Why didn't I do this years ago!!

[krasuskyp]

Originally Posted by full quack

You know ignorance is bliss....right up until somebody (or even yourself) enlightens you......then you just feel like a moron, sheezzz.

No worries - Ima moron too... you're in good company.

er - wait - maybe that *should* worry you?

8-)

Originally Posted by full quack

....it's sunny in Seattle...all is good!

Mark

Gee, THANKS - we got all yer rain here... f'n monsoon here again. Course I took the 'ole hooooor today in anticipation of the rain lifting early... bzzzzzt.

[Miguel Antonett]

Guys, not to highjack the thread - but falls under the same title, I just refurbished the suspension bushings and schocks... WHAT A DIFFERENCE on the car... amazing how we get used to sloppiness.

[911st]

...You would be sucking in un-metered air anytime vacuum was present, and leaking out pressurized air when on boost. Bad scenarios, both...

If there is a brake in one of the tubes or the can to atmosphere that could be a vacuum leak of unmetered air with the typical effect?

If the internal spring or the diaphragm fail, I am thinking the deaccel valve would just effectively pass air around the throttle plate with no effect on metering but it would effect idle quality.

The effect might be unstable idle, lazy return to idle, and or no of the intended de-accel valve function.


The thermo time valve closes the Vac-Retard line to the pot on the distributor which has the effect of advancing timing and speeding up idle speed.

If it fails open, idle would be low on start up. If it fails closed idle would be elevated when hot. If it fails creating a restriction it might slow the return to idle.

Disabling the thermo valve should make for a lower idle speed when cold.


It would seem that either or both of these could have created the issue Dave described.

[RarlyL8]

Yes it us easy to get used to CIS components slowly degrading in function.
I stripped the CIS completely off the engine and rebuilt then returned only the critical components; fuel head and WUR. I found the AAR, CSV, and TTS not necessary where I live.
EFI? Not a proponent at this time but I understand why some are. When EFI works it works well. I've heard soooo many nightmare stories of $10K builds that never run right and are not supported by the manufacturers. CIS is crude but the gap is bridged by adjustable or custom WUR's. For a fraction of the cost of EFI you can rebuild or repair the entire CIS. I think for most, EFI is best left to the 400+WHP builds.

[drmatera]

I'll argue the cost point of EFI. There is absolutely no need for a $10K EFI conversion on a run of the mill street 930.

I also find humor in the guys that say "your going to trust your $20k Porsche motor to a $500 EFI system?" while they are using an antiquated worn out poorly controlled rube goldburg fuel system. Please don't take offense as i am not being mean-hearted or cruel. Just an observation from someone that switched from CIS to EFI

[Craig 930 RS]

EVERYTHING is off my car. Only thing remaining is the WUR - all else....gone.
Just needs a bit of foot for less than a minute upon startup until slightly warm -

[911nut]

Originally Posted by e170drvr

Hmmm, I just put my decel valve back in.

Me too. Finally couldn't stand the loud popping.
Figured out how to fix it (was getting very slow opening).

[911st]

EFI or CIS, it is all good depending on your point of reference. Me I find CIS interesting and vintage.

I guess one could put an ITB EFI system with distributorless ignition on a 73 RS and it might run better, get more MPG, make more HP, and be more drivable.

However, it just would not be as much fun and a lot of what makes it an RS would be lost!

EFI is probably better in most cases but I love CIS!

[drmatera]

911st - well said

[911st]

[mark houghton]

Originally Posted by drmatera

I'll argue the cost point of EFI. There is absolutely no need for a $10K EFI conversion on a run of the mill street 930.

I also find humor in the guys that say "your going to trust your $20k Porsche motor to a $500 EFI system?" while they are using an antiquated worn out poorly controlled rube goldburg fuel system. Please don't take offense as i am not being mean-hearted or cruel. Just an observation from someone that switched from CIS to EFI

Well that pretty much sums up CIS. Yep, pretty old-school I admit. But if you're a tinkerer and love being pissed off all the time because one of the many CIS components just isn't quite working in unisen with everything else, then CIS is for you. I think there's a point where we run out of patience and say F- - - it, I'm going EFI.
But you hit the nail on the head....."poorly controlled" CIS is a bad thing, but properly set up they work just fine...until they decide not to. I swear, it keeps me in league with the Devil's brew.

[RarlyL8]

You haven't experienced pissed off until you witness a guy $30,000 into his 3rd failed EFI system. All done by "reputable" shops.
There are stories for every situation. It realy boils down to what you are comfortable with, what your goals are, what your skills are, and budget. I wouldn't even attempt an EFI conversion unless I could do it all myself.

[drmatera]

Rarlyl8 - you could megasquirt/EDIS6 your 930 over the weekend. But you are right, buying the fancy ECU's capable of launching the Space Shuttle into orbit can be a bit daunting and very complicated.

If people could just get past the low price of MS and realize the hardware it uses is better than some $2500 units on the market they would understand us MS'ers and why we are passionate about it. Just the timing control should be enough to make you guys switch

Most of you guys that tune and maitain your 930's could do the conversion easily

[mppickett]

I agree about the value of the Megasquirt EFI system implemented with an EDIS6 ignition module. There is a growing number of folks running MS and most are ready to help out. It is better if you have someone in your area to help you tune, but with the new TunerStudio and a starter map, you can get a pretty good install and tune over the weekend.

It helps if you don't mind wiring and using a computer. If you can hack your CIS, you can learn Megasquirt.

[mark houghton]

So, the total cost of a megasquirt conversion? Part numbers, stuff like that, or do you need to call the dudes at Mega to design specifically for the 930? (not that I'm planning on changing from CIS mind you, but who knows where the future will lead)?

[RarlyL8]

I looked into Megasquirt about a decade ago and assume they are more advanced now. It looks easy enough but I was always bothered by the thought of one bad electrical connection and you are stranded. Mechanical systems tend to fail gradually where electrical systems fail instantly. I am sure that modern electronics have come a long way in their robustness.
There is a Megasquirt kit out for the 911SC which I also looked at to modify for use with the 930. Anyone interested in MS for the 930 should take a look at this too. The biggest expense may be the custom injector spacers.

Back to the original posting; realize that removing these faulty CIS components makes the system less user friendly. Arguably, a brand new 930 of yesteryear started and ran like an EFI 930 of today, when all the CIS components were brand new and functioning perfectly. I've worked on a few garage queens that operated in that manner. Layers and layers of CIS gizmos that all play a little part in making the operation of the engine seemless. Granted, EFI is a lot less complicated in appearance but do remember these cars didn't run bad when new.

[drmatera]

Brian, Megasquirt has come a long ways. Besides none of it's electronics are inferior to other EFI systems, in fact better in some instances, but I understand you about electronics failing instantly.

The simplicity of mechanical injection does have apeal but I wouldn't trust it for making big power reliably and repeatably.

Originally Posted by RarlyL8

I looked into Megasquirt about a decade ago and assume they are more advanced now. It looks easy enough but I was always bothered by the thought of one bad electrical connection and you are stranded. Mechanical systems tend to fail gradually where electrical systems fail instantly. I am sure that modern electronics have come a long way in their robustness.
There is a Megasquirt kit out for the 911SC which I also looked at to modify for use with the 930. Anyone interested in MS for the 930 should take a look at this too. The biggest expense may be the custom injector spacers.

Back to the original posting; realize that removing these faulty CIS components makes the system less user friendly. Arguably, a brand new 930 of yesteryear started and ran like an EFI 930 of today, when all the CIS components were brand new and functioning perfectly. I've worked on a few garage queens that operated in that manner. Layers and layers of CIS gizmos that all play a little part in making the operation of the engine seemless. Granted, EFI is a lot less complicated in appearance but do remember these cars didn't run bad when new.

[drmatera]

Mark, The cost depends on what intake you use (Carrera or stock with adapter blocks). I went over what I spent in my EFI post. If you factor in the factory parts I sold the net cost was extremely low.

[mark houghton]

Sorry, missed your original cost estimate. $500 net with selling the stock stuff.

For simplicity I would probably keep the stock intake. Though I would probably keep all stock pieces just for posterity...or for that buyer 30 years from now that will pay $150,000 for a stock 930 (asuming we still have gasoline available by then, and assuming I make to 87).

Who distributes Megasquirt systems, or is it a direct buy from the company itself?

[drmatera]

Megasquirt is available from a number of places. I buy from DIYautotune. com . It helps to contact them to discuss what options you want as they will build it to order. And they have good customer service. Matt is who I deal with.