ColoQuattro

I have reopened this post again as I still, after a new IAT, new Flywheel sensor (only replaced the one that showed up on a VAG as being intermittently bad (that was the grey lead wire), cut down flywheel sensor bracket by 1/1000, new BPV, new N75 Solenoid, new Boost Cutoff valve, new Idle Stabe Valve, new MFTS, required vac lines, new correct plugs, new correct wires, new dist. cap, new correct rotor, new crankcase vent hose, re torqued knock sensors, dielectric greased connections, verified operational Idle Potentiometer, and new carbon canister solenoid (N80 solenoid), the car still violently misfires under load. It's like someone is turning the engine on and off with a light switch and I'm afraid that I'm going to break something.

Now for some more symptoms...1) The car will run into 1.9 BAR under load..This problem usually occurs after this happens. It also makes 1.9 BAR at Less than full throttle but not at full throttle. Probably because the turbo cannot volumetrically fill the intake under WOT like it can at less than WOT 2) If I shut off the car and restart it the problem will not occur again until I do a boost to 1.9 BAR a couple of times. Shut the car off and fire it back up immediately. 3) The issue starts as a slight miss under boost that you can feel then after about the third shot at 1.9 BAR...WHAM..Chug...WHAM....Chug...WHAM....Chug.... and so on. 4) The car is easy to start first in the AM and if I shut is down for less than about 20 min it fires right up. It takes a 2 second crank at least 4 times to start when I shut it down for more than say 20 Min approx. I have cranked straight it to start only once and that took 10 sec (I know not a good practice but wanted to see if it would start at all....plus I was pissed). I don't know if this is related or not.
Is the turbo over boosting and mind F'ing the ECU? I did have some over boost codes when we Vagged it. If this is related what is causing the over boost? Is the over boost causing the miss? Is this also causing the hard start? It sometimes but not always seems like a fuel problem on the hard start, but if is is a bleed down of fuel why is it easy to start in the AM?
Kneale, Boxerfan, Chad, itsaV8, Serf or any of you guys have any ideas? Posted to MG as well since this is getting to a point of being hard on the engine and I'm really concerned after throwing all of these parts at it and still comming up with nothing.

Kneale Brownson

Is this a stock ECU?

There are lots of reasons you see overboost. Read through Scott Mockry's discussion of boost and overboost <a href="http://www.sjmautotechnik.com/trouble_shooting/20vboost.html#oboost">HERE</a>

Have you installed the A/C clutch wiring harness insert Audi made up for 200q20vs?

Dave from Gig Harbor

I was told by Scott Mockry that Audi does not have these any more, and he does not have them. I think my radio popping (two radios tried) my be caused by lack of that.

As always, thanks for your help in keeping the beast running.

Kneale Brownson

Absolutely, if the radio is popping too, you need it. No idea where to get it though if Scott no longer has them. He does describe an alternative DIY fix. The other solution would be to replace the A/C clutch. Replacements have the fix integrated into them, I believe. You might check with Scott about that possibility.

Otherwise, I'd check with everyone who reports they're parting out a 200q20v or 91 100 or V8 to see if they have that harness. It's pretty evident if it's installed.

Or you can pay World Impex $100 or so: <a href="http://www.worldimpex.com/search_by_partno.html?searchmode=partno&partno=443 298008&x=40&y=4">KIT</a>

ColoQuattro

Now I'm into over boost....The only thing that I have yet to check is the functionality of the wastegate. I do not believe that the car is chipped.
Scott M. made up a A/C clutch diode jumper cable for me. There is a diode in the relay that is supposed to do the same thing, but that burns out and the Jumper, according to Scott, is for redundancy and to help with big current spikes. So you need both the relay and the Jumper functional. I need to provide feed back to Scott on the install. As I see it the ground on the jumper going to the threaded screw is too tough to get to without moving the whole compressor assembley. I replaced the screw ground with a larger eyelet type connector and grounded it to the mounting compressor bolts. Other than that the Jumper works great. Scott's price was about $30.00. I'll call him and give him feedback.

itsav8

You sure your plugs are gaped correct?

boxerfan

First question: When the misfire happens do you pull codes right away?

Second question: Are you overboosting and nailing the fuel cut?

Third question: Are you using good gas and avoiding the knock sensors?

Dave from Gig Harbor

Thanks Kneale! You are a wealth of information.

ColoQuattro

happens at partial throttle but not full throttle. How would I know if I hit the fuel cut out.

ColoQuattro

if I shut car down immediately on the side of the road and start it again problem stops. Boost doesn't go to 1.9 BAR at WOT only at partial under load or at high speed on a hill.