The car: 1986 (early) S3 - 5 speed.

Similar to another thread here: the hotter it gets, the higher the idle gets. It can sit at 1200 and higher if it's good and warm; it's a big leak. Works OK when cold...the hotter she gets, the higher the idle will go. Some info below.

I have done stethoscope, smoke test, propane...these methods revealed some areas that needed attention but I have not been able to find/address the issue described above.

I'm looking for input, stuff I can look at / check...honestly I am kind of out of places to look so any ideas of stuff to re-check etc. are welcome and appreciated. Car is apart, side plenums off, MAF out, ICV out, middle "T" out.

Rebuilt MAF
Installed O-Rings in Throttle Body butterfly shaft
New TB O ring where it bolts to air guide
Replaced Intake boots not too far back. Replaced 4 of 8 of them within last month.
Replaced Throttle Body "T" boot - upon inspection it is in good shape, with no thin areas.
New TPS
Porkenized with chips V4.0
New FPR 87+
New fuel dampers
New TPS short harness
Tested 0 Ohms at pin 3 on LH (idle) hot or cold (this makes me believe my injection wiring harness is in decent shape)
Tested 0 Ohms WOT at LH
Replaced 1 way valve at brake booster, with new grommet.
Replaced hose from booster to intake side plenum
Replaced small rubber hoses attaching to brake "venturi"
Replaced ICV to TB hose
ICV working correctly (replaced 2012) with Bosch unit
Intake runners R/R 2012 by mechanic - inspection shows they are dry where they bolt to engine
All cam cover bolts secure and snug
Vacuum hoses off TB were serviced in 2012 by same mechanic that R/R intake runners
Breather hoses from cam cover to air guide secure and snug
Replaced hose from oil filler neck to Throttle Body "T"
New oil dipstick
New oil filler cap
New upgraded 4 hole injectors - car was idling high before this was done so I don't think I have leaks here..inspection of injector install sites show dryness. Engine smoothness improved and there is definitely less latency when you press the pedal..but issue is unchanged after new injectors.

I have NOT replaced the crank position sensor, however it doesn't look super old and tach works very reliably (not sure if those dots are supposed to connect so...)

Car drives smoothly, great power, WOT works fine. I just can't get past this idle issue and as I've mentioned..I'm pretty much out of places to look. I am not against getting professional help..I'm just kind of stuck at where else they'd look.

Again..stuff I can search/inspect again suggestions welcome. I'm at the end of my rope..i've had this sucker apart so many times I can do it in my sleep...the issue started showing up several months ago...all hose replacement type of work above with exception of work noted with dates was done to address issue and does not appear to have made any difference.

Thanks to anyone for any ideas.

Matt

 

RIght there with ya. That said, I did just cave and order a new ISV to replace my new ISV, based on Speedtoys' thread.

 

Argh...they don't give those things away anymore either...I think mine was $170 and its only a few years old....frustrating!

Can you let me know how it goes? If you get relief that will have to be my next move...I just can't find anything else.

We'll get there ....it runs so darn good..well it did...now it's all apart again..even the ICV is out at this point.

I'm playing around with the idea of seeing if I can remove the airguide without the intake runners...I believe it can be slid out the back...I may take it out and just go over it well..maybe replace the breather hoses to the cam covers...not sure....

Let me know how it goes..thanks.

 

You got this figured out right?

 

Yeah...the electrical thing was a crossed wire in the TPS short harness...idle was going to WOT pin in LH, WOT was going to idle pin...made a small mod to the connection that goes to the LH harness ...disco.

Wish my idle woes were that easy...I'm going to see how SMT Cape Cod does with a new ICV...if his stuff works out I'll pop for one....if not I'll admit defeat, do a couple more minor to do's on the air guide and get some professional help....I got no problem admitting defeat if it means I can have Cruella back.

Thanks Sean for the info on the LH harness and for checking in

 

to test your ICV you want to see if its sticking at any part of its travel,

what happens with your type is that the brushes wear 3 holes into the armature,
the brushes then grab this and the the vane cant turn as easily till it jambs,
this then with burn out the computer

 

My 85 is doing this exact same thing. It idles very low when I first start the car in the morning, but as it warm's up, the idle just keeps going up. Mine stops at about 1000 rpm because I adjusted the air bleed screw (the one in front) to about 1/2 a turn from fully closed. This brought the idle down some.

I replaced this short ISV cable last October because mine was in bad shape.

Can you tell me which color wires in the replacement ISV cable to check?

 

On mine the outside two wires were crossed. My car would idle erratically..up and down constantly and when I floored it for WOT, the car completely dies. Lifting accelerator off the floor / disengaging WOT circuit would bring it back. I did not tear into the harness but smoothed off the keys on the log sides of the short harness end that plug into the LH harness so I could reverse the plug. I left the attaching keys on the short sides in place so the wire clip would work to secure the connection.

If you aren't experiencing what I describe above I would not guess your short harness has this issue but I don't know what kinds of things this could cause to other cars...again mine is modified with Porken's chips, V 4.0.

I hope SMT gets relief with his new ICV ...sounds like this idle issue is occurring in multiple S3's....now I'm beginning to wonder if there might be something happening in their construction...

I installed mine in 2012....how old is yours KillaV?

Mmerlin I did remove the ICV earlier this year, fully tested it with a Radio Shack 12V rectifier and cleaned it with brake cleaner...it was snapping open and shut as fast as I could move the wire from one side to the other....that isn't saying that as things heat up something isn't leaking or maybe it starts to stick at that point....with it not occurring with the engine cool it becomes harder to look for it....as I have limited amount of time to prepare the engine for smoke tests and such (removing MAF to avoid contamination from the smoke and plugging the air guide, etc. takes more time because I wear protection to guard against burns)...frustrating for all of us experiencing this.

I hate that anyone is experiencing this issue but maybe this gives us a gleam of hope; with symptoms being so similar..or rather anecdotally the same ..especially with KillaV's car being significantly modified from mine and SMT's; is that there likely and hopefully a common denominator for all of us. I would be surprised that we all have some air leak somewhere doing the same thing....wonder if Bosch started making ICV's differently for these cars at some point and we are all experiencing symptoms of failure from that change?

 

I doubt this is your problem, because of the way you've described it getting higher as it warms up, but I had a very idle issue that turned out to be the cruise control throttle cable was caught on something (actually a plastic part that fits up against the bracket in the engine compartment wasn't on right) and it was putting tension on everything, causing a high idle. It's an easy check to rule it out, anyway.

 

Good tip bureau13 thanks...I did have a similar issue with a new throttle cable I installed...I had too much slack out of it and it was pulling the throttle cable forward when everything got hot...will check it out.

 

I bought the car last year the same month I replaced the cable (October) so I'm not sure if my ISV is original or not, but I haven't replaced it in my short time with the car.

My harness is probably ok. Car runs fantastic at WOT, no dying or anything. Just the weird increasing idle issue. It was idling WAY high at the first breakfast I brought it to (I took delivery like 2 days prior), and Sean spotted the unplugged ISV harness right away. The connector was broke and it would not stay plugged together very long. While the car was running, Sean plugged it in, and it idled down immediately, but not as low as it should be.

The manifold needs to come off, and a complete R&R performed, but after reading Jeff's (Speedtoys) thread about his impossible to lower idle issue after basically trying everything on his (daughter's) 85, I'm not confident it will do anything for my idle issue.

I have the Porken chips in waiting, but have some more work to do on the car to get it running tip top before I drop them in.

 

I did give the cruise control cable some additional slack and drove it but no dice unfortunately...

One thing I did notice as I was putting the side plenums back on is that the underneath side of the intake boots were buckling so I put some vaseline both on the bottom inside portion and outer edge of the boots...then eased them on and worked the side plenum up and down until I could be sure nothing underneath was buckling at all.

Apparently that was something I was doing wrong and it resulted in better response and more power but didn't do anything to fix the idling issue...grr...

SMT when are you thinking you'll get your ICV .

 

Care to share where you are buying one from as there are none in the Country that I can find?

 

Eek, this is a concern...aren't the S3 ISVs considered something of a wear item?

 

Echoing Roger's sentiments...these things are harder to find than the Dodo.

I found 4 in stock at Pep Boys..made by Borg Warner...

There's 3 left now they are dear, at $211 plus tax and shipping if you go for expedited.

Figured I'd take the gamble...they made our 5 speeds....

Will post results.