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Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
1). No boost, vac, or exhaust leaks. No noticeable leaks
2). Verify mechanical timing. Fresh timing belt, properly setup
3). Verify base timing.
4). Ignition system. 028, NGk br7es
5). Motor health. Fresh Build, about 1k kms on it
6). Basic throttle body adjustments. Adjusted and tight, TPS is adjusted as well
7). Compression ratio. Je 8.5:1 pistons, but head and block decked, so probably about 9:1
8). Wiring and sensors. All good and healthy, went over the harness and sensors when motor was out
9). No DTC/CEL codes. No
10). Electrical system. Decent battery, and alt seems to work well still
11). Base fuel pressure and injector values. Rx7 550cc injectors, stock 37 psi fpr (for now anyways)
12). Properly calibrated and configured wideband sensor. Aem 30-4110 wideband, seems to log correctly with the analog input option
13). Type of fuel. Shell 91 octane, only option around here
14). ECMlink how-to videos. Watched a ton, but can't find reference to this issue

I'm having an issue trying to get wot tuning correct, I've got start, idle, and cruise damn near perfect, but at wot, between 4k and redline it starts to buck and act like a misfire a bit, not a huge amount, but it feels like a dog when it starts, and makes no power. you can see in the log that the Afr holds steady, but jumps around after 4k, it was a bit lean in this log, but I forgot to include another after I richened it up a bit, but it didn't help, did the same thing, just rich

Ive got boost set as low as I can get it at about 16 psi, and timing is set low so as to rule that out, but I can't figure it out, I've tried leaner, richer, full rich across the board, nothing seems to really change it

The car used to have a tuned emprom chip for this setup, but for the stock 7.9:1 Cr, so it had too much timing for the new higher Cr, hence why I got ecmlink, but it worked fantastic overall, pulled like a bat outa hell, so I know it's not something in the setup, it's a tuning issue, anyone have some thoughts on it?

Build is on my profile

https://www.dropbox.com/s/zs7615n0357q0ok/new log.elg?dl=0
 

gdb1039

Proven Member
124
26
Dec 16, 2007
vancouver, Washington
On your check list for boost leaks you put no noticable leaks, have you done a proper boost leak test? If not then that's where you should start. The tester is cheap enough to buy or make. No since in even try tuning the car until you are 100% sure there are no boost leaks.
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
On your check list for boost leaks you put no noticable leaks, have you done a proper boost leak test? If not then that's where you should start. The tester is cheap enough to buy or make. No since in even try tuning the car until you are 100% sure there are no boost leaks.
Since it's speed density, as far as I understand, a boost leak is less important than if I had a mad, but anyways, I pressurized the system with an air compressor, and there were no leaks
 

Crackerman

Proven Member
126
36
Feb 28, 2018
Alvord, Texas
Is a 2 step/rev limiter turned on? Invert the signal needed and see what happens
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
It's not that, I've got it set to 4500, and I can rev to 7k, and I have nlts off since my clutch switch is disconnected

Honestly, it feels like a misfire or something, but I don't know why, I know it's a tuning issue, but I can't figure out if it's too lean, rich, or a timing issue, or maybe injectors or something? I know it's not the build since it worked fine with the old tune, just too much timing
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
Would a bad, or failing fuel pressure regulator cause this sorta issue? It would make sense right? If fuel pressure isn't raising 1:1
 

perrytheplatypus157

Proven Member
69
14
Jun 18, 2017
Fall River, Wisconsin
Would a bad, or failing fuel pressure regulator cause this sorta issue? It would make sense right? If fuel pressure isn't raising 1:1
Yes. It can definitely cause the issue. Whether it's a bad regulator or boost source feeding the regulator. If you have access, take a compressor and apply pressure to the regulator, and verify that it rises 1:1. If you can add 25 psi and the gauge reads the correct pressure accordingly(probably 62 psi if base pressure is 37), then you can cross it off as not being the issue.

oh ok, I didn't see a link for the logs.
You can click the dropbox he has linked. Even though it says you can't preview the information, you can still download it. From there, you can view the log.
 

stillrunning

Proven Member
129
56
Oct 10, 2013
brandon, Florida
Even if fuel pressure isn't on a 1:1 rise rate you can actually tune around it, you would be basically be increasing the injector pulse rate as fuel pressure dropped to make up for the lack of fuel pressure rise. Not that I think it's right but a non 1:1 can definitely be tuned around.
Would probably be beneficial to actually know what your fuel pressure is when the problem occurs, maybe fuel pump pressure is dropping off.
You should be getting a noticeable amount of knock if going lean as well, if you're going lean enough to feel it then odds are there would be allot of knock.
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
Even if fuel pressure isn't on a 1:1 rise rate you can actually tune around it, you would be basically be increasing the injector pulse rate as fuel pressure dropped to make up for the lack of fuel pressure rise. Not that I think it's right but a non 1:1 can definitely be tuned around.
Would probably be beneficial to actually know what your fuel pressure is when the problem occurs, maybe fuel pump pressure is dropping off.
You should be getting a noticeable amount of knock if going lean as well, if you're going lean enough to feel it then odds are there would be allot of knock.

I don't have a fp gauge, and for the price of a gauge, id be able to just put a new afpr on, but anyways, what you said makes sense, if I richen it up under boost where it starts to buck (it's literally like it has no fuel for a second), it helps, but still does it a little bit, but mostly is rich overall, would also make these 550s run out pretty quick, probably around that 16 psi mark, since it seems to be ok below that

Does that make sense? Or am I overthinking this?
 

perrytheplatypus157

Proven Member
69
14
Jun 18, 2017
Fall River, Wisconsin
https://www.amazon.com/Fuelab-71501-0-120-Pressure-Gauge/dp/B00378V6ZU
If you have an 1/8" NPT bung on your fpr like most have, this works great and is a nice little tool. Tuning around it is definitely possible, but so is the fact that you're just plain running out of fuel. Between the 12.8 volts at WOT and the small injectors, your fuel pump may not be getting the voltage to pump out the correct pressure. And since you have less pressure at the injectors at this point, they'll flow like a smaller injector. Just food for thought, check out the 255 flow difference from 13.5 to 12 V.

I also see a considerable amount of knock. Just so you're aware, 1* of knock is roughly 3 counts. I'm seeing upwards of 12 counts. I try to stay under 3 counts generally, unless I'm tuning a stock block where I like to see 0. Hopefully this helps!
 

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Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
https://www.amazon.com/Fuelab-71501-0-120-Pressure-Gauge/dp/B00378V6ZU
If you have an 1/8" NPT bung on your fpr like most have, this works great and is a nice little tool. Tuning around it is definitely possible, but so is the fact that you're just plain running out of fuel. Between the 12.8 volts at WOT and the small injectors, your fuel pump may not be getting the voltage to pump out the correct pressure. And since you have less pressure at the injectors at this point, they'll flow like a smaller injector. Just food for thought, check out the 255 flow difference from 13.5 to 12 V.

I also see a considerable amount of knock. Just so you're aware, 1* of knock is roughly 3 counts. I'm seeing upwards of 12 counts. I try to stay under 3 counts generally, unless I'm tuning a stock block where I like to see 0. Hopefully this helps!

I just ordered an afpr, which should be here Thursday, so I'll find out if that fixes the problem, but I think your on to something there, it's probably not enough fuel, as for the knock, ya, I'll pull more timing out

Also, my clutch fork just snapped in half, so I'll be fixing that before I can test these theories out.
 

perrytheplatypus157

Proven Member
69
14
Jun 18, 2017
Fall River, Wisconsin
I just ordered an afpr, which should be here Thursday, so I'll find out if that fixes the problem, but I think your on to something there, it's probably not enough fuel, as for the knock, ya, I'll pull more timing out

Also, my clutch fork just snapped in half, so I'll be fixing that before I can test these theories out.
Oh my, sorry to hear. I have a few laying around if you don't want to buy new. But you don't necessarily have to pull more timing out. Too much retard is just as bad as not enough. You can over boost more easily and create a ton more heat in the exhaust which can cause cracking. If you just make a smooth transition into upper rpm timing, it'll be a lot more efficient and better on the engine.

As far as voltage drop goes, I would guess that your alternator is just not outputting enough voltage in the upper rpms. Start simple, check grounds and power wires throughout the chassis. This can be often overlooked. If all checks out, have the alternator tested. You should be seeing around 13.8-14.1 at WOT. FWIW, I run 2 fuel pumps, dynatek ignition system, and a nitrous solenoid, and I see 14.1 up to 8500 rpms.
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
Oh my, sorry to hear. I have a few laying around if you don't want to buy new. But you don't necessarily have to pull more timing out. Too much retard is just as bad as not enough. You can over boost more easily and create a ton more heat in the exhaust which can cause cracking. If you just make a smooth transition into upper rpm timing, it'll be a lot more efficient and better on the engine.

As far as voltage drop goes, I would guess that your alternator is just not outputting enough voltage in the upper rpms. Start simple, check grounds and power wires throughout the chassis. This can be often overlooked. If all checks out, have the alternator tested. You should be seeing around 13.8-14.1 at WOT. FWIW, I run 2 fuel pumps, dynatek ignition system, and a nitrous solenoid, and I see 14.1 up to 8500 rpms.
Could be the ground system from it, I'll do some digging, as for the clutch fork, I've got another one here from a junk trans I used for parts, but it's still a royal pain in the ass to have to pull the trans again. It looks like the fork was hitting the trans, I'll have to make sure to adjust it correctly this time around
 

Compound1g

Proven Member
58
1
Feb 10, 2019
Qualicum beach, BC_Canada
Ok, new shift fork, shifts great now
Added an adjustable fuel pressure regulator, increases base by 10 psi, and also found the correct settings for these injectors, starts up and runs waaay better now, also added another ground strap from the alternator to the chassis, that seems to have fixed the voltage drop, holds steady at 13.3-13.7v now at all rpms.

Don't have a log handy, but from the testing I've done so far, I should be able to get a reliable 25 psi with this setup, but I've stil got some work to do with the ve table, I'll post a log in a bit here and get some opinions on it
 
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