Bad ECU? Ok guys please help me

[AshevilleS4]

2001 S4 6 speed. 104,000 miles.

Ok here are the codes. Hard codes. Unable to clear

16490-Manifold Abs. Pressure or Bar. Pressure Range Performace
17795-Control Module Defective

Car idles and drives great. BUT it lost its Performace. Feels like it's in limp mode. No or very low boost. One foreign mechanic specialist said bad turbo. Another said maybe bad ECU. Has anyone experienced this? Suggestions please. I've spent hundreds trying to figure this out.

Joe

[jimmer009]

I would worry about the 17795 code first. Is it a stock ecu??? Do you have nefmoto???? Are you comfortable using it??? If you have a chipped ecu it could bad. Or it could be just a low battery. Have you tried fixing this on your own???

On 16490 it sounds like your map sensor is bad. Unless your pushing more psi than the map sensor can read. If you have vcds look up what block it is and you tell if it's good or bad from there

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And FYI 16490 is probably putting you in limp mode

[AshevilleS4]

First off, thank you so much for responding. Ok so when I bought the car in December it was chipped. Revo makes the software that my car has. It ran INCREDIBLY strong since then until the check engine light came on. As far as working on it, I changed the MAF sensor out myself. Replaced it with a Hitachi OEM unit. I also replaced the coolant temperature sensor. Had the timing belt done in March of this year. I have no idea what a nefmoto is. Also, what is VCDS? Sorry for the questions. I sure have a lot to learn.

[jimmer009]

O yes you have a lot learning ahead of you. Our cars are smart and limp mode is just a way if it protecting its self. So the maf sensor you took out was it a Hitachi??? I'm not sure of the year I think it's 01.5 and newer b5 s4's used the Hitachi maf sensor and older than that used the Bosch. You can only inter change them if want to properly tune for it(nefmoto software & nefmoto.com it's a crazy thing and a very steep learning curve)

Good to hear on the timing belt. Gotta do up keep first. Vcds is simply software that works via a odb2 to USB cable. It allows you monitor pretty much everything in your car. You have a ton of reading ahead of you lol. I bought the ross-tech cable it was expensive but worth every penny. Ross-tech.com is worth at look also.

But when you start your posts the biggest thing is info on your car and the setup of your car. The more the people on here know about your the problem the better. And if you search I'm sure someone has had and fixed this problem before.

With the info I got now I think you need to find out what maf sensor your tune calls for. revo should know. Or figure out what you had before you changed it. And also tell them the codes you are getting. Good luck I hope you figure it out

[AshevilleS4]

The Maf removed was a Hitachi. This is why I replaced it with the same part. You are correct about the 2001.5. I'm gonna search the forums and see what I can find. Could you recommend where to get a new ECU and MAP sensor ? Thank you for your help.

[phila_dot]

Don't buy a new MAP.

Barometric pressure sensor is onboard the ECU.

[88ninety9]

The Maf removed was a Hitachi. This is why I replaced it with the same part. You are correct about the 2001.5. I'm gonna search the forums and see what I can find. Could you recommend where to get a new ECU and MAP sensor ? Thank you for your help.

You can pick up ecu's in the classifieds quite regularly. Also, fortitude has a decent classifieds section as well. Gl!