Hello. Have a 1995 Toyota Tacoma 4WD with around 230K miles. Recently, it has been ‘skipping’. When we are driving or idling, it’s like the engine sputters out and jerks along but it never stalls and always starts. Had it to dealer and another mechanic - plugged it in said it was catalytic converter and 02 sensor. We changed those, along with: plugs, wires, air filter, oil. That did not fix it. Have no idea what this could be. If anyone has any suggestions on where else to start to look for this vehicle. It’s been the greatest little truck. Thanks
The skipping sounds like misfires. You need fuel, spark, and compression to get a cylinder to fire. You seem to have spark, that leaves fuel and compression.
Can you isolate one or two cylinders that are misfiring? Sometimes evidence will be a wet spark plug for instance. You can also disconnect each fuel injector to see if it changes the missing. If it get worse that injector and cylinder are OK, check another one by one and see if you can locate the problem cylinder(s). You can do the same by disconnecting each cylinder’s coil or plug wire.
With those miles you really might have a compression issue, just an old tired motor or perhaps burned valves. A compression check of each cylinder is in order. If a couple are low, you might need to pull the head(s) and do a valve job. After that you’d need to replace the rings to restore compression.
Those symptoms are common for a failing ignition coil(s). Have you tried a new set of coils (your Tacoma has coil-on-plugs, so you would need a new set) ?
We did put new cap, rotor and coil in as well because we thought that was it, too. Uncle Turbo - we will definitely try to isolate the cylinders tonight and see if that works. We hadn’t thought of doing something like that.
You might edit your title for the correct year (1995?). Hover over and click on the “gear.”
Ha - good call. I didn’t even notice.
My car is a early 90’s Corolla 4afe engine. Your truck I think is a different engine, but probably very similar design to the 4afe. You have an ignition module and single coil inside the distributor, right? But other than the electronic ignition system, is a conventional distributor.
hmm … are there any diagnostic codes stored in the engine computer memory? I presume there was something, otherwise your shop wouldn’t have replaced the O2 sensor and the cat. I’m guessing it was probably a code for lean or rich operation.
Ok, I’m a driveway diy’er, and here’s what I’d do in that situation if my Corolla acted up like that
- read out codes
- hook a lab o’scope up to the coil primary side and see if anything unusual on that signal
- new spark plugs, distributor cap, ignition rotor, and spark plug wires
- new fuel filter
- new engine air filter
- check idle rpm, and ignition and valve timing
- measure rail fuel pressure, not just at idle, but when this symptom happens
- test map or maf sensor, whichever you have
- if you didn’t use a denso oem o2 sensor for the replacement, re-do that with the oem version
- check valve clearances
- check compression
What engine, the I-4 or the V-6?
IMHO George has listed an excellent process for where you’re at right now.
I’d start from the bottom and work upwards, however. A compression check and check of the valve clearances could yield a great deal of valuable elimination… or eliminate a lot of possible suspects. Although I have to admit that it sounds an awful lot like erratic ignition or fuel supply.
By the way, while you’re checking the ignition system, check the distributor shaft for lateral or axial play. I’ve had a distributor-based system with that problem, and I could have saved a lot of work if I’d checked up-front for worn distributor shaft bearings.
gas filter looks like it was missed. Compression test and or valve adjustment might be a start, so many possibilities