3.2L Induction Options ?

[Tspringer]

Given the huge volume of problem threads on this and every other Porsche forum I have checked out relative to stock 3.2L injection systems (DME Motronic) and the fact that it appears a large percentage of folks have an extremely hard time getting this system to work correctly (it appears lots of folks NEVER get it to idle right) I am wondering if the best move is to simply trash it and start over.

Seriously, it seems to me that the DME Motronic systems are seriously flawed and give massive amounts of problems. At any given time, there are 2-3 active threads on issues with these systems and more often than not there is no happy ending.

Its gotten me thinking.... perhaps the real solution is to completely replace it with something either simpler (carbs) or more modern and effective.

So, going to carbs, would Weber 40 IDA's work? Are there any known issues? Are specs for jetting and such well known? I read in Bruce Andersons book about a stock 3.2 being modified to Webers but keeping the DME for ignition timing and getting some great looking HP figures. Sounds good.... but I would not want to keep the DME for timing, can an earlier car distributor be installed without having to dismantle the engine?

What about ITB EFI systems? Are there any proven and reasonably priced systems that would give more power, better running and allow the junking of the Porsche junk DME?

Any options are greatly appreciated.... pics are even better!

[MotoSook]

There is nothing wrong with the Motrinic system! Its actually very effective and reliable.


The problem with the Internet is that you only get a small sampling of any issue which then becomes the norm.

[Tspringer]

Yea...Yea.... I knew I would get the faithful in response and to be fair I do know that the majority of people have no issue, but that holds true with all mechanical issues. Browse threads here on Pelican consistently and the volume of Motronic issues clearly stands out. Honestly, I cannot think of any other single issue that is posted on more often from what I can tell.

Its a situation that to me at least screams for a better aftermarket solution.

[dion914-6]

I got rid of my Weber equipped engine for the motronic system, and I will never look back. Even with some of my idle issues, it still runs better than my car with those mysterious black boxes called webers.

[DUK]

Megasquirt your 3.2 and be very happy.

[Tspringer]

Originally Posted by DUK

Megasquirt your 3.2 and be very happy.

Do you speak from experience? Can you post some pics of a megasquirt conversion? What is typically used for ignition?

[DUK]

Yes I have a 3.2 in my '75 with MS running the injection and the msd ignition. My conversion is completely simplified from a typical one because I did a total rewire of the car. But it can be done with the stock wiring with a little patience and determination.

We did one about a year ago, I'll see if I have any of the pics. The hardest thing was doing the tps and intake air temp.

[DUK]

DIYAutoTune.com

These guys are the best and are in Suwanee.

[gregwils]

Originally Posted by Tspringer

Yea...Yea.... I knew I would get the faithful in response and to be fair I do know that the majority of people have no issue, but that holds true with all mechanical issues. Browse threads here on Pelican consistently and the volume of Motronic issues clearly stands out. Honestly, I cannot think of any other single issue that is posted on more often from what I can tell.

Its a situation that to me at least screams for a better aftermarket solution.

To be fair and you will find the same with CIS and carburetors too. You're probably right about the single most posted issue, but that would have to include the ignition aspect of the DME, not just the induction.

I would only swap mine out if there were a serious unrepairable failure, not as a proactive maintenance item.

[dion914-6]

If you are worried about cost, and assuming there is nothing seriously wrong, I find it hard to believe that a good mechanic is going to cost anywhere near a megasquirt conversion.

DUK, what was your ballpark cost?

[DUK]

Did it for under $600.

[Tspringer]

Originally Posted by DUK

Did it for under $600.

Whoa! Now I really gotta hear more!

Come on, details please and pics!

[MotoSook]

The DME system is very simple if you take the time to understand how it works...

Keep in mind I am also a defender of CIS. Plenty of Weber guys wish they could just hole in a drive off in a DME car.

You will have your fair share of megasquirt problems...we use to sell Megasquirt!

It's your car...do what makes you happy

[Todd Simpson]

OK, I'm not helping but Motronic has been great to me, in a bunch of different cars. Clean emissions, easy to start, solid idle, great mileage, easy to diagnose.

I won't tell you it howls like MFI or carbs, but you already knew that.

[dion914-6]

Unless they are starting to make plug and play MS kits, don't you need to be half programmer, half FI expert to put one together that cheaply? I'll admit, I haven't followed the MS threads that much.

Seems that the guys on the 914 boards have some success with these replacing the D and L jet systems, but they spend just as much time tryin to get them tuned in as they would trying to fix the original system!?

[Shaun @ Tru6]

Terry, Bosch Motronic is probably one of the most stable, reliable systems Porsche ever used.

A few things you have to consider these days when coming upon threads you mention:
1. Most people can afford a 911, not many can afford to properly maintain it. Problems are sold rather than fixed.

2. There are a great number of backyard mechanics who think they can properly diagnose and fix something as complex as Motronic FI with no tools, no experience and no analyzer. I've seen so many cars with WTF syndrome.

I've only had 4 Carrera's, and driven another 10+ of other friends cars, not a huge amount of data, but in my experience, Motronic has been as reliable as a front bumper. You get in, turn the key, it starts and runs.

Sure, when folks start mucking around with them, they won't behave, but that's anything.

If you are having a problem you can't solve, you must have a local shop that can diagnose and fix the problem. Certainly better than spending $3K to $5K for another FI system or carbs. I suspect your problem is the small breather running off the main oil intake on your oil tank.

Originally Posted by Tspringer

Given the huge volume of problem threads on this and every other Porsche forum I have checked out relative to stock 3.2L injection systems (DME Motronic) and the fact that it appears a large percentage of folks have an extremely hard time getting this system to work correctly (it appears lots of folks NEVER get it to idle right) I am wondering if the best move is to simply trash it and start over.

Seriously, it seems to me that the DME Motronic systems are seriously flawed and give massive amounts of problems. At any given time, there are 2-3 active threads on issues with these systems and more often than not there is no happy ending.

Its gotten me thinking.... perhaps the real solution is to completely replace it with something either simpler (carbs) or more modern and effective.

So, going to carbs, would Weber 40 IDA's work? Are there any known issues? Are specs for jetting and such well known? I read in Bruce Andersons book about a stock 3.2 being modified to Webers but keeping the DME for ignition timing and getting some great looking HP figures. Sounds good.... but I would not want to keep the DME for timing, can an earlier car distributor be installed without having to dismantle the engine?

What about ITB EFI systems? Are there any proven and reasonably priced systems that would give more power, better running and allow the junking of the Porsche junk DME?

Any options are greatly appreciated.... pics are even better!

[brads911sc]

$600 for EFI? Only if done totally rigged and half assed. My 24 Lb Fuel injectors alone were $300, MS 2 V 3.57 was another $400. Stainless fuel line and AN connectors another $400. Relay board another $100. Fuel Regulator another $150. This is NOT a $600 dollar project if done right.. All in with PMO ITB's, MS, Fuel Regulator, Injectors, Fuel Line, wiring loom, relay board, sensors, etc was about $5000 and its as professional looking as any Shop would do. Even if you use the T Bitz kit which means very little hardware its 3,000 with the injectors, kit, fuel regulator. I tuned it myself. Its about 90% there at Normal operating temps.... This is not a project for the faint of heart...

Originally Posted by DUK

Did it for under $600.

[brads911sc]

[Rodsrsr]

I've heard of CIS systems being somewhat troublesome but this is the first time I have actually heard anyone say the Motronic system is prone to problems. That was the one of the benefits of the 3.2 over the earlier cars. I personally think the system is almost foolproof. You also have to remember that a Motronic car can now be up to 27 years old, so some of the sensors like CHT and reference/speed should be replaced as they have served their purpose. New sensors, dme relay, and no vacuum leaks and there should be no need to mess with it. Mine runs like a perfect computer controlled car should every time I drive it.

[Lorenfb]

"I am going to have to dig out my manual and do some more research as I know nothing about the 3.2 injection system. IE - where is the O2 sensor?"

- Tspringer - 3.2 idles badly... hunting

Could that be the reason he started both threads???