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Fixitman
Fixitman, Master Technician
Category: Toyota
Satisfied Customers: 17142
Experience:  ASE Master Certified, AA Degree Auto/Diesel Tech
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I have a 2000 Tacoma with the 2.4l engine, manual tranny. I

Customer Question

I have a 2000 Tacoma with the 2.4l engine, manual tranny. I have been battling a check engine light for some time, with P300 codes for engine misfire. My biggest problem is that when I start the truck in the morning, it idles really rough and I can't even rev the engine or move the vehicle...it's like something is not allowing fuel or air delivery. If I start the truck in the afternoon when it is warm, I have no issues and can drive all over. I recently replaced my mass air flow Senser, O2 sensor (before the Cat) and PCV valve. My dealership says I need a valve job, but this seems more electronic or Senser-related, to me.
JA: Does the light stay on, or does it blink?
Customer: Stays on. I may have to drive it a week or more before the light comes back on.
JA: Are you fixing your Tacoma yourself? What have you tried so far?
Customer: Mostly fixing myself, as my original code noted leading oxygen Senser. Truck ran really rough after that and my P300 misfire codes started. Took it to a dealer and got fleeced out of $1500, for a supposed high mileage tune up. (Has 240k miles on it).
JA: Anything else you want the mechanic to know before I connect you?
Customer: Don't think so
Submitted: 2 months ago.
Category: Toyota
Expert:  Fixitman replied 2 months ago.

Hello, my name is***** sounds like you do need a valve job. What the dealer is not telling you is that there is a common issue. It is very common for one or more valve to not fully seal on its seat until the engine warms up allowing expansion to seal it. It is easy to diagnose by doing a cold compression test. This is not a cheap job either but it is what is needed. If you have further questions please let me know.

Customer: replied 2 months ago.
Hi Bobby, I have not yet performed a cold compression test to rule in or out the valve possibility. I know I had similar performance issues at 120K miles, and lashed the valves at that time. Now, at 240K miles it may be needed yet again, if possible. However, I have a hard time believing it is a valve issue, in that the only time I have performance problems is on cold mornings. If I start the truck in the afternoon, no problems. Might it be my EGR solenoid or valve? If you think that may be a troubleshooting possibility, can you help me locate it? I'm having a heck of a time finding a diagram online.
Customer: replied 2 months ago.
Oh, and to note that I let the truck run rough on a cold morning for 25 mins...long enough to warm the engine to normal for about 5 mins or so, with no improvement on performance.
Expert:  Fixitman replied 2 months ago.

Most of the time the valve seat leak is so small once the engine is warm and you start driving it seals. I would start with the cold compression test. It can also be the other parts you mentioned but that is not nearly as common.

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