Wobble in AFR
11-28-2007, 12:06 PM
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Staging Lane
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Wobble in AFR So After a Heads/Cam/Intake swap, install and tune by Tom Wong I put down 400/362 on his Mustang Dyno.
Torquer V2 - Mildly Hand Ported 243s - Supermaxx Long Tubes - LS6 Intake - VaraRam and additional supporting mods like oil pump, timing chain, valvetrain etc etc...
I was satisfied with 400whp (I even made 410 on a non heat-soaked pull) on a Mustang dyno through my DTE 4.10 Rear... but i was curious what the real gap between Mustang and Dynojet was... So after a couple weeks i tossed it on a Dynojet with a bunch of friends at a Dynoday, no changes made to the tune or engine.
I lost something like 20hp at peak - and I'm missing near 25lb-ft of torque at 6000 RPM!!! (Something like 350lb-ft @ 6000 RPM on the Mustang Dyno and only 320-325 lb-ft @6000 on the Dynojet)
Look at my AFR! As Early as 4.5k RPM it's going all to hell! Any idea whats going on there?
I'm planning on bringing back down to Tom and checking things out... maybe my MAF is loosing it. Any other suggestions before i head down there would be helpful.
(ALL Numbers are SAE Corrected)
Thanks,
Dan
Torquer V2 - Mildly Hand Ported 243s - Supermaxx Long Tubes - LS6 Intake - VaraRam and additional supporting mods like oil pump, timing chain, valvetrain etc etc...
I was satisfied with 400whp (I even made 410 on a non heat-soaked pull) on a Mustang dyno through my DTE 4.10 Rear... but i was curious what the real gap between Mustang and Dynojet was... So after a couple weeks i tossed it on a Dynojet with a bunch of friends at a Dynoday, no changes made to the tune or engine.
I lost something like 20hp at peak - and I'm missing near 25lb-ft of torque at 6000 RPM!!! (Something like 350lb-ft @ 6000 RPM on the Mustang Dyno and only 320-325 lb-ft @6000 on the Dynojet)
Look at my AFR! As Early as 4.5k RPM it's going all to hell! Any idea whats going on there?
I'm planning on bringing back down to Tom and checking things out... maybe my MAF is loosing it. Any other suggestions before i head down there would be helpful.
(ALL Numbers are SAE Corrected)
Thanks,
Dan
12-03-2007, 10:23 AM
#2
Staging Lane
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Bump -
I'm surprised.... nobody has any comments on this problem? No input on the newfound wobble in my AFR? I suppose i could post this on the Tech forum but i figured people troubleshoot Dynosheets a lot in here...
-Dan
I'm surprised.... nobody has any comments on this problem? No input on the newfound wobble in my AFR? I suppose i could post this on the Tech forum but i figured people troubleshoot Dynosheets a lot in here...
-Dan
12-04-2007, 02:53 PM
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Staging Lane
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Maybe in the Peaks - but why then does my TQ Peak only carry for 300 RPMs instead of ~600RPMs on the mustang dyno? The TQ Curve starts falling much sooner when the Wobble starts compared to the nice Carry on the Mustang dyno.
And if you look at 6000 RPM the BEST run i'm at ~380whp but then drop 5-8hp and work my way back up to 380 by 6500.
And around 5800-6000 RPM the Blue run is costing me 20hp.
I'm actually shocked that with all the **** Dyno Tune experts around here the consensus is "It's not important, nothing serious is wrong, or you're not losing any HP..."
-Dan
12-04-2007, 03:29 PM
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Alrighty - a 'Run Log' is that a text file or something i can get from Tom? I mean, Tom will be looking at all the data too, but the more minds the merrier - i just don't know all of what is needed for troubleshooting these tuning problems.
-Dan
12-04-2007, 04:11 PM
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Mustang/Dynojet/SAE/STD doesn't change wobble in AFR and Shape of TQ Curve.
-Dan
12-04-2007, 04:46 PM
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Edit: Also - if one is SAE and the Other not - why are my Peak TQ's abot the same. 362 Mustang 366 Dynojet. Those numbers look right. I made bout 4 more TQ (SAE Corrected) on the Dynojet, and had the TQ carried correctly, i should'e made about 4 more HP too...
If the mustang dyno was STD - that means, my SAE TQ numbers should've been something like 350? I don't think so...
A friend of mine w/ a Z06 made 362 TQ and 375whp on that VERY Same Mustang Dyno. And made 380hp 372TQ on the Dynojet - which is a gain of about 5hp 10tq on the Dynojet vs the Mustang Dyno. It doesn't make sense for me to gain 4TQ on that same Dynojet, but loose 20hp...
-Dan
Last edited by LS1-Inside; 12-04-2007 at 04:54 PM.
12-04-2007, 05:46 PM
#11
The discussion of the differences between the two dynos alone should tell you that you need to take that variable out of the equation...go back to the original dyno and see what happens (as you already know). The wobble in AFR could be any one of a number of things, some of which could be related to the tune. This is something that will have to be systematically tracked down one variable at a time if you want the right answer...
12-04-2007, 07:31 PM
#12
That Mustang dyno sheet you provided shows "Total Power (HP)" That is as measured, without correction. SAE corrected numbers should read "Eng Power T WC (HP)"
There is a lot of info here on both of those types of dynos, how they work and measure power. Once you understand how each works, you'll see why you absolutely CANNOT compare the two, period.
There is a lot of info here on both of those types of dynos, how they work and measure power. Once you understand how each works, you'll see why you absolutely CANNOT compare the two, period.
12-04-2007, 07:39 PM
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That Mustang dyno sheet you provided shows "Total Power (HP)" That is as measured, without correction. SAE corrected numbers should read "Eng Power T WC (HP)"
There is a lot of info here on both of those types of dynos, how they work and measure power. Once you understand how each works, you'll see why you absolutely CANNOT compare the two, period.
There is a lot of info here on both of those types of dynos, how they work and measure power. Once you understand how each works, you'll see why you absolutely CANNOT compare the two, period.
However, this is the data I have - and the AFR, Wobbles!
Are you telling me that Dynojets see Wobbles in AFR's that Mustang Dyno's dont? Because One AFR is Screwed up, and the other is not!!
-Dan
12-04-2007, 08:04 PM
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Tom said the wobble could be from a couple things really. 1) The MAF is freaking out and getting weird readings, which the PE table uses to create a weird AFR 2) There's turbulence in the Intake and it's screwing up the airflow. And he also mentioned a couple other things - i guess I'll start there.
Hopefully i'll get it fixed when i get down there, i'll of course, post the results.
-Dan
12-04-2007, 08:21 PM
#15
Yeah we could argue the dif in dynos all night. Point being Mustangs dont necessarily read lower automatically. OPERATOR ENTERED CORRECTION FACTORS. Thats all ya need to know.......
Back to your A/F wobble. If your dyno run on the DJ was 6 seconds, and the Mustang was 10, the dif could just be the accuracy of the shorter run.
In other words, if you blow up the mustang run, lengthen the graph, it may have the same dippity doos. The mustang graph is physically shorter, yet time wise longer, which would make it less defined.
Back to your A/F wobble. If your dyno run on the DJ was 6 seconds, and the Mustang was 10, the dif could just be the accuracy of the shorter run.
In other words, if you blow up the mustang run, lengthen the graph, it may have the same dippity doos. The mustang graph is physically shorter, yet time wise longer, which would make it less defined.
12-04-2007, 08:34 PM
#16
I could post graphs of different cars on the DJ224 that I use that show the difference in being 12.6 to 12.8/9 but I'm sure that for one reason or another they wouldn't qualify for what you are looking for. I'm not trying to hurt your feelings or insult you, but though your AFR is wavy, it's not that far off. Nearly any real change from straightening it out is just going to net a few at peak. I'm sure it isn't even noticeable on the street like this vs corrected. Best of luck straightening it out, but don;t let it worry you or cost you any sleep.
12-05-2007, 01:04 AM
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I could post graphs of different cars on the DJ224 that I use that show the difference in being 12.6 to 12.8/9 but I'm sure that for one reason or another they wouldn't qualify for what you are looking for. I'm not trying to hurt your feelings or insult you, but though your AFR is wavy, it's not that far off. Nearly any real change from straightening it out is just going to net a few at peak. I'm sure it isn't even noticeable on the street like this vs corrected. Best of luck straightening it out, but don;t let it worry you or cost you any sleep.
Now look at 5800 RPMs. Notice the AFR difference between the blue and Green runs: 12.7-13.1. Now observe the HP gap: ~20HP between the runs. The Peak Differences may be marginal - but 20 hp up's and downs - which for all I know, are getting worse from some problem, aren't something I'm happy about. Or do you have graphs showing me how Power under the curve isn't important as long as My peaks are close?
Edit: Also I understand that Dyno's are different, and out of curiosity I would like to know why when we take 2 cars, run them both on the Mustang dyno and see a ~20hp Difference, then take the same two cars and run them on a Dynojet a couple weeks later, and only see a 1hp Difference between the cars? (no Changes on either, except mine does the wobble now,and it didn't on the Mustang)
Edit2: I mean, it may not just be a slight lean/rich condition. If i've got some serious airflow issue, turbulence or something, the AFR may dip rich not from the injectors spraying more fuel, but from an air shortage... now a .2-.4 AFR difference may not make that much of a difference, but what about that slightly Rich AFR combined with low/restrictive airflow. It seems to me that if there's some other problem there, the AFR may just be a symptom and not actually the problem. But i'm just guessing here...
-Dan
Last edited by LS1-Inside; 12-05-2007 at 01:22 AM.
12-05-2007, 10:31 AM
#18
You are missing one important part of this puzzle: you don't know if the Dynojet was having problems on that particular day. Those numbers are only as accurate as what was measuring it, and you have no way of verifying its accuracy. For now, you need to discount those numbers, and go back to the original dyno if you want to do a comparison.
I agree with what was stated above...the fueling changes are not enough to produce what you are seeing. I'd think timing being pulled by your computer would cause that before I'd look at the fueling based on those graphs...
You can guess until you are blue in the face, but IMO, you are just adding to the problem instead of trying to fix it. Toss the questionable dyno graph, and try again.
I agree with what was stated above...the fueling changes are not enough to produce what you are seeing. I'd think timing being pulled by your computer would cause that before I'd look at the fueling based on those graphs...
You can guess until you are blue in the face, but IMO, you are just adding to the problem instead of trying to fix it. Toss the questionable dyno graph, and try again.
12-05-2007, 11:21 AM
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You are missing one important part of this puzzle: you don't know if the Dynojet was having problems on that particular day. Those numbers are only as accurate as what was measuring it, and you have no way of verifying its accuracy. For now, you need to discount those numbers, and go back to the original dyno if you want to do a comparison.
I agree with what was stated above...the fueling changes are not enough to produce what you are seeing. I'd think timing being pulled by your computer would cause that before I'd look at the fueling based on those graphs...
You can guess until you are blue in the face, but IMO, you are just adding to the problem instead of trying to fix it. Toss the questionable dyno graph, and try again.
I agree with what was stated above...the fueling changes are not enough to produce what you are seeing. I'd think timing being pulled by your computer would cause that before I'd look at the fueling based on those graphs...
You can guess until you are blue in the face, but IMO, you are just adding to the problem instead of trying to fix it. Toss the questionable dyno graph, and try again.
Anyways - I want to go to the Original Mustang Dyno - but he's in Vancouver WA and i'm in Olympia. The Road down to Vancouver is called I-5... not sure if you guys have heard yet, but it's being Raining a bit up here in WA...
I-5
-Dan