View Full Version : No Temp Gauge, Replaced Temp Sensor, Rough Start, Rough Idle, Running Super

01-27-2015, 01:08 PM
Picked up a audi really cheap locally that had a bad oil leak. Well the leak was the oil return gasket which I fixed. Now I am trying to troubleshoot why it takes 5 times to start the car. It is running super rich and you can smell fuel both in the bay and at the exhaust as well as black smoke. I have no temp gauge and no oil pressure gauge at any time driving or idle. I have replaced the temp sensor with an extra new one I had laying around and the problem is still occurring. My knowledge is in VR6's not these bad boys so any help would be appreciated.

01-27-2015, 01:21 PM
is the car stock? was the temp sensor OEM? Pull the vac hose off the fuel pressure regulator and make sure it hasn't taken a shit and dumping fuel in the vac line also scan it for codes.

01-27-2015, 01:30 PM
Swapped the FPR out with an extra 3bar. The sesor I replaced it with was OE. I have scanned it with both VAG and a normal scanner both come back with no CEL. CEL is not on but every once in awhile I will get a random miss due flooding the cyl. The car did have a stage something yada yada GT28RS but after closer inspection it looked like the guy had sucked up a 10mm socket into the intake turbine. I replaced it with a hybrid ko3. I am not sure what injectors it has at the moment. I do know they are blue.

I should mention that the "tuned" ECU shows the EPC light but no CEL. I swapped it out for a stock ECU for the moment.

01-27-2015, 02:33 PM
if you swapped it out with the stock ecu maybe it has different than stock injectors, check the number on the injectors and compare.

01-27-2015, 02:52 PM
I have two ECU's the one that came with the car that has the tune on it and the one without. Both have the same effect with rough crank and rich. Although the one with the tune has a EPC code that I have not scanned. I don't think that would create the same effect as the stock ECU though. I also cleaned MAF and made sure everything was plugged in lol. The last owner was a special breed.

01-27-2015, 03:06 PM
Try running with out maf plugged in

01-27-2015, 03:08 PM
Same old with the maf unplugged. I have diagnosed it pretty well so far but as I said I am not much of an audi guy, 1.8t or anything over 98 lol. But hell it was cheap enough I am going to give it to the wife as a DD. So bare with me on my newly found learning curve.

01-27-2015, 04:36 PM
Stock injectors, found the 550cc in a plastic bag under the driver seat. o_0 So as of right now it is all back to stock besides the exhuast.

01-27-2015, 05:35 PM
Swapped the FPR out with an extra 3bar.

Just some food for thought: the B5 1.8T uses a 4bar FPR stock.

01-27-2015, 08:19 PM
Ah I assumed it was 3, I just threw in my adjustable from my 3.1 VR6 to try it out. Still running rich so 3 or 4 is null.

01-28-2015, 05:19 AM
What is the ECU seeing as the coolant temp value on cold start?

01-28-2015, 09:02 AM
I will check after work. Thanks guys!

01-28-2015, 12:20 PM
So drove it home from work and finally got it to scan. I am assuming MAF and or Cam Sensor combo.

P0304 - Cylinder 4 Misfire Detected
P0102 - Mass Air Flow Sensor (MAF/G70): Signal too Low.

or a vac leak.

01-28-2015, 12:37 PM
Why do you think cam sensor? The cam sensor can't cause a misfire.

Check CTS value at cold start (before and after cold start, and a warm reading as well would be great).

Log MAF value at warm idle, and on a 3rd gear WOT run if possible.

01-28-2015, 01:05 PM
No but it can cause the car to not fire during crank over. Just suspect not going to throw parts at it. I will check both CTS values and MAF values.

01-28-2015, 01:21 PM
Bad cam sensor causes long cranking, just did a mk4 2.slow monday with a failed cam sensor, plugged in or unplugged same code and same long cranking before it fired and CEL as soon as you'd clear it and wouldnt rev over 3k. Log the maf values like walky says, look at the crankcase breather system too for possible vac leaks.

01-28-2015, 01:45 PM
Yea my VR has had bad crank, cam/hall and speed sensors over the years. And VW is infamous for bad ignition switches which will also cause intermittent spark. As I said before I am pretty well versed in VW's but nothing this new. [headbang] . Thanks for your help fellas ill post up more info after the car cools and I can runs cold and warm values.

ps. The reason why I suspected cam sensor is because I can crank if for 4-5 seconds 4 or 5 times before it will fire. But that could be due to rich conditions also... So as I said it is just a suspect.

01-28-2015, 10:24 PM
In message block 4 I believe the temp got up to about 45 c after 5 mins of the car running... below are all the codes. I just swapped out ABS controller this morning. Mass airflow registered null... I will replace CPS and MAF and go from there.

18057 - Powertrain Data Bus: Missing Message from ABS Controller
P1649 - 35-00 - -
17834 - EVAP Purge Valve (N80): Open Circuit
P1426 - 35-00 - -
17840 - Secondary Air Injection Solenoid Valve (N112): Open Circuit
P1432 - 35-00 - -
16727 - Camshaft Position Sensor (G40): Signal too High
P0343 - 35-00 - -
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -

ABS module faults :

1 Fault Found:
00287 - ABS Wheel Speed Sensor: Rear Right (G44)
30-00 - Open or Short to B+


01-29-2015, 05:48 AM

You've got a blown fuse. #34

Explains all non-ABS codes except maybe the cam sensor. I would not advise changing any parts until you actually get power to the circuit.

01-29-2015, 06:18 AM
fuse 35 is missing along with 43 ... 34 is a good fuse. I checked them a few days ago.

Ignore EVAP and SAI they were deleted before I got the car and he never put a resistor on them. So for now it is MAF / Cam Sensor and Wheel Sensor.

update: the guy told me both the maf and the cam sensor have been replaced with working parts.

01-29-2015, 08:25 AM
12v wire on MAF was dead, hooked up 12v to it and MAF is reading great... any idea why I am not getting voltage on the 12v but I am on the 5v?

01-29-2015, 02:20 PM
Ignore EVAP and SAI they were deleted before I got the car and he never put a resistor on them.

Argh. These aftermarket modifications are raining on my diagnostic parade. [:(]

Must be a break in the MAF wire, if the fuse is good. Not sure what year this car is, but I believe the EVAP and SAI get power from the same circuit. So if those wires are handy (and working), you could just steal power from there.

01-29-2015, 04:29 PM
I stole power, and I agree no point in deleting some of it. I got the MAF working and voltage and ohms at the cam sensor plug look good. I am going to borrow a sensor tomorrow and see where that gets me.

01-30-2015, 02:44 PM
Let me introduce you to my 4 window hall sensor wheel blender. The guy said there was chain noise developing ... Idiot.


02-02-2015, 12:32 PM
Still no temp guage and only blowing warm. Any suggestions?

02-03-2015, 08:56 AM
Finally though a code for the coolant system. P1296

02-03-2015, 10:03 AM
Check CTS value at cold start (before and after cold start, and a warm reading as well would be great).

Also check CTS value in cluster at same times to compare.

02-03-2015, 11:22 AM
Disregard .. I will update you shortly.

02-03-2015, 01:55 PM
Starting the car after letting it sit for 2.5 hours after driving it the temp registered 20C After driving it for about 30 mins it reaches a whopping 54C ... The upper radiator hose is hot going into the top sensor behind the head, the bottom hose is luke warm and so are the hoses running into the heater core.

02-04-2015, 06:23 AM
Sounds like your t-stat might be stuck open. I'd suggest you replace with genuine OEM and take a nice peek at the water pump impeller while you have the t-stat out.

02-04-2015, 06:27 AM
Yea I thought so also. Normally you would get some fluctuation in the temp guage if the tstat was stuck. I noticed on the temp sensor one of the wires was frayed off near the pin. I am going to solder that back together and see if I get a reading. It might actually be both issues since the coolant hoses running into the dash are warm and after about 20 mins of driving it will blow warm air.

02-10-2015, 08:41 PM
So I have temp guage now but no heat... The coolant lines on the back of the motor are hot.. The lines on the front and side "therm housing" are cold... I let the car idle for about 15 mins in the driveway with no change.

Changed CTS and thermostat with OEM.

02-11-2015, 10:41 AM
I have heat after bleeding the system a few times. Drove about 5 miles and the cam chain is rattling like a mf'er. Great.