StrokinIT

Hey everyone, I have a 1976 280Z with a few problems right now that I'm trying to sort out before I start upgrading. I bought the car a few years ago and just finally got it on the road last year, sort of. We bought the car from CT and trailered it back to NH. We hadn't registered it or anything due to it being late fall, winter was coming, and we were going to begin the restoration on it that winter. So the only driving we did with it was in the neighborhood in mostly first gear. At the time I knew very little about cars, and we had a "reputable" shop look over the engine and they gave it a clean bill of health. Fast forward to last spring, and the car was finally ready to get on the road. It went back to the same shop to diagnose why it was idling poorly and sputtering under throttle. $350 later and the invoice says "check fuel, make adjustments" and it is still running as crappy as before. So I finally took it to a Z specialist who fixed a few vacuum leaks, replaced some of the fuel lines with actual fuel hoses, and then told me that he thinks the cam timing is off. Since I didn't have the money to shell out for him to do any more investigative work, we were unsure of whether or not it was the timing chain needing replacing or that the head was shaved and the cam towers weren't shimmed properly. Also, my headgasket leaks a small spurt of oil out of the front passenger corner whenever the car is shut off, but my compression seemed fine. Well, relatively low across the board (which could be due to the cam timing being off?) but it is consistent. Sorry for the long backstory, I just wanted you guys to have enough information to help without guessing and wasting your time. Anyhow, my goal for the car is to replace the factory dished pistons with flat tops, but keep the 2.8L displacement. I have an N42, with unknown amounts of headwork, I'd have to sort through some old paperwork from the previous owner. I believe he had a 3 angle valve job, aftermarket cam, new valves and valve seats, possibly rockers and springs. I will check on that tonight or tomorrow and post up that information. Of course, doing any sort of head/cam work on the stock ECU is somewhat pointless, so I was going to go with megasquirt. My question is this: I've heard that you want to get your car in proper running order BEFORE you set up megasquirt or other ECU systems, reason being that you already know your engine can run properly so you know when your tune is good. Does it make sense to get a stock N42 head to try and get my car running properly, then get megasquirt? Or should I go ahead and do the timing chain, new pistons and headgasket, then install megasquirt? Thank you all in advance, I've been stressing out about which way to go with this for quite some time now.

Tennesseejed, I believe you are talking about the auxiliary air regulator, but please correct me if I am wrong. I'm also almost positive we did that test and that there was no change.

Hopefully someone can confirm or deny my suspicions here. I have a 1976 280z, and I dropped my car off at a local shop, they've usually taken pretty good care of me, my dad, and my brother. However, they mostly do older muscle cars, not so many older imports pass through there. Any way, my symptoms are high idle that can't be lowered via the idle speed screw; hesitations and stumbles during acceleration under 3500 rpms; occasional backfires after these stumbles; I have no way of telling if fuel mileage is abnormally poor or if its because I just tend to keep the car at higher rpms so that it won't stumble. The car runs well above 3500 rpms though. We already replaced the spark plugs and the auxiliary air regulator, they helped a little bit but it still has most of the symptoms. I have read through the EFI Bible and come up with a few suspicions that I wanted the shop to look into for me. I asked them to check: -valve clearance -throttle plate closing -AFM has proper movement -check for intake manifold leaks -check fuel pressure With the combination of issues that I have, my hunch is that there is an intake leak somewhere, or the throttle plate doesn't close all the when the throttle is released, however I could be mistaken and there could be more than 1 reason for these symptoms. I spoke with them today and asked how the tests went and they said they were trying to get it to idle properly before they would do the tests. This doesn't make a whole lot of sense to me seeing that one of the main reasons I brought it in is because it doesn't idle properly. My thoughts were that if they performed those tests, it would guide them to the problem so they could fix it. I know more about cars in theory than I do in practice, so maybe I'm missing something here, but do any of those tests require that the car is running optimally before they be performed? I do have an aftermarket cam in there from the previous owner, and just sent them a scan of the cam information. I know aftermarket cams don't really get along well with the factory EFI but I would have thought that the cam would cause the idle to be lower by having less vacuum at idle and low rpms. I will attach the JPG of the cam information card for reference. In case its hard to read, the lobe separation is 110 and the intake opens at 7* BTDC. Thanks in advance, Josh

Thanks guys for the answers, I think I should be able to run the fuel map based on speed-density using the MAP sensor. However the main problem I'm running into right now is how to control spark with MS. I can't go check right now since my car is at my dad's house, but I think the 76 distributor has a VR sensor in it, correct? If so, I can set it up so that MS reads the VR sensor and subsequently will be able to control the spark. I would like to eventually convert to EDIS but I don't feel that I could properly install that setup myself while the engine is still in the car, and have it running for this summer. I have literally spent about 5 hours reading up on the spark aspect of MS yesterday and today, and am so confused. So if someone could clarify the best way to go about it with my current setup (stock 76 distributor), I would be eternally grateful. Thanks in advance.

Yikes, I'm not sure if I can afford that right now. Perhaps I should be looking for an open 3.9 for now, you wouldn't happen to have one of those as well would you?

I hadn't really placed a price limit on it yet, was just looking for something reasonable. How much are you looking to get for yours?

Hey guys I currently have a 76 280z with headers and exhaust, intake, and an unknown cam. I believe the ignition system is stock, and so is the ECU. I’d like to upgrade to megasquirt to take full advantage of my mods, and have a few questions. I went through the thread on “MS useful thread links†and found this thread <http://forums.hybridz.org/index.php?showtopic=48292> thinking it would have some answers. It was very informative but is a few steps ahead of me right now. Can MS control spark based off the 76 distributor? Or am I limited to controlling fuel only until I upgrade to a different ignition system? Based off of what I read in Braaps thread “BRAAPs L6 EFI-induction advice and tips,†the tuning I need to do to take advantage of my cams and exhaust work is tuning the fuel maps with MS, and then I can mechanically tune the distributor to get the proper ignition timing. One thing I’m worried about is, do I need to get a throttle position sensor? Or is MS able to read off the stock throttle position switch that I currently have? I believe the stock ECU is closed-loop until ¾ throttle and then is open loop above that, so I feel that I could run the stock throttle position switch and then when that switch tells MS to go from closed loop to open loop, have the open-loop tables based off of MAP instead of TPS? (I have never tuned before, so I’m not sure if that idea even makes sense. What would the closed-loop tables be based off?) As for the MS system I am looking to get, I was thinking of getting this unit (http://www.diyautotune.com/catalog/megasquirtii-ems-system-smd-pcb357-black-case-p-171.html). I was thinking this unit because I would eventually like to be able to control spark as well, and have been considering the idea of a turbo build in the future, so I think this system would allow me to go in any direction without having to upgrade my ECU system in the future. I would also be ordering a wiring harness for it, an IAT sensor, wideband O2 sensor, and a MAP sensor. What is the difference between an open and closed element IAT sensor? As for the wideband 02 sensor, it seems most people use the Innovate one, but I heard that they burn out relatively quickly, and was thinking of going with the AEM kit (http://www.summitracing.com/parts/AVM-30-5130/?rtype=10). Does anyone know if MS will play nice with this gauge? I think this might cover most of my questions, although some of them are probably very basic. I appreciate any and all feedback you can give me.

I would like to buy a 3.9 LSD, as well as the correct speedometer cog. Will need it shipped to 03249, or can pick up local in New England area. Thank you. edit: must be an R200 by the way.

Thanks so much, I will try this later on in the week and hopefully I can track down the problem.

Thank you for that information, however I'm still slightly confused. The rheostat, is that the dimmer knob down and to the left of the steering wheel? The one that dims the dash lights? When we were checking these connections, it was generally my brother and I outside checking for the running lights to come so I do not know whether or not the dash lights even came on at all, but before when the running lights came on with the brake pedal, the dash lights never came on. Could it be that there is some interference at the rheostat? And if so, would I need to get behind the dash (or take it out) to get to it? Also, what do you mean by jumping the wires? Sorry for the extremely simple questions, my car is currently 75 miles away and my dad isn't home so I can't have him check for me. Thank you

Ok, so I was finally back up at my dad's house this past weekend and we fixed the issue where the running lights only came on with the brakes. We think it was caused by using double filament bulbs where single filament bulbs should have gone. We put the proper bulbs in and not only are the brake lights and turn signals much brighter, but the running lights no longer come on when the brakes come on. Except now, we can't get the running lights to turn on. We were messing with the wires in the combination switch on the steering column, and from time to time we would be able to get the lights on but pretty much anything would cause them to turn off, e.g getting out of the car, coughing, pretty much anything that would send any sort of vibration through the car to move any of the wires just the tiniest bit. We have the FSM for my 76 280z and I spent a couple hours looking through the wiring diagrams, and I thought I had figured out which wire was the one to control the running lights (Green with white stripe), but that didn't work. Does anyone know which wire from the combination switch actually controls the running lights? I am back home now and will be back up to my dad's on Thursday night for a long weekend. I am planning on registering my Z this week and this running light issue is the only thing keeping it from passing inspection right now. I would gladly appreciate any and all help. Thanks again.

Thanks Oddjob, I will look into it. I had a hunch if it wasn't a direct wiring issue it had something to do with a ground issue.

The brake lights only come on with the brake pedal pressed. The side marker lights and running lights only come on when the brake pedal is pressed, regardless of the position on the headlight switch on the column.

Hey everyone, I couldn't find any information on the exact issue I'm having, the only thread that seemed somewhat similar was the one started by Josh817, Help! Running lights are dead on my '72 240z, any clues? however our running lights aren't blowing fuses; although we haven't been able to keep the running lights on long enough for a fuse to really have the chance to blow. So here is what I am experiencing. My running lights do not come on when the lights come on, they only come on when the brake pedal is pressed (whether the headlights are on or not). My dad and I think that we might have wired something wrong in the steering column, does that sound right to anyone else? Has anyone else encountered this issue themselves? Thanks, Josh

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