Are these symptoms related?

[white92tsi]

Background: I purchased a 1g TSI AWD a few days ago. When I bought it, it had a small idle bounce that I figured was a small boost or vacuum leak. No worries, I took it home. I have since changed the spark plugs and wires and the air filter. When I replaced the plugs, the idle jumped up to 2500 RPMs. Strange, but I was able to get the idle back down with the set screw. Also, the idle bounce is gone.

Even after the tune up, I am still getting an occasional misfire or fuel cut, and the AFRs are bouncing at idle and cruise. They go rich while accelerating. Also, the idle will occasionally creep up to 2000. If I shut the car off, wait a few minutes, and start it again, the idle will settle back down.

Any thoughts on what I should look at?

Thanks!

 

[95blackGsTurbo]

Do you have a wideband telling you it is rich or a pretty light that goes rich to lean because those are useless. Ideally you should not have to move the BISS because the computer will try and readjust for any change you make with it. What kind of spark plugs did you use? Did you check for any boost leaks yet?

 

[jbeaton9292]

what are you considering rich. the car should start to get rich when boosting not drastically for low boost but still should some.

also what turbo are you running and at what psi. guessing the car is still on a 1g mas? if so and you are running more than stock boost you could be hitting fuel cut; where in the rpm range are you feeling the symptoms.

do you have a way to run a log so you can see for sure what is going on if not i would suggest you get a way to do so.

 

[white92tsi]

I don't currently have any way to data log. My first step to doing my mods is to get ecmlink, but I won't be able to for a bit. I'm pretty confident that the vibration I'm feeling under acceleration is the carrier bearings. I got the car in the air and saw that they are pretty much shot. That also explains some of my vibration on the road.

As far as the wideband, I have an AEM UEGO that I will be putting in shortly, but for now, it's just the auto meter BS that was in the car when I bought it.

It's boosting around 10-12 lbs. I attempted to do a BLT, and found that my BOV line was leaking a bit, but I couldn't find much more b/c the air was apparently being passed through the exhaust and spinning up the turbo. I never saw this when I was working on turbocharged SR20's. Strangest thing ever.

I also found that the throttle cable was pulled just a bit tight, which is why my throttle was settling at different levels, and sometimes never fell. I got that sorted and am going to look up the song and dance for setting the idle properly.

As far as the AFR's bouncing, it comes and goes. Often it won't do it after I start the car for several seconds, or until I get up to cruising speed. Then it hardly goes away. Also, the bouncing idle comes and goes even if the AFR's are still bouncing; however, I have noticed that when both are happening, they coincide... rev up is richer, and when the AFR's fall, so do the revs.

 

[jbeaton9292]

As far as the AFR's bouncing, it comes and goes. Often it won't do it after I start the car for several seconds, or until I get up to cruising speed. Then it hardly goes away. Also, the bouncing idle comes and goes even if the AFR's are still bouncing; however, I have noticed that when both are happening, they coincide... rev up is richer, and when the AFR's fall, so do the revs.

well get link that is your first big step to find out what all is happening with the car.

as far as your afr's in a sense that is what should be happening with them the more gas given (higher rpm) should in theory get richer (to a point) and vise versa now its hard to say what is truly going on without a way of logging and without a true wideband them autometer gauges are a waste of time. also your afr should always be bouncing around 14.7 without making boost richer with boost it will never just sit consistent EVER

 

[white92tsi]

ECU EEPROM conversion is on back order for 2-3 weeks. Not much I can do there for the moment. I've read about other data loggers for these cars (using a cable and a palm or something) that I'll look into, but if it's costly, I'll just have to wait or find an EEPROM ECU (salvage yard, perhaps?).

I'm aware that the cruising AFR should be around 14.7 and get rich with throttle and even more so with boost. This is my first DSM, but not my first boosted car.

The weather here is still a bit cold some mornings, this morning especially. When I went to start my car, the idle was high (as expected), and when it fell, it was bouncing extremely fast. AFRs were bouncing equally fast.

Something else I noticed... The last owner (or someone before them) deleted the emissions. There are four ports on top of the throttle body. As I understand it, one of these ports gets positive pressure. Instead of capping off the ports, they are connected together (the two on the left and the two on the right) with a single piece of vacuum line (making two U shapes). Could this cause any issues?

 

[white92tsi]

Well, my issues got about as bad as they could get this morning. I'm guessing the idle set screw was getting brittle (it's just plastic) because at some point on my 20 minute trip this morning, it busted and was blown out of the throttle body. As you can imagine, it idled very rough after that... hardly at all.

I called a buddy who had a couple of spares, bought a new o-ring, installed the replacement screw, and set the idle using the two pin grounding method (diagnostic and timing pins). The idle bounce is gone, she purrs right around 900 RPM give or take 100. The AFR gauge isn't bouncing around as much, but it will still occasionally bounce all the way lean and then back to what I'm assuming is around 14.7 while cruising. I'm not sure what's going on there, but I'm going to have to get ecmlink before I can really diagnose it.

Long story short, replacing the BISS and setting the base idle solved 90% of my issues.