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Issues after having motor replaced

A year ago I blew motor in 2009 toyota venza, replaced with used motor with low miles. Dont think this is motor issue, however. Since getting it back all kinds of weird problems, at first not all windows would work with drivers control and flashing green lights on the door panels. This went away and they work fine. Problem is warning lights come on randomly, trac control, abs, check engine. Codes cleared several times( po353,c1201,c1280). Sometimes it’s good for a few weeks, then ding…they come on and car starts running rough and at higher speeds feels like transmission slips. The most concerning thing is about a month ago the brake light came on ,and my brakes went out. I turned off car and when I restarted it the light was off and this never happened again? I suspect this is some type of electrical issue with the ecm/ pcm but how do you tell your mechanic all this without sounding like a paranoid schizophrenic? Any thoughts?

Yeah, I think it is highly likely a ground wire or 2 got left off when the motor got changed. Explain EVERYthing to your mechanic you did to us. You won’t sound paranoid, you will be giving the mechanic good, solid information to help him find the problem!

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If I was in your situation, the first thing I would do is to have the alternator output tested. Modern electronic devices do not take well to variations in voltage output–as can happen with a failing alternator–and the result can be some fairly bizarre–and transitory–electrical problems.

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I feel you pain. I once had a rebuilt engine put into an old Mercury Marquis that had overheated while my mother was driving it, and it ended up being a giant headache over the next couple years because of everything else that was wrong with the car, but I had to keep driving it to justify the cost of the rebuilt engine.

Electrical issues can be particularly difficult to diagnose, so finding a good mechanic who specializes in electrical problems should be your first priority.

Tangentially related to this post, this kind of problem is something people should think about when they consider replacing an engine in a car that is more than 6 years old. How often are the non-engine related headaches you’re going face going to be worth it?

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Well I have explained all this but I’m looked at like a crazy female! When I told him about the brake issue he said there would have to be a leak in master cylinder or air got into brake line. I’m no genius but brake issues dont go away magically like this This has to be some type of malfunction in the sensor or computer I would guess…

The brake problem does not come from an electrical fault, but the others certainly could. First things first: is the battery good and its connections clean and secure?

By “brakes went out” what happened when you pressed the brake pedal? If it sunk to the floor with no braking action and you were on dry pavement, that suggests an internal leak in the master cylinder. That does not heal itself and can recur.

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P0353 is a coil failure on cylinder # 3, the other two faults are from the ABS module stating that there is a fault in the engine control module. Have that coil replaced, it is a common failure on these engines.

I don’t know if you are a genius or not, but it sounds like you are smarter than your mechanic.

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I’ve had 2 coils replaced already, although why the right one wasn’t replaced I dont know? I am aware what the codes mean, my question is when the codes are cleared, the warning lights sometimes stay off for weeks, even a month sometimes, then they all come on at once. A coil would not intermittently fail? Could it be the wiring that the coils are connected to?

Yes battery and connections are good. As far as brakes, it was dry out, normal driving . I hear a warning alarm and see on dash the brake! light comes on , and brake pedal goes to floor. I had to go into turn lane and up a hill to stop. I had another adult with me who was my backup when I told the mechanic. This was several months ago and never happened again?

The motor itself is great, no issues at all. I had no choice but to replace it as I still have to pay on the car for 3 more years. It’s the bs that was overlooked or done in a hurry that is causing my problems.

Ok will try that too.cant hurt at this point.

That may be normal. Once cleared, it takes a certain sequence of events and sensor readings (drive cycles) as you drive to cause the code to be posted again. For example for a code to re-appear you may need to drive at a certain speed for 5 miles, followed by another speed for 5 miles, and the fuel tank must be between 1/4 and 3/4 full for the entire time.

The problems you are reporting make me think there’s an ECM-configuration problem. That’s the engine computer circuit board. There’s a match required between the engine and the ECM and the ECM software. When the car comes off the ass’y line all those parts are new, so they match. The matching involves what state the emission system is designed for, auto vs manual transmission, options, etc. But when the engine is replaced the required matching between all three afore-mentioned components may no longer be matching. When the engine was replaced, was the computer from the replacement car installed into your car? Or do you still have the original computer? If you have the original computer, ask your shop if it would make sense to try installing the computer from the donor car instead. As you might imagine this configuration matching can prove to be complicated. Mechanics who install replacement engines must have a way to figure it out, but it may require some expertise that your particular mechanic doesn’t have. So one option is to find a mechanic who specializes in replacement engine configuration problems for consulting. There must be folks who provide that service somewhere. A dealership’s expertise may be required to get to the bottom of this.

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I would do a good visual inspection of the coil wiring

Is it properly plugged in . . . do you hear a click when you plug it in?

Carefully flex the wiring . . . anything seem frayed or broken?

Any damaged terminals?

Thanks! I will add that to the list of things the mechanic needs to check!

I’m hoping to avoid the dealer, as you can well imagine. I thought the ecm resets itself after disconnection from battery and will relearn driving habits?

Yes that’s true for many newer vehicles. How long it takes to fully re-learn varies however.