Back after hiatus, car upset, please help

[Spectre23]

So I sold my car back in 2006. I regretted it as soon as I did it. I recently had a chance to buy it back for half what I sold it for. However, it is not running well and I am hoping you guys can help.
Here are the relevant stats on the engine:
CA18DET
New pistons and rings, done prior to me getting it back
Butterfly things locked open
444cc injectors
GT28R
Nismo FPR (set at 55 psi)
Custom tune by me back in 2002
Huge radiator
New water pump
Stock manifolds
3" turbo-back
Walbro 255 LPH High flow/high pressure
Greddy Profec B Spec II for boost control

Before I sold it, it put down 300HP/300lb-ft at the wheels on a Mustang AWD dyno at 15 psi boost and 276 HP/250 lb-ft at 12 psi boost

Problem: Now it is detonating as soon as it starts to pull boost. Even on low boost setting
What I have done so far:
New Nismo FPR set to the same as before
Retarded timing as far as it would go
Went to new colder NGK plugs
Tried new coils
Tried new crank angle sensor
Put in a new fuel filter
Put in a new coil wiring harness
Insured fuel lines are all connected properly
Had injectors flow tested (one was 4% low, 2 were 10% low)

Thoughts:
10% doesn't seem to be enough to matter on the injectors until it is fully loaded on high boost. Then I could see it making a difference. But on low boost at low RPM, I don't see it being the problem. Injector guy wants $100 to clean them. Or I could buy new ones for $300-400 I think. But if I get new ones, should I get 550cc instead and run lower fuel pressure? Or would that mess with the tune too much? Been so long since I built this car...
Could it be a fuel pump? They seem to usually just completely take a dump rather than just not flowing enough. But I could be wrong as this is the only Walbro I have had.
It did not seem to detonate with the original engine in it, however that one developed a rod knock. That is why the guy got this engine and put new pistons and rings in it. Then I bought it all and changed out the engine. Is there anything else I could have missed that would only cause detonation? Because it runs fine when not on any boost at all. I am not positive my boost controller setting were not messed up, But I am positive it makes no power before detonating a lot.

Hope you guys can help...
Thanks

[boost_boy]

55psi on a NISMO FPR? Why so high? Perhaps the fuel pump is getting lazy as well. Did you check the timing to make sure it isn't going off the scale in the upper rpm? Are you sure the crank angle sensor if functioning correctly? So many questions I could ask, but you should start in the areas I'm concerned with.

[Spectre23]

55psi on a NISMO FPR? Why so high? Perhaps the fuel pump is getting lazy as well. Did you check the timing to make sure it isn't going off the scale in the upper rpm? Are you sure the crank angle sensor if functioning correctly? So many questions I could ask, but you should start in the areas I'm concerned with.

55 Psi because back when I built it the first time, that is what a Nissan Tuner friend of mine in Japan said they were doing with similar setups over there.
Double checked timing when I put a new water pump on.
Tried 2 crank angle sensors and there was no difference. And one came off a working engine.
Do the Walbro pumps get "tired"? All I have experienced is pumps that completely die or work. No grey area.

[float_6969]

First off, lets talk about the actual problem. Detonation during boost.

When you say detonation, I assume you mean you're hearing knock during boost. This situation is caused by 3 scenarios. First is too much spark advance. You've eliminated this variable by retarding the timing as far as it will go. IIRC, when the CAS is set to full retard, the base timing is actually ATDC. That is enough timing retard, that if the issue was related to spark timing, it would have gone away, so we know it's not timing.

Then there is the air to fuel ratio. The AFR under boost has a direct connection to the amount of spark advance that is needed for any given situation. If it's actually leaning out enough to cause knock, you could tell by monitoring the voltage from the stock narrowband O2 sensor. An engine usually has to be pretty lean (13:1 or leaner) to knock.

Next is a lack of octane for the combustion environment. This can mean A LOT of different things. The first thing to try is to run the boost as low as it will possibly go. If this solves the issue, it's either a lean situation, or the combustion chambers are dirty and are creating hot spots. If this doesn't fix the issue, empty as much gas out as you can. Then go buy 5 gallons of Toluene. You'll have to go to a painting supply store. It's usually used as a paint thinner, but it's a petroleum product like gasoline and has a VERY high octane rating (AKI = 114). If the issue is related to poor gas quality or combustion chamber deposits, this WILL fix it.

I just thought of this... did you see the new pistons? What if they're CA18DE pistons? If so, you now have 10:1 compression and you're trying to run boost on top of it. I can tell you FROM LOTS OF EXPERIENCE, this is almost impossible to do on this motor on 91 octane pump gas. If you don't know about the pistons, I would do a compression test and see what the numbers are like. If it's new DET pistons, compression should be around 175psi. If it's DE pistons, it will probably be closer to (or even over) 200psi.

[Spectre23]

I did not see the pistons. However I did do a compression test and it was actually lower than desired. However at this altitude no engines actually meet spec. But I am positive it is not higher than stock compression. If anything it's a bit low.

So Float, what is your opinion on changing injector size? If I bump up to 550cc injectors and drop fuel pressure back down to close to stock levels, do you think it would be similar to 444cc injectors at 55 psi? I don't think I want to pay the guy $100 to clean my 444's when I can go buy some Deatsche Works for $300-400.

[float_6969]

I missed the part in your first post that you said you were running 55psi. Almost all injectors are rated at 45psi. (actually it's 43.5psi, which is 3 bar). Running a 444 @ 55psi isn't enough pressure to get it to behave like a 550.

Stock fuel injection pressure on a CA18 is way lower than the normal for other engines (36psi IIRC), but 10psi in the scheme of fuel injection doesn't make much of a difference in flow rate.

eg; a 360cc injector at 36psi, is only a 400cc injector at 45psi. This also means your 440cc injector being run at 55psi is only flowing 480cc's. You would have to run that injector at a base pressure of 70psi to get it to behave like a 550. At that kind of pressure the flow rate of your fuel pump is going to start to plummet and it MAY not be able to keep up. Another thing to keep in mind is that the flow rates of injectors aren't nessicarily linear in relation to fuel pressure. What that means is that if you increase the fuel pressure, the peak flow rate might be what you want, but it might not be a linear increase in flow rate. It might flow too little fuel at a 50% duty cycle and too much fuel at 70% duty cycle.

It's possible to tune for this situation, but if you're looking for a solution for your problem (drop in injectors for a pre-burned ROM), I would buy some 550's. My guess is that you're running WAY too lean.

[TheMAN]

I would try to find out specifics on which pistons were used
55psi is too high IMO... but walbro pump failures are not unusual.... seen them here and there, this is why I prefer Denso pumps myself

anyway... what fuel filter did you use (brand, which car, etc)? did you install a fuel pressure gauge and watch the fuel pressure as you drive? Has anything been done to the exhaust? Is there a cat? What are the EGTs? What MAF are you running?

most important question: how long has it been since the car has been driven? DO NOT dismiss bad gas!

[Spectre23]

Fuel filter is the Wix replacement that is the higher flow version. I installed a fuel pressure gauge, but it is under the hood, so I did not watch it while driving. And I am sure it had bad gas, it was stored with an almost empty tank. And that fuel is long gone. The girlfriend was driving the car to work on a fresh tank of fuel for a few days. She just couldn't take it over 4500 RPM.
It has a full 3" turbo-back w/o cat. No clue where EGT's are. It ran fin with this setup for 10 years. So I am sure it's a matter of something worn out. I am ordering some 550's today along with a new Walbro.

[Spectre23]

Well, I went ahead and got a Deatschewerks pump and 550 injectors. Got the pump locally due to better warranty and fewer reported problems than the Walbro. Injectors I had to order. CA injectors seem to be a low demand item, imagine that... They should be here Friday.

[float_6969]

well keep us in the loop and let us know how it's going.

[Spectre23]

Well, installed the new pump and new 555 DW injectors. At 30 psi fuel ressure it won't even idle. At 40 it won't rev. At 50 it seems happy. Fixed some issues with the settings on the Greddy Profec B spec II and it is now only hitting 9 psi, btu still sounds like it is detonating. I was running 15 psi on the high boost setting before. I think now that I have everything else as sorted as I can I will try dinking around with fuel pressures. Guess I should get a A/F gauge. And good values on those you guys know about? I think my Greddy DP may have a hole for a wide band. Guess I better check that.

[TheMAN]

why don't you start with the simplest freaking thing first... drain the gas tank and put FRESH gas in!!!

[float_6969]

...And I am sure it had bad gas, it was stored with an almost empty tank. And that fuel is long gone. The girlfriend was driving the car to work on a fresh tank of fuel for a few days. She just couldn't take it over 4500 RPM...

[float_6969]

Are you sure the tune hasn't been messed with or the ROM changed out?

[Spectre23]

Well, the ECU is the same ECU, however I do not have my original rom file to compare it to. However I am positive neither of the people that owned it after me have the equipment or technical know-how to reprogram the EPROM themselves.

[TheMAN]

give it the benefit of the doubt man

[Spectre23]

I did find a possible source of unmetered air pre-turbo. So having eliminated that. It still is not happy, but the detonation is just different. Less power loss tied to it and not quit as pitchy. So I am thinking I may now be flooding it. My next steps are to screw with fuel pressure some more and check for possible vacuum/boost leaks. I have looked for the obvious loose hoses and such, but I will see what the ether test reveals.

[Spectre23]

Well, Got a new O2 sensor. Thought I did that already, but turns out I didn't. Checked the old one and it appeared to be reacting slower than I thought it should. So I got a new one. No difference. Checked resistance on the dropping resistor (this is also called the ignitor right?) FSM says it is supposed to be "approximately 6 ohms" across all connections. Mine is 7.6 ohms on every one. Does that mean it is bad? Going bad? Still ok? I would say 7.6 is approximately 6. Approximately means different stuff to everyone. AAC valve also has slightly more resistance than it was supposed to have. FSM says 9-10 and mine is at just over 11 ohms. Played with settings on the boost controller. Now I am only letting it get 8 psi boost. And detonation is still the same. BTW, plugs are tough to read. The threaded portion looks insanely rich, yet the grounding strap is almost white.

I guess my next step is to mount to gopro under the hood looking at my fuel pressure gauge to make sure it is doing what it should be. But any input on the dropping resistor or any other ideas to check are appreciated.

[TheMAN]

the threads don't matter, what matters is the ceramic insulator at the base of the tip, the tip (electrode), and the ground electrode

[float_6969]

pics of plugs please

[Spectre23]

Here is a picture of a plug. All of them look identical. BTW, I also check continuity on the power transistor thing for the ignition and it checked out ok as well.

[float_6969]

That plug looks fine to me. You're running a little rich, that's about it.

[Spectre23]

OK, now I could use some more expertise. I checked the resistance on the coils. I have made sure they are all firing. However, all 7 of my functioning coils measure at 2.1-2.2 ohms as checked how the FSM says to check them. The FSM says they are supposed to be .6-.8 ohm. I find it to be too much of a coincidence that all 7 are bad and pretty much the exact same amount of bad. Is there different years that were supposed to be 2.1 ohm? Or could these of somehow been exchanged with coils from an incorrect application at some point? Like I said, it just seems really odd that they would all be the same yet all be bad. However, if they are that far off, I could see this causing my issues.

[dash]

Checked resistance on the dropping resistor (this is also called the ignitor right?) FSM says it is supposed to be "approximately 6 ohms" across all connections. Mine is 7.6 ohms on every one. Does that mean it is bad? Going bad? Still ok? I would say 7.6 is approximately 6. Approximately means different stuff to everyone.

dropping resistor is an entirely different component from the ignitor

[Spectre23]

Checked resistance on the dropping resistor (this is also called the ignitor right?) FSM says it is supposed to be "approximately 6 ohms" across all connections. Mine is 7.6 ohms on every one. Does that mean it is bad? Going bad? Still ok? I would say 7.6 is approximately 6. Approximately means different stuff to everyone.

dropping resistor is an entirely different component from the ignitor

Yeah, think I figured out that the power transistor is what the SR guys call an ignitor. The dropping resistor is just for low impedance injectors.

[Spectre23]

So I got my hand on a real multi-meter (Fluke) and the coils are .7-.8 ohm. So I assume they are fine since that is in spec. However, that just gives the low end resistance. Shouldn't we be able to measure the high end somehow? I tried all pins to ground and all pins to the little carbon guy in the boot and ground to the carbon guy. None of them gave a resistance number at all.

[TheMAN]

I don't think you are supposed to get any sort of measurable resistance on the secondary system, on the highest ohm scale