ClubRoadster.net banner

1 - 16 of 16 Posts

·
Registered
Joined
·
67 Posts
Discussion Starter #1
I've been doing alot of research but I can't find the exact problem to how to fix it. I'll try and make this short and precise as I can.

1992 Manual Transmission | 113,XXX miles

Has hard start (sometimes it would fire right up) and when stepping on the gas the car

would seem to be choking or some kind of rattle to it, until I floor it then it would bog and

the power would kick back in and act normal again. Sometimes would hear the exhaust pop

back. (Clogged Cat maybe??) #4 and #3 spark plugs are carbon fouled sometimes wet

fouled. The car is not throwing any codes and I have no idea how to approach the problem

From what I've been reading the symptoms seem to point to the CPS. But if that was bad

wouldn't it be throwing codes or make the car not start at all??? I want to figure out what

the problem is before buying a new CPS since their so pricey. Also I have horrible gas

mileage.

Any help is appreciated. Thanks for your time.

Replaced
New Spark Plug Wires
New Set of Spark Plug but now fouled again
Replace Fuel Filter
 

·
Registered
Joined
·
296 Posts
My bet would be a clogged cat. Mine had very similar symptoms and the cat had come apart and had lodged chunks in the midpipe.
 

·
Registered
Joined
·
67 Posts
Discussion Starter #3
My bet would be a clogged cat. Mine had very similar symptoms and the cat had come apart and had lodged chunks in the midpipe.

Did you have hard starting issues too?? I do hear rattles in the midpipe or something being tossed around. How did you go about your problem?
 

·
Registered
Joined
·
296 Posts
Oh yeah. Definitely had hard starting problems. Then it would mysteriously go away and be back within 20-30 minutes. After racking my brain I decided to remove the cat and found its contents compacted against the back wall and strewn throughout the rest of the exhaust...... I made a test pipe and got what bits of catalyst out that could and bam. The car was fixed. Except for an irritating rattle from the remains of.the cat bouncing around in my muffler.
 

·
Registered
Joined
·
67 Posts
Discussion Starter #8
Oh yeah. Definitely had hard starting problems. Then it would mysteriously go away and be back within 20-30 minutes. After racking my brain I decided to remove the cat and found its contents compacted against the back wall and strewn throughout the rest of the exhaust...... I made a test pipe and got what bits of catalyst out that could and bam. The car was fixed. Except for an irritating rattle from the remains of.the cat bouncing around in my muffler.

From what your saying, I'm starting to doubt that the CPS is not the problem. I'll take a look this weekend on the cat.
Never took off a cat before, so any tips on how to approach it? Or is it just regular nuts and bolts being taken off?

I assume your Check Engine Light wasn't on or throwing codes. Right?
 

·
Registered
Joined
·
296 Posts
In reality the only way you'd have a cel for a cat is if your car was obd-2. But its a 92 so you're stuck with obd-1. As far as removal, its pretty straight forward. Just remember penetrating lube is your friend.
 

·
Registered
Joined
·
67 Posts
Discussion Starter #12
In reality the only way you'd have a cel for a cat is if your car was obd-2. But its a 92 so you're stuck with obd-1. As far as removal, its pretty straight forward. Just remember penetrating lube is your friend.
THIS^^^^^^^ PB Blaster or the like soak them nuts and bolts for a day if you can since its a old car. Then have at it. :twisted:
Alright I'll give it a go this weekend. Thanks for the input.
I'll give feedback when I'm done
 

·
Registered
Joined
·
1 Posts
Try swapping the number 3 and 4 injectors with 1 and 2. see if the carbon fouled/ wet fouled travels with it. If so you may have leaking injectors . As far as the rattle before removing anything and poss breaking bolts why not get a rubber mallet or your hand if its cold and tap on the exhaust to find if the rattle is coming from there and if so what part
 

·
Supporting Member
Joined
·
2,284 Posts
You are approaching the problem wrong...the '92 has built in diagnostics...and not every problem will 'throw a CEL'...there can be a fault, including a no start condition, with no CEL lit..

and all you need is a paper clip...jump the diagnostics box...located under the hood on the drivers side fenderwell..between GND and TEN...and turn the key to the on position...then see what the CEL lamp does..it will probably flash...count the flashes...then consult the list found here..

http://www.miata.net/garage/Engine_Diagnostics.html

To clear any old codes, disconnect the battery, step on brake pedal..then reconnect the battery

Your issue could be a couple things...the igniter on it's way out...a bad coil (there are 2 on the coil pack)..or a bad CAS...Cam angle sensor...start by checking the timing...if it has drifted off of the stock setting, look at the crank pulley and keyway...the short Nose Crank problem is not limited to the SNC 1.6...a keyway problem, which will affect timing and starting, can affect any Miata..have you recently had the timing belt done?
 

·
Registered
Joined
·
67 Posts
Discussion Starter #15
Try swapping the number 3 and 4 injectors with 1 and 2. see if the carbon fouled/ wet fouled travels with it. If so you may have leaking injectors . As far as the rattle before removing anything and poss breaking bolts why not get a rubber mallet or your hand if its cold and tap on the exhaust to find if the rattle is coming from there and if so what part
I tried swapping #1&2 to 3&4 and yes 3&4 still fouls them. So I'm not sure if it is following it. Any ideas?
 

·
Registered
Joined
·
67 Posts
Discussion Starter #16
You are approaching the problem wrong...the '92 has built in diagnostics...and not every problem will 'throw a CEL'...there can be a fault, including a no start condition, with no CEL lit..

and all you need is a paper clip...jump the diagnostics box...located under the hood on the drivers side fenderwell..between GND and TEN...and turn the key to the on position...then see what the CEL lamp does..it will probably flash...count the flashes...then consult the list found here..

http://www.miata.net/garage/Engine_Diagnostics.html

To clear any old codes, disconnect the battery, step on brake pedal..then reconnect the battery

Your issue could be a couple things...the igniter on it's way out...a bad coil (there are 2 on the coil pack)..or a bad CAS...Cam angle sensor...start by checking the timing...if it has drifted off of the stock setting, look at the crank pulley and keyway...the short Nose Crank problem is not limited to the SNC 1.6...a keyway problem, which will affect timing and starting, can affect any Miata..have you recently had the timing belt done?

I don't know when the previous owner changed the belt. What I do know is that I have tried diagnosing it several times but the CEL never flashes, I double checked everything and still no flashes. That is why I'm so stumped and don't know how to approach it.

And yes at first all the signs were pointing to the Crankshaft Position Sensor but another person wrote that he had the same problem as well and it was due to his clogged catalytic converter. So now I'm having doubts about the CPS being the culprit. I checked the timing and it seemed fine.

Any more ideas would help, thanks.
 
1 - 16 of 16 Posts
Top