I have been following the chat for a while. It is really informative. I got really good advice and tips about my 3rd generation Prius maintenance. I have a question about identifying a faulty fuel injector. I have an error code indicating Cylinder #3 misfire (Techstream). Am I right to think that this means 3rd in the firing order so I should check the 4th cylinder fuel injector? (1342) Thank you in advance.
Not that the fuel inject could be the problem but I doubt it. More likely a carbon clogged EGR circuit is more a common symptom of engine misfire. If you car is getting up in mileage (100,000 or more), the EGR circuit probably needs a thourgh cleaning. Do a search of this topic and you’ll find a lot about the EGR system and related diagnostics.
No, it is the third cylinder from the front of the engine. What makes you think it is an injector rather than a plug, coil pack, or other more likely cause?
And the "front" of the engine is (as you stand in front of the engine bay), on the left end. So it's 1 through 4, left-to-right. The front of the engine is the end not connected to the transmission. Put numbers on all the coils and swap them round, maybe do the same swap with the plugs, and see if the misfire moves? If not, then maybe the head gasket? Losing any coolant? If not, try a leak-down test? How many miles, and has the EGR circuite and/or intake manifold been cleaned?
Thanks for the advice. Unfortunately, I went through that cleaning process already. I cleaned the EGR and the manifold. I also changed the EGR cooler. According to the Techstream the EGR flow is good. I guess the next step is the injector.
The cooling system is fine, no sign the level of the liquid going down. The problem occurs when the engine warm, add on low RPM. When I use 98 petrol much better.
That's a higher-than-regular octane at your gas stations? Maybe just pre-ignition then, due to carbon build-up. Still, how many miles (or kms) on it, and have you ever inspected the EGR system. Watch @NutzAboutBolts video on EGR pipe check, pinnned at top of 3rd gen maintenance section. A clogging EGR will cause the engine to run hotter, which in turn can cause all sorts of mayhem.
I could be wrong here but this also could be a failing head gasket.. This is very similar to the issue I just had worked on where #1 had a misfire. I assumed coil pack or plug but when diagnosed, the head gasket was failing in between #1 and #2 causing a misfire in #1. Coolant going into #1. In my case, in seemed the previous owner never cleaned the EGR circuit so this could be something as easy as a coil pack. Keep in mind, my coolant level wasn't a noticeable loss with this slight symptom but it was enough to cause the misfire.
My goto misfire procedure is exactly what @Mendel Leisk suggested since each plug gets its own coil. First swap the ignition coil from #3 to #4 (since they are actually opposite piston heights) and clear the codes. If the misfire moves to #4, it's the coil. If it stays on #3, pull the plug and inspect. I would also stick a camera down into the chamber to look at the piston head just to see if there is any signs of coolant (just to be safe). If all that looks good, replace the spark plug. If there are signs of coolant, take care of the head gasket now before possibly destroying the lower end. Just for fun, in vehicles with a coil pack, my procedure is: replace plug, replace wires, replace pack (least expensive to most expensive) in that order.
