Tacoma not running right, dies at idle?

Hello everyone, new to the site!

I have a 1997 2.7l Tacoma 5-speed that has been giving me hell for some time now. I was having some charging issues and figured I would replace the alternator. I also cleaned the throttle body and replaced the IAC as I was having a high idle issue (1200rpm).

The problem:
the truck starts right up no problem, if i put it into gear it will die (just pushing the clutch pedal in won't kill it). If i turn on the headlights or fan it will die. NOW if I let it warm up (temp gauge reaches the normal halfway point) everything runs fine just as it should.

and even after the new IAC the high idle remains, cold/hot doesn't matter. I messed with the throttle butterfly valve (I think that's what its called) and it is indeed closing all the way.

I am more concerned with figuring out the charging issue first as the high idle is more annoying than it is harmful. Can anyone help me out with some ideas?

The fact that it runs after warming up tells me maybe the battery has to charge just a little bit more to support the truck? but when I used a multimeter the battery was showing 12v and the alternator 14v. I am getting the battery tested tomorrow but I can't see how that could be the problem. I just find it so weird that putting it in gear kills the truck only before it has had a chance to warm up. So confused need some help!

 

Would need more info:

WHAT charging issues do you have? A low charging alternator will allow an engine to die with just a small load on the engine.

Are you saying that you can push in clutch, and it will stay running, but shifting into gear, without even engaging clutch, will cause it to die??

First thought other than a charging issue would be the cylinder head temp sensor being bad, or disconnected, or a bad wire. This sensor is different than the ECT sensor. The sensor I am talking about is threaded into an aluminum coolant piece bolted onto the back of the cylinder head.

 

Curious as to what your rpms are dropping too when engaging the transmission. Could be too much draw and you got the wrong alternator and it's creating a stall issue.

 

by charging issue I mean I was having symptoms of a bad alternator. Scan gauge was telling me 12v (should be at least 13v), dim headlights, etc..

Yes


I have never heard of this part before. In my research the ECT was mentioned. on my way to Google right now...

 

Okay in my search for the " cylinder head temp sensor " i have found


"Coolant Temp Sensor"
http://www.rockauto.com/catalog/moreinfo.php?pk=1099564&cc=1278996

"Air Intake / Charge Temp Sensor"
http://www.rockauto.com/catalog/moreinfo.php?pk=39914&cc=1278996

'Throttle Positioning Sensor"
http://www.rockauto.com/catalog/moreinfo.php?pk=444234&cc=1278996

"Camshaft Positioning Sensor"
http://www.rockauto.com/catalog/moreinfo.php?pk=2417404&cc=1278996

"Crankshaft Positioning Sensor"
http://www.rockauto.com/catalog/moreinfo.php?pk=40359&cc=1278996

I really don't want to start throwing parts at this. I figure the Coolant Temp Sensor and the TPS are the only two that could really affect anything?

 

You have two different ECT sensors. One is for the gauge, the other is what the ECU uses for calculations. The one for the gauge is at the upper radiator hose connection on the front top of the engine, passenger's side. The one for the ECU is on the back of the cylinder head. While they are BOTH called "ECT sensors" I narrow them down to specifics for ECT (gauge) and "cylinder head temp sensor" for the ECU. 83420AA010 is the factory part number for the gauge sensor, and 8942235010 is the part number for the computer sensor.

 

So you really think a sensor that only measures temps could be causing all this? including the high idle?

EDIT:

Should I go OEM with these? I did a quick search and OE is around $50 where as RockAuto was $3.38 (CRAZY difference in price!)
http://www.toyotapartszone.com/oem/toyota~sensor~water~temperature~for~e~f~i~89422-35010.html

And would replacing the dash sensor really be worth it? I don't seem to be having any problems with the gauge cluster temperature readings.

 

A bad sensor, depending on what it is sending, can cause all sorts of stupid stuff. I do think that an electrical charging issue is a major problem. That is why I asked. I may be totally wrong on the coolant sensor. I was just giving you information so that you could check yourself. A simple scangauge/ultragauge would tell if the coolant sensor for the ECU was bad. You jsut need to access the data stream.

 

Really...I happen to have a scan gauge...what would i be looking for to help me diagnose this problem?

 

Just look to see if you have accurate ECT data.

 

Start where you KNOW a problem exists an go from there. That would be charge. If your battery is at 12v, it's dead. With the engine running you should have the exact same reading at the battery and the alt. If you don't and the alt is producing a charge you have an issue between the 2. That will kill your engine with a load on it.

Fwiw wiring is metal which expands with heat. A marginal connection may work better once it's hot.