this is my first na and i am having a hesitation at 3800 4000 i have done all of the grounging procedures and have made shure that the 5th and 6th port actuators move freely
so i am lost as to what to do
i know it is possable that the cats are rotted out and i may not have enough back pressure to actuate the ports
is there any test i can do for back presshure or any actuator tests
i would like to wire them open just to rule the 5th and 6th ports being a problem
does any one have a write up on wiring them open
thanks for your help

 

its your injectors. am i right on this guys? your secondaries kick in at 3800 its like that there is a spot on the fuel map where primaries shut off and your getting a lean spot. so your car starts to knock. easy solution would be to get rtek to overlay the secondary injector turn on. it would be about 3500 so there would be an overlay

but of course i could be wrong....btw you prob want to take off any grounds that you have. if you have extra grounds they often fight with one another....so just clean the grounds you already have and make sure they are working properly

any one else?

 

then again this problem has been driven into the ground with a hammer so you might not get to many responses

 

i do not see grounds could fight agenst eachother
i am pretty shure its the secondaries because when i ran a scan on the car it said there was a comunication failure
which means the o2 sensor is reading lean without being able to correct
can i ground each injector or do they need to be grounded back to the ecu
thanks

 

Where did you add the grounds? At the sensors or at the ecu? I would also recommend getting the injectors cleaned for sure. Grounds at the ecu on all the ecu ground pins should solve the problem.

Grounds dont fight with each other. The entire chassis is grounded.

 

could be the tps too. mine had sooo many dead spots. crazy bogging..

 

your injector wiring clips might be not touching when connected. Unplug your secondary electrical connectors and examine them. I had same problem, except mine got so bad that it would just bog down. I ended up having to remove the part that clips on and just connect the 2 wires directly. It also might be just a shitty cat.

 

Emissions Control Unit (ECU)
The ECU is the real brains of the car, coordinating everything from spark timing to fuel delivery to idiot light functions. Unfortunately, this device is subject to two types of electrical malfunction. The first is bad solder joints. Go figure, eh? The second is bad grounding. As the car ages, the ground connections dirty up and corrode. This makes them intermittent and high resistance. The effect on the ECU from both these conditions is erratic operation, which can cause all manner of engine related problems. Perhaps one of the most common is the infamous 3800RPM hesitation. Coming up to 3800RPM, the engine may hesitate horribly. This is usually related to ECU problems. Cold solder joints can be repaired by resoldering the ECU and the grounding problem can be fixed by regrounding. A dealer may want to replace the whole unit though, and this would be at great cost.

 

Then you haven't been formally educated in electrical theory. Without going in depth, just pretend for a moment that all of your grounds are actually the power wires for the car. Now pretend that you have 3 different power wires for one single computer, because you added two. Next pretend that the voltage fluctuates on each of these 3 wires because of strange resistance loads (known as impedance, or inductive and/or capacitive reactance). If you were a computer running on these 3 different voltages, you'd be confused, would you not?

That's basically what you're doing by adding grounds, simplified greatly for your viewing pleasure...

You guys that are grounding your ECUs to the nearby chassis need to know that while the alternator is turning, IT is the source of power for your cars' electrical system, not the battery. I'll get no arguments from that statement, I'm sure, but here's the clincher- if the alt is the power, it is also THE ground potential. Your ECU's ground now has to flow through the chassis, through the bonding strap on the tranny/ firewall, and through the housings to return to the alt's potential...And we all know that long runs on a 12v system result in voltage losses, now don't we?

In other words, we now see the reason Mazda put the ECU's ground out there on the rear rotor housing- it's near the alt. If the ECU regrounding fixed something on your car, your wiring is shot, pure and simple...Get her fixed the right way, and she'll run even better than before.

Wayne's basic grounding 101 is now commenced for today

 

Damn, you guys got me off on a tangent- I was going to talk about hesitations...

It seems that there are several fixes that have worked for several people, which means that there are probably several causes, but they all revolve around the actual components required to instigate a smooth transition into the secondary ranges, namely the boost sensor.

Either it's not doing its job because of an electrical problem (which also tends to affect the ECU's handling of its input), or because the engine's manifold pressures are not what the ECU thinks they should be to kick 'em in (again, perhaps due to the boost sensor's malfunction)...

One theory of mine is not mentioned much- if the aux ports aren't doing what they're supposed to be doing at exactly the right time (let's say they open a bit early), the added airflow is enough to kill the pressures necessary for the boost sensor to help the ECU kick everything in. Hence, the hesitation for a bit until the manifold pressures reach the point that the ECU WILL kick them in...

I don't know if this works in reverse also (ports opening too late), but I would imagine that scenario would also add to the ECU's confusion...

Of course, with the turbos' 4 port design, this theory wouldn't hold...

 

If I had to put money down, that's what I'd pick. Check the TPS. The standard tests look at only the zero throttle and full throttle situations. You also need to check the sweep. It's not as easy, but if you use an digital meter or preferably a oscilloscope you can slowly sweep the full range of the TPS and see what happeneds. If it's really jumpy in a certain spot or spots, then you probably need to replace it. It makes a lot more sense that the transition is going to fail before the peak values go off.

As for the wild grounding theories, I REALLY doubt that is going to be the problem. We're dealing with DC power not AC power, so there isn't a wave (or at least one worth mentioning for this kind of case) that can get out of phase.

 

i grounded the engine bay the boost sensor and the ecu
today i will check the tps and do a preshure test on the boost sensor and check the injector connecors
thanks

 

No ground loops are very very common on cars. A ground loop is where the ground potential is different in one spot than another.

For example. BMW uses structual adhesive between the sub body panels along with spot welding. Because of this the ground circuit potential to the battery can be off as much as 2 ohms from the front lights to the tail lights. Sure, all the panels are grounded, but there will be a difference between the ground in the trunk and in the engine compartment.

Now, how much difference in ground potential is between the body panels in a 15-20 year old japanese car? This is why Mazda grounded the ECU to the engine. So that a majority of the electronics for engine control have the same ground potential.

This is a very very very common car audio problem. Where the headunit has a different ground potentail (and/or grounding location) than the amplifiers; causing a high pitched whine in the audio system (that usually varies based on alternator speed). Of course star (or single point) grounding (just like Mazda used on the ECU) generally solves this ground loop problem.

Remember alternators also run on AC voltage that is rectified into DC, if a diode fails in the rectfiing circuit; a minor amount of AC voltage is introduced into the electrical system.

 

It makes sense that such a situation might occur in audio situations, but I'd be quiet surprised if it effected the operation of the digital circuits or sensors (which are slow compared to the frequency of say a high pitched whine). Semiconductors have a range between which they switch "on" vs. a point where they switch "off" that is different from the pure ideal. Take a pulsed signal like the CAS. It's not going to subsantially matter if it's slightly off phase from something else, because the difference is going to be relatively consistant. Even with an inopportune spike, I wouldn't expect a little additional voltage from a non-pure DC wave to really effect these things. Even if there is no diode failure a rectified signal is not perfect DC, in fact it can be surprisingly non-DC, but the car's sensors and electronics work anyway.

 

In a sense, you're right, but not right on. Here's why-

The alt's AC wave is basically chopped in half at the point of ground potential (0 volts) by the diodes. The upper half of the wave is allowed to pass, all positive voltage. Depending on which part of the wave you're looking at, however, this voltage could be anywhere from .1v to 15v (just for graphic purposes, we'll assume the peak of the wave is at +15v potential). So you're right, it's not perfect DC, but it IS DC, because it only "flows" one way...

There's also a little something called RMS voltage, which is the actual "power" derived from the wave. Mainly at play in an AC voltage system, our cars' DC system resembles it. Even though the wave may peak at (say) 18 volts, the actual system voltage is read as 14v on your meter (some meters, notably the Fluke digitals, actually have an RMS setting, or advertise that it's an RMS meter). The reason I'm going into this little RMS lecture is that this is what the sensors and computers "sense" when the alt is running- the RMS voltage, not the peak-to-peak voltage...

So in an RMS sense, it is perfect DC voltage


For you guys that seem to think extra grounds don't hurt anything, do this- run a bonding jumper directly from the alt to the chassis , keep the OEM tranny-to-firewall bonding jumper in place, and the main ground near the starter. If your OEM grounds are in good shape, report back to us how the car runs...

 

Perhaps I didn't phrase what I was thinking very well. When one thinks of an ideal DC signal they're thinking of an infinite frequency wave. I'm well aware that a wave that never produces a negative voltage is obviously not an alternating current.

Measuring voltages at the ECU you're dealing with a closer to infinite frequency wave. I'm not sure if a filter capacitor is used to level out the variations of the wave (eg. how it's done in a AC to DC transformer-rectifier), but you don't have a substantially differing wave that's being averaged out. When I was refering to perfect DC, this is what I was trying to talk about. This voltage isn't a perfectly even +xV, but it's not fair to call it a +Y to 0 sine wave. This brings up another point worth mentioning, all the inputs/outputs on the ECU likely have a filter which eliminates some of the invalid frequency components that may have been added for whatever reason.