Strange happenings on the dyno
 

So I ran on the dyno with my car this weekend. I have a rebuilt stock redtop with the t25, 370's, fmic, 62 ecu, 14psi, good clutch. I managed to pull 176 to the wheels on the dyno. To me this sounds low. I did the math (whp/.75) it came out to 234 at the crank? Right or wrong. Also my curve was kind of jumpy. My friend with a stock setup at 8psi pulled exactly the same....and ideas or was he just pulling high?

Here is the dyno sheet. Attachment 62299

Yeah I would guess if you were boosting about a bar your car would look a little bit more peaky on the graph apposed to a bone stock SR. 235 sounds about right as for crank hp, but you might want to double check your timing and your intercooler lines for a potential boost leaks.

What are your AFR's? 14psi on the T25 and 370's is a recipe for disaster. What dyno was this on as that will effect your numbers as well. Keep in mind a dyno is a tuning tool, they all read different from the next.

True. It seems to me that mobile dynos like dyno packs usually run a little less hp then stationary dynos like Dyno jets. I think its the difference between axle hp and wheel hp.

It was on a dynojet. My afr's are 11.9 to 12.2 when wot and full boost. I have NO boost leaks. I charged the system with a compressor and it holds. I just found it weird that my friend running 8 psi bone stock managed to pull the exact same power but with a smoother curve. Any explanation about that?

Attachment 62301

thought I would throw this in here too

I think it's your dual fpr setup that's giving him the advantage

Its most likely:

A: your turbocharger
B: your plumbing

could also be
1. boost leaks (aka plumbing)
2. bad ignition timing
3. bad gas


My bet is on the turbo blowing hot air. turn the boost down to 8psi and see what it makes. Then, change it.

i just noticed that...WTF? :eek3:

Isn't two FPR's better then one tho? lol
:ddog:

Could be IATs. 14psi is about the limit for a t25 and if its hot out or your intercooler is blocked or otherwise inefficient it could cause low power and a shaky graph like you've got. But if A/F is ok and your butt dyno is satisfied, then i wouldnt worry too much.

Do you have a psi/afr graph? It seems low even by dynojet numbers. I have a t25 thread with dyno numbers. It was done on a dyno dynamics but you get the idea.

We advanced my RB256 exhaust gear 1 degree on the dyno.... lost 64hp at the wheels, retarted it 1 picked up 22 over 0 degrees... There is too much to tell based on a dyno sheet.

From electric, to timing to overall condition of parts.

I used to drop fuel pressure at 15psi..... ended up being a oxidized wire to the fuel pump, redid the wiring and retuned for another 100WHP.

So what I am saying here is check everything out, from plumbing to pressure, to cleaning wiring terminations. It all matters

a real T25 as found on a ca18det ( other called T25H or T25G are closer to a T28 ) outputs IATS around 150-160°C at 15psi . After going through a big cooling core (admitedly not the better), i had it down to around 60°C.
At that pressuren the turbo is overspinning and has such crappy efficiency it has no flow.

See my point ? you DONT want a [email protected] period.

I wasn't even aware that such temps develop during compression. That's crazy.

Very eye opening guys. Lol yeah I'm not running the dual FPR thing anymore though I was on the dyno. I have drilled out my oem fpr and its now literally an adapter. I will try turning down the boost to 12 or so. A few car friends of mine suggested "Since the dyno curve is so jumpy the ECU might be saying no bitch your running stock powah and pulling timing" Who knows.... I'll try 12psi and let my ecu reset by leaving it unplugged overnight to see what happens.

Also is the sr20det 62 ecu self learning? It was suggested to me I should reset my ecu by unplugging the battery overnight to learn my new 12psi boost pressure and related fuel curves

What brand front mount do you have? Where are you taking the boost reading from?

Crank horsepower would be 198 considering 15% drivetrain loss, it's nowhere near 25%.

Nothing strange your shit is stock and slow, why waste Dyno time

Yes, but it doesn't learn boost like you're suggesting, that would be outside of closed loop, that statement seems funny based on one of your posts. Anyway the ecu will learn sensor voltages, and fuel trims long and short, unplugging the ecu shouldn't clear them, alone. Unless the capacitors are discharged. Use a program like conzult, nds or nistune, 1click and then relearn begins vs overnight or hour's then relearn. Ps I have a really good stock tune that has been oversold, that ill give to you just post you're graph. Oh the graph has to show power and torque, options are boost, egt, and afr

Sent from my Highly Tune Galaxy S3.4!!!

The only thing that self learns on the factory ecu is tps closed voltage

edit: if the ecu has been unpowered for a while it re learns this the first time it powers back up. This is why it is wise to not put your foot on the throttle before cranking.

This is the common problem people have with lean/jerky under light throttle.

.34 volts is not the magic place to set your tps voltage, that is just where it was from the factory, it can be changed (on accident) at any time.


PS, Dyno jets are junk, your running too much boost for a t25, I have never seen any gains after 12psi on a sr with proper tuning on a t25 and most of the time they actually prefer 10psi. I guess it just depends on the intercooler used.

Cotbu: I didnt mean it would learn boost directly I meant would it re-learn my maf voltages, inj pulse, and afr's in order to make a new map? From everything I read I would be able to unplug my battery and let it sit overnight to drain all residual power from the ecu. Then my ecu will have a clean memory and can re-learn my fuel maps....? How incorrect is this? Is there a cheap tuning alternative? I was thinking maybe enthalpy or nistune but I'm still stock everything. FWIW I want to upgrade injectors, maf, ecu and turbo in the near future but aquiring parts overtime when i stumble upon deals.

Also, the shop did you speed based. They dont know what they are doing..... Dyno jets are bad pieces of equipment because all they do is estimate hp by how fast you accelerate the roller. Then they figure your tq off of your estimated hp. See how this is a flawed practice? Now take a shop that dont understand their equipment even further and they dont let rpm get input into the dyno, tqXrpm/5250=hp. Well lets put it this way, everything in that entire equation is an unkown. Somehow they were able to make up a hp number? Waste of a $30k machine.....
Any shop that know so little about dynos, that they will buy an inertia based dyno most likely dont know much about tuning either, so just keep that in mind if you decide you want them to tune your car.

It dont know any of that stuff. Between throttle position and maf voltage (real time) it decides load. Those are the cells in your map left to right and then with the corresponding rpm info that decides the pulsewidth.
The only real other factors are multipliers based on percentages it modifies the pulsewidth from cts or iat.

have you every watched the wideband on long steady throttle trips (cc), tps and mafs voltages stay steady as well as speed and rpm, the wideband will lean out. I've seen a steady 15.2 afr myself on 301. I believe this to be my long term trims kicking in.
So it won't learn the fuel map it will follow the fuel map and what 4x4le is saying is true the ecu will interpolate when you fall into the invisible cells via tp(cells read 28,32 but your in tp 29) tp load determines which cell to pull from. Im saying the longer you stay in the cells controlled by the ecu via the 02 sensor the more fuel is trimmed for max fuel efficiency. This won't help you make , more power on the dyno, but it will help you with that 10-15mpg thread.
what I mean by learning the sensor voltages is, not every person has the same stored voltages for mafs, and tps closed, this is apparent to me because, I've bought faulty oem z32 mafs based on this premise alone. Once the ecu learns the operating voltage the mafs work flawlessly. all i do is clear self learn. That's probably why isis mafs work for me a lil, lol.
The tps closed voltage can be tricky, unless you have nistune, conzult programs or software that can tell you when the tps is registering closed visually, most people miss it. Usually, i find it's accompanied by an 1100rpm idle, tps showing not closed @.45v.55v.60v(the sweet spot was .445v) but to get the range back I had to clear self learn.
so, apparently they just turn the "idle" down. The ecu hasn't learned to idle because it doesn't know when too. So after restart and warm up, (80c) the idle is still 1100rpm.
I hook up nistune and can see the flag not lit, the flag now says tps idle, it used to say tps closed IIRC.
If your looking for it?

Also I'd like to say some people are removing the coolant lines from the IACV, I recently used clearing self learn for this issue as well. The high uncontrollable idle issue.

The tune i referenced is based on 13psi, for a stock mafs and injectors, it usually nets 220-230 on a dynojet from the Midwest to the east cost.
mafs seems like it's the weak link in my records.

I love nistune should probably check for a new version soon. I'm stopping everything at 450hp or 400ft, WCF. I'm still internally stock minus studs and headgasket now. Nistune can be used on a stock setup, and is a better alternative for someone willing to learn to tune, has a nistune tuner local or used to rom tune.

make sure pin 105 on your ecu plug is hooked up mine was unhooked and we hit 168whp on a mustang dyno after it was hooked up did 208 on 7 psi fuel pressure control module red with a white stripe

I'm still not sure why my friend pulled the exact same power as me at 8psi when I was at 14...? Thanks for all the useful info guys

Did he dyno at the same place? Does he have the same setup as you?

Hes bone stock with the smic at 8psi. I'm running stock with a fmic, 3" exhaust intake, afpr, and fresh rebuild at 14 psi. We dyno'd the same day on the same dyno only a few cars apart