I am trying to diagnose a severe cut-out during WOT, around 3000 rpm, and 5-7 psi of boost in first or second. It's not as sever in the other gears.
This is for a 1997 Audi A4 TQMS. It has a TAP Stage II kit.
I get the following DTCs using a VAG-COM:
16492 Manifold Absolute Pressure/Barometric Pressure Circuit High Input.
17963 - Charge Pressure, Upper Limit Exceeded - but I think that is because of the chip.

Do I have a bad sensor? Does anybody have a list of measuring blocks so I can try to read it? Can anybody tell me where this sensor is?

Thanks,

John Baas<ul><li><a href="http://www.geocities.com/xr4tic">John's Audi site</a></li></ul>

Check your MAF meter and its wiring. The first DTC points to a bad connection at the MAF or a faulty unit.

On a car that is maladapted I have seen a string of DTC's. If you have a VAG tool Clear all DTC's and then run a Throttle ADP. Go to block 098 and then change to basic. Once you get the ADP ok status change back to normal and exit. Start the car and let it idle for a few minutes..

An ECU plug that is not fully seated may also cause DTC's that report bad sensors.

If none of this works then measure the MAF unit with a DVM. I can look up the specs in the bentley manual if you do not have it.


Clark

I have cleared all the DTCs, and ran the throttle ADP. And the problem went away for a day, and now it's back. If I clear the code, and start the car, it comes right back. I tried running the throttle ADP again, with no luck.

If you can give me the MAF specs that would be great. I had to decide between the VAG-COM and the bentley manual. The Bentley manual will have to wait until the next pay check.

Thanks.

From the Vag-Com list:

"I would start with the most obvious possible culprit first, that being the modified ECU you received from TAP."

I repeat because you never mentioned what TAP had to say. My bet is that they did not ask you to return your ECU for inspection. John, a good hunch tells me that you have a bad solder job on that chip.

IMO, you are knocking your head against a wall if you don't first check the ECU for proper operation. No criticism intended, just trying to save you some trouble. Try getting a hold of a known good ECU, or send yours back to TAP and have them resolder the chip.

I called TAP, gave them the info on the problem and my number. They never called me back. I am going to call them again after I've done some more looking.
I can't afford the downtime to send them my ECU and wait. If they are willing to send me one on an exchange basis, fine, but I don't think they'd be willing to do that if I don't have all my bases covered first.
If they ask me why, I would like to be able to tell them I've tried everything else already.
It's probably trouble either way :)
I'm going to try to mooch some info from the local dealership tomorrow morning.

Sorry to hear about trouble. When I first received my AutoThority .8 bar chip, there was a problem with the ECU. AutoThority sent me a new ECU the next day via FedEx (I bought a spare ECU).

Personally, I would ditch TAP, insist on a refund, or fight the credit card charges (you have good reason), and contact a different tuner for help. But that's just my opinion and it's not based on any personal experience with TAP, only hearsay.

Having said that, what you really want to do is get your hands on a known good ECU. I assume you had none of this trouble before you got chipped with TAP, correct? Did you try reseating the connectors to the ECU as MC mentioned?

I would put money on it that you have a bad connection or solder job. <b>Call TAP and don't hang up until they get someone on the phone who will help you.</b> Be firm and courteous and tell them that the ECU they sent you has caused numerious DTC's and a check engine light.

Maybe your dealer has a spare ECU they can let you use?

Hehe, I'll probably need it.
In regards to getting my money back, that will probably never happen. I bought the car with the TAP kit in it already. I have no idea what a stock chipped ECU would do.
How much is a new ECU? Would it be worth upgrading my 97 ECU to a 99 or newer?
For the little amount of time I talked to TAP, they were courteous and did offer some suggestions, but I had tried them already.
I am still optimistic that TAP will help me out.
It's raining out (has been all day) so I haven't checked the connections yet.

sounds like a bad maf sensor sub. with a known good one.

If you are out of warranty, spring for a new chipped ECU a la APR, GIAC or another reputable tuner. Send your ECU back to TAP, have them fix it. Then sell your TAP chipped ECU.

From AWE: A4 1.8T (97-99.5) w/ new ECU $1160 47 hp

From APR: $1179 MY97-01 chip with spare ECU

The final result means no downtime. If you can spare the cash, this wouldn't be a bad way to go.

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/maf1.gif"></center><p>This is the range table.. Read Colume 4 for MAF. It should be in the values shown.

<center><img src="http://pictureposter.audiworld.com/AudiWorldPics/2000/mafeval.gif"></center><p>I/E what to do if its not in range..

You cant check the MAF without a special adapter harness from VW. You can use your Scan tool to check range..

Hope this helps..


Clark

Well, I checked and everything is within spec. I watched the 02 sensor voltages when the problem happens, the voltage starts at 0.8, then drops to around 0.1, so it's going major lean. I checked the injector times, and they are at 16.x ms, and is the same when it is running right.
I don't understand it, if I let up just a little, it goes away. It's almost as if the fuel pressure drops, then kicks back in. Maybe the fuel pump gets shut off? Is there a way to tell?