84 Carrera 3.2 rough running at low RPM

[Cwglade3]

Thanks in advance Pelican Team...

I have an 84 3.2 that I purchased 2 years ago and put about 1500 trouble free miles on....I drove the 911 for a week without issue being shipping her Germany.

She arrived last week Rotterdam and I drove her without incident home... 600km

BUT, noticed that when cold stared she idled continuously at 1200/1500 RPM, normally during warm up she would seek for a minute or 2 and then go rite to 800RPM....

She is also running rough under 2,000 RPM "city driving"

I should mention this is a 45,000 mile 911 in amazing condition which is why I bought her !!!

Lastly she is outfitted with a Monty Dual Exhaust System, Steve Wong Chip and Autothority MAF unit....all from PO

The only new variables that I can think of are 2 fresh fillups of German Bezin "GAS" and now being on a different continent..

Over 2,500 RPM she performs her Magic and driving the Autobahn in her is a real treat..

Thanks in Advance for any suggestions

Also anyone heard of Motol ???? I cant get Brad Penn here

[Caferacer]

Do you know what octane the SW chip is programmed for? Also, I am no expert but I wonder if a bottle of Techron might not help...

I have no doubt you will get some excellent advice forthwith from the real experts!

[Tippy]

Mine has ran rough under 2000 since I've owned it.

Now, it won't even run without bucking/surging/cutting out until I am above 2000 RPM.

The chip burner for mine (it has a turbo) says I need to adjust the Lambda screw (it moves the vane inside to adjust AFR's) under the Airflow Meter. To do it right, you really need a wideband O2 to adjust it correcty in my opinion.

I wanted to rule out everything else before adjusting AFR's (air/fuel ratio) on mine - so I wasn't masking something like a vacuum leak or faulty sensor.

I would do a search for your exact symptoms (bucking, surging, hesitation, etc. for Carreras), kick back, and start reading. There's a lot out there.

There are some experts like Steve Wong, icschmitz, Lorenfb with great advice.

[stlrj]

Start with an ignition tune up and mixture/base idle adjustment.

[ischmitz]

Oha, here we go again.....

Cwglade3, I suggest you do a search with the key words "Carrera DME idle" and there will be many many threads coming up with lots of good information. Most will suggest doing a regular tune-up (plugs, cap, rotor, filters) first and then start looking for reasons that can cause the rough idle.

From there on out it's a slippery slope where you'll get bashed for having a chip, be warned not to simply "mess" with adjustments, be told to throw parts at it, etc. That's when the fun begins. Read for yourself and you'll see.

Cheers and welcome to the board. Post a picture of your ride when you have a chance and haven't already done so.

Ingo

[Tippy]

Ingo (sorry to the PO for hijacking but I never got word on mine),

Is there anything in the DME that can cause his symptoms which are just like mine?

Is it chip related?

[ischmitz]

Tippy, I thought you planned to go back to the vendor of your turbo setup to confirm what modifications are made to the part-throttle maps and what the fuel pressure is supposed to be.

While not likely a stock DME can go bad to where one of the inputs doesn't work. However, the first steps are to look for the obvious (tune-up, throttle linkage, idle switch, etc.). After than you check the mixture and then if it is off do some more troubleshooting to find what's causing it.

[Tippy]

Went back to vendor and he stills wants me to adjust AFM and world fuel settings in the DME.

[Cwglade3]

All

Thanks for so many responses !!!!! so quickly...

I started with Basics....

I ran a Bottle of Techron thru the fuel system yesterday !!!! Amazing... she is back to normal ...drove her 200km...95 Octane fuel

Scheduled her for a full tune-up next week...Plugs/wires/cap/ rotor/ fluids and filters

Any input on Motul for my oil change ???

Thanks

Charles

PS how can I identify the Specs. and actual SW Chip that my Carrera is running ??