Afshin

Wow! I can't believe how difficult this problem has been to solve. At this point you have checked every sensor at the sensor and at the ECU, you have swapped all the major EFI and ignition components and also checked for broken wire to ECU, ruled out vacuun leaks, checked fuel delivery and all is still negative. Considering this and that both your timing advance and fuel mixture are off my best guess is a short which is throwing off the ECU which would acount for both fuel and ignition problems. Since you already swapped ECU's, dizzy and AFM, it seems most likely that the short is in the harness itself. Checking resistance in each wire end to end obviously won't let you know about any shorts. You could check resistance between each wire/pin at the ECU end and the body for a ground short, since they are the most common type (on non ground pins off course). If all is OK you could then check for resistance from pin to pin, but that is a pain in the ass specially since some of them (i.e. comming from the same sensor) should have some continuity. At this point I would check for a ground short first, if negative I would call every nissan dealership in NJ and find one that has the factory ECCS analyzer which can check for proper input to the ECU as well as proper output from the ECU. Of course you could also try to locate another zxt harness, it would be relatively easy to install. I just can't think of anything else since you have been so thorough in checking all individual systems components. The only thing left is a short

I'm so sorry and absolutely embarrassed, that was a big slip (I was picturing a different non ZX rear suspension set up in my easily confused mind), the ZX rear strut assembly clearly does not affect camber since it has a pivot point at the bottom...

Hi Jon, the car does use a strut, so moving the "top" via a camber plate would change the camber as would moving the trailing arm. The camber is set based on the relative angle between the strut top and the trailing arm. The MSA camber kits works by sloting the bushing middle hole and as such allows one to change the pivot points on the bushing end. the saw hole kit is to slot the bushings, the washers will hold it in place. This will give some adjustability for both camber and toe. This should work, however i don't know how durable it is or how good of a job it does at maintining any new angle that you may set. The MSA guys claim that it works very well, so far my experience with them has been very good. I will hopefully purchase and install the kit later this year. Please post an update to provide some feedback on the kit if you end up using it.

Hi Jersey, have you had the chance to do any more diagnostic work on the car? I'm really curious as to your progress and finding what is causing all of your problems. Also did you say that after resetting the timing it always goes back to 20 after you run the car ?

You're right Z driver, I can't believe that I forgot to mention the four wheel disk brakes as a plus, it must have been past my bedtime. I know what you mean David, I never would have guessed that the Z was about as aerodynamic as a brick. But my understanding is that cutting thru the air (i.e. sloped nose) is a small part of aerodynamics, most important is turbulence and drag from creating a vacuum in back of the car when moving forward. The Z was never tested in a wind tunnel and there are many modern large grilled four door sedan these days with Cd's in .27-.29 range because of low turbulence above and below (quite important) the vehicle and little drag in the back.

Juan, I think it will be worthwhile to look into fitting the 12" as you mentioned. It seems like the extra cost of making the bracket will be offset by the 12" rotors being so much cheaper. More importantly I think most people have 16" rims and would miss out on a potentially wonderfull and flexible brake upgrade kit. So we are with you, keep thinking about how you would offset the bracket to work with the 12 rotor. We appreciate your effort. Good luck and continue to keep us posted with your progress.

Hi Juan, I'm real glad that you seem to already be working on the ZX brakes. I can't tell you how badly I want them. And yes, 13" sounds great, specially since I have 17" rims. However make sure the set up works on 16" as well or you may not have enough people who can buy them. I already have money set aside for the kit, so please get it done soon (I'm not very patient when it comes to my toys ). Also the 240sx TB spacer kit you sent me is fantastic. Thanks

Pro's for 240Z: Classic design and nicer body Less weight in 240 (280Z and Zx weight are almost the same), hence more nimble Faster and better response Better steering feedback Much more aftermarket parts, therfore often cheaper parts More information available on modifications (mostly for suspension and brake related set ups) Pro's fo 280ZX: Stiffer chasis Better aerodynamics ( Z's Cd was 0.467, for the 280ZX they spent six months refining the design using a wind tunnel to get the Cd down to 0.385. Additionaly lift was reduced by 60% and sidewind stability was significantly improved) Safety related to chassis, stronger doors, real bumpers and increase in weight. Given equal platforms and design, the damage sustained to a car is related to the difference in weight squared. So if a 4000lb car hits a same design 2000lb car the damage sustained to the lighter car will not be twice as much but 2 squared which is 4 times as much. Less significant benefits: T-tops, better AC, better doors,.locks, power mirrors....(which can all off course be seen as negatives based on personal perspective and track vs. daily use...) 5 spd tranny and R200 diff. (half shafts on turbo model) Personally, if I was to put in a V8 I would opt for the 240Z because of classic design, much more aftermarket parts and more info on mods. I would also then consider a cage for safety mostly (what can I say, I'm getting a little more conservative with age and parenthood)and also for chassis stiffening (specially fro V8 ). As a turbo addict, I recently got a 280ZX turbo ( i had turbo swapped a Z before and had another 280Zxturbo) because everything was already there (turbo, half shafts, R200 ....) and then started further modifying it. If I was to keep the original engine I would definitely get the 240Z over the 280ZX. But I would still rather get the 280ZX turbo (it's very different from the non-turbo) over the stock 240Z (because of power/torque) Most of these comments are obviously subjective and can be viewed differently based on personal preference, and priority (speed vs handling, track vs street use, daily driver or not...). In the end both cars properly modified will be a blast and they both have well proven track records. As JohnC already mentioned, the most important factor relates to the car with the least amount of rust (i.e. cancer). Make sure you check the chassis carefully. In terms of cost, it's always more than anticipated, but in my highly biased opinion, it's worth every penny .

How about swapping the caddy engine and 6 spd tranny into the Z About the car running rich, most common causes in Z's relate to dirty connectors. A faulty head temperature unit (most often a dirty or lose connector) is a common cause of Z's running really rich and barely starting. Of course check fuel pressure, FPR and inspect carefully for vacuum leaks as you already mentioned ( the turbo EFI doesn't use a cold start injector so that can't be the problem). Just make sure that you CLEAN and inspect ALL the main EFI connectors (e.g. air flow meter, head temperature sensor...and also unplug the connectors to the ECU and clean them as well (even if they look clean). Anyone here can share a million stories regarding poor EFI performance related to dirty/faulty connectors, they are so so common in these cars. As far as other things to look for in these cars there really isn't much else outside of rust. The cars are incredibly robust and as you probably are already aware of parts are cheap and working on them is very straight forward and enjoyable (as opposed to my late Q45 and many other cars I have played with). $400 is an absolutely great deal. In case you haven't owned a turbo car before, be warned, boost is highly addictive.

The crank angle sensor has two diodes one which reads rpm (diode 1) and tells the ECu about RPM and is used to set timing. The second diode is used to signal TDC. I think it may be possible that the first diode has failed and timimg does not respond to RPM and that the second diode is still providing info for TDC and setting the fixed timing of 20. I don't know if this could happen for sure (i'm making a guess) but I would strongly consider swaping the whole ditributor with your cousin's and see if any thing changes. If this does not work another guess would be a short causing errors in the ECU reading or output. You should also swap the AFM if you already haven't since it could cause your rich mixture and maybee a short in the unit is throwing off the ECU and timing.

There are 2 components in these posts, the problem (easier to identify and agree on)and the solution (no perfect one, and difficult as usual) The problem relates to the preservation of this site as a nice medium for the exchange of interesting ideas, experiences and fun relating to making real modifications, all while preserving a sense of community. As such the influx of members who do not fit “the mold” or who make noise as opposed to contributions is appropriately being targeted. From my interpretations of others post, I feel that most would agree and be supportive of this endeavor. However, the challenge is delineating who “those” folks are, and most difficult and crucial is how to deal with the issue. I believe that the manner in which we deal with distress is what best defines us. We understand that this forum was born out of the V8 conversions however, as you well know, it is much more than that. Within it lays the spirit of craftsmanship, customization and performance. This, at least, is what I felt after visiting this site and is why it represents the only online forum of any kind that I have ever joined. The reorganization/consolidation of the many forums makes sense, and it’s only fair that the administrators’ perspective on how to do it should reflect their perspective on what best represents the overall goal of this site. What needs to be worded and carried out carefully is classification of a group of diverse people based on a common feature that does not represent them fairly, in other words L6r’s, and so on. It’s not the L6 that’s a problem, it’s someone who thinks that it is better or someone who has no interest in true/significant performance modifications as you stated yourself. Now while this sound mostly like semantics, it does set the undertone, comments such as “people with L6’s can go elsewhere” will be unduly offensive to many contributing members of HybridZ, whereas saying Nissan purists or people who create noise as opposed to contribute should be banned, whacked in the head.. (which you have now made clear is your purpose) and so on is highly appreciated. In the end, you guys are responsible for a great site and I loudly applaud your efforts to keep it special as opposed to let it degrade, even if some of us take offense during the process or disagree with certain aspects of your solutions.

Even as a new member to HybridZ, I have become very disheartened by the idea of changing the direction of this wonderful site from it’s current logo ‘HybridZ where stock just don’t cut it” to “HybridZ where only V8’s will do”. Was I wrong in my interpretation of the purpose of this site as a forum for the exchange of interesting ideas pertaining to the modification of Z cars? If this site came out of the need to create a community of open-minded and technically oriented performance enthusiasts who had creative performance conversions, how could it think of defining itself in such a narrow way “V8 or nothing”. Isn’t this too close to the narrow-minded view common to some of the classic Z sites? Interestingly the previous announcement which was very nicely accepted by the HybridZ community related to “why us vs. them” as it pertained to the so-called ricers. So, then why now is the thought of taking the us vs. them mentality growing so strong and extreme as to entertain the idea of separating true technically oriented Z car conversion and performance enthusiasts based on the preference or choice of engine ? I can assure you that most of us, turbo or any other modification group of HybridZ members are in no way different than ones who have V8’s. I have chosen the Datsun/Nissan Z platform for the sole purpose of making modification to enhance my driving pleasure and have fun. Those “other Z or L28 sites” as was put may share the same engine that I do, but they don’t share the same goal, level of passion or technical expertise in making performance oriented modifications. On the other hand, the general HybridZ group is an exact match for my interest and perspectives on performance. Until now, I had never thought for a moment of HybridZ members with V8’s as different than those with L28 or RB’s.., and frankly I refuse to. So, even as the most junior member of HybridZ I urge the administrators to keep the view that all mature members who share the same spirit and passion for technically oriented modifications on the Z cars as one community as opposed to drawing a line of distinction based on number of cylinders.

Hi Jersey, I still don't think that your primary problem is low vacuum. If you had low vacuum from all sort of horrible things like valve or piston or ring problems, the problem would only get Worse when you add a vacuum leak. Since the opposite happens in your car, it only makes sense to me that the primary problem is too much gas/too little air. This would explain the marked improvement you are getting with the addition of unmetered air(vacuum leak). I'll continue to think more about this problem and let you know if I come up with any other ideas.

I think that ANYTHING causing your engine to idle low and poorly would cause your vacuum to drop, when you create a vacuum now (letting more air in) you improve your A/F ratio which increases your RPM and hence the amount of air that is being sucked into the engine which results in overall increase in vacuum. In other words your vacuum change is a reflection the amount/velocity of air being sucked in, which at idle (fixed throttle plate position) relates directly to your engine RPM.

Well as you describe if your car is running so rich and corrects with creating a vacuum leak I think it is less likely to be a major engine problem since a problem with rings or valves should not correct so easily with creating a vacuum leak or necessarily cause the degree if richness that you are describing. I also think it's less likely to be the TPS since I have never found the unit to cause such a drastic difference in idling (my car idle barely changes with unplugging of the TPS). Off course I am wrong quite often and checking compression and TPS are clearly worthwhile. Here is my list of more common (not all) reasons for a Z to run very rich: -Faulty head temperature sensor unit or connector. -Faulty connection of harness to ECU (unplug you ecu harness, spray with cleaner even if it looks clean and snap back on) -Increased fuel pressure, have you checked the pressure, that could also cause some leak at injectors or rails causing the gasoline smell you have from your closed EFI system. -Faulty air flow meter or connector (again at either end i.e. AFM or ECU connector), check the flap on the AFM if you already have not for smooth opening... also try and see if the car runs better with you pushing the AFM flap just a tad more open (without the vacuum leak). Keep us posted.

the Z's Cd was 0.467, for the 280ZX they spent six months refining the design using a wind tunnel to get the Cd down to 0.385 which was a major leap forward for it's time. Additionaly lift was reduced by 60% and sidewind stability was significantly improved. (I got this info from Brian Long's book called datsun 280zx/nissan 300zx)

I had a great time seeing all the Z's and meeting the local HybridZ gang (too many names to write). On the way back I was all pumped up like a teenager behind the wheel and smoked a new lowered, tinted windows, huge rear wing...celica GTS (yes, I know not fair competition) only to blow my turbo piping coupler hose off 2 minutes later Good thing I always keep some tools handy

I actually used to own a 77 280 Z with a 83 turbo motor and an 1983 280zx turbo at the same time and would drive both on different days of the week. I just recently bought another 280zx turbo. In my experience the difference between the stock suspension on the Z and the ZXT are quite significant and clearly in favor of the Z. However, the suspension of the ZX can very easily be tuned to match the Z. And while the semi trailing arm of the ZX is technically inferior, the difference is not noticeable and indeed Paul Newman'z winning (highly modified) 280zx was still using the rear semi trailing arms. A significant benefit of the Zx is a stiffer chasis and much better aerodynamics (the aerodynamics on the Z are lacking). Also the ZX maintains better suspension travel when aftermarket lowering springs are used so it does not bottom out as easilly. SO the 280zx suspension can easilly be set to perform as well, you will need aftermarket performance springs and shocks. (my experience between the 2 cars relat to agressive street driving, lots of mountain roads, twistes and "weekend races", I can't tell you about differences when settinp up the cars for open track races.) Another issue is the steering feel which is bettet in the stock Z, however the use of larger diameter (16 or 17") rims and wider tires (225's) do abolute magic to eliminate the overboost feeling of the stock 280zx steering. A counter point in favor of the Z is significantly higher availability of aftermarket parts and nicer (classic) lines on the car. Off course getting the car with a working turbo already in it is quite nice. In the end I liked both cars equally, was slightly more attached to the Z (was more customized), but actually after setting up the suspension, my ZXT performed as well if not slightly better than the Z (280Z not a 240 Z) with the turbo swap, and was more stable.

Hi Jersey, I had a similar experience where the car suddendly started to idle terribly and even stall at idle. However it still drove quite well with good power when on the throttle. I also had noticed decrease vacuum at idle. I thought it would be a vacum leak but was not finding anything at first and then realized that I had a leak between the AFM and turbo (was difficult to see), I know you inspected it once, but I would inspect it again very closely. However, I'm not sure if this would explain why the car runs better when you create a vacuum leak. Another thing that comes to mind is a poor connection from the head temperature sensor, it's common and I believe would cause the car to run rich and idle poorly, which would improve with unmetered air entering (vacuum leak). Good luck

I clearly remember reading an article a while back claiming that nissan was actually paying royalties to Mercedes for using/copying their design. this does not mean that Prince motors was not responsible for the final product. Unfortunatley I can't remember the source of the article, I will try to look for it in my personal archives.

one of the most important steps in painting is the prep work which no cheap shop will do appropriately. The good thing is that basic prep is easy to do. Get some paint degreaser/wax remover from the paint shop and apply it to the car. this is an easy an important step which is frequently missed (I would defintely do this even if you end up taking it to a decent shop), any wax or grease will cause the paint to peel. Furthermore sanding does not remove all the wax and grease, since they penetrate into the paint. After using the degreaser you can use fine sandpaper to go over the entire car (the goal is only to scuff up the paint and remove surface junk, not to remove paint, so you just do it lightly and consistently until the paint is no longer shiny). These 2 easy steps will usually make even a cheap Maaco paint job stay on for a good few years. Off course it will still look like a cheap paint job, but it won't peel and crack in a year. Good luck

In terms of size 225/50/16 are a nice fit and match the original rolling diameter. However, some have had slight clearance problem in the front with 225/50/16 ) obviously there is some variace based on rim width in addition to tire. As for tire I have had way too many to recount but keeping price as a important factor I tend to vote on the Kumho 712 since they are very predictable with great grip. I have used them both on a 280zx turbo and a supra twin turbo with great results. They do well in the rain too

I did some more homework (OK, OK, I really did this during work) and found this company called long acre racing (I have never dealt with them). They have some very nice article on using pyrometers and tunning suspensions. They also provide a lot of information on they pyrometers (infrared vs probe tip), and sell both types of pyrometers ranging from $80 and up. Here is the link: http://www.longacreracing.com/articles/art.asp?ARTID=16 Does anyone have a good reason (ie negative experience) not to get the cheapest model ? they all seem to accurate and perform the same function (there is a difference in temperature range)

Wow! that's outstanding. I expect that you have nicely balanced mods resulting is such nice Hp and torque output. Specially with a factory CPU and I guess relatively stock motor ? (yes/no?) Would you mind posting all the relevant mods you have. I would like to compare it to what I have done, i.e. T3T4, 60mm throtle body, MSD, 3"exhaust, rebuild stock P90 head,original bottom end and what I am planning to do next, which is a Z31 swap before I install the supra TT intercooler (one step at a time so I don't confuse myself too much when it doesn't work out on the first run). ALso what do you mean by modified MAF ? and is that what's allowing you to run the 370cc injectors with correct air/fuel. I think I would be grinning like an idiot with 417 ft-lb torque on tap whithout having fully depleting my savings account (oops, too late). Nice job man

thanks for all the input (and the very comprehensive response from Tim). The oversteer that I am experience is mostly felt from entry in the turn and most pronounced at the apex of a sharp turn. the bothersome part has been that prior to the apex it has become more difficult to modulate the slide since it tends to give out a little unpredictably while maintaining the throtle. In terms of off throtle oversteer, it feel s no different than these cars always have and remains reasonably predictable. The dynamics with braking in the turns is not very different than expected. Actually one can even feel the rear of the car overturning as opposed to nicely following the front in moderate turns at slow speed with no sliding and without the suspension being maxed out. In essence I am trying to fine tune a slight turn in oversteer (the car handles quite well, but it's still not "fully right". I won't take the rear sway bar off just loosen it (stock bars, with good mounting points). I 'm thinking about buying adjustable end links for them. For tire pressure I was going to start with 32 psi all around and then try 32 rear and 28 up front. I'm also thinking about getting the pyrometer. Can any of you share any practical experience/use with the pyrometers? Also what are you experiences with the control arm bushings that allow for camber adjustement, do they do agood job of maintaining whatever setting you have or do they deform,slip...?