing as how you are up in Alaska and the temps are lower right now then what the readings specify you could simply buy a new sensor, leave it under the hood for a while (overnight?), and then take a resistance reading of both sensors to compare them side by side.  Not sure what the parts houses will do for you up there but I know the parts houses down here won't take an electrical part back IF they can tell it was previously installed.

 

Good luck.

[alaskaloyale]

Thanks, I'll test that tomorrow. The main problem seems to have entirely gone away. I think maybe some of the leaked coolant that sprayed all over the engine bay must have iced up something important, because after I thawed it out it ran great, and hasn't had the problem since. It still runs a little lean, and hesitates a little when the engine is very cold so I need to keep poking around till I find out whats wrong, but nothing severe enough to make driving difficult. I suspect I've got a slight vacuum leak somewhere that I haven't been able to find yet. Here's to problems that solve themselves!

Edited December 31, 2013 by alaskaloyale