93 civic lx, engine won't start; numorous questions

My car turns over but will not start. It showed no obvious symptoms other
than not starting one morning.

The battery has plenty of juice and the starter is fine. I peeked through
the oil filler hole and saw the valves moving, so it is not timing belt.
The distributor is new, so that rules out the ICM, coil and the other
sensors in there. The rotar and cap are new as well. The wires have
acceptable resistance and the sparkplugs spark when tested.

When I turn the key to the on postition I can hear the Fuel pump charge.
I don't have a fuel pressure guage so I can't check that, yet.

I tested the voltage to the Idle Air Control and also the resistance, both
good. I started to do the same to the Throttle Position Sensor and got
stuck. I checked the voltage and it was fine but can't figure out how to
check the resistance. The book is kinda cryptic with it's proceedures and
refers to pictures that have the important stuff out of frame.

So, I was under the impression that TPS sensors can be replaced, fairly
cheaply too. But I can't see how to get it off. It is attached to the
throttle body but not by any fastener that I've ever seen. The end that is
exposed looks almost like a rivet.

My friend and I have gone back and forth over whether it's a fuel problem
or a sensor problem. There are no error messages in the ECM.

Questions:
1. How do I test the restistance on the TPS?
2. How, if needed, do I replace the TPS?
3. Any other ideas on what it could be?

 

Hi

Are you getting spark on your plugs while the plugs are on the car? In
other words, you are getting spark using your distributor, right? At
the risk of stating the obvious, but just because plugs spark in one
car, doesn't mean they'll spark in another one.

I wonder if your fuel injectors are working. Not being absolutely
positive here, but the car would try to start regardless of trottle
position, wouldn't it? It may not run right or keep running, but it
should do something indicating that you're getting spark and gas.
If you have a scope, perhaps make sure you see pulses going to the
injectors while starting.

It could also be that the belt jumped a couple of teeth.
Hope this helps you find it.
Remco

 

Hi

Are you getting spark on your plugs while the plugs are on the car? In
other words, you are getting spark using your distributor, right? At
the risk of stating the obvious, but just because plugs spark in one
car, doesn't mean they'll spark in another one.

I wonder if your fuel injectors are working. Not being absolutely
positive here, but the car would try to start regardless of trottle
position, wouldn't it? It may not run right or keep running, but it
should do something indicating that you're getting spark and gas.
If you have a scope, perhaps make sure you see pulses going to the
injectors while starting.

It could also be that the belt jumped a couple of teeth.
Hope this helps you find it.
Remco

 

It is easy to test, the problem is that the book does not say what
resistance you should see. Disconnect the three-pin plug from the TPS.
Measure the resistance between the outer two pins. Pulling numbers out
of my posterior orifice, I would say a normal TPS would read more than
500 ohms and less than 100 k Ohms. I would expect a few thousand ohms.
Make a note of the result, let's call it x.

Now measure the resistance between the center pin and one of the two
outer pins. As you move the throttle between fully closed and fully
open. You should see the resistance reading vary smoothly between
something like 1/10 x and 9/10 x. Then measure the resistance between
the center pin and the other outer pin as you open and close the
throttle. Again, you should see the resistance vary between something
like 1/10 x and 9/10 x, but this time in the opposite direction of what
you saw before.

That said, a failed TPS would not cause the engine not to start. It
could give you erratic idle, but the engine would still start.

 

Sorry about the double posts -- using the new google beta stuff.

On checking the signal to the injectors: I think you could put a small
bulb in its place to see if they are fired.

Remco

 

Instead of asking all these questions, maybe the most obvious question
is being missed:

__ Why has this car stopped running overnight, all by itself__ ? ? ?

Is that the question you want the answer to, or don't you need your car
for the purpose of going somewhere ? ?

'Curly'

 

Could it be a bad cold sensor, Bad intake temp sensor, Bad fuel injector
power source, Bad fuel mixture, Bad timing? Got a timing gun? Smell gas
at plugs? I am assuming that the CEL light goes on and off as usual. If
you want to remove the TPS, drill out rivets but no replacement parts
available. Still connected, the TPS voltage goes from zero to five. Five
being at full throttle with ignition on. To reset the cold sensor, just unplug
the connector and start it up.