ib042129

Yeah I agree on the welds. I would like to weld some of those couplings. Especially that pipe that goes from the IC back into the engine bay, the one that has the BOV. It was kind of retarded that I ended up with 3 couplings there instead of 1. Just all the lengths and the BOV bung welded in a weird direction.

You want the BOV return AFTER the AFM because otherwise you end up with a vacuum leak. The AFM reads the air that came in, but instead of going into the engine, it goes out through the BOV. By routing the BOV AFTER the AFM I just create an internal loop so you don't loose any air. The only way for the air to escape is through the engine.

JSM

Yeah I edited my mistake out. But you quoted it before I got it out!

It should be routed back before the turbo and after the AFM / MAF because the air measuring device in the system has already measured the air.

If you just vent it to atmosphere,when you decelerate quickly after boosting, the engine will run very rich and if you have to get on the gas again quickly you lay down a lot of smoke and don't have as quick a response because the A/F ratio is off.

snwbrderphat540

the problem i could foresee with the AFM the way it is is see under that black plastic color, is a slide wheel on a coil spring and on the very bottom of that is a weight, the way you have it sitting that weight is not doing it's job in assisting in the resistance. it actually might be working against it, that could cause fuel mixture issues.

JSM

Did you "bead" your IC pipes?

http://www.theturboforums.com/smf/in...topic=140645.0

and

http://www.roadraceengineering.com/e...icpipebead.htm

and

http://forums.turbobricks.com/showthread.php?t=58790

snwbrderphat540

Awesome stuff^^^^

P.s. stick that techIII in my old 260 and donate it back to me haha. Let me know if you have any questions on that car man. I remember most of its little habits. I think there are a few small holes in the hidden compartments behind the passenger and driver seats. Only real rust on the car. i think I sand blasted them up n sealed it. But didn't patch them. FYI.

ib042129

Finally an update.
I had to take a weekend off due to a trip,
and then I forgot to fabricate some parts for the last weekend.

Well, in any case at this point everything that needs to be hooked up was hooked up.
And I tried to start the engine.
Checked the fuel pressure, fixed a fuel leak.
Started cranking the engine, found an oil leak, fixed it.
Got the engine running more or less, found an exhaust leak. (Hopefully fixed.)

In any case, the engine is being very inconsistent. Sometimes it starts right away, sometimes it needs help with me on the throttle.
Once started, it eventually runs pretty smooth, but the idle is pretty high (above 1k). Also, it hesitates when I press the throttle before revving up.

So, there are still some issues. I got brave enough to let the turbo spool up just once, and that worked okay. But no driving it yet, still need to troubleshoot this thing.

I will have to check every individual spark plug and injector just in case.
Aslo, I have not played too much with the off boost fuel pressure, I just left it at about 30 psi.

My one suspicion is that my blow off valve (bov) is causing a vaccum leak, or is not working like it should in general. I capped all the vacuum ports connected to the bov and I think the engine got a lot better. I htink I need some suggestions on this.
So this bov, has a screw at the top which you can adjust, and two vaccum ports. One in the front, and one in the back. I assume the front one goes to the intake manifold. I don't know what to do with the one on the back.
Any suggestions on how to deal with this one?
And any other suggestions on how to proceed troubleshooting this?

BOV by ib042129, on Flickr

JSM

You can take the BOV apart and check for rips or tears in the cup. Did you get instructions with it? I'm not sure why one have one vacuum reference and others two.

I would double check all your connections, grounds and make sure they are clean too. Electrically they tend to have little corrosion gremlins.

JSM

http://www.ls1tech.com/forums/forced...lp-please.html

http://highboostforum.com/forum/show...-your-TiAL-BOV

ib042129

It's is a fake Greddy Type-S Bov. And even the original ones sometimes have tears in them. So maybe it is the bad guy in my system. But I think I can isolate it while testing.

The second vacuum line is optionally routed to the turbo to assist in opening quicker.

I think I will try to first just cap that second line just in case it leaks. See if things improve.

I did not have a chance to play with the car after Saturday, but thinking about it, I have a growing suspicion that I might have an issue with either one spark plug or one injector.
No conneciton, bad connection, or bad injector.

The reason for it is that the exhaust is not always smooth.

Actually, could timing be an issue? I did not play with the distributor position yet, but I was always off boost.

Also. Any suggestions on why the engine would hesitate before revving up when I open up the trottle?

JSM

Any updates?

ib042129

Yes! Finally some updates.

I was out of town for two weeks and could not work on the car. But finally started her up yesterday again.

So. Here are the good news first:
I actually drove it 20 miles yesterday from my friend's garage to my place!
It makes good boost and the engine did not explode.
I get a ton of power under boost 2.5-4000RPM.

But there are still a few big problems.
The idle is really shitty. Starting the car is quite tricky and I have to play with the throttle a bit to get it going. But it will idle in the end.
Then it really hesitates when I open up the throttle from idle. I have to ease the throttle in, the engine would struggle, slowly creep up to 2000PRM, then it would work normally and give me a ton of power. Takes maybe 5 sec to build up to 2000PRM, and the engine shakes a lot when that happens.

Also, it is really rough if I do anything with the throttle quickly. The engine will kick if let go of the throttle for example.

I am trying to figure this out. I am still suspecting the BOV to be giving me at least some of the trouble. One of the issues with it I see is that if I let go of the throttle, the valve opens and this creates a high pressure at the AFM which slams the AFM shutter closed. I think I will bypass the BOV for a while jsut to be sure.

Another possibility is the injectors. (I think.) I tried disconnecting them one by one, and the engine began to run worse with one injector disconnected. (This is the only way I could think of how to check them without taking them out. A more definite check would be nice.) But maybe the sockets on the injectors are bad. Is there a good way to refresh those sockets?

And maybe a vacuum leak is also possible.
Ideas? Suggestions?

ib042129

Yup. You were right. Basically all the issues at idle were because of the low fuel pressure. I dialed the pressure back to above 30psi and the car idles better and the engine does not hesitate when i open up the throttle. (But the car does idle high even after I tried to adjust it. )

I drove it again today with the higher fuel pressure, and I am actually kind of scared of the car I ended up with. There is a ton of power under full boost. The road was wet, and I was afraid I would spin out if I oped up the taps.

Just need to work on fine tuning it now.

A couple of questions/issues.
1)The BOV did work, but it opens up for a very short amount of time. I can't hear it, and barely feel any air come out. I think connecting that second port of the BOV to the turbo would help. (Letting go of the throttle quickly is rough and I see a spike in pressure. The BOV working better should help with that.)

2)Does the ECU adjust the injector timing solely based on the AFM reading? Or does it that the Oxygen sensor into account as well? Just from reading my gauge, it looks like when I change the fuel pressure the ECU compensates because I was never able to achieve a lean condition.

3)It is kind of hard to get good consistent boost when the transmission is in neutral. Is there a good way to adjust the FMU without taking the car out for a drive every time I change the dial a bit?

4)The car runs with the temperature gauge right in the middle of the range and it's pretty stable. But I can get the temperature to creep up if I am on the gas pedal a lot. I know that a better radiator, and an oil cooler will help. But before that, are there any types/brands of cooling fluid that would work better than your average antifreeze/water mixture?

NismoPick

You are running the turbo ecu right? If so, it uses all 3 sensors to monitor / control fuel (AFM, CHTS, O2 Sensor). If you haven't done so yet, now is the time to break open the AFM cover & adjust the spring tension (search on this... we've discussed it 100 times before).

The turbo doesn't boost in neutral... no normal turbo setup does... The motor needs a load & time for the turbo to spool. Jamming the gas pedal for 3 seconds in neutral doesn't do that.

An oil cooler isn't going to bring down coolant temps... coolant (depending on your thermostat rating) runs about 180-210* while oil temp runs 200-230*. Efficient oil coolers are good for the mechanics of the motor & turbo.

Aside from that, yes, obviously the coolant temp will rise when there is more load on the motor, which is multiplied on a high CR motor (like your n/a motor running boost). A cooler thermostat may help, but start with measuring the coolant temp at the thermostat housing vs coolant temp at the lower radiator hose. If your radiator is cooling effectively, there should be a 20-30* drop.

ib042129

No. No turbo ECU. Remember?
I use the stock na ECU+ BEGi FMU to account for the boost.

I have read a few write-ups on messing with the AFM, but I want to try and work with the fuel pressure first before moving on to the AFM. We will see how that goes. (My air/fuel gauge rarely gives me a stable reading though, it always bounces around between reading something reasonable, and overload on the rich side. I hope it is just a shielding issue. BUt I might just try using a multimeter for the tuning.)

I want to first set as low of a fuel pressure as I can at idle while still running normally. I think I candial it down quite a bit as of right now. Then try to set the right FMU rate at full boost. And only afterwards mess with the AFM settings to fine-tune this.

Why wouldn't the oil cooler help? If the coolant temperature starts to creep up, that means the radiator can't handle the heat load alone. An oil cooler is additional heat dissipation through the oil.


Oh and to answer one of my own questions. I took off the BOV and tested it with one of the vacuum pumps at work and found a leak. Basically, one of the screws that hold the chamber together cut too far into the membrane. I fixed it with just some silicone around the joints. And also removed one of the springs so that it would open easier. (I mean it should be okay if it is open a little at idle because I am recirculating the BOV anyways, so no air escapes. But it should also be easier for the thing to open under boost.) Checked it again, and got a much better response out of it. I will put it back in next time I mess with the car, see how it goes.

NismoPick

Was already answered with:

Oil runs hotter than coolant... oil is also thicker than coolant (water) so it takes longer to heat up, and to cool down.

Only if your coolant gets in the temp range of the oil would an oil cooler help your coolant temps, and if your coolant is getting above 220-230*, you have other problems.

Dunno how else to explain it in simple terms... so research if you still don't understand. There are many racing forums / websites that explain it in detail.

ib042129

I disagree with you at a level of Physics. An engine under load creates X watts of thermal power. Some of that energy is stored in hot oil. If you assume there is no way for the heat to escape from the oil, the engine and the oil would be at the same temperature. If the engine and the oil is at the same temperature, no thermal energy is transfered to the oil.

Now if we add a cooling mechanism such as an oil cooler, the oil will loose energy into the air. This means that the oil out of the cooler will be at a lower temperature than the engine. If there is a temperature difference, then there will be energy transfer from the engine to the oil.

Therefore it is a FACT that an oil cooler will remove SOME heat from the engine. This is true only if the oil temperature after the oil cooler is less than the engine temperature and does not depend on the coolant temperature at all. As long as the oil cooler is working, it is dissipating let's say N watts of thermal power.

Now, let us ignore the oil cooler and assume that the engine is cooled only by the radiator. Let us say, a radiator can dissipate M watts of thermal power. (Ignoring the thermostat for a second). If M>X then the engine will cool down. If M<X the engine will heat up. And if M=X the engine will remain at the same temperature.

How about we add the oil cooler. The total heat dissipation is now M+N. Therefore the engine will not rise in temperature until X>M+N.
(This is of course a little bit more complicated because M and N depend not only on the heater design, but on the temperature difference between the fluid and the air, and the air flow. But the basic equation still holds.)

Of course, you are correct in that in for a well built car M>X no matter how hard the engine is running. And then the coolant temperature is set by the thermostat which closes the coolant circulation if the temperature is below some set value.
So you are correct that as long as the car is running at the coolant temperature that is set by the thermostat, the oil cooler will not make a difference. This is because if M>X then M+N>X and the thermostat is what regulates the temperature.

But if your engine temperature rises ABOVE the thermostat setting then this means that the radiator could not dissipate all the heat from the engine. Meaning M<X. But of course M<M+N meaning that the oil cooler can help.

The only other argument that I can see is that N is possibly much smaller than M or X and therefore the effect is negligible in real applications. Which could be true given that the oil cooler is much smaller than the radiator.

In any case. I will take your advice and look into a thermostat with a lower temperature setting before I spend money on an oil cooler.

NismoPick

You still don't get it... And I never said an oil cooler isn't needed (I have an oil cooler on my 280zxt)... I said an oil cooler won't drop your COOLANT TEMP.

It is a fact that engine oil runs hotter than coolant... If you don't believe me, grab yourself an infrared thermometer & measure the temp of the thermostat housing, and the bottom side of the oil pan. Your readings at running temp will be about 170* for coolant, and 210* for oil.

An efficient oil cooler may drop the temp 10-20* which will still be 190-200*. What is your coolant temp at? 170 (regulated by the thermostat)... oil is still hotter than coolant.

As I stated before, please research this. I won't argue a brick wall.

ib042129

Ha that last one is kind of funny.
As usually on the internet it is better to just shut up. But for the sake of entertainment alone I feel like having a bit on an argument. To day is being a slow day.

I feel like you have not read my post carefully.

1)I never claimed that you were against oil cooler. In fact it is probably a very smart thing to have on a car that has an oil cooled turbo.

2)I completely agree with you that during normal operating conditions the coolant temperature is set by the thermostat.

3)My point is that the coolant temperature is set by the thermostat because the radiator it able to dissipate MORE heat than the engine develops.

4)Do you agree with my statement that if the radiator dissipates LESS heat than the engine develops then the temperature of the ENGINE will go above what is set by the thermostat?

5)Do you agree with me that if the temperature of the oil after an oil cooler is less than the temperature of the oil before the cooler, then some heat generated by the engine is dissipated through the oil cooler?

6)Do you then agree that an oil cooler + a radiator can dissipate more TOTAL heat than the radiator alone?

Please tell me if you disagree with any of the points above because my argument rests on those.

Now as an example lets say my thermostat is set at 170*. But under heavy load (for example going up a hill) the car heats up and runs at 180*. (After the hill with normal driving resumed the car will go back to running at 170*.)
Assuming all the points that I have made are true. Wouldn't it be logical to conclude that by adding an oil cooler, and having my car go up that same hill, the car will now heat up to a smaller temperature. (Perhaps 179.5*)

I think in the end, we are arguing two different things. You are trying to say, that the coolant temperature should ONLY be dependent on the thermostat and if it ever goes above that, then you should clean/upgrade/fix the radiator because you have a problem. And that an oil cooler is not the right way to fix this.

NismoPick

I understand everything you've said, but you have either neglected to mention the fact that as coolant temp rises, so does oil temp. Obviously they don't rise linear to each other, but you've left out half the problem...

As I stated before: OIL TEMP IS ALWAYS HIGHER THAN COOLANT. If your coolant temp is out of control, what do you think the oil temp is doing?

I get what you are trying to prove... I really do... and you are trying to dangerously cut corners instead of fixing a problem correctly.

ib042129

Sure I understand your argument that the temperature of the engine should be kept in check by the radiator alone. And of course that is the safest solution. And it is the only solution if the car has serious overheating problems.
But as a counter example, I can say that often stock cars are made with different cooling systems depending on whether they are sold in the north or south. And cars sold in the south would have extra radiator fans and oil, power steering, transmission coolers. So even OEM solutions are not always focused on coolant. Of course, this is all theoretical.

As far as my car goes. I am not sure if I have an overheating problem or not yet. The temperature has been stable at 1/2 the gauge dial. And only at one time did it creep up to 3/4 of the gauge dial. THat was when I first drove it and with a low fuel pressure and pushed it to high RPM, so it was under a big load with probably a lean mixture. When I drove it that night back to my house, without pushing it the temperature was fine. And when it was running at a better fuel pressure yesterday I did not have any problems with heat even when I pushed it.
I did a visual inspection on the radiator and it looked clean. Of course that does not mean anything. I will get an IR thermometer from work tomorrow. (Along with a hopefully fully functional BOV and better intercooler mounts.)

I do agree with you on oil always being hotter than coolant, and I do want to get a thermostat wil a lower temperature setting. It should bring the oil temperature down for normal driving at the very least, and that will be good for the turbo.

Does the 280zxt have a bigger radiator than the n/a car?

In any case. I am getting ahead of myself. I should get the air/fuel mixture right first.

NismoPick

eh? I worked for Nissan and can tell you that is 100% not true... how could a car manufacture predict where a car will spend it's road life, just by the location of the dealer it's going to? Did they assume no one will ever drive their car out of the city in which it was bought?

ib042129

Well. I could be wrong, but I heard it on several occasions from unrelated people. And from personal examples, my friends 1996 Maxima which was originally sold in NY did not have a transmission cooler, while the same models in California did. Also, hondas sold in Canada had a single radiator fan while the ones in California had dual fans.
You can't predict where the car will be all it's life, but never the less cars sold in California usually have a lower speed limiter than those from the east coast. (That is of course regulation dependent.)

Well. In any case. This is irrelevant to turbocharging a 280zx and in my experience annoying to people who might possibly read the thread in the future. I will stop now.

NismoPick

You're comparing those cars to CA standard??? Yes... California has different standards from the rest of the world, thus the reason for "Federal" and "California" car models. That doesn't have anything to do w/ "North vs South" or cooling. It has to do w/ emissions.

Nuff said... lets move on.

ib042129

First day of tuning results are in.

First I played with the fuel pressure at idle. I could not get the car running smoothly at idle at any pressure below 30PSI. In the end I left the base pressure at about 35PSI.

When the car is running, the fuel pressure is not constant but pulsates a few PSI back and forth. It pulsates more at higher RPM. I am not sure if it is a problem, or not. (My Honda does not do that.)

After I set the fuel pressure to 35PSI, the car would idle and build RPM ok. But it would idle high, and choppy. Idle RPMs would fluctuate.

At this point I finally opened up the AFM to try and mess with it. The car was clearly running too rich. I swept the shutter of the AFM from the almost closed, to really open position by hand first. At the either end the car would struggle then as you sweep the shutter it would idle smoother, then build RPM at idle until it maxes out at some value. This should be the optimal setting right?
Before setting the AFM to where it gives me the highest RPM, I wanted to see a correlation between the setting of the AFM and what my Air/Fuel gauge gives me. Here is the weird thing. Again, I can not get the gauge to read a lean condition. The mixture is leanest around where the car runs best, but the gauge indicates a rich condition for both the very closed flap of the AFM and the very open. Anyone know why is that?

So, I kind of gave up on using the Air/Fuel gauge to set this for now, and just set the AFM flap to the point where I get the highest RPM at idle. And actually at that point the idle became reasonable and much smoother. (That point was toward the leaner mixture which is reasonable since the injectors are bigger.)

I have not messed with the FMU setting just yet. I just set it somewehere in the middle.

After all that I drove the car around a little bit. It drives pretty well. I think it is still quite rich though.
The fixed up BOV works wonders actually. Before, if I let go of the gas, I would get the pressure to oscillate and slam the AFM flap closed. With the BOV the pressure response is quite smooth.

One problem while driving though is that I loose boost at very high RPM. After 4000RPM at wide open throttle the pressure starts to creep down. I think is saturates somewhere around 3PSI instead of the normal 6. Why would this happen?

ib042129

I realized yesterday that the way I was tuning the car was conceptually wrong.
So I tried to think of it in mathematical terms of fuel flow v.s. air flow. I think that normally, this would be a straight line. Changing the AFM setting, would change the slope of the fuel v.s. air line, and changing the fuel pressure would change the intercept. This means that I can't adjust the pressure first, then the AFM. But that I should adjust both, and use at least two points of air flow.

What I did yesterday, was exactly that. First I adjusted the car at idle. Then, using a zip-tie to hold the throttle open, I ran the engine at 2500RPM and looked at how far my AFM adjustment was off. I then moved the AFM half way to optimal at that RPM, and then adjusted the fuel pressure until I was about at the optimal point. I then ran the engine back at idle and checked how far my settings were off from optimal at idle, and once again adjusted AFM half way and fuel pressure half way. I repeated the process 3 times or so and in the end at both RPM values the settings were close to what was needed. The only problem now is that I only adjusted it by sound, because I can't seem to get a reasonable reading from the oxygen sensor. (I think I will end up taking it to a shop for tuning once I save up some money. I am kind of broke right now due to business travel, it takes forever to get reimbursed at my work.)


I drove the car around, and managed to open up an exhaust leak by bottoming out on a speed bump.

Also can someone please tell me what is this thing? Why is it connected to the same vacuum canister as my AC, and why it makes an annoying squealing noise?

2011-06-26_15-12-50_44 by ib042129, on Flickr