Intermittent hard-start / no idle

[fuddy_duddy]

I've been having some problems with a 94' Camry that I just bought used.. I was curious if anyone had the same problem or has heard of a similar scenario.


Ok.. here goes. Actually it's a little complex because I haven't done a lot of the basic tests to isolate my problem yet.

The car is a base model 94 Camry, 4cyl 5S-FE. About 180k on the odometer. (yeah JEEZ this car must have been damn well used)

I have a presumed ignition problem that is intermittent. The scenario is this - the car may start up fine, run fine for over 1hr (stationary in the garage) and all of a sudden, cut out. I checked fuel pressure and the fuel pressure is about 43-45psi during cranking. I didn't check spark but I am able to get the car started with a small squirt of starting fluid / ether. Once started, I have to rev the motor to hold the rpms a bit higher than idle or else it'll die.

I noticed that if I hold the throttle steady at about 1.5k - 2k rpm, I can visually see the tach jump and hear the intermittent misfire in the ignition system. During this time, I see the check engine light flash in quick succession after the misfire condition is occuring. For instance, i'd be holding the throttle steady at 2k and the tach might go haywire, dropping 50-100rpm at a time randomly, and the CEL might flash right after or during the "miss". I don't know if Toyota uses the CEL as a misfire indicator.

If I just let the throttle go, the car just dies. After this, cranking does nothing to start the car unless you squirt a little starting fluid. Then it starts, but of course you have to hold the throttle.

What does not make sense to me at all if there was an intermittent "SPARK" or weak spark problem, why would the car start with ether every time and then just die if not kept steady at higher rpm when the problem is occuring?

I would think that even with ether / starting fluid that if there was an intermittent spark or weak spark that the car wouldn't start all the time, even with ether.

At this point i'm just confused. The distributor assy. was changed with a non-OEM part at about 156k and I don't know if that would be something to point the finger at. I don't think the previous owners would have had this problem for almost 30K miles. At this point i'm thinking there could be a possible bad connection to the ECU's cam signal wires or power wires. I swapped the ignitor myself with a different part just to make sure it wasn't the ignitor.

Can anyone relate to a similar problem they may have experienced?

Any help would be greatly appreciated.

-Dan

[93celicaconv]

Your CEL is trying really, really hard to tell you what is wrong. Get the code(s) and let us know what it/they are.

You could have a bad/loose spark plug wire, igniter, coil, or wire connection problems. But your CEL wants to let you know for sure. So get the code(s).

[fuddy_duddy]

Ok, did a little more probing.. well there are no DTC's stored in memory.

The check engine light is not on.

After running the car for about an hour or so, it died of course. So I checked for spark. Crank no start - no spark. Fuel pressure ok. So I squirted some starting fluid into the car and it starts up. Magically, there is spark after the engine gets going off of the starting fluid. Wtf?

I don't know what the root cause of the problem is, because it doesn't make much sense. Ok. Let's say the distributor is bad. When it gets hot, the cam signal from the hall effect sensor gets intermittent. That means intermittent spark. Maybe the cam signal is intermittent when the distributor gets hot and doesn't supply a steady signal at low RPM? If I keep the rpm high, about 1.5k or so, the car will run. But as soon as the RPM drops, the car just completely cuts out. So when it's acting up, the distributor doesn't send a spark signal below a certain RPM. That means, no spark during cranking. I can crank and crank and it won't spark nor start. So when I squirt starting fluid, the engine pings and knocks like crazy but that jump in RPM is just enough to trigger the faulty pickup in the distributor for a few cycles so the car starts up and stays running while the throttle is held?

OR? A friend of mine told me 4th gen Camry's were prone to ECU failure.. intermittent cutout. Possible Bad ECU?

At this point I can only really point the finger at either the distributor or the ECU but i'm not sure how to really isolate the two. I think I would need a scope to see the ignition signals to and from the ECU?

What do you guys think?

Any help is greatly appreciated.

-Dan

[93celicaconv]

First, the stored OBD codes just don't go away, they need to be manually cleared. When your CEL light was on, it set a code. The code is stored in memory. Even when that CEL goes back out, the code stays. Did you clear the code(s) since 4/18/10 by disconnecting the battery or pulling the fuse tothe ECM? The code(s) would have told us so much. How did you check for codes anyway? If you have the old OBD-I system (I think you do), did you jumper TE1 & E1 in the diagnostic connector, key on, and watch what the CEL was doing?

Sure, the source of the problem could be a bad coil in your distributor. Could be a bad igniter. Could be a bad ECM. Could be faulty spark plug wires. Could be a poor or non-existent ground connection. Could be bad wiring. Could be your timing belt jumped and is out of time. Could be a lot of things.

If you have a weak spark condition, during the time you are cranking your engine over, you have low system voltage (your starter draws down the battery voltage due to current the battery is generating). So you may not have sufficient spark to ignite the fuel/air mixture. The starting fluid is far more volatile, and it may ignite under a weak or even no spark condition (like a diesel engine). Once the engine starts, it runs off of that starting fluid for a bit, battery voltage picks up a bit, and the weak spark may sustain running a little. Get the engine to rev, the alternator increases system voltage, improving your weak spark, and it runs better. Plus, the engine momentum at higher speeds gets it through the a lot of the non-spark times until it comes back a bit. At least this is what I am thinking.

I know you had an ECM code stored, wish I knew what happened to it. Maybe you can run it in its current condition, like you did in your first post, and get the CEL to come on momentarily and then get the code(s). Otherwise, you can test the coil in the distributor to diagnose it or physically see it to see if it has any cracks or anything, and start from there.

[LittleWhiteBubble]

Sounds like the coil. I had to replace mine. When coils start to wear out they can crap out when they get hot. It'll start running worse and then one day it wont start at all. Had this happen on my old f150. The coils seem to be a common failure on these cars too. I've owned two that had this problem.