JeffTT

Right do not worry about the dash lights they do not go out until the engine starts. Non starting in your situation is usually caused by 1) flooding Poor connection to temp sensor, after cleaning up, you will need to do a fuel clear out by turning the engine over with the fuel pump fuse removed and foor flat on accelerator( located in slim black box by brake master cylinder ) ignition back off, refit fuse, then restart without touching the accelerator 2) lack of spark PTU clean connections and then undertake a flooded engine restart 3) lack of fuel Run out of petrol? Cas unit connection not giving crank signal ( check connection and refit located on cam belt cover front right of engine) One or more of those will apply, if it was running fine previously it is not anthing too bad, ....JUST A CHRISTMAS GREMLIN Jeff TT

Gavo, the fault indicates a failed 02 sensor as Znut mentioned, as a get you by for now disconnect it at the back of the engine the ecu will then resolve a fixed but constant figure, which is the better of two evils rather than a fix. To get an error code the sensor or cable must be short circuit as even a dead on e will rarely cause an error code. Safety boost cannot be caused by this O2 fault, lower than normal performance can be cause by many things and a ConZult diagnostic is the only sure way method of sorting it, ask if any members close by have one. Get the sensor swapped after Xmas when you have more time. Meanwhile MERRY CHRISTMAS Jeff TT

The text below is long but very descriptive and should go some way to answering the question about restrictive exhausts, however it is a generalisation and not specific to the 300zx personally having dealt with 300 or more chip /boost upgradeds over the last few years its not a problem that I have seen, I do believe there is more issues with badly set up engines and badly written eproms and there are more of those than is admitted to! A proffesional set up engine will have had all the detonation issues dealt with, unless poor fuel used at a later date of course.This is one of the very reason buying an eprom from e-bay is a bad idea so is having an ecu done through the post as no engine set up or condition responsibility is taken by the person / company suppling the eprom, seen some sad results due to this. Jeff TT Exhaust Cycle and exhaust design Let's start by looking at the effects of a less than optimum exhaust cycle. A motor has fully exhausted itself (When it is really tired?) when the pressure in the chamber is equal to, or below atmospheric at the end of the exhaust cycle. Several things happen when the motor cannot fully exhaust itself. If the pressure is above atmospheric at the end of the cycle, the result is lowered volumetric efficiency, increased pumping losses, and reduced combustion efficiency as compared to an optimized exhaust cycle. Swept Volume, Clearance Volume, and Compression Ratio. -------------------------------------------------------------------------- In December's port timing article, I stated that top dead center, or TDC refers to the point at which the chamber is at its smallest possible volume. The space in the chamber at TDC is referred to as the clearance volume, and this in part determines the compression ratio. The compression ratio is specified as (Volume at BDC/Volume at TDC) Using an '87 13B as an example, the chamber volume at BDC is 9.4 times greater than the volume at TDC, for a compression ratio of 9.4 to 1. The difference between the volume at TDC, and BDC is referred to as the swept volume, or displacement. This is the volume of gasses that will be displaced in one complete cycle assuming 100% volumetric efficiency. A little bit of high school algebra shows that the volume at BDC is 44.66 cubic inches, and the volume at TDC is 4.75 cubic inches, or 10.6% of the total volume. Volumetric Efficiency ------------------------------------------------------------------------- The exhaust gasses that occupy the clearance volume will be carried around into the following intake stroke. As you can see, even at 100% volumetric efficiency the mixture will still only be 89.6% fresh intake charge. If the chamber pressure does not reach atmospheric by the end of the cycle, this 10.6 %, or 4.66 cubic inches of exhaust gasses will be pressurized, and will take up even more space once they are allowed to expand as the chamber volume increases during the intake stroke. This will reduce volumetric efficiency considerably, as the exhaust gasses will occupy space that could be used for fresh mixture. These exhaust gasses effectively "take away" from the swept volume, or displacement of the motor. The goal of the exhaust system then, should be to evacuate as much of the spent gasses as possible. Inertial Scavenging ------------------------------------------------------------------------- Inertial scavenging is easiest to understand if you think of the gasses in the exhaust system as a big piece of elastic. While they are not directly connected, a change at one end of the system will have an effect on the gasses at the other end of the system. For instance, towards the end of the cycle, the flow through the exhaust port slows down, but the high velocity gasses from earlier in the cycle are still travelling through the system. (Note: A system made up of 100" long, 1/34" inside diameter header tubes, as you might see on a race car, will contain about six complete cycles worth of exhaust gasses per pipe.) These high velocity gasses will "pull" on the slower moving gasses near the exhaust port, helping to evacuate the chamber. This is inertial scavenging. Just imagine two cars rolling down the road, connected to each other by a bungee cord. If the car at the back slows, it will not immediately be jerked back to speed, but rather gently pulled back up to speed by the car in front. As some of you may have guessed, a series of resonances will then occur, with each car alternately pulling at the other. This is very much like what happens to the gasses in the exhaust system. Pumping Losses ------------------------------------------------------------------------- Well, here we are at pumping losses again! Luckily this is quite easy to explain and understand. It all comes down to exhaust flow. Not just the airflow capability of the exhaust port, but of the entire system from the port to the end of the exhaust pipe. Quite simply, if the exhaust flow is insufficient, the blowdown period will only account for a small amount of the total exhaust gasses, and the remainder will have to be squeezed out by the rotor itself. Physically forcing the gasses from the chamber through a restrictive exhaust system requires a substantial amount of horsepower. So much in fact that many diesel truck engines have a mechanism which blocks the flow of exhaust gasses to slow the vehicle down, thus saving wear on the brakes. Just think about slowing an 18 wheeler with nothing but exhaust pressure, and you get an idea how much this can affect your engine. Combustion Efficiency ----------------------------------------------------------------------- We have already discussed how insufficient exhaust flow reduces volumetric efficiency, but the presence of exhaust gasses in the intake charge (Exhaust gas dilution) causes other problems as well. The rotary engine is known for its poor combustion characteristics. Due to the shape of the chamber, and the location of the spark lugs, a large percentage of the intake charge does not burn in the chamber. The end result is a fair amount of unburned gasses, or hydrocarbons being passed into the exhaust system. This reduces power output, because a portion of the mixture that we tried so hard to put into the engine did not burn. This also reduces fuel economy, and increases emissions. Another effect that is not often realized is excessive exhaust gas temperatures. These hydrocarbons will then burn in the exhaust system raising the exhaust gas temperatures. The addition of exhaust gasses to the intake charge will reduce the already poor combustion quality. The end result is that the mixture is harder to ignite, and when it finally does light up it will burn at a slower rate further reducing power output. In a turbocharged engine excessive exhaust gas dilution will cause its own unique set of problems. Detonation ------------------------------------------------------------------------- We tend to think of combustion inside of the engine as a series of explosions, but in fact the combustion occurs at a very slow rate, at least compared to an explosion. In the absence of detonation, the mixture in the vicinity of the spark plugs is ignited first, and the "flame front" travels from that point, through the rest of the mixture in a fairly controlled manner. Detonation occurs after the combustion has initiated, and the pressure, and temperature in the chamber rises to the point that the remaining mixture literally explodes. Anyone who has ever experienced detonation understands that it certainly is an explosion! Detonation is caused by a combination of heat, and pressure, and so it stands to reason that excessive exhaust gas dilution, (remember these are hot gasses) will increase the likelyhood of detonation. As most of you know, detonation will destroy a turbocharged engine in a big hurry. A "Perfect" Exhaust Cycle ------------------------------------------------------------------------ Now that we have all of the pieces, it is time to put the puzzle together. I personally have a hard time understanding anything unless I can see it in front of me. For that reason I will refer once again to the illustration of the engine during its different phases. As the exhaust port opens, (#13 in the illustration) the high pressure in the combustion chamber will force the gasses through the port and down the exhaust system at a high rate of speed. This, as you remember, is the blowdown period, and a large portion of the gasses will exit the chamber at this time. At the same time that the flow is initiated, a high pressure wave will travel towards the end of the exhaust system at the speed of sound. (Note that this high pressure wave will help to propel the slower moving exhaust gasses with it.) Further into the cycle (#15) as the pressure differential between the chamber and the exhaust system has decreased, (ie., the chamber has "blown down") the velocity through the exhaust port will also decrease, and the remaining flow will be the result of the decreasing chamber volume. At this point, approximately half of the exhaust gasses will have exited the chamber. At 135 degrees after bottom dead center, (between #15, and #16) the chamber will be at its maximum rate of decrease of volume. In other words, it is at this point in the cycle that the rotor will be travelling at maximum velocity. If the exhaust flow is insufficient, it will require a great deal of force to expel the gasses from the chamber. This is where the pumping losses during the exhaust stroke will be the greatest. Keep in mind that these losses cannot be eliminated, but they can certainly be lessened by providing sufficient exhaust flow. Moving on to #17, and #18, the chamber volume is decreasing at a very slow rate, and the motor is doing very little to mechanically expel the gasses from the chamber. It is at this point in the cycle that pressure wave tuning comes into play. The high pressure wave that originated when the exhaust port first opened will have travelled to the collector, and been reflected back as a low pressure wave. (Remember last months section on pressure wave tuning?) If timed correctly, the wave will arrive at this point, just before the intake port opens. This low pressure wave, in conjunction with the "pull" created by the high speed gasses still in the exhaust system will lower the pressure in the chamber to sub atmospheric. When the intake port opens, this vacuum will help to initiate the flow of fresh mixture into the chamber, which will increase volumetric efficiency. Looking back to December's port timing article, you can see that the intake port does not open until approximately 30 degrees after top dead center. That means that for the first 30 degrees after TDC, (The distance between #18, and #1 in the illustration) the chamber volume is increasing, but because only the exhaust port is open, the chamber will be filling with exhaust gasses by pulling them back out of the exhaust system. This is called exhaust gas reversion. If the exhaust gas velocity is low, (Such as at low rpm) the vacuum created by the increasing chamber volume can easily reverse the flow and pull the gasses back into the chamber. If, on the other hand, the exhaust gas velocity is high, it will take a great deal more energy to reverse their flow, and the result will be less exhaust gas dilution. This is why large exhaust ports, and large diameter exhaust tubing reduce low speed power. Low RPM Operation ------------------------------------------------------------------------- The above paragraphs describe a "perfect" exhaust stroke, and unfortunately this can only happen over a very narrow rpm range. Let's look at what happens when we halve the rpm. We will assume that the above example is at 8000 rpm. Now let's look at the same cycle at 4000 rpm. Since the exhaust cycle lasts twice as long at 4000 rpm, the chamber will have reached sub atmospheric pressure approximately half way through the cycle, assuming of course that we have sufficient exhaust flow. This sub atmospheric condition will send a low pressure wave travelling towards the end of the exhaust system at the speed of sound. (Remember that a pressure wave is intiated anytime pressure deviates from atmospheric.) This wave will reach the collector, and reflect back as a high pressure wave. Since we have halved the rpm, it is likely that this wave will arrive near the end of the exhaust stroke, (#18) and so the chamber pressure will be above atmospheric when the intake port opens. This will result in excessive exhaust gas dilution as compared to the 8000 rpm example. In addition to this, the exhaust gas velocity will be low, and during the period from TDC, to intake valve opening, the exhaust gas flow will reverse momentarily. This will also add to the amount of exhaust gas dilution. If we wanted the exhaust stroke to be optimized for this lower rpm, several changes would be necessary. 1. Later exhaust port opening. Since we have more time to exhaust the chamber, the total exhaust duration can be lessend. The result of this will be that we can hold pressure in the chamber for a greater period of time. This will increase the amount of time that torque will be applied to the eccentric shaft. 2. Smaller cross sectional areas. Decreasing the cross sectional area of the port, and the exhaust tubing will increase the velocity of the exhaust gasses. This will result in less reverse flow, or exhaust gas reversion after top dead center, and will make the inertial scavenging towards the end of the cycle more effective. 3. Longer tuned lengths. Since the exhaust cycle occurs over a greater period of time at low rpm, the pressure wave must be further delayed if it is going to arrive at the appropriate time. In the case of optimizing the system for 4000, rather than 8000 rpm, the header lengths would need to be approximately twice as long. This is easiest to understand if you think of the headers as a delay source. What we are trying to do is delay the wave from the time it initiates to the end of the exhaust cycle. The further that the wave travels, later it will arrive at the exhaust port. As you can see, we can only optimize the exhaust cycle over a fairly narrow rpm range. If at first this seems discouraging, it is important to consider that an optimized cycle over a narrow range is much better than a less than optimum cycle throughout the operating range. A "perfect" intake stroke can also only occur over a fairly narrow rpm range, and so it is important to consider the trade-offs when contemplating performace upgrades. If for instance you wish to "street port" your engine, you must understand that the increase in top end power will be accompanied by a decrease in low speed power. The intent of these articles is not to make specific reccomendations, but to give you the knowledge to make informed decisions, and sort through the hype. For all of you racers, using the lessons learned from the exhaust system articles will allow you to make sense of exhaust tuning. If you apply these theories, and do some trial and error testing, you will likely unleash some hidden power. Now that you have the facts, you will understand why one system affects the engine differently than another, and this will make it much easier to arrive at the "correct" setup.

Assuming all the cables are back in place now, does the igntion lights stay on when sitched off but dimmer then when the key is turned on? if this is the case the ecu has been damaged and is backfeeding through the ecu pcb. Jeff TT

Be worth draining the box remove the pan and clean out the strainer, chances are its blocked with debris. Of course the problem may return but a cheap option to try first and may just pay off. Jeff TT

Before you go trying to force more power from your new zed you need to do some research on getting it running correctly, from your description it really should be much better. I was heavily into Cosworths when they were new, had an almost new moonstone blue saphire and over almost 5 years ownership it had numerous engine tuning parts suspension parts, upgraded bushes, tyres wheels, lights, eventually I rebuilt the engine from a Graham Goode RS500 block, balanced pistons beefed up crank, wire ringed head Amed Bahoo chip ( Fords own rally programme writer) 3 bar map sensor, light green and then dark green injectors eventually got the eight RS 500 set up and matching turbo, la la la on and on........ Then I drove a 300zx Twin Turbo...... sold the Cosworth the next day! and bought my first 300zx That was nearly 14 nearly ago and have been involved with 300`s ever since, the handling the performance and looks made the Cossy look dated then and makes it look even more dated today! and as I and others are saying if the performance is not exciting you then something is wrong with the set up, maybe easy to correct but once its is then you can look at raising the power, but do not make the mistake of comparing the two cars both are high performance but in very different ways. Of course all of this is just my opinion and in no way want to offend anyone.:D Jeff TT

The one you have circled is defo the air con belt adjuster pully and should be turning when ever the engine turns, however its very common for them to seize, but would normally expect the belt to be noisy, unless it is slack and slipping over it. Check it when there is more light. Jeff TT

http://www.300zx.org.uk/diagnostics.htm Jeff TT

http://www.tidytees.co.uk/Nissan-300zx-adults-hoody-1315.html :shock: Jeff TT

Try this Jeff TT

Will check the pic again Jeff TT

I can see pic, anyone else can you see it or not? Jeff TT

To check the eprom mapping the easiest way is to get it on a ConZult diagnostic, that way you can check it completely as I have seen stock chips erased and reprogrammed the chip number is not always a secure sign of what is on it. Jeff TT

The auto ecu is not a problem especially if your changing the chip, and as far as the green wires I misunderstood and thought you you meant they were outside of the ecu, the ones inside are standard and are connected to the switch used for accessing fault codes. Jeff TT

Rps street Jeff TT

Jap spec Twin Turbo with automatic box, standard chip, the green wires will most likely be an after market device for altering the a/f signal to fool the ecu into adding fuel, very poor way of been able to run more boost, if you having a chip done, remove the cables and device or it will mess with the new chip. Jeff TT

How did you get on? Jeff TT

Agree fully Jeff TT

Here you are all the info you need. PICTURE EDITED Jeff TT

Right the box has failed mechanically end of don`t beat yourself up about the previous warning flashes. To rebuild the box now will be expensive as it will need what is termed a hard rebuild to include gear clusters, bearings and shafts , torque convertor as you will have damage to all of these now due to the amout of metal filing circulating in the fluid. Auto box specialist Soft rebuilds cost around £1,100 Hard rebuilds cost around £1,800 Good used boxes are available with a bit of research, but a warning who ever fits it needs to remove the cooler pipes and clean them out fully and fit a new cooler, failure to do this will result in a second damaged box, also buy a box that has the torque convertor with it, should cost way less than a full rebuild. Hope that helps Jeff TT

Have a relay in my garage, so will photo it and show the connections you need to know, will post it in the morning. Jeff TT

Did you take the top off the relay and reinsert it and then manual operate the relay and observe the contacts actually touching?

Yes very likely, does sound like a wiring issue, have seen plenty of times the cable from the horn button to the relay but as the relay is clicking if it is a wiring prob it will be the cable legrath said Jeff TT

YOU MUST BE FREEZING Jeff TT

The relay has a perm 12v supply on the coil, when you push the horn button an earth is sent to the relay coil to pull it in, then 12v is then switched to the horns which have a perm earth and if good they should operate. Jeff TT