neward

I monitor my AF ratio meter, and notice that the indicator up to second bar in rich region (green section). Sometime I got some back fire and the exhaust tip turn black. I believe that is running little rich. The car's performance is excellent with AMF Autothority kits.

I think about replacing my ignition coil with Blaster 2 and MSD 6AL. Do you think it will help to solve my rich problem?

OriginalSterm

Do you have a cat? If not, that will cause a little bit of a popping sound in the exhaust. Unless your ignition is very weak, a new coil probably won't cause you to run leaner.

2nd green bar isn't that rich is it? Is that under idle or engine load?

neward

You're right, I don't have cat, and there are some popping sound in the back. Is that normal?.
Are there some unburn gas in exhaust and cause popping?

scottz

Was just reading the 944 FAQ and came across this section from http://www.986.org/sites/944faqs/Kev...Electrical.htm

The switch has detent positions so you can count the clicks to tell where you are set. All the DME boxes I’ve ever seen have been set on position #1, so I call that the stock position. The adjustments can be found in the following table:

switch position fuel mixture adjustment ignition timing adjustment
stock 0 0
2 +3% 0
3 +6% 0
4 -3% 0
5 0 -3 degrees
6 +3% -3 degrees
7 +6% -3 degrees
8 -3% -3 degrees

Maybe position 4 or 8 would help out? Anyone tried messing with these setting?

Rob

It has been stated in the past that the switch setting shown on that site are incorrect (correct for a 911?). Check out F.R. Wilk's page for the correct switch settings.

jimbo1111

Before I installed my wide band o2 I thought it was tuned good until I saw my midrange at 10.5 Rich with no noticable smoke. varify your a/f on a dyno or do what I and many on here have done, install a w/b. There is know other way to tune a car or know what's going on.

TurboTommy

What all did you do to your car? I don't know what "AMF Autothority kits" means. Generally I've found that the "cheapy" A/F meter gauges show leaner than it actually is (a good thing, i guess). You're probably running rich. Would need more information.

neward

AMF autothority kit includes air mass flow sensor, autothority chips and K27/8 turbo.
Jimbo1111. how easy to install wide band meter. where can I purchase at?
I don't know that I should change the switch to 2 to -3% of fuel mixture.

fast951

Do not assume that the FQS settings, as stated above, are the correct ones for the APE chips...

turbite

I wouldnt bother messing around with it, especially based on a narrowband.

When I bought my car it was <10 AFR in the midrange with no smoke, and the narrowband was in the first and second bar green (narrowband) at WOT.

Get a wideband or go dyno.

neward

where can I get a wideband?. I need to replace the oxygen sensor, is that correct?