yodasfro

Yikes might see if you can return that you could of used one from a 12v V6 audi for much less money Bosch 0280120431. Fuel pumps don't usually fail intermittently. Only way to know what it is doing pressure wise is to hook up a gauge.

Nuttynotty

Hi, Wow what a different in price. I'm now thinking it could be the pressure regulator, as the regulator uses the vacuum from the inlet manifold to regulate the flow of fuel, so when the car is idling the regulator return most of the fuel back to the tank, but when you put your foot down the vacuum increases and closes the regulator down so the engine gets more fuel, So I’m thinking if the regulator is not working correctly……… yer I’m clutching at straws I have no frigging idea what’s going on.

I checked so many times for vacuum leaks I can do this with my eyes shut…. Starting also to look at the PCM as the calculation for MPG left in the gas tank is always over 1000 mile to next fill up even when you are on the red….

Does anyone know how to tell if the PCM has been chipped ????? as the car is stock. Don’t know what the PO did to the engine….

yodasfro

You can check the FPR with a mityvac if it holds vacuum it's likely fine.
If fuel is pours out of the vac fitting on the FPR it's bad. Mileage calculation being off may be a problem in the cluster IE bad solder joints. The fuel calculations can be adjusted however the trip computers don't tend to be horribly accurate to begin with. If the ECU was chipped it won't throw off the trip computer. I'm beginning to think your problem is electrical/wiring related. Should you want to check to see if it's been chipped this may help http://www.quattro123.com/AudiECUupgrade.htm plenty other good tutorials on that site too. One last thing how old is your 02 sensor? Somewhere in here is how-to on the fuel calculations http://web.archive.org/web/200608100...%20Guage%20Fix

Nuttynotty

Hi Sir,

You may be on to something with wiring or bad GND at the ECM, I ran her yesterday for around a hour and noticed that she is horrible around town when she is running hot i.e. past the half way mark on the temp gauge, stop and go traffic, but when on the open road and the temperature starts to drop to the first bar on the temp gauge she starts to run better. when in town she tries to cut out as if no fuel when slowing down for lights, pulling away in town, little splutter and again no power even if you slip the clutch to try and bring up the RPM but again hit 2k and she runs better in town not perfect just better, once out of town and on the open road the temperature drops and she start to run a lot better still no power when pulling away but you can slip the clutch and bring the RPM up a lot quicker than you can when she is hot. I ran her in the garage last night till the fan starts to kick in, then I used the oscilloscope to check the sensors voltage and signals out, all looked good even the reference voltage was good? I have no way to easily check the fuel pressure, so I have ordered a new FPR with a gauge from 034 along with a new Fuel Pump. both are still stock from the factory and with 181K on the engine I thought its probably a good time to change them out anyway.
The O2 Sensor is new, was replaced when the problem was intermittent. alone with the multi temp sensor, fuel filter and all the normal stuff, i.e. plugs Dizzy cap rotor, wires.

I do remember reading somewhere about issues with injectors getting hot, can’t remember if it was with the 3B engine or not ?

Nuttynotty

Status update on the QT200 with Idle issues ( high idle and no power between 1 and 2K)
To date have replaced, O2 sensor, Throttle position sensor, Idle stabilization valve, all temperature sensor and multi temp sensor, Plugs , fuel regulation valve, fuel pump, injectors ( all 5).
Have checked for vacuumed leaks by pressurizing the intake system to 10 pounds ( no leak) and when running sprayed carb cleaner all over the intake system with no change in RPM.

She runs smother than ever when over 2500 RPM, But the problem still shows when she is warm / hot, i.e. when driving around town, will splutter and has no power till 2K and the idle is always around 1000 RPM, When you first turn her on she Idles fine no power issues runs great. But when she starts to warm up the idle gos up and when it hits the 1000 rpm mark she loses power. When the Fuel pressure is set ( installed a variable fuel regulator so I can monitor the fuel pressure ) to Bentleys stated pressure ( 47PSI) she runs crappy all the time, when the pressure is turned up to 80 PSI she runs crappy when hot ?

I’m in a funk and have no idea where to go or try.
She is now throwing a 2121 engine code which is TPS, but that’s new and checks out perfectly

Anyone have any idears…..
All reference voltages are good and so is the GND on the engine managerment system

Prospeeder

Sounds like maybe a poor connection at the Temp sensor for the ECU, should be a 4 pin. The sensors when they go bad will leak coolant into the connector, up the wiring, and corrode it all. Causing high resistance (faulty temp signals to ecu) SO it might raise the idle thinking its -40 degree coolant temperature and too rich, causing bog at low end. Once the turbo spools up it isn't really a noticeable issue.

yodasfro

The 4 pin coolant sensor you are referring to is the MFTS and it's not used for controlling the fuel mixture for ECU. There is a separate sensor for that G62 at the back of the cylinder head.

audi_marv

Might not apply....but had similar issues with a Ford 150 once. Turned out the Radiator was clogged. At startup, and on highway the engine was cooler, and ran ok, but was a bum in the city. Flushed radiator, ran a little Dawn detergent in it, flushed again, and all was fine.

Nuttynotty

Hi Guy's

The Temp sensor for the ECU has been changed for new on the off chance it was intermittent like Youda said the temp sensor at the rear of the engine is used for the ECU. The 4 pin dual sensor has also been replaced for the NEW 3 pin type. I rechecked all the sensors last night, and every one checked out bar one. The Engine speed sensor, the internal resistance is 889 Ohms, the Bentley manual said it should be approximately 1000 Ohms.
I am now thinking it is a timing issue where the timing is being advanced or retarded from a faulty sensor which is going screwy when warm, as the problem gets worse when the engine warms up. However when I pop the hood, the engine will start to run normal again within a few minutes not giving much time to fault find.

The Spark plugs when pulled are not the normal golden brown but more of a brown / red color ( Plugs are new).
Question, what sensor are known to give problems and can cause the timing to change !!!!
Remember that this is a 21 year old car with all the original parts ( apart from the ones I have already changed).

Also, the radiator and cooling system are fine, the water pump and thermostat were changed along with the timing belt 5 k ago.

Prospeeder

Wiring, the sensor can be good all day long and if theres any resistance in the wiring, it will completly throw off the reading to the ecu. You need to check the wires integrity, try checking the ohm reading at the pins on the ecu, then at the actual sensor, see how different they are.