Engine issue

[patinthehat]

Howdy all. Long time lurker. Dont post much. But figured I would today. I have a 98 Limited with a gen 1 supercharger. Driving in to work this morning, cyl 4 started misfiring. After changing plugs, coil, wires, etc. it is still misfiring. We ran a compression test and all the other cylinders read about 105 and cyl 4 read 160. So I am thinking valve problem. I asked the shop ballpark what I'd be looking at cost wise, and they said it would be upwards of $2k-$3k depending on how bad it is. My question is, would it be cheaper/better in the long run just to find another motor to swap in? Or anyone else been in this situation have some other ideas that I haven't thought of?

 

[kball]

So... cyl 4 was misfiring and it also was the only one with a good compression test result? Did you get those numbers reversed? Not making sense.

 

[patinthehat]

No that isn't backwards. Cyl 1-3, 5, 6 all read around 105-110. Cyl 4 read 160-165. And cyl 4 is the one misfiring. I watched it on the computer readout screen. That's why I wanted to run it by smarter folks than myself. I immediately think valve issues but in the past on other vehicles, valve issues tend to make the compression run lower than the average, not higher. However, my background has been with NA motors not forced induction like the supercharger. So i figured somebody here may have run across this before and have some insight. To me, compression across the board seems kinda low, hence the reason me asking about a possible motor swap. Motor has 212k+ on it. And going through the Toyota Maintenance history, right around 112k miles it did have a burnt valve problem. Cant remember what cylinder and their website is messing up right now and won't give me that info. Pretty sure it was #6 that had the original issues. Just trying to gather as much knowledge before the shop gets my 4 runner on wednesday.

 

[Diezel]

With a single cylinder That far off from the others. I'm likely to agree you have a valve issue. Time to pop the valve cover and inspect.