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

[BenFenner]

We've managed to get timing working pretty well (minor fluctuations, but we're attributing that to timing chain slop). We had to unbolt the distributor and turn it to an extreme angle (much more than normally available).



It seems the CAS disk is just not designed to work with the FWD set-up. Flipping the disc only gives a couple degrees difference.


We have spark timing working as well as we can hope for right now I think. A permanent solution will have to be found, but for now I'd just like the car to run. It sputters and can rev if throttle is applied, but it seems we're only firing on a couple cylinders. I'm pretty sure our injector output order is fine:




And I think our Ignition outputs are fine:





But we really can't find any documentation on the h[1] reference tooth table. When we change the order in this table, we get either just cranking, cranking and popping/sputtering, or cranking and almost idling but very rough.
What should we have for this table?

[rob@vems.co.uk]

The H1 table is a tricky one to describe and we're still kind of working on it, the values are degrees of trigger seperation, and the ones I supplied will be correct for the trigger you have.  I derived my h[1] table using the setup described here:
http://www.vems.hu/wiki/index.php?page=MembersPage%2FFero%2FSUPRA

What I'm trying to say about the triggering can be seen in the H[2] table, if you rotate the numbers from 0, 1, 2, 3 to 3, 0, 1, 2 you can get sensible timing figures with the CAS in is 'normal' position.

[BenFenner]

Worked on the car the other night. I'll give the short story. Transposing the ignition outputs gave great results, advancing the timing terrifically. The distributor could be placed in a normal spot, and

Trigger Tooth: 3

and

Next Trigger Tooth: 6

are in use. Timing is behaving a lot better now, and seems to be fine now.

The car started and ran a little bit (timing light said it was idling at 40 degrees BTDC, when distributor was turned to retard timing to 20 BTDC the idle got very rough). It seemed my car liked 40 degrees BTDC which I know is wrong. We put the timing at 15 degrees BTDC for cranking and the car wouldn't start anymore. We advanced timing to 40 degrees BTDC and it wouldn't start. I'm pretty sure we just flooded the crap out of it, so I'm gunna give it another go soon. Stay tuned for updates.

[rob@vems.co.uk]

Nice

[BenFenner]

I skipped class today because I thought I was getting somewhere with the car.

Milling things over lunch, Dan and I recalled that when the car did run that one time we noticed spark during cranking at twice the rate we normally see. When we changed the settings back to the preferred settings, we get slow spark again. Wanting to work with a running car tonight, we transposed the ignition outputs one more time (which we did the last time) and just let the car be at 40 degrees advance where it seems to like things. The car started up and would idle pretty well. We slid the distributor around to see where the engine liked it to be, and it seemed to prefer 40 degrees BTDC give or take at idle.

So right now the ignition outputs are:

0  ->  1 (pin xx)
1  ->  0 (pin xx)
2  ->  3 (pin xx)
3  ->  2 (pin xx)

Trigger settings are:

Trigger Tooth: 4

Next Trigger Tooth: 6


We figure the timing readings have to be wrong, but we go ahead and get the tach and fuel pump working on injector channels. We tried to get the radiator fan and idle control to work on the injector channels as well, with no luck.

After the car warmed up, we turned it off, and tried to start it again with very minimal luck. We tried messing with the cranking enrichments, but that didn't get us very much. We left the car flooded, and went to do school work.


We're running into a new problem, as all this has completely killed my starter motor. It makes a high pitched howl more and more often, and when it does, the engine cranks very, very slowly. I'm pretty sure I'm looking at a new starter motor (this one is a factory Nissan unit, only 3 years old) which is extremely annoying, but what ever. It just makes it even harder now to work on the car when we can't even rely on it to work correctly when we want it to.

I'm wondering how this timing situation can occur. We're using an inductive pick-up timing light on the negative side of plug 1. Should we be able to time this way? We've tried putting a wire between the coil and the plug on cylinder 1 to give the pick-up the correct signal at the correct time, but we didn't notice a change. We want to try it again to make sure.




I'm really tired of all this. I feel my car should have been running/working properly a long, long time ago. I'm so close, I know it. But now I have a starter replacement in my future.

Damnit.

Sorry for the rant. I just needed to vent. =/

[BenFenner]

I have a new factory re-man' Nissan starter on the way. $200 USD after core return.

...

=(

[danmartin]

Apparently I know what I'm going on about and I adjusted his setting some and the car starts right up. Next up we are going to time the cop set up properly. I'm thinking of shoving a wire into coil and connect the other end onto the plug and use that wire for the inductive pick-up. Hopefully we will be tuning soon.

[BenFenner]

Yah so, apparently you can't time COPs without cheating a little. Timing the negative return line just doesn't cut it. After finding a way to time correctly, we've found that we're not 40 degrees BTDC, we're spot on 15 degree BTDC during idle. Timing COP problem solved.

And hey, the car idles.

Let's take it for a ride.

Oh, what's that? No power?

Hey, what's that smell? Burning shift linkage bushings? You guessed right!

Hmmm, maybe we should take the car back home and check things out.

Billows of smoke coming from above the catalytic converter sound fun, but really aren't.

Let's pull the plugs and see what's up. Yes, yes, cylinders 2 and 3 plugs look brand new! Let's check the firing order. Yep, it's 1-2-4-3. That's all wrong. It should be 1-3-4-2, right? That's what it says on the distributor...

1-2-4-3   needs to turn into:
1-3-4-2   

Let's swap the output after cylinder 1 with the output after cylinder 4 and we should be on our way!

0  ->  1 (pin xx)
1  ->  0 (pin xx)
2  ->  3 (pin xx)
3  ->  2 (pin xx)

turns into:

0  ->  3 (pin xx)
1  ->  0 (pin xx)
2  ->  1 (pin xx)
3  ->  2 (pin xx)

Let's check the firing order. Yep, spot on. 1-3-4-2. Let's rock and roll.

Oh, the car doesn't want to start now. Awesome. No luck at all. Switch the outputs back.

0  ->  1 (pin xx)
1  ->  0 (pin xx)
2  ->  3 (pin xx)
3  ->  2 (pin xx)

Just for kicks, let's switch the two we didn't touch before and see what happens.

0  ->  1 (pin xx)
1  ->  3 (pin xx)
2  ->  0 (pin xx)
3  ->  2 (pin xx)

Why try this? Because we're cah-ray-zeee! Start'r up Dan-o!

Oh, listen to that engine purr. Why is it purring? Who knows?!

Let's check the timing again with our trusty timing technique. 15 degrees BTDC. Check.

"Dan, when Rob hears about the output order we're using, he's not going to believe us."

Time to go inside and post on the VEMS forum.

*type* *type* *type* Hey Dan, these tables don't make any sense. Seriously. Wtf? I must have fucked up the wiring of the coils. Yep. I must have. *type* *type* *post picture of timing technique*

[BenFenner]

We took the car out to do some tuning. We've got some work ahead of us, but the car was driving very well tonight. We had some break-up at 4,400 rpms. We made sure we weren't running lean, and narrowed the problem down to ignition. We lowered the dwell time from 8.0 to 3.0 and the break-ups stopped.

Oh, and my shift linkage doesn't feel like molasses anymore. Hurray for self healing bushings!

Oh, and my starter doesn't seem to howl anymore. I think I'll cancel the order on the new starter and wait it out for a while.

Hurray for self healing starters? *shrug*

[danmartin]

Yeah Ben timed his ignition by ear. We started the car up the other day (once it did start that is) and he turned the distributor untill it sounded right to him, happened to be exactly what it should have been as we found out tonight. Yeah and when Ben says we made sure it wasn't fuel he means he wouldn't tune it past .80 lambda. I ragged on him about it but I guess he didn't want to take the chance after not having his car for a month. Now we just need to get a timing table dialed in and start tuning the fuel. Also his idle control doesn't seem to work, but neither does mine and I manage, hopefully this will be sorted out later.

[rob@vems.co.uk]

Well at least you're having fun with it!  Engine management is as pleasant as self-harming but leaves less visible scars

When timing COPs you need a short HT lead with a plug cap on one end and a connector on the other.

Idle controllers are fun, is it actually getting driven or is it that its getting driven but its not controlling the idle?

When you start off PID tuning you can set I and D to zero and mess with P to get a responsive system but with out the I&D factors it will cause the RPM to fluctuate, some people, dirty people that they are, then use the Ignition Based Idle control to damp out a badly tuned PID... One individual who will remain nameless decided against an IACV and has a 45degree spike in the bottom left hand corner of his map - when the car goes to stall it moves towards the advance spike which causes the engine to rev...  It hunts like a bastard when its cold but it keeps the engine running!

[BenFenner]

The idle control valve isn't even being driven.

We'll be looking into it very soon.

Thanks for the advice on that, hopefully I won't have to resort to drastic idle measures. =]

[BenFenner]

I canceled the order for the new starter motor. We'll see how long mine behaves.

[BenFenner]

I wanted to get this posted before I go out tuning tonight.
I worked on idle control today, and narrowed down the problem pretty quickly to a specific part of the stock engine harness that did not have continuity. I'm so glad I'm back to dealing with things I know well. Needless to say, it was a quick fix once I narrowed down the offending section of harness. I was just about to run new wire when I took another look at the idle control valve connector:



I've never seen anything like that before. Dan is blaming it on copper eating worms. Sounds plausible to me. Anyway, I fixed that up and the idle started working. It needs some tuning itself, but the car is very drivable now (didn't idle as well as Dan's without idle control) so I'm a very happy camper.

[BenFenner]

I got the idle working a bit better. Not great, but good enough for now.

Dan and I went out and did some 3rd gear pulls, 2nd gear pulls, 1st to 2nd to 3rd races, and one massive, clutch smoking, 6,000 rpm failed launch (Dan forgot my clutch is towards the end of it's life). We got the car tuned pretty well under full load. Partial load still needs some work, but cruising out to the vacant road and back gives enough time to get cruising points tuned pretty well.

Nothing else to report really. Things are going really well.