new tech article at sdsefi.com: batch vs sequ.

Steve Arndt · Post by **Steve Arndt** » Wed Aug 29, 2001 3:12 pm

http://sdsefi.com/techseq.htm

I own both a batch and sequential ECU, projects out the wazoo!

Steve

ray greenwood · Post by **ray greenwood** » Wed Aug 29, 2001 6:15 pm

I work on them both and this gentleman has laid them out pretty nicely. There were a lot of question about the D-type and its batching (type 3 and 4). Yes at idle, you will find the intake ports to be a little wetter, but at speed...its not even an issue. VW/bosch knew about the timing issue a long time ago. The D-type distributor gives just at 180 degree injection activation per side. With the crank making revolutions at 2 to 1 to the distributor...thats 360 degree possible injection sequence on each set of paired injectors. This is not to say that the injection duration delivered lasts for the full 360...thats up to the ECU and the rest of the sensors. But it does give a lot of possibility with tuning it. In my 412, I have adjusted the location of the trigger points to allow a little different injection location to help out the increased lift and duration of the cam. I start a little earlier. The problem is, two injectors inject pretty close to the time that their valves are about two open..and the other two are about 90 degrees away from that point in the stock set-up. Moving the points advanced them both. So the retarded pair is now at about 50 degrees advanced and the other is actually a hair retarded. I also moved the advanced pairs fixed contact inward a little to start its injection early and reduced the height of the cam follower to make sure it didn't lift too far, which would slightly offset the timing cycle start point in the ECU...because it would take too long for the points to close. It helped huge! It also helps to smooth the pulsing of the fuel pressure...which can be read from the guage. It changed the position between the start and finish of the two timing cycles..which helps give time to re-establish the fuel pressure in the ring after injection...hence the fuel guage smoothed out. I am testing a distributor...P series that I have installed a split cam in for the FI. It use the same two trigger points with one using a bridge on the low side of the cam and one a bridge on the high side. The two cam lobes are 90 degrees offset to each other. This starts the timing cycle 180 dgrees faster...so only allows 180 degrees of crank rotation in which to inject. It also will require the ECU to switch these two cycles twice as fast. I don't yet know if it will keep up. With less time to inject...exactly 1/2...I will probably have to move to injectors with almost double the flow rate...or 1/2 again the flow rate and a higher pressure rating. All being said...it will allow all four injectors to fire within about 15-20 degrees before their valves open...in pairs. I'll let you guys know how it works in a few weeks. I still have a few things to do, and I have to find the exact set points...as both cams now have set screws to hold poition on the shaft. Ray

Duc · Post by **Duc** » Thu Aug 30, 2001 8:02 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Steve Arndt:
 http://sdsefi.com/techseq.htm

I own both a batch and sequential ECU, projects out the wazoo!

Steve<HR></BLOCKQUOTE>
What did you use for your sequential setup to give you the reference point. I have seen some "disributor" replacements that just give an ECM the cam timing, does anyone else remeber seeing this?

Derek

ray greenwood · Post by **ray greenwood** » Tue Sep 04, 2001 4:46 pm

I attached a volt meter to each injection lead and turned the engine over by hand to get an idea of where each injector at least is enabled to fire (window). Of course how many degrees of revolution it stays firing is up to the ECU...I used a dial indicator at each intake valve retainer to see where the valve was when injector was enabled. I found one pair close to 90 degrees out in advance...and the other about 10-15 degrees into the the valve cycle before it fired...which means it was just starting to lift off the seat. My object was to put one cam at about where the 10-15 dgeree range was give or take, and the other as close to the beginning of the valve opening point as possible. I opted for around 90 degrees later from this for the second set. That would be 180 degrees of crank...putting the opening point about smack in the middle of the valve cycle for the second pair in actuality, which is a littt;le more advanced than the first pair at 10-15 degrees. I will probably have to move it more. I'm still looking for a pair of higher flowing injectors with the right resistance before I try this. The problem is (and the reason why the original points are set 180 degrees apart) is that one set of contacts has to be closed before the other set is enabled within the ECU. Right now, they way I have them set up...I am using two stock 180 degree duration distributor cams. The other set of points will inject once the first is closed, even if they have been opened during the other pairs duration....but both cams are overlapping right now. I know it will run and start, and that I will have to reduce each cam duration down to something like 90 degrees each, but before I start removing material....I want to get it started. By the way, the programmed valve timing method is what the L-type actually uses. Thats why it does not have the trigger points. The reason why this system (L Type) is not as tunable as it should be is because it sets itself up according to program and ignition timing/RPM...and cannot be manually set, one way or the other for non-stock usage. Let ya know how it goes. Ray

ray greenwood · Post by **ray greenwood** » Wed Sep 05, 2001 2:13 pm

Steve, let me know what kind of sensors you find, please. I have thought about going to optical or magnetic triggers either inside the distributor...or on the crank also. Finding a sensor to take the heat and oil has not been a problem. Finding one that will cycle fast enough to do 5000 rpm top end has been nearly impossible...and still fit in the size requirements. Ray

Steve Arndt · Post by **Steve Arndt** » Wed Sep 05, 2001 11:18 pm

I am either going to use the distributor for cylinder #1 reference, or drill and tap the case and actual camshaft, and install the sensor in the case. I have found a sensor that can take the heat and direct oil contact and work inside the case. Some Ford racing engines use this system from the factory. I will probably use the distributor initially, and reference directly off the cam in the end.
Steve

<BLOCKQUOTE>quote:<HR>Originally posted by Duc:

Originally posted by Steve Arndt:
http://sdsefi.com/techseq.htm

I own both a batch and sequential ECU, projects out the wazoo!

Steve<HR></BLOCKQUOTE>
What did you use for your sequential setup to give you the reference point. I have seen some "disributor" replacements that just give an ECM the cam timing, does anyone else remeber seeing this?

Derek

Duc · Post by **Duc** » Thu Sep 06, 2001 6:03 am

Ray and Steve,

The easiest thing (maybe) to try is the distributor that runs on buses. It does have a sensor in it, what that is I don't know as of yet. I have been thinking of how to do the FI onmy T4. Here is what I have come up with:

Crank sensor
Stock one on the flywheel ( had my fly milled down so don't know if it will work)
Custom toothed wheel behind pulley (faster calculation of speed change)

Cam sensor:
Stock Distributor for FI ? but I really want to go without the distributor
Cam only sensor that goes in the distributor

I found a similar device that was used on a Ford here:

http://www.alternativeauto.com/waterbox

My long term goal is to run one of these CD DIS systems from MSD:

http://www.msdignition.com/1dis.htm

What other sensors are you running?

Derek

ray greenwood · Post by **ray greenwood** » Thu Sep 06, 2001 9:35 am

Duc, I would love to replace the dist triggers with something that is easier to maintain and adjust...but whatever I use has to be cam based...to use the D-type. The crank travels at twice the revs. as the cam. The ECU would not be able to work with that. I believe the dist. sensor you are finding for the later buses is for engine speed sensing and timing. It will not work with D-type. I would rather stay with D as it is much more adjustable. I was not able to get onto the site with the Ford on it. I would bet that it is crank triggered. The possibility of going crank triggered with D-type is there...but you will need one contact point to be able to to duplicate the timing cyle of the brain , as it was based on the cam. That would leave injections happening way out from correct locations. If you went to 2 contacts...they would be injecting at effectively 90 degree intervals to the cams 180 interval. I'm not sure if they could be spaced to the right place or not...or if the ECU could cycle that fast...its all resistors and diodes. Four contacts would be ideal...split the injector grounds apart to let them inject individually...but then you are alternate cycling at four times the design speed...something to explore. Ray

ray greenwood · Post by **ray greenwood** » Thu Sep 06, 2001 5:59 pm

Yep...hall sensors are the way to go, just finding size that will fit two in Dist. and be compatable in resistance ranges will be some experimentation. I'll check out the site...see what I can use. I have taken the stock system a long way...this is the next logical mod. I am also working on a vacume breaker package coming from several manifold positions to act as a 3 stage "sustainer" system for the enrichment diaphram in the pressure sensor, to keep from losing enrichment for a split second when opening throttle from a standing start...into a gear-change. This is one of the hard to tune out ,charateristics of D-type. Ray

Steve Arndt · Post by **Steve Arndt** » Thu Sep 06, 2001 11:15 pm

Duc,
I already have a 2.1 vanagon dizzy. I'm going to remove three of the four vanes from it, and that will work for the cylinder #1 reference for my SMC Autronic. This is common. Steve C. and another guy on here both use this system already.

Ray, finding hall sensors that work up to those frequencys is not difficult.
sensorsolutionscorp.com
browse through their magnetic proximity sensors.

Steve