AEM Lost Tune

[Mikey851]

So I just bought a 91 eclipse gsx with an AEM EMS. The owner claims that it lost its tune somehow. I looked the vehicle over and was very thorough. We started it up and drove up and down the block without a tune supposedly. It idles okay actually but definitely starts behaving strange when you give it gas. You can tell it's running very rich.

I know without seeing the car nobody can really say for sure but I have a few questions.

- Is it possible for an AEM to somehow lose its tune? I saw a thread that said no, but there wasn't any explanation.

- I have a guy 30 miles from the car's location that will tune it for me. Considering everything else seems OK, would you feel comfortable driving it there if you stay out of boost?

The car has some good mods and seems to be alright, but I don't have any way of inspecting it as i'm in town visiting my mom and have no tools or any place to work on/inspect it. It's got a 60mm turbo, injectors, walbro, fpr, magnus intake, speed density, forged rods and pistons etc. Just sparing every little detail about the car so it's not a long list. Opinions?

 

[yhype]

If it lost its tune once it could do it again so that a 1k$ (round about) if you need to replace it.

 

[Seamus]

An aem can't magically lose its tune. At least v1 can't. I doubt v2 can. The big thing is what else is he lieing about? People lie all the time selling used cars. Especially heavily modified used cars. If you buy it, a cheap 30 mile tow is always a posiviliry if you don't feel comfortable driving it to a tuner.

 

[Mikey851]

Yeah I'm going to install the software onto my laptop and hookup to it. If there is anything custom in there I'm going to call him out on that. The good thing is i've only put a down payment on the car so far. Also, I agree and probably will have the vehicle towed and tell the guy I'm not going to give him the rest until my shop takes a look at it.

 

[abelebd]

AEM EMS uses calibration files as tuning maps and parameter setup. It sound like if the car starts and drives it may just need tuned.

 

[Mikey851]

AEM EMS uses calibration files as tuning maps and parameter setup. It sound like if the car starts and drives it may just need tuned.

Yes this is correct. The guy swapped in a different fuel pump that has twice the flow rate without retuning. For some strange reason there is also a boost rising rate fmu/afpr on the vehicle which isn't really necessary if you have total control over injectors.

 

[Mello]

I've used a EMS v1 since 2002 & it has never lost it's tune. It's possible that the EMS has internal issue which could make this happen. If so, then other things related to the EMS tuning would probably be malfunctioning as well. Also, I'd think it may be cheaper to ask the tuner to drive to the car so he could investigate the EMS aspect and help you determine what's true with the car or not.

 

[donniekak]

Offer him a price you're comfortable with in a worst case. If he passes, look elsewhere.



It's not a good idea to own a modded car with a tuning system you have to pay someone to run down any little issue. For modded cars, if you can't fix the problems the car is going to have, don't buy them.

 

[YZFR1]

I had something similar happen once, my calibration got trashed and loaded up all default parameters. I believe it was caused by a loose ground signal while driving.

 

[Mikey851]

I ended up buying it and had it towed over to the shop. My guy looked at it and drove it and said he thinks it was a solid buy but there are some things it needs as expected. As far as AEM goes, I can troubleshoot and do minor tweaking to the tune. What caused the situation in this case is that I bought the car in Dallas but live in Lubbock, so I didn't have a laptop with me, had no place to truly inspect it and no tools.

The worst problem it has is that i'm pretty sure there's a bad exhaust valve stem seal on cylinder #1. It's burning a little oil and compression on the cylinder is about 15 psi low. Or...it could be the start of a problem that is much worse...yay. Anyways, it's been on hold for the holidays, but i'm going to do a leak down test on Monday.

Oh also as expected it grinds going into 2nd. Luckily the guy included a rebuild kit with the car that has all new synchros. He also gave me another 4g63t long block and his extra 60mm turbo that i inspected. All in all I think it was a good buy. Wish me luck haha.

Edit: just realized that the stem seal wouldnt cause the compression loss but could be a valve seat. Maybe a combo of both...who knows until I check it out.