In desperate need of help, car quits when hot.

alec_b · 07-23-2005, 02:01 AM

I have a 1993 SL, 5 speed 1.9 SOHC. I just had the engine rebuilt 6 months ago, it had 185k original miles on it. It ran great for a while, but now whenever the car gets up to operating temperature it starts to lose power, choke itself off, and eventually die (usually at the worst time, like in an intersection.) I am a plenty competent mechanic but this one has got me stumped. I replace the IAC today, which helped my cold starting problem but not my warm problem. I have 38 psi of fuel pressure regardless of wether it's acting up or not so it's not a fuel pump issue. Also, if someone covers up the injector with their finger while it's acting up, it will start easier. Otherwise you have to hold the accelerator to the floor and start it several times to get ot going again, and hope to god you dont' let it die because that'll be another 5 minutes before it will go again. So i'm down to 2 things here: changing the TPS, which is tomorrow, or the computer, which i'm trying to avoid. Any ideas?

**Ssicarman** · 07-23-2005, 04:23 AM

PCM coolant temp sensor and the connector for it if it has any corrosion in the terminals. It is the two wire sensor on the rear lower middle of the head. A search of the board will get you all kinds of info on it.

alec_b · 07-24-2005, 05:27 AM

Well i replaced the TPS today, that seemed to fix the problem. I'm still getting a code 25 and a code 23 though, even though i've already replaced the IAC and the TPS. Now on the coolant sensor, just incase it starts to act up again, where exactly is it? By on the rear of the head to you mean under the intake manifold, accessed from underneath the vehicle? Because i looked back there and there isn't anything on the head like that, at least not that i can see. The only sensors are the crank position, knock, and one other that looks like a oil pressure sending unit. I don't see any 2 wire connectors. But it runs good for now, only thing left is to get the damn expansion valve to unstick on the A/C. Lol. Thanks for the help guys.

**Ssicarman** · 07-26-2005, 01:41 AM

Quote:

Originally Posted by alec_b

Now on the coolant sensor, just incase it starts to act up again, where exactly is it? By on the rear of the head to you mean under the intake manifold, accessed from underneath the vehicle

The rear of the head is the back of the engine. The serpentine belt and accesories is the front. The trans end is the rear. You are looking on the side of the engine.

PurdueGuy · 07-26-2005, 04:27 AM

I just replaced my ECTS (eng coolant temp sensor) yesterday, and it's incredibly easy if you do it right. Some of these steps are somewhat optional, but I feel make the job easier, and thus, more pleasant. I'm talkin "wow that was easy" kinda easy.

Note: Do this on a cold engine - not hot, not warm - cold, like it's sat overnight kinda cold.

You need:
--Tools for taking off intake - for me it was locking pliers for a sprung clamp, some have a clamp that just needs a flathead
--ratchet
--sockets - 13 mm for sensor, 10mm (I think) for battery bracket, 8mm (I think) for battery cables.
--rags - shouldn't need much if you follow directions
--needle nose pliers (angled ones work awesome, but it's not terribly important)

Simple steps:

1) remove intake
2) remove battery holddown, neg bat cable, then positive, then battery
3) jack up the front drivers side of the car and put it on a jackstand (be sure to put on e-brake and use wheel chocks) This step helps reduce coolant drainage, but is far from necessary. I felt it also put things at a nicer height to work at.
4)remove the coolant resevour lid to release pressure, then PUT THE CAP BACK ON TIGHT.
5)unplug the sensor harness. The sensor should be easy to spot looking at the side (technically back) of the engine from the driver's side fender area. It's centered on that side, and in plain view. to unplug, you squeeze the harness. You may be able to do it with your hands, but if not, use the pliers. it should come off easily - dont' force
6) check wire harness for corrosion - if there is any, get a new harness (you may just want to get a new one before you start the work if a place that stocks it isn't nearby - then return it if you don't need it)
7)place some rags under the sensor. When I pulled my sensor, I barely lost any coolant - maybe a soda capful. If you don't follow instructions, you could loose tons of coolant and make a huge mess.

remove the sensor with the 13 mm
9) put the new sensor in (make sure it's brass-tipped and has white or red threadlock on the threads - should come that way). Put it in by hand at first, so you can feel that it's in the threads properly, then tighten with the ratchet. You don't need to really crank down on this - just make sure it's pretty tight.
10) reassemble your car. If you've taken less than 30 min, leave the battery disconnected for a little longer so the computer will reset.