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Is there a way of testing the operation of the voltage regulator on the alternator. The light flickering when the idle smooths out on cold starts is quite severe. It normal to see the flicker however, my lights dim to almost off then flicker back on. This function is controlled by the voltage regulator.
I also noticed that my new red top optima battery needed charging however, I also noticed my negative connection was a bit loose and this has now been corrected. I have looked at all the factors surrounding the high rpm hesitation and also the odd sticky idle control and perhaps alternator and possibly the voltage regulator could be the cause of the issues. The hymee design also restricts airflow around te alternator and heat could also be a factor causing possible failure. I plan on getting a multimeter to test battery voltage then start the car and check the voltage output. Is the battery lead the best place to test alternator output? |
what you are planning is the way i diagnosed that the internal regulator in the alternator was damaged and causing it to output up to 17V. this caused havic with my power steering, ABS and cooked my optima red top (its now dead, wont hold charge at all)!
Buy a multimeter, (fluke if you like the best, but any cheapo one will do the job) test battery voltage with car off (12V-12.5V) start car (ensure all accessories are off eg aircon, lights etc) output should steady to 14-14.5 volts then turn all accessories on, voltage should again steady to approx 14-14.5 volts There is also a way to check the power module output (see service manual). |
if its indeed the regulator, its a relatively easy fix...however the price AUS Mazda charge for the part is ridiculous, hit up onlinemazdaparts.com or similar. Just be weary that different years of the rx8 had two different alternators with two different regulators.
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I have checked my alternator output via a Cobb unit through the obd11 port and only get a 13.5--13.6 Volts. At the battery I will see a different reading. It seems the pcm also address's voltage regulation in our cars. Its not just the built in regulator?
Voltage will drop as the alternator heats up and the alternator is the hottest part attached to the engine ( excluding the header lol). At Road Atlanta i actually melted the edges off my belt when the ambient temps where 105+F. It does have a built in fan--but i do wonder at times--- |
OD I agree heat is probably the cause of the internal voltage regulators failure. (as we all may know examples of basic voltage regulators such as the 780X series are very heat sensitive, im sure this regulator would be no different)
OD If you see only 13V at the battery terminals with all accessories off, your alt may be on the way out? not sure. I believe the PCM sends a control signal (extra low voltage) to 'regulate' the output of the regulator due to conditions such as electrical load, this is through that two pin plug on the top of the alternator. It is hard to see the exact operation of the control signal without an oscilloscope. |
Drove the car yesterday after tightening up the negative terminal and the car seens to run better. I will also look into running some ground wires to alternator, throttle body and coils.
My battery has been relocated to the boot so should I just run the ground wires direct to the chasis. Would it be also be better if I ran my battery ground to the chasis instead of the body panel in the boot, just wondering if it would make a differance. |
no I get 14.1 at the battery terminals but when you check it via the obdII port with the cobb you see the 13.5--13.6. That represends the actually voltage the pcm is letting into the electrical system that drive the injectors, the fuel pump , the ignition coils etc.
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Ground should go to the chassis at the least, a poor ground at best is all you can expect from a bunch of spot welded body panels. The best way is to run a seperate ground to the engine block. Both cables should be the same size and the bigger the better
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Tested the voltage at the battery voltage and it seems to be at 12.5 and at start up with accessories running it is 14.5.
After I disconnected the battery last time for a better grounding position the computer seems to be running on a different cycle. Now, I do not have a cold start problem, and the car idles beautifully. Also while driving normally the idle does not die at the lights as it usually does. However, if I let the revs drop freely from 7000 prm or more then the idle does not catch. However, right now it works great in daily driving and heavy traffic. However, it now idle rpm has changed to1000rpm and when coming to a stop the idle is at 1500 rpm for about 30 seconds then drops to 1000 rpm. Another odd behavior is that if I am in traffic and let the car roll while in neutral the car automatically revs to 1500 rpm as soon as the rolling speed exceeds 5 kmph. I quite like this setting so i do not want to disconnect the battery again as I do not know what computer cycle I will get next as the last one was absolutely crappy. However, i am aware that after a few drive cycles the computer automatically goes to another setting anyway. |
thats the neutral switch on the trans working?
Your charging/alternator looks good! You probably had fuel trim build up etc--did you also do the pedal dance? Any cooling problems/concerns? I finally ( after years of trying) have a stable cooling package for all seasons and conditions. |
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The ECU does regulate the alternator.
From the manual: • The PCM increases or decreases the field coil excitation current by sending a duty signal to the power transistor built into the generator. • The PCM changes the duty ratio of the duty signal to change the energization time of the power transistor. As a result, field coil excitation current is changed. For example, when the battery positive voltage drops, the duty ratio of the duty signal sent to the power transistor is larger, increasing the field coil excitation current. Control • In order to maintain the optimum battery positive voltage, the PCM calculates the target generator current (target output current) and target excitation current according to the generator rotation speed at that time. • The generator rotation speed is calculated based on the ratio between the generator pulley and eccentric shaft pulley, and the engine speed. • The target output current is calculated from the difference obtained by comparison between present battery positive voltage and target battery positive voltage (regulated voltage), calculated based on the IAT, engine speed, and vehicle speed. • When an electrical load is applied, power consumption increases and the battery positive voltage drops, increasing the target engine speed at idling. I haven't looked at this stuff much, but here are some of the tables referenced for generator control. https://www.rx8club.com/attachment.p...1&d=1334935929 |
^ just re-confirms what i said.
there is NO DOUBT the alternator has a built in regulator, i swapped one out just two weeks ago when i was seeing high voltage. However, this regulator gets a control signal from the ecu. From my understanding, from the Two pin plug on the top of the alternator (really a DC generator) ;) |
Originally Posted by olddragger
(Post 4244346)
thats the neutral switch on the trans working?
Your charging/alternator looks good! You probably had fuel trim build up etc--did you also do the pedal dance? Any cooling problems/concerns? I finally ( after years of trying) have a stable cooling package for all seasons and conditions. The HKS only controls certain aspects of the tune. I did notice the vacum line that attaches from the oil filler neck and connects on the intake plastic tube is a bit loose. May be unmetered air is getting sucked in? This nipple is screwed into the plastic and the thread is starting to strip. It is causing a problem I can glue it in. No major cooling problems. Car sat in stop start traffic and the oil temp got to 100 degrees celcius for the first time however as soon as I started moving it dropped back to 80. At the track it can get to 110 after pushing really hard and staying at the 7000 to 9000 RPM range on a constant basis however it will cool down within seconds if I back off a bit. |
Originally Posted by Giustino
(Post 4244830)
^ just re-confirms what i said.
there is NO DOUBT the alternator has a built in regulator, i swapped one out just two weeks ago when i was seeing high voltage. However, this regulator gets a control signal from the ecu. From my understanding, from the Two pin plug on the top of the alternator (really a DC generator) ;) |
Ok, it seems I am having boost problems. It seems to max out at 5psi and i can hear wooshing air sounds from the engine bay while driving when the boost builds up.
the only spot that has oil residue is the flange on the side of the supercharger where the air gets pumped out. It could be where the air is escaping and at teh same time causing my high rpm hesitation issues. This flange is on very tight however the seal may have let go causing air to leak. |
oil shouldnt be there --should itz/
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I get a bit of oil getting blown in through the intercooler and into the intake. It is not noticable when you pull things apart however, if there is a leak it accumulates over time.
I noticed this when I had a seal problem near the plenum. |
i had a problem once with oil blow back like that--I had to vent the crankcase( oil sump) better.
I ended up putting a vacuum line on my catch can. On track I run just a tad under the full mark on the dip stick. That helped. |
I was told that my side seals where wearing out causing the oil to get blown in under boost and there was no where to install a catch can.
The slight oil mist does not worry me as it helps with the rotor lubrication. Just gotta wait it out before the tuner can get the car on the dyno to assess the issues. |
sure you can install a catch can---dont know you told you that. Matter of fact you either have to have a catch can with a better than oem vent system for the crankcase(sump) area or you will always have blowby to deal with.
Old mechanic trick--pull the oil dipstick while the engine is idling--see if the engine sound changes. If it does then you have a BIG leak. |
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Dude logger data. Airflow seems low with sudden drops while accelerating.
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/\ wow - that looks bad even if it was NA .
How are you tuning it ? |
The tune was done using HKS Fcon and it worked perfectly then I started to have problems a few months ago. After a long elimination process I feel it is now down to the tune or a throttle body issue.
The throttle body has various valves within it and it could have failed or I need a retune. Around 6000rpm I get a lot of hesitation. |
WWWOOOOOWWWWW!
Look at how much timing you have going on! Etc. That looks bad man--i wouldnt put any boost on it looking like that. Something is really wrong. |
I will not drive it much until the tuner gets a chance to look at it. I am glad it has survived thus far as I was driving it really hard each time I took it out.
The engine must be fairly robust to put up with so much punishment in FI mode and 7 years of regular track days. |
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