2001 Tacoma Cylinder 4 Misfire

T

Timbo72

Member
I have a 2001 manual tacoma with a cylinder 4 misfire. I’ve taken my truck to 3 different mechanics and nobody can seem to tell me what’s wrong. All of the wire harness, spark plugs, fuel injectors, etc. have been replaced. One of the mechanics said it could be that something is cracked inside the cylinder? I hope I’m making sense, I’m not a big car guy.
 
Timbo72 said:
I have a 2001 manual tacoma with a cylinder 4 misfire. I’ve taken my truck to 3 different mechanics and nobody can seem to tell me what’s wrong. All of the wire harness, spark plugs, fuel injectors, etc. have been replaced. One of the mechanics said it could be that something is cracked inside the cylinder? I hope I’m making sense, I’m not a big car guy.
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Hello Mr Timbo72. I have no idea how to help solve your problem but there is a good dude on this website that goes by the call-sign "JayQQ97". He has a 97 Tacoma and is an absolute genius when it comes to technical stuff. Give him a PM and he will respond I promise ;)
 
Oh and by the way, welcome to Tacomaforums.com It's a great blog and I believe you will find all your questions answered here and express your opinions without being bashed. Have you given a name for your pickup truck yet ?
 
Couple questions.

Mileage on Truck?
Have the Coils been checked?
Crank position sensor?
Is the misfire constant or sporadic?
Are these mechanics all in the same shop?

I'd hesitate to jump to a cracked cylinder problem. If you're not losing oil or coolant, then the cylinder is likely ok. Has the engine overheated in the past?

It also sounds like the previous mechanics know how to load the parts cannon, but are a bit weak on diagnostics.

In my experience, misfires are typically related to an electrical problem.
 
Rock62 said:
Couple questions.

Mileage on Truck?
Have the Coils been checked?
Crank position sensor?
Is the misfire constant or sporadic?
Are these mechanics all in the same shop?

I'd hesitate to jump to a cracked cylinder problem. If you're not losing oil or coolant, then the cylinder is likely ok. Has the engine overheated in the past?

It also sounds like the previous mechanics know how to load the parts cannon, but are a bit weak on diagnostics.

In my experience, misfires are typically related to an electrical problem.
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Hmmm.
 
TexasBigBlue said:
Hmmm.
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Rock62 said:
Couple questions.

Mileage on Truck?
Have the Coils been checked?
Crank position sensor?
Is the misfire constant or sporadic?
Are these mechanics all in the same shop?

I'd hesitate to jump to a cracked cylinder problem. If you're not losing oil or coolant, then the cylinder is likely ok. Has the engine overheated in the past?

It also sounds like the previous mechanics know how to load the parts cannon, but are a bit weak on diagnostics.

In my experience, misfires are typically related to an electrical problem.
Click to expand...
there is 175,000 miles on the truck. One of the mechanics looked at all the wires and checked for any shortages. I know a compression test has been done. The truck has been to 3 different shops in town.
 
Timbo72 said:
there is 175,000 miles on the truck. One of the mechanics looked at all the wires and checked for any shortages. I know a compression test has been done. The truck has been to 3 different shops in town.
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Oh my. I know nothing about that stuff but I'm sure Rock62 and JayQQ97 will chime in soon.
 
is there any noticeable loss of engine coolant? whiteish smoke coming out of the exhaust tailpipe?
 
Hold on a minute or two...

First, swap coil #4 to another cylinder/sparkplug. If the misfire follows the coil, then you found the problem. If the misfire remains on #4, then the coil is no longer suspect. While you're at it, try a new sparkplug in #4.

I still think the chances are high its an electrical issue.

Is the misfire constant or sporadic? If sporadic, what are the running conditions of the engine?
What were the results of the compression test?
What plugs are in the engine? Last plug change was at mileage....?
What codes are being thrown to the OBDII port??

When troubleshooting always, always begin with the simple work to the more complex.
 
electrical issues can be some rather nasty gremlins :(

my corolla has one somewhere, the CEL never shuts off
 
Usually if it throws a code, it'll point to the issue, or at least be able to narrow it down. CEL codes were always exact on my 2001 tundra, and I used a rather cheap OBDII scan tool I picked up just for that truck.
 
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