mfi problems surprise surprise

Can all the learned folk offer me some advice with my Bosch MFI.

Its a 2.4S that was starting and running well but blowing smoke. Decided it was running too rich so had some idle and pump adjustments done. Bad mistake. All I have now is a car that runs very roughly when cold, backfires when cold and at constantly at higher speeds when changing gears. Can't seem to return to where I started from.

Yes, I know now we should have made notes how many notches both were changed. Car runs well after its warm, smoothly and with good acceleration.

Are we thinking pump problems that were hidden the the rich mixture originally or have I just stuffed up the settings now given that the car still runs well despite the constant backfiring i.e the pump is ok


Thanks


Clyde Boyer
Australia

When adjusted correctly MFI will run a very very long time without any problems. I have also found the only accurate way to adjust MFI is with a CO meter and a very knowledgable mechanic. There is also a document that walks you throught the entire MFI setup from the factory. I will see if I can find that and email it to you.

Dan

Hello

Did you cheked the microswith and working process from the stop selenoid ?

Did you checked your ignition ?

How about the pump timing ?

Touching the pump and Throttle bodys is the last step and if you get lost there you might not return to previous function.

Grüsse

Thanks Guys, I have obtained a copy of the Porsche MFI handbook and I am following it religiously, hopefully to a good conclusion i.e No pump problem.

We shall see!!!!



Clyde Boyer

Hi Clyde.
Before I would even start adjusting the pump and all other procedures in the factory manual, ckeck and make sure your throttle bodies and linkages are not excessivly worn. Then I would remove the pump, open up the side covers and thoroughly clean out the insides of the pump with brake clean. Also ckeck for any broken springs and free movements and replace the old cover seals..... That usually cures most of the problems if the pump is at fault.... figure 3hrs work.
Later, Robert......

And for more info than we could possibly post, here's a great link on MFI. Hope you have lots of ink & paper in your printer. ;)
Whoops...gotta try again! I'll be back...

Try once more...
www.pelicanparts.com/tech...TipMFI.htm

Ahhh, sweet success!

As the car actually runs well except for the continual backfiring the pump would appear to NOT be at fault if you can believe all the info around and thanks pwd72s there sure is plenty at that site.

I always thought that backfiring was more of a timing issue but perhaps not in this case.

I will gladly explore any ideas and hopfully track the demons down eventually.


Thanks

Clyde Boyer

Hi Clyde,

My MFI problems, which included some back firing, were traced to a loose wire on the rear fuse box that gave intermittent power to the Microswitch etc. Not sure if this helps but worth a mention

Regards
Dean
Brisbane

Hello

There are different types of backfire.

The upper and the lower backfires.

Mostly the problem is relatet to the fuel delivery and a amlfunction from the shut of seleniod.

Grüsse