Tennesseejed

I didn't intend to turn Matt's OP into my personal idle troubleshooting thread. So, apologies if it seems that way. Hopefully, some of this information might be helpful to current and future MS tuners. I wanted to add this information to one of my previous posts, but can't seem to figure out how to edit, so a new post seems necessary. Without using IAC, there are not many factors that effect idle quality aside from MS settings. Basically, you have the condition of your (1) cap, rotor, wires, and plugs (2) valve lash (3) ignition timing and (4) any potential vaccuum leaks. My intake manifold is stock/non-egr and shaved. Having decided that a MS setting of 3 squirts/simultaneous provides the best idle potential for my car, I set about to adjust the valvle lash and check the iginition timing. Surprisingly, adjusting the valve lash had had a significant effect on idle quality. All other things remaining the same, tightening my valve lash to spec caused the idle rmp to drop. Not exactly sure why that is the case. My ignition advance also had moved to 22 degrees BTDC. The distributor bolt was tight and timing was previously set at around 15 degrees. Returning the ignition timing to 15 degrees made the idle more stable. And lowering the timing further - to around 12 or 10 degrees - would likely increase idle stability. In addition to Matt's idle tips link above, the Fuel and Injector section of Megamanual suggests using alternating squirts for best idle. I did not find this to be the case after comparing similar maps using 2 squirts/alternating and 2 squirts/simultaneous. Essentially no difference between the two. Just my observation. The Megamanual also suggest manually adjusting the VE table at the idle point to obtain the highest vaccuum. I found that manually adjusting VE values around the idle point had virtually no effect on the idle rpms and MAP reading. Not saying this is bad advice, just that in my experience it was not helpful. As others have pointed out, I did find that a richer idle AFR smoothed the idle and reduced the lag or stumble when transitioning from idle to part throttle. 13.5 to 14.0 is in the ballpark for my application. Why adjusting the VE table did not produce a similar result is a bit of a mystery. The last observation may be specific to my cam (Stage III - 270.280/.460). While a pretty puny cam compared to many of the other HybridZ cars around here, the cam does seems to need at least 900 or 1,000 rpms to draw enough vaccuum to idle stable. Below 800 or so rpms, the MAP reading drops dramatically (80-90 Kpa(?)) and the engine slowly dies. My mechanical cam timing was adjusted within a degree within the last couple of months and my head is recently rebuilt. So I have no reason to believe that this condition is related to an engine issue other than the normal operation of the camshaft. Idling at 900 or 1,000 rpms, the car now transitions smoothly between idle and part throttle and the idle quality is not nearly as rough as in the beginning. I gave up trying to turn for 6 squirts/simultenous. While I am not sure why, probably inconsistent fueling across the rpm range due to very low pulsewidths, I could not get the VE table to tune at all using Tunerstudio/Live VE. Maybe someone else will develop a good 6 squirt tune down the road.

Good point, and it helps me understand the 'dynamic range' issue better. With a ReqFuel of 11.8, three squirts adds 2.5ms (14.3ms total), and six squirts - as you point out - adds 6.25ms (18.5ms total). The IDC with three squirts is 75% at 6K rpm and 90% with six squirts. Pretty much maxing out turbo injectors on a NA application at 6K. I stil plan on fooling around with six squirts a little more, just to see if it will tune and idle better, but I'll certainly keep things a low rpms.

Ha, you are absolutely correct. On the other hand, being an optomist, glass is half full kind of guy, if I lose an injector driver, my engine will be running normally at least half of the time. I managed to get the 3 squirts/simultaneous VE map tuned pretty well. The 6 squirt/simultaneous is a work in progress. Having a very hard time getting consistent AFRs. I'll do some more testing before jumping to any conclusions.

Rough idle is the final gremlin I have to slay with my MS install. My car is NA N42/N42 with a 60mm TPS and no IAC. Nissan turbo injectors w/wideband. Although I have a mild cam, my idle surges 200 rpms with a base of about 1000 rpms and the car shakes like I have a V8 under the hood. It's pretty annoying. Until yesterday, all of my .MSQs have used a ReqFuel of 11, and 2 squirts/alternating. If memory serves, I used 2/alternative based on info in Megamanual. When I initally wired my injector banks, I thought I was clever to put 1, 3, and 5 on one bank and 2, 4, and 6 on the other. The idea was to spread the alternating squirts as across all cylinders as evenly as possible. While it didn't hurt anything, I don't think this idea accomplished anything useful either. Might also be exacerbating my idle issues. ? As noted in Matt's idle tuning tips, lowering my idle AFRs from 14.7 to 14.0 did help my idle a little. What made a significant difference was changing from 2 squirts/alternating to 3 squirts/simultaneous. I referred to the permissible injector firing graph in thefuel injector section of Megamanual. The manual does state that increasing squirts per ignition event smooths idle. In addition to a smoother idle and less rmp surging, the car also doesn't seem to hit so hard when the accelerator pedal is pressed, i.e., the throttle is less twitchy. Just so you know, changing the number of squirts requires a new VE table, so you can't just change the number of squirts and expect the same operating AFRs. As soon as I get my VE table adjusted to 3 squirts/simultaneous (shouldn't take long using Tunerstudio Live VE) I am going to work up a .MSQ for 6 squirts/simultaneous. Six squirts is the only greater option than three squirts simultaneous (assuming you are not full sequential using MS3). The one potential isssue with going 6 squirts/simultaneous is that, according to the manual, the 'dynamic range' of the injectors is reduced. While I'm not positive what this means, I think it means that because your injectors are firing much more often, the total amount of fuel that the injectors can deliver at high rpms is reduced. Someone please correct me if this is way off. What ameliorates my concern about reduction of injector dynamic range is that I'm using 265cc turbo injectors in lieu of the 185cc stockers. This could be an issue for other folks though. Another potential issue with 6 squirts is that the idle PW becomes so low that idle fuel consistency is at risk. According to my 'engine constants,' 3 squirts is a calculated PW of 3.9ms. Going to six squirts will halve that PW to a litle under 2ms. This could be too short a period of time to get consistent injector firing. Dunno. I'll try to add to this after futher expirementation. There should be a single injector firing setting which works best - or is at least consensus best among L6 squirters - with the stock intake manifold. So far, I'm a fan of 3/simultaneous. More to follow.

2s2Mad, our AFR tables were very similar. My car is NA with a stage III cam. A couple of days ago I evened the table out some by lowering the cruise area from 14.7 to 14.0 and bumping up the the high rpm areas a bit. Best tune I have run to date.

Well that is curious indeed.

I don't think your electrical problem lies with MS. MS is a load in your electrical circuit. In other words, MS only uses, but does not produce, voltage. And while MS does provide some regulated voltage (5VDC), there is nothing about the operation of MS [that I know of] that can cause your system voltage to spike to 19 volts. My guess is you have an intermittent diode (very rare) or a an intermittent short in your voltage regulator.

Select any valve where the cam lobe is not contacting the rocker arm. Remove the mousetrap spring. Loosen and lower the rocker pedestal (not requried, but makes it easier). Using a long flat tip screw driver (or a short pry bar), press down on the spring retainer using the underside of the cam as leverage. Press the spring down far enough to slip the rocker arm and then remove the lash pad. One question I would have is since your engine does not appear to be stock, without pulling and measuring all of the lash pads (a big pain), how can you be certain that one lash pad you measure is the same as the rest?

Yes, the AAR, which from your OP I see you already replaced. BCCD is good suggestion. Also check the little hose from the manifold to the fuel pressure regulator. The problem with the stock EFI system is that its filled with 35 year old hoses and fittings. I was always troubleshooting FI problems on my '75 until I went Megasquirt. Then I wondered why adding Megsquirt wasn't the first thing I did when I got the car. Dead reliable.

I wired my car without a relay board. Didn't see the need to use one. Wasn't so much a cost issue, as a desire to keep things as simple as possible. I started by looking at the wiring diagram at http://www.megamanual.com/index.html (the V3 schamtic) and the EFI wiring diagram from the EFI Bible (http://www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf) The wires on the stock EFI harness are numbered so they are easy to trace between the engine bay and the pigtail at the EFI box. I located my MSII box where the stock EFI box was and then chose which factory wires to use based on thier use in the stock system, i.e, a ground wire, a battery voltage wire, a sensor wire, etc. In the end I made only one mistake and cut one corner. The corner I cut was not bothering about having my fuel pump turn off when the key is "on" and the engine is not running. On the stock system, the fuel pump relay switch is in the AFM. Since the AFM goes away with Megasquirt, so does the circuit. I could have designed something similar, but just really didn't care enough to bother. The one mistake I made was wiring the IAT sensor. The factory wire I used to connect the IAT initially received battery voltage when the key was turned on. Because the IAT sensors works by having 5VDC applied from the MS box, the added DC voltage cause the sensor reading to default to 70 degrees. When I put a DMM (voltmeter) on the sensor and discovered 15 volts, I realized what the problem was. Simple enough to grab another wire from the stock harness for a substitute.

Josh, check the warm up air bypass system (I can't recall the proper name off the top of my head). Bascially, there is a valve that shunts air across your throttle body that closes after the car warms up. It's bolted to the top of your intake manifold right behind the throttle body. The FSM says to test by pinching the hose after the valve when the car is warm to see if the idle rpm changes. These things notoriously stick open allowing extra air causing both high idle and back fire from lean running condition.

Bummer. You could have a bent valve, a bad valve seat, or one of the valves on cylinder #1 slipped its retainers. You can check the last one without pulling the head. Not so for the other two.

Simon, Send me a PM with your email address and I will send you a good N/A fuel only .msq. I took a quick look at your .msq and saw that you are trying to run the Alpha-N algorithm. Alpha-N is mostly used for ITBs.

Building a race engine and noone checking the wipe pattern on the rockers? No. That doesn't make sense. Your assumption only addresses the change in distance between the crank and the cam sprocket. Your assumption doesn't account for a smaller base circle on a lumpy aftermarket cam. You are probably looking at a new cam, rockers and custom lash pads. I recently cut .050" off a N42 to go with a stage 3 cam. After shimming the cam towers, I ended up using lash pads between .175" and .254" in order to get a consistent wipe pattern close to the edge of the rocker stud side. A page back in this thread you mentioned using .170" lash pads, which I assume you meant on all cylnders. There is no way that you can shave a head, use an aftermarket cam, and be able to use .170" lash pads on every cylinder. I hope you can salvage your current cam and rockers. You have an awesome build going and I absolutely love your car. If you do end up buying new lash pads, instead of trying to buy a bunch of different sizes, consider buying them all at the tallest height you need and then having a machinist trim them down to the exact size you need. Either Xnke or 1FastZ recommended that to me and it was a really good idea.

Shiggy, I was actually incorrect to say you needed the '74 throwout collar. I got confused with all the dates because you have an '80s L28ET with a '77 tranny in a '74 Z. If you have experienced trouble shifting since the engine and tranny were installed, the problem may be that the PO did not retain the throwout collar from the L28ET. If you search around for threads on putting a 5 speed transmission in cars that came with 4 speed transmissions, you will, unfortunately, find a lot of confusing and conflicting information. What you need to know is that you keep the throwout collar that came with the car that you are putting a new transmission in (i.e, the collar matches with the clutch/pressure plate, not the transmission). For example, if you put a 5 speed in a '74 260Z, you use the throwout collar from the '74, not the collar that came with the 5 speed. In your case, you want to be using the collar from the L28ET, and not the '77 five speed. However, since you did not put your engine/tranny together you don't know which collar is in there.

What 240ZDan said. Edit: . . .

Thanks rossman. How did I not see that L-Series link in FAQs? Adult onset retardation I guess. *facepalm*

Forgive the stupid question. I see that many of the forum/subforum stickies went to the FAQ section, but for the life of me, I can't find the old L6 forum stickies anywhere. Someone recently posted the Bosch L-Jetronic schematic and I recall it had been stickied in the L6 Forum. I also searched far and wide and couldn't find it that way either. Thanks. P.s. Feel free to shed/delete this.

Tspite, let me offer the contrarion point of view. Buy the car and drive the piss out of it. You are 19 and going to college. Your disposable income over the next few years is likely going to be ZERO. The S30 is a beautiful chassis and will pull many gals (unless you swing from the other side of the plate - NNTIAWWT). Do not buy this car as a rebuilding project. Buy this car because its cool and very fun to drive. If the outer rust is offensive, sand it down, primer it and hand paint some yellow in it. You obviously know something about cars, so find out if the engine runs well. And if it does, buy it, drive it to college, and then buy a car that you really want to restore after you have a degree and are making a living in either profession or industry. Do not look at buying this car with an eye for what it could be because you probably can not afford to make it what you want it to be. My .02.

KTM, I degreed a cam with the engine in the car last Summer. The process really isn't any different than as explained in BRAAP's sticky and further embellished in post #13 of that thead. While it may be possible to leave the radiator/intercooler in place, I'd recommend removing them first. Having the extra space just makes the job easier compared to the relatively short time it takes to pull them. And if you need an air ratchet to remove your crank pulley bolt, you'll be pulling them anyway. Especially too if you intend to leave your crank pulley in place which will push the degree wheel that much closer to the rad. Piston stop, degree wheel and a dial indicator. And in my case, lots of time, in order to double and triple measure everything. In the end it was well worth the effort and I'm pretty positive I'm getting all of the performance out of a puny Stage III cam that it can give me. Best of luck.

Bourbon. And a bandaid for the hand. Good luck with your project. Share pics when you can.

This. Nothing wrong with a V8/10/12/Jet Engine powered Z car, but to me the essence of the Z car is the L6.

There is no rule that requires a new harness for a MS install. Download the EFI Bible in the Troubleshooting section and all of the wiring diagrams show the wire numbering on the stock FI harness. The wires actually have numbers on them so it is very easy to know which wire you are dealing with. Use the facotory harness. You will not need to add any new wires. You will, however, have to spend many, many hours figuring this stuff out. Every answer is out there - both on Hybrid and the several MS sites/forums. Good luck.

MAG58, here is my theory. The only journals that are not supported on both side are the outermost (#1 and #7). They have, respectively, a pulley on one and a fly wheel on the other. And even if the pulley and flywheel are themselves perfectly balanced, the pulley still has one or more belts asserting lateral forces on it and the flywheel undergoes torsional (twising) pressures every time the clucth is operated. For these reasons, it would make sense for the #1 and #7 journals to develop wear first and before the inner journals. The interior journals, #2 & #3 and #5 & #6 show half as much wear as between the outer journals and the center journal (#4). My theory, which is admittedly not based on actual knowledge or experience, is that the journals on your engine wore from the outside to the inside. In other words, as #1 and #7 began to wear, there was less (albiet a minsecule amount) support to the next interior journal causing your journals to wear from the outside to the inside. Just my undeducated opinion, so that it for what it's worth.

If you use the MAP-only based fuel algorithm, then you can use the stock throttle body. Just leave the sensor unplugged. MS does not use TPS to calculate fuel unless you are running Alpha-N or hybrid. However, you will not have a TPS reading for tuning purposes.