check engine light, P0301 Cylinder Misfire code

I apologize in advance how long this post will be but I felt it was important info:
I bought my 2008 Prius 9-14 with 29,000 miles on it. (rebuilt title-big mistake I now know). I found out after I bought it that it had sat for 5 years before it was rebuilt) I figured it was a miracle the hybrid battery even worked.
I had no problems until 2-4-15 when check engine light was flashing and the car was shaking. The local mechanic said was the “clutch” (torque converter), took the engine and transmission out of the car to fix it ($2200). But he realized the mass air flow sensor (MAP) was not working even after he put a new one in so had me take the car to the Toyota dealer. The dealer found a cut in the engine harness and advised me to replace the harness which he said would cost $2800. The local mechanic saw the cut via my cell phone photo and offered to fix it for free which he did.

The next day check engine light comes on after driven 25 miles with code PO 301. (means misfires in cylinder one). The local mechanic switches cylinder 1 with 4, same code the next day, local mechanic switches the coils to the cylinders, still the next day the same code. He switched the fuel injectors. Same problem of cylinder 1 misfire. He cleaned the oil out of the intake manifold, did fuel injection cleaning, and cleaned gunk out of the fuel line. Car would drive good about 20 miles then same check engine light, same code, sometimes code PO300 (random multiple misfires).

I take the car to a mechanic reputed for repairing hybrids (Curt’s Service, Oak Park, MI). He tests the car for several hours. He notes the problem starts at the beginning of drives then goes away but is intermittent. He spends 45 min explaining the problem could be in the wiring harness (cost $300 to check), could be in the computer control unit (cost $1400 to replace) or could need engine repair.( cost $3300) (local mechanic does not think engine is the problem due to good compression).

Curt tells me to drive the car many miles to make sure it was more than just a stuck valve. I drive the car 120 miles with no problem. Then it drives rough just backing out of my driveway, I drive a few miles on expressway with engine losing power and sounding louder and louder, I see the hybrid battery charge goes to bottom line violet colored. I drive car off expressway, it drives rough, almost stalling at the stoplight, hybrid battery does not charge. Then about 15 min later the hybrid battery starts charging, the car rides smooth again and I drive home. I drive 300 more miles without a problem.

I am caught in heavy rain for 15 minutes and the check engine light comes on, the master light in red comes on and the vsc light comes on plus the hybid battery charge is down to almost nothing again, this time with a red warning light on the charging battery display. This is 2 blocks from my house. Shaken, I drive home. 2 hours later I drive slowly near my house in a circle. I get the vsc light to turn off first and the hybrid battery starts charging again. I stop the car, open and close the trunk, and the master warning light turns off. The next day the car drives good and the check engine light goes off. 4 days later I am driving up a parking structure 5 floors. The hybrid battery charges goes really low. It charges up again soon after on the 60 mile drive home.

Tonight, 250 miles after the last problem in the rain storm, the car drives rough the first 20-25 minutes, the hybrid battery goes to the bottom violet line, then after this the car hybrid battery charges back to normal and the drive home is smooth. The local mechanic and hybrid specialist mechanic do not want me to put more money into the car since they don’t know what the problem is and advise me to sell the car even if I only can get a few thousand for it. I put a total of $14,000 into buying and repairing the car, and I always wanted a Prius after owning 2 honda hybrids so I am hesitant to do this.

If anyone can give a good guess what is the car’s problem I would like to know. I am guessing the hybrid battery is starting to fail but I am no expert on cars. I have photos of the problems described if that would help.
Suzazoom

 

I guess I was trying to make a long post shorter without the breaks but you are right it needed the breaks so I put them in. thanks for the feedback. suzazoom

 

Thank you very very much Mr Wong. The spark plugs were switched. I was thinking of buying my own mini VCI and I will do so at your advice. I will never ever ever consider buying a rebuilt car again. I will ask my local mechanic details about how he repaired the harness wire to see if he did it correctly. We could not figure out what caused the cut. He said it would have had to be cut by something sharp. The dealer said my local mechanic did it when he replaced the torque converter and the local mechanic admitted they made have made it worse when they took the engine/tranmisssion out and he can't believe he did not see it himself when they took the engine/transmission out. I did not get a good look at it due to the placement of it but it looked to me like there was a little rust in it so I wondered if it had caused the torque converter to go bad in the first place. . I will check the engine harness myself for more cuts, upload photos of the cut and location, and have the hybrid specialist check the engine harness for the $300. Suzazoom

 

yes my finger was pointing towards the location of the damaged wiring. it was turned so that you could not see it from the top of the car. Thanks for the information. I have the car scheduled on 4-16-15 to have the engine harness looked at in the way Patrick wong detailed by what was told to me is a hybrid specialist.

 

The hybrid specialist mechanic worked on my car 3 and half hours yesterday but could not find the cause of the previously described intermittent cylinder misfires. He ran a simitech sweep test on ecm and engine harness, inspected all power and ground connections, signal return to all electrical components in fuel and ignition, emission system, run voltage drops and wave patterns, pulled fuel injectors. Found code PO300 (random misfire), PO301 (cylinder 1 misfire),PO303 clylinder 3 misfire) PO304 (cylinder 4 misfire), P3190 ( Poor engine Power). He pinned out ignition coils and power grounds. He did find a fuel supply line fitting that was sweating fuel so he repositioned the O ring for the connector.

 

I had NO IDEA the nightmare buying a rebuilt car would cause me!!!!!!!. I had one in the past that worked fine. I am a social worker who has worked with the poor 32 years and not making that much money myself and after being in a car accident with car insurance rates more then doubled I was just trying to buy something affordable. It is the worst financial mistake I have made in my life. I have looked at sale ads for honda civics and prius in my area at cars.com , craigs list and detroit auto trader for many hours this last month. I already have the seller you mentioned in the post above on my list to visit later today.

 

I bought unlimited car fax reports and vowed to take what ever car I want to buy to a trusted mechanic first. I will contact steve. It is good to know someone on prius.com who believes he can be trusted. My car was not even rebuilt that well on the outside so I doubt he may want to buy it. thanks for your imput, exstudent.

 

thanks for posting this thread that tells about the other woman who had a similar experience with buying a Prius.

I will call Steve to see what he says. My car does not have to be towed as a car works very well about 97% of the time. It only gives me a rough ride every 122 to 300 miles and then only for 6 to 20 minutes. I have figured out that when the car drives rough, which I think is due to only being able to use 3 out of the 4 cylinders, if I stay on surface streets driving 35 mph the problem goes away in 6 minutes where as if I drive on the express way the hybrid battery charge goes down all the way and I have to get off the expressway so the problem will go away. The only other time I had a problem was very driving in very heavy rain for 15 minutes and the car may have skidded on the several inches of water in the road.

I drove the car 167 miles today with no problems, averaging 47.4 mpg. I might just keep it and use it for drives to work (5 miles) or nearby and buy a older honda civic for long drives. The mechanic who worked on it said he felt it was safe to drive the 4 hour drive to my sister's house.

I do wonder if the repair to the engine harness was done correctly. My local mechanic said he knows a mechanic 5 miles from me who specializes in electrical repairs and although I don't want to waste more money on the car I might ask him to check out the repair. I also don't know how much of a hybrid specialist mechanic the one I had work on the car a total of 7 hours, would know enough to inspect he engine harness. He told me the wiring my test well while sitting there but not be able to perform under "a load" (driving) and that makes sense to me. . As Mr Wong said, the intermittent electrical problems are very hard to diagnose.

 

I just looked up the website autobeyours and found that it is only 6 hours 20 minutes from where I live. If he could fix my car for under $1000 It would be worth it to me to drive there. I will write or call him soon. I won't get my hopes up but it is worth a try.

 

you are right that the car has parts from different years. One door on my 2008 toyota prius has a 2006 vin number, the manual is a 2006 manual.The mechanic and his partner did say the engine, exhaust system and transmission looked low miles. as for the rest well...