I need some help or ideas:
The car has sat a lot outside for over a year. It hasn't started for the last 6-7 weeks (minus once), 2 weeks ago it started, I filled it up, next day it wouldn't start and hasn't since. The car cranks, but won't start. Battery replaced 5 weeks ago. Lights on are check emissions, check TPMS. Took it to a mechanic, he said the main computer won't communicate with the diagnostic machine. My friend thinks its old gas and I should put dry gas in, the mechanic thinks it could be anything up to the main computer. The original main computer was replaced around 60k, so this is the second. Any thoughts would be very helpful. When it did start, it ran with no problems and the check emissions and check tpms lights were not on.

 

The car has 79k miles on it. Main computer was replaced at around 60k.

 

If the car has really been sitting for a long time, first task is to check is all of your electrical connections. The leads at the positive and negative posts should be removed and thoroughly cleaned with battery cleaner and a stiff wire brush, especially the inner surfaces of the clamps where they touch the posts. Look for rodent damage. If all electrical components are working, check your starter. Working dash lights rules out a bad ignition switch.

 

I did change out the battery, clamps are good as well. The dash lights are all working. It's been outside in northeast ohio for over a year, I thought if I were to have a problem it would have been after our cold stretch, but the car started right up. I did start the car weekly, and ran it for about 5-10 minutes each time. Any thoughts on the gas? I did put a STP gas additive in and the car started up two days later, I thought maybe a fuel line problem, filter, old gas.... Just not sure. My simple mechanic seems lost without getting communication from the car computer and his diagnostic machine.

 

How come you had to replace your ECU so early? Was that part of the recall or were you having other issues? Have you tried resetting the TPMS light? If you have an emissions light I would think the ECU should be giving off a code for your mechanic to see, if not, my first thought would be to check your replacement ECU. If the engine sounds like its turning when you try to start it but there's no combustion it could sparks, coils, or starter. I would rule out old fuel if its only been several weeks. Also, have you done any upgrades?

 

So the car was violently moving back and forth when trying to shift from 2nd to 3rd gear, took it to the Acura dealership I bought it at, they said a sensor, paid to have that replaced, same problem when driving it home, took it right back, after 6 weeks they said it was the main cpu. Had to fight with them to get it covered. No recall, no upgrades. The problem with getting codes is the first mechanic I took it to said the ECU isn't communicating with the diagnostic machine. I have it going out to an acura-honda guy to look at today. He said well, if the ECU isn't communicating I will have to replace and then see what else is going on. So I'm a bit frustrated to say the least. My thought is what the hell, am I going to have to replace my ECU every 20k miles, so obviously the dealership may have replaced the ECU, but did not solve the problem. Yes, I definitely agree, seems like a combustion issue, but without the ECU communicating, I guess that's a big problem. I've called the dealership, they said call ACURAUSA, I called AcuraUSA, they said call the dealership. I'm pretty much fed up with Honda, this is the third I've owned, done....

 

That's really strange.. I'm not sure if your car is eligible for the recall but there was a recall on the ECU a few years ago, with people having similar problems to what you're having. It definitely sounds like that's your problem to me. Since your ECU isn't responding to anything, that should pinpoint the issue as you mentioned. Hopefully this link helps a little more too.

2006 Acura TSX Safety Recalls

 

Ok, so got off the phone with my new competent mechanic, after about 5 mins he figured out the problem. The was a block in a condensate line for the A/C defroster, the water was backing up and leaking onto the shield for the ECU and the top of the ECU was completely corroded.

 

Wow he diagnosed that over the phone? That sounds like a keeper for future mechanical issues to me. Best of luck with the ECU and TSX.

 

No, had the car towed to him, he had it for a total of 30 mins. Thank you.

 

That is almost EXACTLY what the recall was to address. The recall was NOT for the ECU itself - it was to put a shield around the ECU for potential water damage from the condensate lines and heater core above it.
If the dealership really did replace the ECU - why didn't they do the recall and put the new shield around it? If they didn't, then I suspect you have a strong case against your dealership that replaced the ECU, to replace this one free-of-charge.