cant rev past 6300rpm

[KAT PWR]

For the last few days I've been working on slowly tuning my new motor, just driving it to and from work. I started getting into the higher rpms of the VE map today when I noticed I can't rev past 6300 rpm whether under boost or just revving it. it feels like a hard limiter, but my rev limiter is set to 7500rpm. Looking through all of the settings and some datalogs I can't seem to figure out why this is happening.
I've attached a short datalog of a rev and a 1st-2nd-3rd gear pull.

motor specs
91 nissan 240sx
KA24DE
DIY autotune trigger wheel
LS truck coils
550cc sti injectors

[billr]

Do you have a fuel-pressure gauge or sensor?

[KAT PWR]

I do have one on the fuel pressure regulator, wish I had sensor for the ecu. The fuel system was upgraded when I did the swap and it should able to handle the new motor. Afrs are still in the 10s in high boost so i don't think it's fuel. My duty cycle is pretty high now if I really lay into it because I'm also having boost creep right now. Wastegate is set for 7 and I'm seeing 11 WOT by 6000rpm. Gona unmerge my wastegate from the exhaust and go to a dump for now, which should fix that. My injectors can't spray enough fuel at +11 psi without going over the recommend duty cycle.

Yesterday I tried shorting the gap of my plugs from the stock spec of .46 to the recommend .30 for when boosting my motor, to no effect. I guess it's not needed to shorten the plug gap after converting to coil near plug on this motor from a distributor.

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[slow_hemi6]

Is it just flooding up? Does it really need to be in the 10's for 11psi?

[KAT PWR]

As I said in the first post I am still tuning the VE map and have a good bit of fuel to pull up top. I've been doing it in small increments as I'm new to MS and I've never tuned a boosted motor before. my AFR target in high boost is about 12AFR at 11psi, it was pegging my LC-1 in the low 9s when I first started getting into the boost part of the VE map. its also not setup to go past 7psi right now on Sunday ill be going to a dump tube on my external wastegate which should fix my boost creep, even though I don't want a screamer pipe. I've already seen duty cycles up to 96% (WOT, 175kpa, 6000rmp, ~10AFR). 11psi would put me in the 320-350whp range which 550cc injectors don't support on a 4 cyl, or at least are no recommended without raising fuel psi. which is currently at 43.5 with no vacuum.

[billr]

Does the FPR raise pressure above 43.5 psi when MAP is boosted? Having a way to see pressure right as a problem happens can be very handy. I think I would be reluctant to tease an engine with significant boost without having a sensor to log pressure. Such sensors are so inexpensive, it would be a trivial cost in the over-all project.

I, too, was wondering if it is simply too rich. What do the plugs look like?

[KAT PWR]

I have a 1:1 rising rate aftermarket fuel pressure regulator. I plan on getting a sensor as it will be a drift car and will be seeing abuse, just haven't seen a linear 3 wire sensor outside of the 60-100 range with a pigtail. I already want to log oil pressure and temp just haven't built the op amp circuit to tap into my innovative oil temp/psi gauge without affecting the readings. I will have logging setup before I hit the track again. I can take my fuel pressure tester from work which will allow me to see it while in the passenger seat.

the plugs didn't seem abnormal to me but ill get a picture when I get to my garage. I didn't drive it to work today as I needed to take my welder home to fix my wastegate issues. not trying to cram my new welder in the back of my hatchback.

[chips60bug]

These guys work pretty well. http://www.ebay.com/itm/261260635816

[KAT PWR]

I know it's a cell phone pic but the insulator is a light tan or off white and the base of the threads are black. These plugs have only seen about 70miles so far. Also they are 2 heat ranges colder then the factory plugs.

These guys work pretty well. http://www.ebay.com/itm/261260635816

Thanks for the tip I'll keep it mind

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[KAT PWR]

I've also opted to try shorten the long vacuum line for my Wastegate before modifying my turbo elbow/down pipe to correct my boost creep. I've kinda been an idiot and ran all of my vacuums lines teeing from one 1/8 nipple on the manifold. I think the Wastegate is just lagging, as is a slow rise only over 50% throttle. I got a vacuum block that I will run in line with the brake booster line, before the check valve.

I like having a quite car, ran the same exhaust when I was NA and you cloud hear me from a mile away. I don't think this merge is that bad, it's the turbo manifold Wastegate placement that is poor.


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[CMac89]

What is your tooth number 1 angle?

I was getting the same problem last year. My angle was 150 degrees BTDC then I went to 130 degrees and it raised my phantom rev limiter from 4800 to 5900. I then moved to 71 degrees and I'm guessing the problem is solved. Come to find out, something documentation doesn't mention, it's best to have a tooth one angle between 50 and 80 degrees.

Not sure if this is something that can be fixed in code?

[KAT PWR]

What is your tooth number 1 angle?

I was getting the same problem last year. My angle was 150 degrees BTDC then I went to 130 degrees and it raised my phantom rev limiter from 4800 to 5900. I then moved to 71 degrees and I'm guessing the problem is solved. Come to find out, something documentation doesn't mention, it's best to have a tooth one angle between 50 and 80 degrees.

Not sure if this is something that can be fixed in code?

I have heard of this optimal tooth angle, it's mainly to do with ignition event happing during cyl 1 signal pickup i belive. my #1 tooth angle is 345 degrees per instructions on diyautotune for my trigger wheel. https://www.diyautotune.com/support/tec ... gger-disc/ I did a log today where I slowly when up to 6000rpm in 2nd and it felt like i hit a wall so I let off.
now I could clock my distributor (now it's just a CAS) to change the angle some. I could also technically clock the distributor to a different tooth to get that 50 to 80 degrees but people have used this to success i belive.

I would try that but the car is currently down for the moment. tried connecting wastegate reference to the compressor housing no go. can't tell between boost creep and the 7 psi wastegate spring (i guess 5 or 6 psi after the intercooler). its a straight line from 100kpa to 11psi when looking at the data logs in this config. After that, I unmerged the wastegate, made a simple screamer pipe from the remains, and on install broke a bolt cause my turbo outlet flange is warped. gonna get a machine shop to face the flange and grab some tools from work to extract the bolt before I drive it again.

[Matt Cramer]

What is your tooth number 1 angle?

I was getting the same problem last year. My angle was 150 degrees BTDC then I went to 130 degrees and it raised my phantom rev limiter from 4800 to 5900. I then moved to 71 degrees and I'm guessing the problem is solved. Come to find out, something documentation doesn't mention, it's best to have a tooth one angle between 50 and 80 degrees.

Not sure if this is something that can be fixed in code?

This caution applies to either Basic Trigger mode or very low tooth count trigger wheels, such as a 4 tooth crank wheel. You need a tooth that is relatively close to and before your maximum spark advance. With a high tooth count wheel, you will have teeth everywhere and the tooth #1 is only an issue if you are using a missing toothed wheel and having a hard time detecting the missing tooth wheel while cranking due to compression slowdown. With a 4 tooth crank wheel, this is more critical - the engine speed may have changed significantly between seeing a tooth and the time to fire the spark if there's a long distance between the tooth signal and your timing.

[KAT PWR]

What is your tooth number 1 angle?

I was getting the same problem last year. My angle was 150 degrees BTDC then I went to 130 degrees and it raised my phantom rev limiter from 4800 to 5900. I then moved to 71 degrees and I'm guessing the problem is solved. Come to find out, something documentation doesn't mention, it's best to have a tooth one angle between 50 and 80 degrees.

Not sure if this is something that can be fixed in code?

This caution applies to either Basic Trigger mode or very low tooth count trigger wheels, such as a 4 tooth crank wheel. You need a tooth that is relatively close to and before your maximum spark advance. With a high tooth count wheel, you will have teeth everywhere and the tooth #1 is only an issue if you are using a missing toothed wheel and having a hard time detecting the missing tooth wheel while cranking due to compression slowdown. With a 4 tooth crank wheel, this is more critical - the engine speed may have changed significantly between seeing a tooth and the time to fire the spark if there's a long distance between the tooth signal and your timing.

Thank you for clarifying.

I just read through this about adjusting pots helping some. http://www.msextra.com/forums/viewtopic ... pm+problem I did fiddle with the 2 pots on my v3.0 PCB when I was first trying to get my motor to start as I wasn't getting a crank signal at the time, turned out to be a wiring error. I do have to open my ECU back up to install the zeal engineering dual VR conditioner so I can read my VSS to the ECU. Once I get my down pipe back on ill try to reset the pots for an optical sensor, then play with them if I have to.

d) With a small screwdriver, turn the pots, R52 and R56, about 12 turns anticlockwise (sometimes you may feel
a "click" when the end position is reached, they can't be damaged by turning too far.) and then turn R56 back
about 6 turns clockwise.

Also i attached a log of me slowly hitting this phantom rev limit from yesterday, at the 0 second mark 50% tps.

[KAT PWR]

I adjusted the pots per the manual, now I can go up to 6600rpm. I have also got my fuel maps much closer to target values since this screenshot. Any ideas on what else to try? It's a PITA to open the ecu and adjust the pots aimlessly. is it possible I would have to play with my pull up resistor? Currently I have a 1k ohm to 12v on the crank signal and the MS3x pull up on cam. my boost creep issue has turned out to be a poorly designed turbo manifold and I'm just gonna live it for now as long as it doesn't go over 12psi, now that I have leaned things out to target my injectors should be able to handle it.

6600.png

[Matt Cramer]

The last complete log did not show a loss of sync, suggesting it's not trim pots - but it also showed an AFR in the 9's, which is way too rich unless running E85.

[billr]

Aw, now Matt has me confused. Does the fuel type (like E85) matter for the the AFR readings? I thought WB systems usually (always?) show AFR as if stoic is gasoline's 14.7 The good old "lambda vs. AFR" translation.

[Matt Cramer]

Aw, now Matt has me confused. Does the fuel type (like E85) matter for the the AFR readings? I thought WB systems usually (always?) show AFR as if stoic is gasoline's 14.7 The good old "lambda vs. AFR" translation.

You can set the MS3 to display the real AFR or a "gasoline equivalent" in the logs.

[billr]

I'm still confused, will start a new thread.

[KAT PWR]

Last Sunday I got a full day to play with it. yall were right it was way too rich. I didn't realize the gauge pegs after ~9AFR, calibration says it goes as far as 7.35 at 0v. I started taking big steps in fuel that day 4 or 5% a run vs 1 or 2% once or twice a day. I final got full rpm with AFRs in the mid 11s or close to target but it didn't feel right. It would hit boost quick and pull hard for 1000rpm then fell sluggish. After that it would to fell like a NA motor with a little more balls, while sucking down 11psi of boost. I was pulling so much fuel I was confused ended up pulling about 35% VE total past 5000rpm from a base map i copied from a MS2 PNP. looked my VE map, looking like this when I stopped trying to tune it.

ve.png

It then came to me that my exhaust was choking out my motor. My current exhaust that is pieced to together, by a shop be before I started welding. It has 3in and 2.5/2.25" sections (muffler and cat delete) after a 3" downpipe. Tonight ill be making a full 3" system, its gonna be straight pipe for now from scrap 3" exhaust off a R32 and a S14. As I currently don't have money for a muffler, it shouldn't be too loud for now. I should be able to get back to tuning later in the week and see what this motor will really do.

Once I'm happy with how it runs ill put in my cam gears from my old motor. I don't like how unadjusted hot cams (using 2 exhaust cams) run in a KA24DE, no power till 4,000rpm then it wants to make power past red line up to probably 8,000rpm if you let it. In my old motor (NA), I ran it intake +5 and exhaust +2.5, shifting the power band to 2,500rpm to 6,500rpm which should help with spool some. I was playing with desktop dyno 2000 last night and may advance both cams another 2.5, as it was still showing more gains from 2000rpm-6000rpm, with only a 1% drop in HP between 6,500rpm and 7,500rpm.