Engine Missfire.....

35thSC2

Registered User
I got a problem, the engine in my 35th anny. has started missing. It isn't random missing either. When im driving along it feels like its only running on 3 cylinders and the car jerks when it kicks back in again. Im gettin no indications light wise and it doesn't stay missing. It only happens about 5-10% of the time and its the same every time. Its either missing bad or its not missing at all. No rough idle unless its missing. Just curious to know if anybody KNOWS whats wrong before I start replacing items. I already have a crank sensor and cam sensor that I havent changed yet. Thanks
 
I forgot to mention that I already replaced the DIS as well. Im thinking that I should just go ahead and replace the sensors and the harmonic balancer while i have it apart to avoid doubling maintenance.
 
Any fault codes?

If the cause is sensor related there will probably be some stored fault codes in the EEC. This isn't always the case, but it's a good place to start. When you replaced the DIS, did you also apply a thin coating of heat-sink compound (available at radio shack)? You could possible have an issue with the DIS overheating. Other possibilities are bad plug wires, a vacuum leak (that doesn't show up until the engine heats up), broken balancer bolt that is allowing the balancer to "walk" away from the crank sensor while driving, etc. It doesn't take much for these cars to run like junk, but generally it is a fairly simple fix. The hard part is isolating the cause.
Invest is a cheap code reader if you don't have one. It will be the best twenty-something bucks you ever spent on tools...
 
Like previously stated I would look to make sure that the bolt that holds the HB on the crank has not broke frist then make sure you have plenty of heat-sink compound on the DIS otherwise it will overheat once the motor begins to warm up. If all else fails then a basic spark plug and wire change could be in need.

Shane
 
The car doesnt seem to be temperature sensitive. The missing is very brief, and it is either missing on half the cylinders or it isnt. I would tend to think if it was the DIS module, the missing would be sperratic and not sequential. This car has 193,000 miles on it, im just thinking it needs to be redone completely. The missing and head gaskets is the only thing wrong with it and head gasket damage is extremely minor. Ive replaced plugs and wires 5,000 miles ago or so and haven't had any problems until recently. Now i havent thought of dropping codes. Where can I get my hands on a code reader???
 
RE-Miss

You can get a code reader at any auto parts place Auto Zone checks your codes for free If you dont want to buy one. Thats where I would start and go from there.Always check codes frist thats why tech. do it so you don't start replacing everything Best of luck!!
 
badtoyz said:
You can get a code reader at any auto parts place Auto Zone checks your codes for free If you dont want to buy one. Thats where I would start and go from there.Always check codes frist thats why tech. do it so you don't start replacing everything Best of luck!!

Some Autozones may not be able to scan your ECU for codes. Some local Autozones around me will only do OBDII. Good luck with your car man!

Shane
 
If there are times where the problem "just goes away". (and after checking to see if the HB bolt head is still there). I would first try to tighten up the bolt holding the crank sensor. If you get any movement at all from the bolt, I would reset the clearance on the old one and try it. If you just replace it, look and see if there are "scuff" marks on either side of the plastic channel. If there are, your sensor and HB sensor vanes were touching every now and then.

To adjust the clearance, u can use a match book cover BUT put it on both sides. (if one side, tightening with cause an ever so small movement of the sensor). This seems to guarantee that there will be some clearance on both sides. BUT before starting, maunally turn the crank to make sure nothing touches.

I had to join the SCCOA (thanks guys) to eventually get mine fixed. It went on for years (and finally bought my 2nd SC because it was leaving me on the curb) before I learned what it might be. From the posts, it usually self destructs when it goes taking the sensor and sometimes the harness with it. I guess I was one of the "lucky" ones where it just got intermittently worst. I guess touch, not touch, touch. Replacing the crank sensor (and adjusting it 3 times (finally on both sides)) fixed mine right up.

Hope this helps
--Fred
 
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