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L28 4bbl EFI build - help/input wanted!


michael wales

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Took the Z out for its first long drive today. A good mix of city and highway out to Poquoson, Va to Tidewater Z Auto Service. The Biggest difference isn't performance wise, Coming from triple webers I wasn't expecting much change there. Its the responsiveness and smoothness. My Z seems like a completely different beast now. Idle is smooth and consistent it needs no warm-up time and highway and city driving were both pleasantly uneventful. I am beyond happy with the changes in everyday drivablity with no loss of performance and the ability to make drastic performance improvements in the near future. 

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Next question is how/if i can to get the timing control activated. It needs one of these apparently

 

http://http://www.summitracing.com/parts/msd-8421?seid=srese1&gclid=Cj0KEQjwmqyqBRC7zKnO_f6iodcBEiQA9T996HxnWaph7nVBK2s-gXx3bXg-a7RKNyWfqm08GAeygm4aAm8n8P8HAQ

 

but i don't know how i  would get the MSD part to work on my Mallory distributor

 

http://www.summitracing.com/parts/maa-4563901/overview/year/1977/make/nissan/model/280z

 

Anyone have any experience with this?

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Also if anyone has any insight of a blow thru setup I would really appreciate it. I have the manifold and stock turbo but I will be pretty much winging everything else. I'm sure there are atleast a few build threads with carbs that should be very applicable and even a link would be great.

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post-29167-0-76566600-1431628103_thumb.jpgpost-29167-0-92128400-1431628113_thumb.jpg

 

Before i take the Z to the Tidewater Z car club show this weekend i figured id give it a once over to check the new setup and replace the sparkplugs so i can keep an eye on the supposed AFR discrepancies that the 4bbl intake can cause. according to ngks own guide my plugs look fine but these were admittedly ran on my triple setup for the last few years and only about 150 or so miles on the new setup.

 

 

 

 

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Nice work here. Glad to see that manifold is going to good use ( I sold it through Gnosez). I'm also surprised to see how well this MSD EFI system is working for you. For years these types of systems (Holley) has been poor. Glad to see MSD got it right.

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EGT Probes and WBO2 sensors in each port will be a bit better than plug reading for cylinder-to-cylinder variation.

It will be difficult to get more than a 30-second top gear pull to get requisite stabilization for accurate readings.

 

Using plug reading to try and counter AFR/EGT information garnered from instrumented Dyno (Engine and Chassis) testing is not really accurate. As some would say "comparing apples to wheels"!

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The MSD Comes with one wideband that it uses to monitor AFR, beyond that will probably be beyond what I am capable/willing to implement I.e one WB02 for each port.. As far as Egr I'm assuming this is usually done with a probe/gun while on the Dyno?

 

On another note I may have made some strides towards getting the ignition timing under control of the MSD Unit. I was able to speak with eiji Of Datsun spirit while attending tidewater Z car clubs show this weekend and he expressed that he should be able to mate the adjustable rotor to my distributor.

 

On a third note my Z took home 3rd place!

post-29167-0-67808000-1431897171_thumb.jpg

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Both the AFR and EGT are done using a header modified for the requisite instrumentation. Data logging consolidates the readings to a single timeline making interpretation easier.

 

EGT is limited to a 25F spread generally. The WBO2 in the collector is used for ECU Correction and is logged against the individual cylinders.

 

That was all done on an engine dyno so it was possible to hold load points precisely for stabilization of the readings.

 

At least that's how we did it building up the Bonneville car, and again with JeffP's Turbo Prototype.

 

There are 6 cylinder Aircraft Engine Analyzers that make this type of monitoring an in-dash affair in regards to EGT.

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well after putting some decent miles on the system i have run into a road block. 

 

my car is currently having an intermittent no start situation. The MSD EFI unit is not receiving any output from the dist/6al ignition box. at first MSD tech line told me i had wired it incorrectly to start with and that was remedied by running the tach input for the EFI unit to the spade connector on the 6al for tach output.

 

this resulted in a quick start for my car and all seemed fine. after trying again i am again having strange symptom where it only shows rpm outputs immediately after i release the key from cranking but again is not starting. I think there is an issue with the wiring mess i have where the ignition(key on) positive is as there are multiple connections that i have no idea where they go or what the function they serve all connected by a single nut and bolt. this is in addition to some other wiring that is around the factory ballast resistor that seems questionable.

 

i also noticed while i was checking the connection from the mallory distributor to the msd box and the tach out put connections that there seemed to be some type of relay turning on and off that i am unsure of both its location and function and i am no longer hearing (i heard it click right before it started last). 

 

i know this is alot and probably not the most coherent. i will try and update after i work with msd tech line hopefully i can get some resolution to my no start issues.

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You didn't mention the basic "confirmed spark" or "starts with starting fluid".  At least you'll know if it's spark or fuel.

 

The Unilite modules aren't the most durable, I think.  Here's a test procedure, if you find that you don't have strong spark - http://static.summitracing.com/global/images/instructions/MAA-unilitedistributorwiringdiagramtestproced.pdf

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Time for basics.  Power to coil, etc.  You just installed a completely new electronic fuel injection system, MSD ignition system, and electronic distributor (assuming the Mallory is not points).  Some meter work should be a piece of cake.  Seems like you're in denial that one of your new parts might have broken.  Could just be that a wire fell off. 

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this will certainly be within my means, just the main thing (electrical/wiring work) that seems to overwhelm/ confuse me it seems. I wish i was able to work from scratch and not have to infer and work through so many changes and modifications from previous owners/mechanics over the decades. The intermittent nature and the strange rapid clicking were what made me think there must be a relay somewhere underhood that is responsible for the seeming lack of power. I will update when/if i make any progress on this front.

 

Thank you for your inputs I appreciate and willingly take any and all info from the more experienced and knowledgeable around here. 

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UPDATE:

 

After tracing and confirming all of the wiring related to the ignition was intact and in good condition I decided to start testing the individual components. Everything seemed normal until i opened the distributor and noticed how filthy it was. It seems that the self contained optical module was covered to the point that it was not registering that the engine was turning over and not sending either spark or registering engine rotation to the EFI either. I was both shocked and amused at how such a simple act such as wiping the module between optics solved what was such a perplexing issue. 

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The cover was missing on the optics?

 

I've seen a few CAS units that someone took that cover off, never knew why they didn't put it back. I retrofitted Opticals into cars that now have well over 110,00 miles on them without covers but they aren't as fine-sized as the Nissan Stuff.

 

Some VW & Suzuki Distributors (and my high boost turbo) have a cap venting system that draws in filtered air from the air cleaner, to the cap, and then into the intake vacuum source. Keeps filtered, fresh air in the distributor flowing...meaning under boost there is a lot less chance of ionization in the cap and jumping spark somewhere other than where it's supposed to go.

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After doing some research it seems the optics are left open with a rotating disk (looks like a open circular drill bit) with cut outs serving to shroud and un-shroud the the two lenses from seeing each other. Seems odd to me as well that this is left to collect dust and debris but I guess they were expecting the module to fail before it was as filthy as mine was, mallory seems to have poor reviews all over and may no longer be made in the configuration I have. Either way I'm glad to have the Z going again and I'm going to try to move forward on collecting the final bits for adding the turbo.

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