3.2 Carrera not running right after mods!
 

A brief history.....
'88 3.2 with 89,000 mi.
well maintained, doesn't burn a drop of oil
always ran like a new car. I run 93 octane

Than I did this...
Cat bypass, Dansk 1 in- 2out sport muffler, Wong chip (I thought the car would run sweet after these simple, tasteful mods)
Now it runs a little different. It pops when it idles down after revving it, and on deceleration. When I drive it slow, the idle sticks at 2,200 rpms even after you push the clutch in. A quick rev with bring the idle back down perfectly. When I do this rev, a small puff of smoke comes from the tailpipe. The car does not smoke normally at idle or during acceleration. The car at times actually feels like it has less seat of the pants power to me. I would think these mods would be good for 15-20 hp. I should feel that. Either way, the car is simply not running right. I'm guessing AFRs are screwed up but shouldn't the Wong chip have taken care of that? The car has fresh plugs, cap and rotor, fuel filter, air filter. I'm not quite sure where to start. Thanks,
Tony :confused:

Have you tried contacting Steve?

check the 02 sensor was not damaged during installation of cat bypass

I have the same MY and have a fluctuating idle as well. Also have a cat bypass w/stock muffler.

My chip is not SW, but the Russel Berry chip by MAXhpkit comes in 3 standard forms depending on exhaust type, fuel type, and air meter.

I'd look at your throttle assembly in the engine compartment to see if you are suffering from this problem
http://forums.pelicanparts.com/porsche-911-technical-forum/541862-big-scare-today.html

Make sure you did not bend a terminal on the prom when installing it .

Thanks for the advice. I have not yet called Steve. I would like to try to solve this first. The chip install went very smoothly. I am certain I did not bend any of the legs on the chip. The O2 sensor is a different story. Those are always a pain. I used heat, penetrating oil, a pipe wrench and LOTS of bad words to get that thing out. So, how do I know if its OK? The inside of it looked good, just the outside (nut side) looks like it had been through the war.
If it makes any difference, the elevated idle gets worse as the engine gets hotter. It does not do it cold or warmed up. Just when the motor gets real hot. (and it has been warm here lately) Is there a way to check AFRs without a dyno? Thanks again,
Tony

I also get popping like you described - I think it's normal. Not an expert but it looks like readjusting idle mixture is first step due to new chip. I'm sure this is wrong but it works for me. I lowered the air & idle screw almost all the way down then increased idle a bit so that motor runs smoothly, then increased air mixture to normal level.

I had Steve make me a chip(s) years ago when he was just starting. I originally had a MAF intake system that was nearly impossible to correct with different chip setups. We must of went over half a dozen chips before coming up with one that was suitable. Even so, I ditched the MAF and went with the stock intake and had some more chips made to work. My car is a 3.4, twin plugged, 20/21 cam, bored throttle body and Extrudehoned intake, and SSI's. Its not a typical set up and needed some custom work. Anyway, he got it tuned in and put down some nice numbers at a dyno. Lots a variables in making chips and the first thing I would do is get a hold of him, he knows what to do.

Tony,

I have an 89 with basically the same stuff as yours,my throttle would hang as well and i thought it was the SW chip causing this but it was the throttle linkinge where it attaches to the gearbox that needed some cleaning and lubing ...
Now with the warm weather,my car is doing it again and i will go in there and clean and lube again.There was roughly a 4000 km interval since the last time i did this !

Cheers !
Phil

Did you jumper B & C to correct the idle per the instructions?

Also if you are a California car did you disconnect the brown wire under your seat?

Just and FYI - if the chip would have been damaged (bent pins, etc.) the car would not even start. It is a black-and-white scenario. Once it fires up the chip works.

If your air/fuel ratio is off there can be many reasons for it. Intake leaks, exhaust leaks, bad O2 sensor, bad AFM, CHT, and the list goes on.

Then you could have knocked off a spark plug connector or an injector connector. Test these first to rule out the simple stuff.

Ingo

I think there is also a micro switch on the throttle linkage at the throttle body. If it not working properly you will get idle running problems. Check the throttle linkage for full closing and listen for a small click from the idle microswitch .Even better to check it for continuity.

Yes. Thanks forgot that detail.

Nice info as usual guys. I don't remember seeing anything about a b-c jumper. But this sounds like it may not be relevant if the car only does it when very hot. Correct me if im wrong, but the jumper would cause consistent problems. I'm thinking that Wilcat077 (Phil) may be on to something. I remember that I took some of the play out of the throttle cable a few weeks back as long as I was under the car. This may prevent the microswitch from actuating when I let off the gas. I will definately check this.
Brown wire disconnected.
ISchmitz- there seem to be a ton of things that you mention may cause these types of problems. Is there a good place to start? Common vacuum leak areas or something similar? I know that it was the work that was recently done that is what's causing the problems. The car ran beautiful before. Literally like a new car. Thanks
Tony

BTW, does the jumper apply to my year? This is an '88 w/28pin chip.

Tony,

the "jumper" everyone is referring to is actually a homemade wire that is used temporarily to adjust your base idle at your throttle body. The wire "jumps" holes B and C at a service connector underneath the black plastic cover next to the coil. Your base idle is usually adjusted after any adjustments are made to your air/fuel mixture at the air flow meter (AFM).

I see. It seems as though base idle is fine. The problem is probably a sticky throttle cable or too tight of adjustment to hit the idle switch. All good ideas though. I always learn so many other things in searching for the anwers I need.

Yes base idle may be fine but stays high at times which was my problem. I fixed it by adjusting idle/air mixture and to properly do this you need to disable the volumetric control system hence jumper of B & C on left side of engine compartment. Invest in 101 Projects book.

Contact Steve as he will have valuable input to finding out what is going on. BTDT and the knowledge that he contributes is priceless.

As for the smoking your valve guides are very likely worn. If you removed the cat for the pre-muffler you will see the smoke that the cat burned up. I rebuilt my engine at 88,000 due to two broken head studs and worn valve guides. Mine didn't show any smoke until the cat was taken off. Beware of the "while you are in there addiction":D

Why not go with the obvious? If your car was running fine before and the only thing you did that would change these issues is the chip, why chase other factors? The exhaust changes won't cause the problems you have. There are several factors in chip construction, spark advancement, fuel ratio mixtures, and more. I would think one of these is not correct for your specific car.

Something like this I backtrack & check everything I did. I do it more than once if necessary. You might surprise yourself. Hope this helps.