NISSAN SKYLINE – LAUREL R34 – C35 with RB20 DE NEO L / B motor – “Power loss, poor dynamics
The increase in the fleet in developed countries always puts the environmental issue first. Tighter emission standards are one of the reasons forcing automakers to release new engines, and car owners to update their vehicles. For this, there are various insurance mechanisms, including the purchase of obsolete cars, surcharges and the purchase of modern ones that meet the new toxicity standards. This is the development of the scientific industry, engineering, technology, economics, etc …
Undoubtedly, the constant race of raising standards pursued by the government of developed countries is also an attempt to limit the import of foreign manufacturers, especially from developing countries, whose vehicles, due to lack of technology, cannot fit into certain norms (including crash tests) ), but successfully sold in other developing countries.
This approach is understandable – the government takes care of preserving jobs, economic stability, protects its market from low-quality goods (and not just cars), but at the same time fuel in this country corresponds to the highest class at all gas stations, roads are called roads and high-speed regimes comply with EVERYTHING without exceptions. It is not clear when there are no roads, instead of gasoline – …. the rules are not written, but EURO 4 for the elite was introduced as a customs pass, although no one wants to achieve it, and it’s impossible. Just “differentiate financial flows” – that’s possible.
Part of the leading companies, foreseeing toughening toxicity standards, invests a lot of money in advance in research and development, developing technologies that further help them survive and compete.
One such TOYOTA, the LEARN BURN series of engines, was an intermediate step.
transition from stoichiometric to depleted engines. If we differentiate them by the ratio A / F, then this:
In the second and third cases, for different models, you can put the sign “approximately” instead of “equal”.
The second case includes LEARN BURN motors, and the third is D4 and all the analogies of NEO Di, FSI, etc..
These “transitional” motors of this period of group 2 include the motor RB20DE NEO L / B (Learn Burn), which NISSAN released from approximately 1998 to 2002, until the NEO Di series replaced .
What is cardinal in this engine, unlike its predecessor RB20E and its contemporaries RB25DE NEO, that it received the prefix L / B ? The main ones are the combustion chambers, the timing system and phases, the installation of a higher energy ignition system, the introduction of mechanical shutters Swirl for depletion. Deep feedback on DC was introduced and one HF rotation sensor was added. All this made it possible to “remove” 155 forces from a two-liter in-line six, keeping within the toxicity standards of 2000 for Japan. Many may ask – what is so little? But here the question is not the number of “horses”, but how to keep within the toxicity of the exhaust. After all, all the declared cars with their declared power must fit into these standards – otherwise they cannot move on public roads independently – only on a tow truck. Please – there are tracks, brought the car, paid for the emissions of the reformed engine, annealed the rubber – back to the trailer and to the garage, “tune” further. But on the streets you can breathe. In general, there are many ways to improve the ecology of streets (but all of them imply high-quality gasoline to start with).
That such alteration of the motor required to change the intake manifold – it became integral – to accommodate the dampers Swirl, stopping the access of the fuel-air mixture to one of the inlet valves. (on this engine, 2 intake valves per cylinder).
Since the nozzle is in front of the inlet valve, the fuel-air mixture is formed in the intake manifold, but the nozzle is in front of one of the inlet valves, so blocking one channel increases the flow rate and improves mixture formation. In fact, the damper covers only air for one of the intake channels, since the mixture formation is carried out in the second channel, where the nozzle is located. The dampers operate discretely – either closed at idle (low loads) or fully open. A malfunction of this system leads to a sharp decrease in motor power. But the main thing – with the introduction of such a collector, NISSAN received one problem that is not typical for engines of this series. Since the car uses separate “weights” and ground points for power and signal circuits, in this motor the signal mass of the sensors was always located on the intake manifold in the area of the coolant temperature sensor on the ECU (output to the upper radiator pipe). The collector is always screwed to the block and this connection never caused problems on the RB series. It is noteworthy that for the sake of economy, NISSAN used three-wire DCs, in which the signal “mass” was the sensor housing. All this led to a change in the DC signal relative to a given one, namely, the appearance of a threshold.
Consider Figure 1, which comments on the emergence of code such as DTC P0131 – Heated Oxygen Sensor 1 (FRONT) – LEAN SHIFT MONITORING
In the left picture (fig. 1-1) – everything is fine, the DC signal exceeds the level of the rich RICH mixture, the threshold of which the ECU set 0.6 volts (for reference, the lean mixture threshold is 0.35 volts)
If the DC voltage is higher than 0.6 volts – “rich mixture”, less than 0.35 – “poor”. Such a hysteresis loop allows you to accurately distinguish between transient operation, as well as determine the inactivity of DC. If the DC signal is constantly in the area of poor mixtures, then there is a problem whose solution includes checking the DC, nozzles, air intake, fuel pressure, etc. In addition, due to savings on the 4th wire of the DC, its signal “mass” is determined by the quality of the contact in the threaded connection of both the DC with the exhaust manifold and the exhaust manifold itself. Why so – all because of the separation of power and signal “land”. If a poor contact occurs in the thread of a DC (increased resistance), then a certain part of the DC signal falls on this resistance, lowering its value at a constant level. This causes the waveform to shift down – Fig. 1-2 (the signal amplitude does not change), but the positive half-wave ceases to overcome the upper threshold of the trigger hysteresis in the ECU. The decision on the leadership is to “overshoot” the DC. So to speak – “this is not is always simply” not only because of accessibility, but also because of the inability to unscrew the recreation center without damaging it (dents on the case are unacceptable).
Another reason for P0131 – poor contact in the signal “mass” – it is also recommended to retighten it. Installing a 4-wire DC solves some of the problems – the signal does not depend on the state of the exhaust manifold, but you have to lay an additional wire.
All this is very good, if you have a car diagnosis corresponding to EURO OBD, in which there are codes for such cases. And if you have a machine with a 14 pin connector, the ECU of which does not contain such codes – but in DATA STREAM mode, you graphically determined an insufficient signal level of the DC, retightened the signal ground bolts and the DC – but it did not help, then for this motor you need to “ground ”The very point of the signal ground. To do this, just connect the two points with a wire whose cross section is not lower than 3 mm ² .
Photo 1 Grounding point of the signal part of electrical equipment
Photo 2 Point on the intake manifold to which the signal mass must be connected.
How to check the need for such an operation without a scanner that displays the real date – turn on the ammeter between these two points. If the current exceeds 0.2 A, then it is necessary to finalize the design.
What were the customer complaints:
– “power loss after warming up the motor “, – This is the main reason for the appeal. After reaching a temperature of 60 degrees, the fuel correction is significantly taken into account according to the testimony of the recreation center, and the owners complained that after warming up in motion “threw gas – pressed, and as if the trailer was hitched to a car”
– “rpm is growing, but there is no acceleration “ etc.
Another rating: – “Very sluggish acceleration to 3000 rpm, then it seems nothing”.
Of the messages in the forums, most of them changed the spark plugs five times from simple to iridium APEXi 7 (with photo reports on the work done), all sensors in a circle (starting from MAF, etc., fuel pump, nozzle flushing, who like …).
Some even managed to sort out the automatic transmission, and I personally met with such. Surprise knew no bounds. It is understandable – there are no errors (and they will not be on this motor), but the problem is unsolvable. It’s just that the collector on the RB25 is solid, but here on the spacer of the SWIRL dampers there are gaskets on which the mass resistance grows over time due to oxidation. In DATA STREAM mode, when the O2 B1S1 signal is graphically displayed and the points on the collectors are connected, the signal immediately changes its appearance from NG to OK (Fig. 1) and the machine receives full acceleration dynamics, and the owner is surprised at one wire.
© Legion Avtodata
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