How well does your MFI engine run?
 

I have been told more than once that MFI engines can't be expected to run perfectly, even by mechanics. I personally think this is total BS, but I myself have never been able to get a good steady idle at a consistent RPM (+-100 rpm), and my warmup performance (especially idle) has never been that great for the first 15 minutes I drive the car. I'd like to know if there really is a light at the end of the tunnel and a properly set up MFI 2.4T really CAN run as well as a carbeurated car.

I ask this mainly because I have never met (in person) a properly running MFI engine, but I have faith that they are out there!

This is a great question. I'm anxiously awaiting the results of this poll. Thanks for posting it.

I believe that not all porsche mfi engines were created equal in the driveability department. There have benn reports that the 2.4T is the hardest to get to run perfectly.

Michel Richard

After a complete tune-up by Otto, my 2.2E runs fine. Idle is low, but that is where John set it. Otherwise, very smooth.

Mine does idle fine, runs a little rich, but otherwise fine. It pulls like a champion to redline. I do, however, have some inconsistant issues that I attribute to my ignition and distributor(No time to tinker). I even have the MSD to install, just no time!:rolleyes:

At almost 49,000 miles on the old beater, the MFI is running just great! Idles smoothly, and pull like a freight train from 5,000 to the 7300 red line. And the sound of those stacks above five grand? MUSIC! :D

How long do you have to drive from a cold start before you get a nice smooth 900 rpm idle?

How about from a warm start?

This is all very good information and the 4 votes so far for "perfect" are encouraging.

From a cold start? I need the time for the oil to warm up...depends on ambient temp, but usually 5-10 minutes fo running does it. From a warm start? BOOM! I start the car, it idles smoothly..and this with the "wild" 911S cams.

My car runs great, just suffers from high idle. I am fairly certain I need to pull my throttle bodies and clean them thoroughly, run well enough that I can live with it until I feel flush enough to have the bodies and pump redone. The motor only has about 4K on it, so these would be the last mechanicals to be redone. It has been too hot to work on in the garage this summer, but Fall weather beckons! My mysterious over run backfiring summarily dismissed itself over the summer, may have been the JB weld on a couple of pin holes inthe muufler pending install of new SS muffler. I think there's light! ( a train maybe?)

After following the procedure provided by a wonderful article downloaded from the 911S registry site, my MFI runs really well ('70 911E, bone stock, 73,000K). Starting and idle are no problem, although I do make liberal use of the hand throttle. I'm sure it runs rich, but it is allways smooth and strong. The pump had been rebuilt by the previous owner. The throttle shafts are worn so my idle is a little high (1100 RPM). The car ran very poorly when I puchased it. By carefully following the procedure laid out in the aforementioned article, the car was transformed. If I can do it, anyone capable of following instructions should be able to do the same.

uh - people's MFI's DON'T run well???:confused:

Mine starts up and idles fine warm or cold (taking into account the usual fiddling with the hand throttle.) It sings happily right up to the 7000 RPM redline. The only "mod's"

1) MSD ignition
2) Cold start enrichment done at the solenoid rather then the infamous spray nozzles.
3) I adjusted the richness by feel since I don't have an gas sniffer.

If you are having trouble with an MFI engine running well, it is usually not the MFI that is the problem. The distributor, CD box, coil, plug wires, spark plugs and injectors need to be operating at a very high level, because with MFI they are being asked to! If after all these have been checked, repaired or replaced, and you are still having problems, then you can begin to look at the MFI for worn throttle bodies, pump, linkages, etc. Once all these are cleaned and checked, then you can begin to tune the rack with an air/fuel meter on a dyno. This is what I had to do with my 2.7RS MFI. We ended up replacing the plug wires, CD, coil, distributor, two injectors and cleaned the rest, adjusted all the linkages and then tuned it on a dyno. It does in fact run perfect now from idle to 7300 rpm, so it is possible to achieve, and it is worth it. :)