Aeka GSR

iTrader: (4)

I've been wondering for a while now if I should go from 850 primaries back down to 550 primaries with 1600 secondaries. I've got an FJO driver and T04s with a half bridgy. Running 10psi (365whp) but plan on 15 if I ever get my boost controller back from my old boss. I think I have a Denso pump, whichever comes with the rx7.com fuel kit.

I'm tired of the crap rich idle and having to run -.40 lag (yes .4 not .04) to get something decent, but it isn't enough. I also have problems with light throttle cruising where the AFRs are 11:1 since I can't dial back the duty any further. Not to mention all the other nice hiccups of running retarded amounts of lag.

How many out there run 550/1600's and how is the secondary transition? Basically im getting old (well, almost im only 30) and seek better drivability. Is going that route wise? It seems nobody runs that setup. Is it because everyone is on a quest for more power or is it because they don't like the transition?

arghx

iTrader: (3)

go with top feed primary injectors if you want to go larger than 550. I run Greddy/Denso 720 primary's with the rx7store 1680 and that was more than enough fuel for 21psi on a T04S. Base fuel pressure is set to 40psi. I don't even use negative lag, I have used +.03 with success. I can idle at 13:1 no problem even with a large street port and I have no staging problems. I use the OEM 86-87 1/2 model rx-7 resistor pack (6 ohm) for all four injectors.

Aeka GSR

iTrader: (4)

Thats cool and all. And I might do that when I've got money. But money is an issue right now and I've got some 550's lying around I would like to try.

Banzai-Racing

iTrader: (11)

We have many customers running 550cc/1600cc combo. It works well. With your setup you will need to keep an eye on your duty cycles. It is not difficult to install them and see how you like it.

Light throttle cruise with a bridgeport takes a lot of tuning to get smooth, this is much more time consuming then WOT.

Aeka GSR

iTrader: (4)

Oh yeah, but on top of all that it took me a while to find out that I had the requested fuel in the map lower than what was allowed but I didn't realize it because the AFRs were very rich. It caused some serious bucking when the tps requested fuel under subtle movements because the maps were lean in that spot even though cruising was rich.
After that it was easier to fine tune that part. It isn't 100% but I understand bridge ports are a bit wild under light load. I'm more interested in a leaner cruise and a leaner idle. Sounds like I'll give it a shot. Any particular percent transition you like to start with?

Banzai-Racing

iTrader: (11)

Start with 35% with 1.112ms.

Just making sure, you do not have the FJO wired into the primaries, right? -.40 lag is insane. When everything is set up properly, you can get 13.0 afr at idle with 850cc primaries. The TPS setting is critical, it can not be set too high. The PFC needs to know that it is in idle. The major issue that you will run into is the poor vacuum that the engine pulls.

Aeka GSR

iTrader: (4)

Thanks for the tip. Yes I have the FJO wired in the primaries. I was told it just runs as a pass through. I wired them up that way for failure reasons. If the FJO fails, I want all my injectors to stop. I don't need a blown engine to find out the FJO lost power or failed. I've also been running -.40 before I even had an FJO.

Also yeah the poor vacuum is fun to drive in stop and go. I wired up a vacuum pump into the system as a supplement but I found that it was too slow. It sorta helped, but not enough. What I can't understand is the braking is really **** poor even after I pull a ton of vacuum from engine braking, I don't have any vacuum leaks either. I even took off the vacuum pump to make sure that wasn't having an effect.

thewird

iTrader: (8)

FJO can be wired into the primaries. The unit can detect the high impedence and run them. Its actually recommended in the manual to run your stock high impedence injectors before switching to make sure you wired it in right.

Switching to 550 primaries is a great idea. 850's blow.

thewird

Banzai-Racing

iTrader: (11)

I don't wire the FJO into any high impedence injectors.

There is a one-way check valve in the hose going to the booster, check to see it it has failed.

Banzai-Racing

iTrader: (11)

What manual? Every one I have ever received has been a single sheet wiring diagram. I am not saying you are wrong, but I can not find anywhere that says the unit can detect high impedence injectors. Also every time FJO mentions the driver they type it in all caps "The LOW IMPEDANCE INJECTOR DRIVER...."

http://www.fjoracing.com/products/injdrvr/index.php

thewird

iTrader: (8)

Oh sorry, not in the manual. I asked FJO directly about this. They say the driver will work with both high and low impedance and you can mix the 2 as each channel is independent.

thewird

Banzai-Racing

iTrader: (11)

Oh, I see....I think I just will stick with the way I have been wiring them up. Low impedence injectors to the driver, high impedence to the ECU. I have never had any problems and I really see no benefit to having them all quit at once if the driver fails. At least the cars will still be able to make it home running on primaries only if that does happen.

Aeka GSR

iTrader: (4)

I'd rather have no fuel than half fuel at WOT. I've blown an engine due to a failed secondary wire. I'd rather not see that happen again. I'd rather get a tow, then have to spend thousands on rebuilding.

Banzai-Racing

iTrader: (11)

You can do whatever you want with your car. If you have a secondary injector issue, you will never make it to WOT. The car will start bucking and running lean at 3500-ish RPM, can't blow it up unless you try to force it. No reason for anyone with a wideband installed in their car to try to push through a lean spot. If you are worried about them spontaneously failing while you are already in high boost at wide open throttle, turning all your injectors off will not save you an engine. The very fact that you need to run -.40 on the primaries tells me there are things about your car that are not set up correctly.

thewird

iTrader: (8)

I had the same experience with the 850's having to add a ton of lag just to get them into the 12's.

If all injectors fail under WOT, it would be like a boost cut. Generally there is nothing wrong with that on a properly tuned car. If its a slow failure, that would be a problem I think.

thewird

Aeka GSR

iTrader: (4)

I'd really hate to question if you've ever dealt with a complete failure of a secondary injector since you're a knowledgeable voice, but I wouldn't be so quick to rule out what happened. The car had a wideband, everything felt fine and looked fine. This was a stock non-seq motor. I gave it wot, everything was fine until I heard a ping, before I could react and as I was trying to let off the gas, there was a rapid fire of pings. I blew out one apex seal and it junked a housing and rotor. I can't remember what RPM I gave it wot, I just remember things being rather immediate, followed by some pounding on the steering wheel by my fist with anger.
I've had several setups and engines between two cars that have had 850 primaries and every one of them has had -.04 lag. My current setup is the only one that needs -.40. I thought it was odd indeed and followed chuck's book to make sure things were right. The only difference between my other engines and this one is the fact that it is bridge ported, single turbo, with a 3 bar map sensor. If you have any suggestion as to why I might be needing -.40 by all means let me know what it could be. I've asked others on this board and it seems I'm not the only one who needs -.40.

Banzai-Racing

iTrader: (11)

Of course I have dealt with secondary injectors that are not firing at all. Like I said it is very difficult to get past 3500 rpm.

What you are describing sounds more like detonation from bad gas or bad tuning. I don't know what boost you were at, but you would have known if a secondary was not firing very early in the RPM and boost. You would not have gotten a ping and your AFR's would have spiked lean off the charts. Who knows maybe you had the ultra-rare spontaneous secondary failure in mid-boost, that caused no change of AFR and a blown engine.

I am not familiar with anything about your car with exception to what is in this thread, I have no idea how you have it set up. I don't even know what your base fuel pressure is set at. It is impossible to tell you what is wrong. I do know this, I tune 1-2 cars a week with 850 primaries and not one of them are at a negative lag time and all have high 12, low 13 AFR idles.

Aeka GSR

iTrader: (4)

Yeah it was odd, didn't feel lean or anything. I've had my hand in tuning before. I've tuned several sand cars. It took me a long time to figure out what the cause was. I thought it was bad gas at first since I had just filled up. It wasn't until I decided to cut the wiring open and found a broken wire, or more actually I found the problem when I was re doing my wire loom for the new engine and found the broken wire.

thewird

iTrader: (8)

I still think a complete failure of injection would be better then just the secondaries failing under a WOT scenario already in boost...

thewird

Banzai-Racing

iTrader: (11)

You can have your injectors fail however you like. I prefer to have the car set up to prevent any injector failure/fuel cut from occuring.

Do you have your FJO driver mounted in the engine bay?

thewird

iTrader: (8)

In an ideal world not ever having to fuel cut would be ideal, however realistically there is always a chance of something going wrong, whether it be mechanical failure or human error. I just don't see how having only the secondaries die is good thing. Your scenario for driving it home assumes it happens before your in boost and therefore cannot get into boost or high RPM to do harm. I actually tuned a car where one of the secondaries wasn't working and know exactly what your talking about. But what if it happens when your in full boost WOT, high RPM. Do you still think having the primary squirting fuel is a good thing?

My FJO driver is tucked away in the kick panel where it should be. Don't see how that is relevant though. Actually using your patch harness since I like the idea of being able to easily swap the harness without having to rewire everything.

thewird

Banzai-Racing

iTrader: (11)

I guess I will deal with that when I actually see one of the FJO drivers that I have installed fail. Up until now, not one of my customer's or myself have ever had an issue. So your hypothetical situation is a waste of time. If they start having any failure rate I will discontinue using them and go back to installing resistors, which have been working for decades.

I get the impression you are just trying to start an argument. I certainly am not going to change my installation practice based off of someone on a forum that claims to have "talked" to someone at FJO and they said it was OK to connect high impedence injectors to a low impedence driver. Especially after they had state it was in the manual, that doesn't exist.

Location is completely relevant as I have seen numerous people on this forum believe it is OK to mount them in the engine bay where it exceeds the recommended 185F. This is asking for failure. "It is designed to operate over the temperature range from -40 to +185 degrees Fahrenheit (-40 to +85 degrees Celsius)."

thewird

iTrader: (8)

I don't want to start anything. I merely want to get the facts straight. My manual or sheet (I don't remember) did in fact say to try your high impedance OEM injectors first to make sure you wired it in correctly. I went searching in my e-mail, here it is direct. I removed unnecessary parts of the conversation.

Also again, your assuming every single FJO unit will function as it was intended and will never fail. What I am talking about is worst case scenario IF it does fail for whatever silly reason.

NASA had a team of engineers and millions of dollars for research and development but did that prevent the shuttle from having its incident?

Would you like to test the scenario on the dyno at 6000 RPM full boost wot, pulling the secondary injector clip and see what happens? That is what I am discussing ("arguing" as you put it) here.

Well, I did mount mine away from heat in the kick panel as I did read the manual or sheet. But that still has nothing to do with the fact that having ONLY the secondaries fail is not perfectly fine.

I have no interest in what you do in your shop. I am merely expressing my opinion and gave reasoning for it.

thewird

Banzai-Racing

iTrader: (11)

Installation "manual" is right on their website, it does not say that you should test the high impedence injectors first or even hook them up.

http://www.fjoracing.com/products/in...&%20wiring.pdf

Never once did I say that having ANY injectors fail under boost would be "perfectly fine".

You can do all the testing you like. Make sure you log your AFR's and boost, this way we will see if it blows up without any warning. You don't need to waste money for a dyno, just connect one (or both) of your secondaries to a toggle switch. First try your senario, turning off all your injectors under boost. If the engine survives, then try the secondaries only. I think it is really incredible that you are willing to potentially sacrifice an engine and turbo(s), so that we can all see what happens when an FJO fails under load.

On a personal note, I think it is kind of wasteful. If the FJO had any type of high fall-out rate none of us would be using them. It is a cheap part and to potentially destroy thousands of dollars in engine and turbo parts to prove your "opinion" is well beyond stupid. The amount of time any of us spends at WOT, compared to light load/cruise is a very small percentage in reality. Most people are at a WOT for 20-30 seconds max, then let off, even a 1/4 mile track should be 14 sec. or less. The likelyhood of an FJO failing at just the exact same moment that the car is under full boost, is exceedingly slim. However, as with anything with very long odds, it could happen.

thewird

iTrader: (8)

My paper said it and FJO even responded to it. If your so doubtful you should give them a call. I have posted their e-mail where they said it was fine. When I e-mailed them I wasn't sure if all the injectors had to be high impedance or low, or if they could be mixed without issue.

I am not willing to do any testing of the sort. I was merely trying to point out if your so confident in your setup, you should try it. And that is exactly my point, the likelihood of it happening is small yes but the possibility will always be there no matter how you look at it.

Since it works like normal having it wired into high impedance primaries. There is no reason whatsoever to only do the secondaries since there is no downside to wiring them together.

I know without a doubt there is nothing wrong with boost cut if its done right. There was this one road coarse car I tuned that had a wastegate problem and fuel cut at least 10 times that day under WOT spiking to 18-20 PSi on pump gas (The car was tuned to run at 16 PSi). If fuel cutting was such an issue, the engine should have been toast. I have also hit 25 PSi on my own car due to a boost controller incorrect setting and fuel cut, again on pump gas and the motor is still perfectly fine. The only reason fuel cut is bad on the stock ECU is because if you reach at point, your already running lean to begin with.

thewird