1994 Nissan Sentra SE-R going VEMS, then turbo.

[BenFenner]

No way... That's just ridiculous if the RWD and FWD SR20s are that different.
Do you have access to a RWD SR20 that you could measure the distance from the plug seat to the valve cover seat?
I can compare it to mine and see if it'll work.

I was going to go COP anyway, and I have the money, so I don't see a reason I shouldn't do it. I'm pretty sure the spark issue with VEMS was just my insane negligence securing the ECU connector properly. I do still have problems with my outputs, mainly the P259 channels, but possibly INJFET channel 4 as well (it won't control my idle valve), but that's not going to be affected by swapping to COP.

Edit: I can always ask the guys at www.sr20forum.com if the COPs will fit. They'll know.

[rob@vems.co.uk]

My COPs are at the engine builders, and he's not around to measure them.

The heads are different in that they have the distributor so the rocker cover is not designed for COPs rather for the HT plugs, I think the FWD is the same as the Pulsar which has slight changes all over the place - like solid lash adjusters rather than the hydraulic rubbish that the RWD has.

Its not so much about the money, for me its always been about seeing what's available and trying different configurations.

You can force the INJFET channel by deselecting it from the idle control, and using it on the WOT/RPM actuator so that you should hear the solenoid click - or better use a voltage meter - when the throttle is pressed.

As for the P259, its a very low current device so its possible that its not with us any more   Not too much of a problem as theres lots of other channels to choose from.

[BenFenner]

Is there a common point of failure for the P259 channels? Maybe a fuse, or a resistor or something that tends to go? I can open up VEMS and try to locate/replace it. I'd prefer to get them back. No doubt it was some crappy grounding that ruined them back when the cable was loose. =/

[rob@vems.co.uk]

What goes is the p259 itself, and what usually happens is it blows when EC36-pin26 is connected when the other grounds are not, or when the other grounds are connected and EC36-pin26 are not.  The reason for this is that we keep the low current grounds seperate from the high current grounds so that an external connection allows the rise in ground voltage to average out across both circuits, if the connection isnt right the high current side will ground through the P259.
When this happens the chip blows and pulls the voltage supply to the VR sensor chip down - which is why I was asking if you were getting an RPM reading - but I forgot that the Hall inputs are not effected by the death of the P259.

The P259 can be replaced, but its a surface mount component so it requires some smooth skills with an iron, the first one I did had me binning the PCB, so now I use the smallest side cutters I could find (trust me they're uber small), cut the pins so the chip comes free (some people use a razor blade to saw through the pins), then desoldering the pins.  I have replaced the chip, but with a 4 cylinder I dont bother, I use the FETs and IGBTs to drive the relays and solenoids.  For fuel pump and fan relays you have the possability of using the steppers, in fact any solenoid that draws less than 1Amp can use them.

[BenFenner]

So I'll still have enough outputs to take care of a boost controller, and possibly one or two other components?

[rob@vems.co.uk]

Yes, loads of the things!  I prefer to use FETs and IGBTs first because their current handling abilities are so substancial, then the stepper outputs as they'll handle 1amp and have internal flyback.

[BenFenner]

The consensus is that the RWD COPs are not a direct fit. Apparently a bunch of guys are having success in California running the COPs from the Honda CBR 600 motorcycle. I've found a good set with pigtails on eBay that I'll be purchasing. It should be around $75 USD shipped.

[BenFenner]

The auction for the COPs ended last night. They sold for $29 shipped to some other guy because Dan's wireless internet sucks. Lesson strengthened: don't try to bid snipe on eBay with a crap connection. There's another for sale in 3 days I'll jump on. More time without the car. =/

On the bright side, Dan's car is running well. See his thread for updates.

[rob@vems.co.uk]

Get down to the scrap yard and get an EDIS-4 coil pack off a 4 cylinder Ford engine, that will have you running wasted spark which will be a good stop-gap until you can get the COPs you want

Rob

[BenFenner]

Good idea. I'll give that a try.
How would it be wired, and what ignition settings should I use?
I assume it's pretty straight forward.

[rob@vems.co.uk]

EDIS-4 wiring is pretty well documented across the web, give it a google for the pin outs (I dont use the Ford ones myself otherwise I'd tell you from memory!)
You group the two cylinders that come to TDC at the same time so if your firing order is 1, 3, 4, 2.  You have 1&4 using one coil, 2&3 using the other. 

Ignition outs are 1..0 and you could use Coil00 and Coil01

I do remember the Ford EDIS coil needs a dwell/charge time of 3.8ms (why do I remember crap like that, I don't remember people's birthdays), add 1 to 2ms for the 6V value.

[BenFenner]

I got the COPs in the mail today. We've installed them and tried again to set the timing correctly. We seemed to be able to get sort of close, but we just can't seem to get the value of 'TDC after the trigger' between 40 and 60. We tried different values for 'Trigger Tooth' but we don't seem to be getting to where we need to be. Can 'Next Trigger Tooth' be changed from 6? Can we put it at 12 maybe?

Perhaps if you'd be so kind as to explain how these values work in a coil-type trigger. I've read Chapter 9. Sensors and it seems to be very good for missing toothed wheel information, but I just can't seem to wrap my head around how my trigger works, and how the 'Trigger Tooth' and 'Next Trigger Tooth' values correspond.

There's some good news though.

TDC after the trigger: 14
Trigger Tooth: 0
Next Trigger Tooth: 6

This gets me to 0 degrees BTDC, and when I put 10 degrees for Cranking Advance, the timing advances 10 degrees. This is a first I believe, or the first time this has worked in a long time. Usually adding cranking advance has had no effect on the timing.

Still, I believe we are in a bit of a rut. I'd like to get this worked out, as the car won't seem to start anymore. It may not be related to this, but I thought we should get this right first.

[rob@vems.co.uk]

Okay, so if cylinder 1 is at TDC 14 degrees after the trigger then we need to start looking at the next cylinder in the sequence - set trigger tooth to 2 and start timing the TDC value.

Did you try moving the disk round the other direction?  That will give a different trigger geometry.

[BenFenner]

Did you try moving the disk round the other direction?  That will give a different trigger geometry.

We were going to do that today. We'd stopped because it was raining, we were frustrated, and it was late. We'll try both suggestions.

[BenFenner]

Dan and I are going out again tonight to try to figure this out. I know Rob, that you understand what you're getting on about, but it's agonizingly painful to try to read into your instructions when you leave so many things out (you seem to assume I know what you know, which if that were true, I wouldn't be asking), and fail to answer the (mostly) simple questions I'm asking. I'm not saying I'm not infinitely grateful for the help you've given, I just feel this whole process would go much faster, and would involve much less of your time and effort if you'd take another second or two to actually answer the questions I've posed. It's nice to get advice, but a lot of the time I have a problem, post the problem, and then ask questions about it. I'm trying to gain the information it will take to solve the problem. The advice is good, but if it doesn't work, we're at square one again, where-as if you'd answered the questions too I'd have 30 or 40 other things I could try in a night before coming back with more information. If there is a website where my questions are answered, by all means just point me the way.
If you feel it a waste of time to flesh out your explanations, think of it this way: if you can get me up to speed to the point where I understand what's going on, with my Nissan at least, I can help your work load on the forums quite a bit by answering other people's questions. I'm the helping type. I will do it, I could teach others too. I see how much time and effort you put into this alone. This may be a way to help ease that. This is what forums are for, after all.


I understand how the trigger system works with a missing tooth wheel. How does it work with a wheel like mine?

How does it decide which of the 24 holes to use for TDC when it can't possibly distinguish between them?

What does 'Trigger Tooth' mean in my context?

What does 'Next Trigger Tooth' mean in my context?

Does it make any sense to change the 'Next Trigger Tooth' value to something other than 6? (I've tried and got interesting, possibly helpful results, but I don't know if they are red herrings or not.)



The last instructions you gave were to try flipping the disk, which we plan on doing first. You also mentioned we may

need to start looking at the next cylinder in the sequence - set trigger tooth to 2 and start timing the TDC value.

My firing order is 1-3-4-2, so you want me to put the timing light on cylinder 3, change the 'Trigger Tooth' value to 2, and try again to time to TDC? This was my parsing of your directions. Dan seems to think you can't possibly mean what I think you mean.





We'll have more information when we get back from working on the car, but our hopes aren't high.