More Engine Idle problems

[TorqueEffect]

I can't for the life of me figure this out.

On my B6 swap, the idle is quite high. (around 1200-1300 rpms) and at the same time it lopes by about 50rpms, and when trying to adjust the idle lower (Around 800 RPMS) it lopes by about 100-250rpms and idles really rough.

I have tried looking for vacuum leaks by soaking every single possible opening for extra air to get into the system, and can't find anything. I even sprayed the ducting in case of cracks.
I tried swapping in the B3 ecu and VAF, and mix and matching them, nothing changes.
Checked the cooling system for air, so I popped the radiator cap and topped it up and started it, no air bubbles at all even when squeezing hoses, and it got up to operating temps too.
Tried unhooking the IAC, wouldn't even stay running.
Tried tapping the IAC valve to see if the idle changes, nope nothing.
Listened to the injectors using a screwdriver stethoscope, injectors sound fine.

Only thing I can think of is maybe ignition system, but the coil and ICM worked fine on the B3 and didn't show any of these symptoms, and Zoom Zoom said the spark Plugs, wires, and dizzy cap are fairly new.

Now I don't get a check engine light on the road, but grounding the STI it does blink a code for the purge solenoid. But we removed that during the B6 swap and plugged the line coming from the tank with a bolt, also I don't even see a connector for it on the injector harness on the B6. But parts lists clearly state that the 80s tracers had a purge solenoid. But I don't see how a emissions thing like a purge solenoid would even matter in this case.

I am completely baffled.

[zoom zoom]

Purge solenoid is mounted on the firewall ran off a branch from the strut tower area, i stuffed that harness back in the hole lol, you can pull it back out and plug in a solenoid and the code should go away, I dont recall having any codes for it but mine was plugged in with no vacuum lines to it. I can send one to you if you need one.

[TorqueEffect]

Ahh. But like I said, it probably has nothing to do with the high idle.

Sent from my LG-LS720 using Tapatalk

[skeeters_keeper]

You wouldn't happen to have one of those beautiful el-chepo VC breathers on yours, would you? Like this one:



I ask because I was hunting the same problem on my swap. No CEL and runs good except at idle, high idle more or less masks the problem but trying to get it to idle nice at 7-800 like I prefer was a big problem.
The problem seems to be the breather sucking in unmetered air at idle. At idle the PCV valve is open, allowing vacuum from the intake manifold to pull unburnt hydrocarbons, water vapor, etc. With the stock setup when there is a vacuum on the crankcase it pulls the extra clean air it needs to maintain equilibrium from the intake tube post VAF, when you put the breather on now it allows unmetered air into the intake via the PCV, so the ECU is stuck trying to idle using wrong information on the quantity of air being consumed, and consequently hunts back and forth.
To check the theory on my car I unhooked the PCV from the intake and plugged the intake port. The idle began to behave! Since I don't want to delete the PCV, I need to tig another bung into my intake tube. I haven't gotten to that yet... I've just been dealing with the hunting idle for the last few months. Some day soon hopefully I'll be able to fix it up proper though, and then we'll find out if it fixed the idle. I'm hoping it'll help pick up my mileage too.... but I doubt it. I used to get 40-44mpg with my 1st gen B6 swap all the time. I'm only getting 35-36 with this one.

[zoom zoom]

I wonder if that cheap plastic piece on the pcv valve is doing it? That was on the engine when i bought it. Maybe throw a b3 pcv on it and see it that helps?

[TorqueEffect]

I wonder if that cheap plastic piece on the pcv valve is doing it? That was on the engine when i bought it. Maybe throw a b3 pcv on it and see it that helps?

I did, that was the first thing I checked. I put a B3 PCV valve, and a new piece of hose, and nothing. I did find a small leak at the intake resonator hose, so I removed the resonator and plugged that opening. Like I have said, I have soaked just about every cap and hose that deals with vacuum with starting fluid and can't find a vacuum leak.

I changed the coolant sensor on the throttle body after work today, and nothing changed there. What are the chances that there is air stuck in the system? I ask this because when I removed the old sensor I could see the coolant down in the hole but it seemed like the sensor was completely dry. But I have ran the engine with the radiator cap off and seen no bubbles.

Also no, I don't have a breather filter on the vc skeeter.

[zoom zoom]

I don't know about the air in the system. Never had a problem with these engines needing bled out... Or at least never noticed it.. Try running the engine and loosen the sensor till antifreeze comes out?!?!

Have you checked the timing? I wonder if the adjusting it after turning the idle screw down would calm it down?

[TorqueEffect]

Yeah I am starting to think the timing may be off as well. I am wondering if it may have jumped a couple teeth on the timing belt?

After I changed the water pump on the b3, it was off a few teeth and had a high idle. I wonder if this may be the same thing.
Is there a way to check if it is off a couple teeth without removing all the crank pulleys and checking the crank sprocket?

[zoom zoom]

the timing mark lines up with TDC on the crank pulley when the cam pulley is at 12 & 3....I think lol, you should be able to see the timing mark on the oil pump vs the indent on the timing cog.. won't be easy to see but it's doable without that upper cover on. don't use the camshaft bolt to turn the motor over! pull the plugs and its alot easier.

[william]

Hope you figure this problem out if you do let me know, I'm having a similar problem with my b6d it idles great when cold but then it's warmed up its all up and down and kinda a miss at idle.
I checked and replaced everything I could think of so I just deal with it. Lol

[TorqueEffect]

Everything seems to line up perfectly at TDC.

But the only indentation I found on the crank pulley I marked, but running a timing light, and getting the idle as low as I could, and moving the dizzy all the way forward or back, I can't get the mark where it should be, at one extreme it is just on the edge of the timing scale, and the other, it is at the top of the pulley. I also can't seem to really effect the running of the car at all at these extremes, I can't hear any knocking either.

Anyone want to time my engine for me? I can't figure this out for the life of me. It was easy on the B3, but that didn't have idle issues.

I'll pay them to do so, or get them a 6 pack or two of beer.

[TorqueEffect]

Found at least a culprit.

The TPS.

Googling about high idles, lots of places mention TPS.
So I searched for a tps test method here on the forum, and found one. The bottom 2 pins on the TPS are supposed to have continuity when the engine is at idle.

So I got out my multimeter and at closed throttle I checked the bottom 2 pins on the tps, and got nothing, also nothing on any mixture of the 3 pins in terms of continuity. So now I thought either a faulty TPS or it is in the open throttle position, so taking the handle for the floor jack and wedging it between the seat and gas pedal to give a WOT, I test the top 2 pins, and got continuity. Then I marked the TPS position before adjusting it, and moved it just a hair and locked it down.
Removed the improvised WOT wedge from the gas pedal, and tested the TPS at the closed position and had continuity on the bottom 2 pins, then tested for just a hair of throttle, and had no continuity, then full throttle and I had continuity on the top two pins.

Had a bit of a scare with a pinging sound from the valve cover (almost like someone tapping on it with a screwdriver) and what sounded like a quiet knock as well, but didn't get worse at higher revs, and wouldn't get better or worse when adjusting the dizzy timing. Come to find out the VAF doesn't like being upsidedown, because as soon as it was right side up again the pinging and knocking went away.

[defprun]

Your TB clean?

[TorqueEffect]

Yeah, I still haven't been able to get this figured out. =/

[defprun]

I thought Id never find my issue, hang in there bud!