Looking for car mechanic opinions. Title says it all. when the car sits for a couple of days I’ll get a distinct engine miss soon after starting. It’s not causing any problems but with 125K miles I’d like to get ahead of any problems. The car runs fine otherwise. Should I invest in a computer reader or are sporadic misses not going to show up?
What engine parts are at the end of their duty cycle for this car? It’s been a peach so far and I’d like to keep it that way. I’ve changed out the plugs, PVC valve, changed out all the fluids.
A scan tool (mine cost $3000) will have a misfire counter that tells which cylinder is missing. I highly doubt that a code reader ($100-200) will access that info.
Ignition coil packs are a common cause of that sort of symptom, as are ignition modules. But there are other possibilities, including but not limited to a sticky valve, an intake manifold gasket vacuum leak, and carbon deposits in the intake. In the absence of testing, I’d suggest start with a bottle of Techron fuel additive - it’s a cheap thing to try and it could work if it’s a carbon deposit problem.
At that age and mileage, plug wire problems are common. While they don’t usually act up in the way described, I wouldn’t say it’s impossible. I think it would be wise to replace them as preventive maintenance. If you’re inclined to do that, may as well do it before spending time and money pursuing other possible causes.
Thanks, Techron is going on the shopping list and I’ll check for vacuum leaks. I don’t suppose the ignition modules/coils are a cheap swap like the old Ford TFIC modules? I use to carry a spare just in case back in the day. I miss being able to fix my car in 5 minutes.
Nope. The module is likely to run around 150, the coil packs (there are two) about 50 each at a parts store. Makes “testing by parts replacement” a bit pricey.
Nope. My $200 tool (similar to this) will do so. And did, when one of my injectors failed. It reads pending codes (like you get for intermittent failures) as well as ones that persist long enough to light the check engine light, and also tells you things like the ignition timing, fuel trim, intake and coolant temperatures, oxygen sensor readings etc. in real time.
I only got the free AutoZone check once, before I got my tool, but IIRC their printout shows the pending codes as well, but not all the sensor readings.
Oh, and the codes for misfire are different for each cylinder, so even the cheapest code reader will tell you which cylinder is misfiring, if it does so often enough to light the check engine light. I suppose it’s possible that the very cheapest ones won’t read the pending codes.
Yes, I expect any code reader will read misfire codes. However, Magiver did not mention seeing the Check Engine light, and probably doesn’t have any codes to read. The misfire counter feature I mentioned is separate from any codes, and will give an actual count of the number of misfires on each cylinder even if the misfires don’t reach the threshold to set a code. That’s the function I don’t believe the code readers have.
I have a '97 Saturn. Started having misses on the engine, especially accelerating. Engine Light kicked on for a couple of hours, before going out. I figured the engine was burning too rich a mixture, but couldn’t diagnose the problem. One night, on a hunch, I opened the hood and started up the engine and manipulated the throttle fast and slow. I noted a corona was arcing from the ignition coil up the 1st cylinder spark plug wire. The higher the revs, the longer the corona. I bought a new set of plug wires (Fram?) and the problem went away never to return–that was at 180,000 miles and I now got about 265,000.
Eats a quart of oil every 600 miles though (since mile 50,000); probably worn out valve stem seals.
I was thinking about doing a night time check with a mister to see if anything arced. Mine has always consumed oil but the stem seals are in good shape. I only replaced the plugs because I didn’t want them to weld to the aluminum head. They were in decent shape for 90K miles. I’m still using the original plug wires and that may be the problem. I had trouble getting one of them off when I changed plugs.
I’m just going to drop this in and let someone correct me if this was a unique experience. If you replace the wires, replace the plugs at the same time. I had a plug wire problem on once of my old cars…I replaced the plug, and the wire somehow bunged up the new plug. I then replaced the wire, but the old, corrupted plug pulled a doozy on the new wire, so I ended up replacing each part twice. It was very strange, but resistance and voltage through the fouled wire were different from all other wires (which matched each other), and once I replaced both, things were normal.
I would be willing to bet that the plug wires are the problem, especially if they cross over the top of the engine. I’m not familiar with the SL1 engine, I’m a LS1 guy myself.