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iiNFAMOUS
11-01-2014, 09:59 PM
I recently picked up a '98 A4 B5 with the 2.8L 30v. Got it in a ridiculously good trade deal, so i couldn't pass it up. Always wanted one, and i'm handy with tools and repairs. In my mission of not throwing money at my problems, I am here. Previous owner(no idea why, I assume for the money) cut off both catalytic converters, and replaced ONE with a flex pipe, the other is still missing, the rest of the exhaust is intact. I have the o2 sensor from the missing portion in my room currently.


I got the car, hopped in started up right away, no problems. It idled, albeit very loudly, but it idled nonetheless. Idle seemed smooth, nothing out of the ordinary. Popped it into 1st, took off all is good....then all hell broke loose.

It accelerated fine for a second, then it just lost all power, no throttle response....almost like a massive boost leak(obviously not the problem, NA motor). Let off the gas, got back on it power is restored....for a few seconds, then loses power again. So i Let off, get on it for a quick second and then let back off. When I let off, it doesn't slowly drop in RPM, the tach goes all weird and the engine becomes silent, no loud exhaust sound, no audible dropping of RPM.....silence, but the car does NOT shut off, pressing the gas again causes it to once again accelerate, and repeat the problems. So I limped my way back home in the 40* weather.


The next day, I hop in start it up, temperature outside is about 33*....starts up right away, again, like expected....and immediately shut back off again. Started up right away again, shut back off. Repeat x3. I then started it up, gave it a little bit of gas and she purred like a....very loud kitten. Let my foot off the gas, dies again.


And this, ladies and gentlemen, is where I come to you wonderful people. I do have a CEL on, and will be getting a OBD2 scanner tomorrow to find out for what, but in the meantime i'm open to suggestions.



tl;dr. My car loses power, wont stay running in the cold, without gas pedal assistance.

B72011
11-02-2014, 02:12 AM
Air leak? Ignition issue? Fuel pump issue?
Gotta get the codes or its a guessing game.

seanf86
11-02-2014, 05:07 AM
unplug the maf and try starting it and see how it runs, I'm also willing to bet you'll need vag com to do a throttle body adaptaion. I'd also be checking my fuel pressure if power comes back on like you say after letting off the gas, you could have a bad pump/plugged filter.

Drifter420
11-02-2014, 05:59 AM
Bad maf unplug it ^

iiNFAMOUS
11-02-2014, 06:33 PM
I held the throttle at 1K RPM for 5min with the heat on full to warm it up, it idle peacefully at ~800RPM. I tried the throttle body adaptation with VAG Com but block 60 the last line for adaptation had an error and wouldn't allow me to do it. Pulled the codes, had one relating to throttle, 4 o2 Sensor/Heater codes, Coolant Temp Sensor, an MAF code(i imagine the previous owner disconnected the MAF). Cleared the codes, turned the car off and back on. 4 o2 sensors came back as well as the throttle code, which i cannot currently remember what it was exactly. CTS and MAF codes did NOT come back again.

So, after that I unplugged the MAF while running, no change at all. Hopped in the car and lightly pressed the gas and the car shut off immediately, no RPM increase, just shut off.


Hopped in the car, went for a drive and it has the same problem. While accelerating the car just loses all power completely, like i'm letting off the gas, but I don't. When this happens and I let off the gas, the RPM bounces back and forth between 1K-1.5K.