Rocks7ar

Greetings.

I have searched through many threads, and found useful, yet not exact, information regarding my situation. Hopefully I'm not stepping on anyones toes with this. Here goes:

With the car sitting in the driveway, cold, it will start and run, however, the idle is very rough at 500-600RPM's. Basing this on the sounds I hear, it sounds as if all the cylinders are not firing. The car can be driven, but as it gets warm/hot/driven for 20 or more minutes, coming to a stop(say at a stop sign) without applying the gas, will result in the engine stalling, as the RPM's drop to zero. if you let the car cool down it will usually repeat the process, however, the first time this occured, All the cylinders were firing when I restarted it, and it ran fine, as long as I applied gas when the car was not moving...

Any help, or oppinions you gentleman can offer, would be more then helpful. I have nothing but respect for the knowledge and time you guys have put into these platforms.

If anything could be clarified by me, please ask.

-Kevin

Guest47904

Did you look for dead cylinders?

Did the car ever run correctly?

Rocks7ar

How could I check for a dead cylinder?

Car ran excellently, then one day this started happening.. Maybe it's due to me redlining it more often? (and by more often I mean I actually went to redline before shifting.) Which would make it the Opti-spark, I believe?

Thanks for asking. Let me know what you think!!

koolaid_kid

The first thing I would do is put an inductive timing light on each plug wire to see if it is firing.
Do you have any type of data logging software/laptop/etc.?
Fuel pressure gauge? I ask this because this is how my car ran when the fuel pump failed. It would run until the pump overheated, then stop. Just a thought.

SoloExceptional

I would agree with this, make sure you have enough pressure as well as volume.
Is the vehicle hard to start on cold starts? Like taking more than about 2-3 times turning over to start. Also check IAC function, coming to a stop without it functioning would definitely result in a stall/dashpot scenario as well as the issues on cold start because it could not advance the throttle plate enough.

Edit: Also a torn boot on a vacuum line or a cracked vacuum line might cause the same issues. My 95 had a similar issues where the boot on the Evap Purge solenoid line to the throttle body had dry rot and cracked.

Guest47904

Let's face it there are literally 10 to 20 different things that could cause it to idle like crap.

When it idles like crap and runs like crap, my first inclination is find dead cylinders.

If a cylinder is running correctly, if you do something to cause it to not run. The engine will change the way it was running. You can either take away spark as in pulling the plug wire while it's running. Or you can take away fuel while it's running, as in pulling an injector clip.

To me, it's much easier to pull an injector clip while the engine is running then pulling a plug wire. Plug wires will cause you to burn your knuckles.

Now when you pull an injector clip, it should run worse. Then put the clip back on and move to another cylinder. If you pull one, and the engine doesn't change the way it's running, the cylinder is dead. Now you have to figure out what is missing that was causing it to be dead. It could be spark, fuel or compression. Spark is most likely. Fuel less likely and compression the least likely cause.

REMOVING THE INJECTOR CLIP TO FIND A CYLINDER DEAD DOES NOT MEAN THE INJECTOR IS BAD.

If you check the cylinder for spark and it has spark. Then you check the injectors.

Rocks7ar

Speedy,
I noticed there has been no mention of the Opti- Is it possible that the Opti is the reason cylinders are NOT firing, or as you and the rest of the qutomotive world put it, dead? Tonight I am going to check for spark and I will make sure to post my results/failures.
Thanks for the quick replies..

Guest47904

The opti could be the reason. However, it if were only cutting out some cylinders and not others, it could only be due to a bad cap or rotor. Which is a normal tune up item.

People like to think that the opti's cap and rotor is supposed to last longer than a conventional distributor.

You have to rule out certain things first. Not just jump right in to something difficult and hope it was the problem.

I would like to point out that it should have a good tune up at LEAST every 60K miles. Including O2s, plugs, wires, distributor cap and rotor, coil and of course a fuel filter and air filter if it's the OE paper type. I also suggest a can of good injector cleaner in the fuel at each oil change.

This stuff is awesome but to costly to be using at every oil change
BG 44K

Rocks7ar

Speedy,
I appreciate you pointing this out. I was thinking along the same lines, albeit in a much simpler manner(I learned what a Camshaft was two weeks ago), and I am making a list based on what you said regarding a tune up. Would you care to be more definitive and or in depth? I would appreciate your taking the time, and I appreciate the time you have already taken.

On the same note, I think my mindset was along the lines of: OMG THE ENGINE IS DEAD [edit] IT MUST BE THE ABSOLLUTE WORST POSSIBLE SCENARIO!!!!!..

-Kevin

Guest47904

About the tune up or the problem?

I'm going to assume you want more depth to the problem to which I refer to this earlier statement of yours.

First, you must must know if there are any dead cylinders. Those must be addressed first and foremost.

Then see if you still have a condition after warm up. If so, there are 2 main causes. Either you have a control problem when the engine goes into closed loop operation. Or you have an electrical item breaking down after it warms up.

Let's take a minute to say something here. Computer controlled engines are nearly impossible to diagnose without having a scanner. My recommendation is one that not only gives you DTC's. but also real time sensor data. Off my soap box now.

The quick way to determine you have a closed loop problem is unplug one of the O2s. This forces the engine to stay in open loop control. If your problem where merely from closed loop, forcing it stay in open loop should make it run as good as it did when it was cold and prove you have a closed loop problem.

It's a good idea to start searching either here or google for information regarding open and closed loop control as it pertains to engines.

If the engine runs just as poorly in open loop as it did before, then chances are it's an electrical item breaking down. These are more likely one of the ignition items and are the coil, the ICM or the optical distributor. The wiring between those items is not as likely to be an issue from warming up but should be looked at none the less.

To find electrical items that are breaking down is fairly straight forward. While the engine is dead cold (when you say it normally runs good). Start it up for just a second or so to be sure it's running good and then quickly shut it down. You don't want to get anything hot by running the engine too long. You want to control what you get hot, one device at a time. Now get a blow dryer and warm ONE item of the ignition system up with the dryer to point of just being too hot to touch. Now start up the engine and see if it runs good or bad. Good, you haven't found the item yet. Bad you did. Get it? If it runs good, don't run it long so as to not warm other items up. Understand?

If it ran good, shut it down quick and move the dryer to the next ignition item. Do the same warming procedure and start it up again. Runs good then, you still haven't found it. Runs bad now, you found it.

Don't jump to conclusions. Investigate in the order I recommend. One last note. I always use second and sometimes third methods to back up what I suspect is the problem. By that I mean, retesting in other ways to confirm what you believe is the problem. A dumb example is heating something to find out it is making it run poorly. I could then use a can of freeze spray (available at electronic shops) to cool the suspected item back down and confirm the engine runs good. Then reheat the same item and confirm it runs poorly.

Another way might be to take the suspect item to a place that can test them off the vehicle. While they test it, heat it up as you did before and see if it then fails the test. Just my way of not making mistakes or jumping to conclusions and getting the wrong part. Ultimately saving money.

Rocks7ar

I pulled a code 16. What does this mean? (low res pulse-Distributor..GOt it. ;P) I need a new opti spark?

Injuneer

Clear the code and see how soon the code comes back. If it keeps coming back, at the same time the engine is stalling, or not starting, its either the optical cam position sensor in the Opti, or the wires/connectors between the Opti and the PCM. Check for corrosion and bent pins in the harness connectors.

But DTC 16 shuts the engine down.... might not account for the misfiring, roughness. That would be more typical of problems with the high resolution pulse (also from the optical cam position sensor), but that would set DTC 36.

Rocks7ar

The car doesnt seem to die anymore.. It just idles around 4-500RPM's and is Extremely rough.


Thanks.

DirtyDaveW

Did you get it resolved?

Rocks7ar

Negative...
I had the Opti replaced.. Car is running great... for twenty minutes.. As soon as I got it off the freeway? The idle starts dropping again. Is this the IAC? Someone was listening to it run at a stop sign and randomly asked why i had pulled the timing.. I have no idea what they meant.. Perhaps thats the issue?
I also spent alot of money having the shop replace the part. Which sucked.

TL;DR Idle problem is not solved (vehicle has not died yet, idle just drops below 500). Solutions? THanks for everything so far..


I wish one of you lived in Cali so I could pay you guys to fix my car..