[urq] dissin on CIS

[Scott Justusson]

LOL, I don't diss on CIS, I still have a couple, and work on several.  Let me share my 35 years of CIS experience (back to my 91 Pro Rally Scirocco), and 20 on urq's specifically.  First, the problem with urq CIS is not the starting... Several years ago, I had a 'sold' urq in my shop for almost a year, and when I needed to move it every couple months it started right up....  It's 'after' that cold start that 2 major issues come into play.

First one is a nitpick of mine, the Mac02 IMO, was never designed to have an Oxygen sensor.  When that circuit was added, there is a noticeable fallout stumble in the transition to Closed Loop operation.  I have yet to *not* see it in the 20 some urq's I've worked on, and the 'later' Mac02 programming slighting improved, but didn't eliminate the problem.  A finely tuned urq will have 'less', and average urq will have more.  I operate on two minty low mileage ones over the years, it's there...  Always.

Second, it's not the cold start, it's the hot restart that creates a problem.  This is caused by a hot turbo and exhaust manifold heat guns, located directly below the intake and cis lines and injectors.  Again, based on tune and hot start circuit condition, it can be 'better' or 'worse', but it can't be eliminated.  IME2 at altitude it's more pronounced (regardless of tune).  I have pictures of more than 1 urq at our early Steamboat urq reunions, of various 'non starters' getting towed around snow covered parking lots.

Lastly, any boost leak in an urq, will and can strand a driver on a restart..  A boost leak in motronic has to be a hose missing...  BTDT to both.  I will say this, I've never owned a CIS car without a 3mm allen in the glovebox.  Even my CISE cars have them, albeit not used often.

Me, I say anyone that hasn't owned or DD driven a Motronic converted urq or 4kq, will be the ONLY one's that will defend the CIS.  There is just a refinement there that can't be matched by the best state of WX tune.  I still own both, this is more obvious a statement than it might appear.  

Finally, you guys need to really look at the resto-mod market to understand where the market trends are.  Guys that can afford $30k+ urq's (or 50k muscle-cars) don't want to carry tools, work 3mm allens, don't want to have a hot start problem with the valet on a night out in their toy, don't want to be stranded for a flooded urq.  They want to get in the car a drive it like their wife's toyota SUV.  Not borrow the wife's SUV because 'urq happened'.

Performance tuning?  Only an incidental, not primary benefit.  I will say this, a 2.5bar chipped 3B with a k24 is what I DD in my 4kq.  Without question, it could have 'more', but the torque and the response and refinement of this setup, is really tough to beat.

There is nothing simple about CIS sitting on the side of the road with no tools, and pissed off passengers.  BTDT2.

Cheers

Scott J


 -----Original Message-----

From: urq <urq at pacbell.net>
To: urq <urq at audifans.com>
Sent: Wed, Jul 10, 2013 10:17 pm
Subject: Re: [urq] dissin on CIS


I agree. It is difficult to beat CIS for simplicity.  While I no longer have
the WX, my plan is to complete the MC-2 in my car with the CIS-based MAC-12
it came with ... the MC-2 can put out some pretty good numbers and retains
the character I like from the original powerplant.  

I suspect many of the folks who love the 20V/EFI are looking to tweak their
powerplants for maximum power ... and there's little question that a modern
EFI system can optimize the combustion process for each cylinder.  The thing
is that I know folks who have done the 20V turbo swap into their urq and
have spent a lot of time troubleshooting issues ... 

I think it is a bit of a crapshoot ... either version can be easy or a PITA
... perhaps it is the luck of the draw ... 

Steve Buchholz

-----Original Message-----
From:  Stephen Kraus
Sent: Wednesday, July 10, 2013 4:40 AM
Subject: Re: [urq] dissin on CIS

I like CIS, and its actually fairly adaptable. I thought it would be a pain
to re-setup on my engine swap, but it actually worked like a charm On Jul
10, 2013 1:30 AM, "David Glubrecht" <daveglu at hotmail.com> wrote:

> Does everybody have such big problems with CIS?  I have none.
> Drove an 84 4kq to ~350k miles and needed 1 pump.  Don't drive it much 
> now, but occasionally need to move it and it fires right up and runs 
> fine after sitting months at a time.
> 83 UrQ same
> currently using an engine and CIS from a 87 5kt in a project that sat 
> for
> ~10 years.  Was careful to put fresh fuel right at the dist, (jump 
> start the fuel system with another car) and hacked it to run without 
> the computer (because racecar).
> We (teammate and I) run a couple of old CIS basic systems on other 
> cars actually hacked to run an ABA 2.0l motor.
> Although I will certainly go to aftermarket stand alone EFI on my UrQ  
> when I get to my 3B conversion.
>
>
> David Glubrecht