Bad Idle

[Firefighter637]

When I start my car up from a cold start, and put it in drive or reverse and take my foot off the brake it wants to stall. The RPM's jump between 800-1000. After a few mins when the car is warmed up it's ok. Changed all the spark plugs and still having problems. Car only has 31k. Ideas? Suggestions?

[swrt83]

Rough idle usually indicates MAF/02 sensors or coilpack issues. Did you check your trim levels? I would start there first.

Oh and I was looking for some pics of your crazy red interior in the other post a while back. You ever get photos of that? I'm still on the fence about doing this..

[Firefighter637]

Rough idle usually indicates MAF/02 sensors or coilpack issues. Did you check your trim levels? I would start there first.

Oh and I was looking for some pics of your crazy red interior in the other post a while back. You ever get photos of that? I'm still on the fence about doing this..

Copy that. What do you mean by the trim levels? I will take pics tonight!

[swrt83]

Your trim info tells us if your engine is running rich or lean, depending on the amount of fuel/air mixture. Just hook into the vag com, engine module, block 32. Your %'s should be within -/+ 10% for normal healthy firing.

General info here: http://wiki.ross-tech.com/index.php/Fuel_Trim_Info

Here is an example (my output):
Address 01: Engine (8E0 909 559 L)

Group 031: Lambda Control (Lambda Sensor Voltages)
1.000 Lambda Control Bank 1 (actual)
0.945 Lambda Control Bank 1 (specified)
1.000 Lambda Control Bank 2 (actual)
0.945 Lambda Control Bank 2 (specified)

Group 032: Lambda Control (Mixture Adaptation)
0.0 % Adaptation (Idle) Bank 1 Sensor 1
-2.3 % Adaptation (Partial) Bank 1 Sensor 1
-0.4 % Adaptation (Idle) Bank 2 Sensor 1
0.0 % Adaptation (Partial) Bank 2 Sensor 1

Group 033: Lambda Control
0.0 % Lambda Control Bank 1 Sensor 1
1.520 V Sensor Voltage Bank 1 Sensor 1
0.0 % Lambda Control Bank 2 Sensor 1
1.540 V Sensor Voltage Bank 2 Sensor 1

[A4TL]

when my n80, braided hoses, and check valves were toast i had nasty idle and hard starts. fixing up everything put it back to normal. gotta do alot of PM when the cars get some age on them man or they start running like butt.

i still haven't figured out why my dinan stage 2 335i is getting the same mpg as my apr stage 1+ ??!! i took great care with all the fluids (tip/brake/synth 5k,plugs 5k, tire pressure 38psi) tried everything. trims were fine. new o2 wideband. maf cleaned and verified gm/sec against other cars to ensure maf was flowing properly. never did figure it out :(

[viajero22]

i had i similar problem with my a4 b6 that i just bougth a couple months ago, rough on idle when it was cold, but after looking around i found a vacuum leak one of my check valve was broken in half i think the part number is
A60 133 528A and is located somewhere between firewall and intake manifold, sorry don't have any picture but try looking between your vacuum hoses turn car on and gently move hoses a little bit to see if u find any hissing.

[Firefighter637]

i had i similar problem with my a4 b6 that i just bougth a couple months ago, rough on idle when it was cold, but after looking around i found a vacuum leak one of my check valve was broken in half i think the part number is
A60 133 528A and is located somewhere between firewall and intake manifold, sorry don't have any picture but try looking between your vacuum hoses turn car on and gently move hoses a little bit to see if u find any hissing.

Yea, car is running worse now. Idle is bad when starting up. I'll see if I have any leaks. I guess it will be noticable if I do find one.

[jonnies]

Amazing. I just had the same rough idle problem, and found the same cracked vacuum valve that viajero22 mentioned.

But in looking around for the part online, I can only find p/n ---133529A for about $17, which is called a vacuum check valve and looks like the right part, but its not 133528A (which is the number molded on the part).

Were you able to find it online, or did you get it from the dealer?

[viajero22]

i had i hard time finding this part on line and since i wanted the part quick i had to go the dealership audi dealership was asking 72 and vw dealer was asking 55 for part so guess where i went, when i got the part they gave me one with part #A60 133 528D which is suppost to be an update

[jonnies]

Aha -- the "D" was the answer (searches using the "A" part turned up nothing) and I easily found it online for about $37. Its called a Crankcase Vent Valve.

Thanks viajero22!
js.

[SlappyB6]

What do you consider bad idle? I ask because since I've put my TP on, when I first start the car, it's idles around 1100 RPMs, then after about a minute it drops back down to around 900. Is this normal, or should I be checking for leaks and/or rich/lean conditions? It doesn't idle rough, and I don't notice any smoke or heavy deposits, or marked differences in gas mileage.

[swrt83]

What do you consider bad idle? I ask because since I've put my TP on, when I first start the car, it's idles around 1100 RPMs, then after about a minute it drops back down to around 900. Is this normal, or should I be checking for leaks and/or rich/lean conditions? It doesn't idle rough, and I don't notice any smoke or heavy deposits, or marked differences in gas mileage.

Seems normal to me, the idle regulator is supposed to start high and gradually come down once the car is warm.

[SlappyB6]

Seems normal to me, the idle regulator is supposed to start high and gradually come down once the car is warm.

Cool, that's all I wanted to know. Thanks.

[04QuattroTurbo]

Can you guys post a pic of the crankcase check valve and it's relative location under the bonnet? I would like to check mine, since my idle has been a little rocky lately, funny thing is that the tachometer has been steady. Happens cold or warm.

[justincab]

This is a worst case scenario, but on my 03 3.0 cabriolet I was having rough starts in the morning too. After the dealer replaced pretty much the entire fuel and electrical systems, they got into the motor and found that the cylinder sleeve was shrinking and leaking a tiny amount of coolant into the engine (don't quote me on this, it's the way the dude explained it to me) and making the car run like poop. When the car warmed up tho, the sleeve expands and the car runs like a champ. I guess this isn't the first time they've seen this happen. Long story short, they're replacing the motor (thank god for extended warranties), and I hope this isn't what you've got going on.

[Firefighter637]

I checked my engine bay for vacum leaks and didn't find any. Now I guess I will clean the MAF with the cleaner and see what that does tomorrow. Hopefully its that. Tired of the idle problem!!!

[04QuattroTurbo]

I checked my engine bay for vacum leaks and didn't find any. Now I guess I will clean the MAF with the cleaner and see what that does tomorrow. Hopefully its that. Tired of the idle problem!!!

So it the idle actual erratic? Meaning RPMS change and don't stay at 800 at idle?

[Firefighter637]

So it the idle actual erratic? Meaning RPMS change and don't stay at 800 at idle?

When the car is in neutral or my foot is on the brake the idle is around 800 steady. It's when I take my foot off the brake or put it in drive or reverse the idle goes down and acts like it wants to stall and shutters. Especially on a cold start!

Update: Cleaned the MAF and changed the spark plugs.. runnin like shiot.

[aaronz]

Could it be your transmission? Seems like the computer is thinking it should be at normal idle, but the transfer to the transmission is taking more out of it, thus the lower rpms. Have you changed your transmission fluid?

[Firefighter637]

Could it be your transmission? Seems like the computer is thinking it should be at normal idle, but the transfer to the transmission is taking more out of it, thus the lower rpms. Have you changed your transmission fluid?

No I haven't changed the fluid. Haven't changed the O2 sensor yet either.