ECMlink Dyno tuning questions

[kjlinwi]

Took my wife's 97 eclipse in for an actual tune at a performance shop on a dyno for the first time. All previous tuning had been done by me as I figured out how to manipulate the ecmlink software.

Tuning shop made one run one on the dyno and said that the clutch is slipping. Never had a problem with the clutch other than I hate the way it engages (its a two stage clutch, I forget the brand name) its been in for two years and less than 5k on it. I've never had it slip and it still passes all the tests.

After the clutch was "slipping on the dyno" the engine still increased about 100 horsepower and 30 lb/ft of torque and both were still climbing at a steep angle on the dyno chart when they shut it off at 5000 rpm.

This doesn't look like clutch slipping to me but I'm curious what others with more dyno experience than I have to say about the dyno chart.

 

[Ben-Stian]

Clutch slips because of too much torque, not directly hp. You can make great hp as long you limit tq. Your dyno operator will notice when clutch slips. Maybe your clutch started to grap after it slipped a little...? Have seen it a couple of times on my dyno...
Maybe some else can chime in with their experiences?

 

[kjlinwi]

I thought about that but
1) if the clutch started grabbing, why stop the dyno pull?
2) Why would you only do one pull?
3) How does a clutch slipping change afr (it got leaner at that time on graph)
4) Would Boost stay the same with a slipping clutch?

 

[donniekak]

Dyno graph looks like the clutch is slipping.

 

[kjlinwi]

Because?

That doesn't explain any of my questions....

 

[ThunderChild]

Because?

That doesn't explain any of my questions....

Sharp fall off at 3850 for tq and hp, right as you hit ~20psi, then it slowly recovers but looks ragged, seems pretty obvious the way the graph looks thats where it's slipping. Without throttle value it's harder to say, but that looks like what I'd call slipping, unless you have the most jacked up tune ever.

Had the same thing happen for me recently, albeit not on a Dyno. I had used my eBay clutch for around 15k with good results for the price, and only had one slip issue when I attempted to slip it on a launch vs just 2 stepping it like I had. Then the car was down for a winter and most of the summer while I got the new I/c working. Took it out after finishing up, hit 13-14 psi like I'd done before (was as high as 20 before) and the clutch started slipping bad.

Time for a new one, so I went with south bend and CC flywheel/clutch fork. Sucks to take the car apart again, but it should only take me a day to do. Welcome to the club

 

[Ben-Stian]

I thought about that but
1) if the clutch started grabbing, why stop the dyno pull?
2) Why would you only do one pull?
3) How does a clutch slipping change afr (it got leaner at that time on graph)
4) Would Boost stay the same with a slipping clutch?

Good questions that I dont know the answers, only guessing...

1: Maybe it slipped so bad they hit the rev limiter? I dont know if they use a rpm pickup on motor, or just calculated roller speed...
2: Because they hit the rev limiter or wouldnt fry the clutch completely.
3: Rev limiter or hit a lower load point in the tune as the load decreases when the clutch slips, or they let off the throttle?
4: Not sure, but if it slips bad, I think it will be lower...

 

[brian9397gsx]

Look at your peak it drops then rises back up. Its probably not slipping so bad you'd notice on the street but on a dyno with feedback measuring the power it will pick it up on the graph.

 

[kjlinwi]

it slips at 20 lbs of boost but grabs at 24 lbs of boost.....?
Rpm is engine RPM and not roller rpm. Did not hit rev limiter.
If they let of the throttle that would be causation and not symptomatic.

Besides not understanding how it's grabbing and climbing at 45 and 60 degree angles under 24 lbs of boos (def no slip going on),Why did the AFR go lean? Either the tune was way wacked in that RPM range as someone else alluded to (which is poss, I did all the tuning myself) or there was a fuel or throttle input change.
If you rev car in neutral (Max clutch slip) the AFR goes rich.
So how do you know with only one pull that the clutch is slipping with the information at hand? That's my problem. If the clutch is slipping, then I need to understand how that caused AFR to go lean since that is counter intuitive and not that there is a problem with AFR, throttle control, MAF sensor, (running a GM 3" MAF), MAP sensor, etc that caused the car to lose power in that power band (rpm range), since it had no problem holding and making power at higher rpms. I have seen MAF cause driveability concerns on other cars with flat spots in acceleration, but those were worse and were diagnosed without a dyno. I definitely don't feel that when I drive the car on the street, but that's why I went for a dyno tune...

What is the cause or relevancy of the AFR moving at the same time as the power loss? I don't think that can be ignored.

 

[Vegas Smith]

What is the cause or relevancy of the AFR moving at the same time as the power loss? I don't think that can be ignored.

A dyno operator and wiseman have told you the clutch is slipping so I'm not sure why you're questioning this. It's possible that the slippage caused the car to get confused and use a different load value. Different load/rpm cells use different AFR targets. That's all I can think of.

 

[kjlinwi]

That is a possibility, but how do we prove that? I don't make repairs based on guesses. Everything needs to line up and be understood before you can make the appropriate repairs. Otherwise its just guessing with possibly no results. I.e. how does a clutch slip at 3800 rpm at 20lbs boost and grab @ 4500 rpm and 24 lbs of boost? I know that there are examples of that happening and if that's what it is, then a new clutch is on the horizon. But not until I know that's an issue. Cars don't get confused. That's a human condition (like now? ) (that's not aimed at anyone other than me btw). They run off of inputs and software and output controls. Our job is to understand that which means not disregarding known information. How do we know it's not a MAF frequency problem? Which is one of the places that load is calculated from for the computer.

Which leads to the next stage of questioning and reasoning. How do you determine precisely what is going on?

 

[kjlinwi]

Dyno chart with of a car with proven clutch slippage. AFR did not change at all during the clutch slipping.

 

[1990TSIAWDTALON]

Do you have a log of the pull? I would be looking at that as the AFR's leaned out. Very possible some surrounding boxes in the tune are screwing it up, but if it has been smoothed out already then all should be good there. Torque is where I found the limiting factor on my clutch, not the HP. You have done a BLT after the dyno run haven't you, just to be sure everything is good and holding? I find a GOOD hill and do a pull up it, it will tell you if you have a clutch problem, log it though.

 

[kjlinwi]

They did not provide a log of the run and they did no tuning on the car. I did a boost leak test before I took it down and they did a boost leak test before they put it on the dyno. I did do a long pull up a hill before I loaded it on the trailer to bring it home and a couple of quick hard launches and didn't notice anything. I have not done a data log session until I've decided what exactly I should be looking at.

 

[19gsx91]

...I feel like all this has been answered but I guess we gotta get the spoon out. Donnie and Brian both putting answers in should of been plenty sufficient.

1) if the clutch started grabbing, why stop the dyno pull? - Because it started to slip. no dyno operator/shop wants any type of failure on their dyno and have to deal with an angry customer
2) Why would you only do one pull? See above
3) How does a clutch slipping change afr (it got leaner at that time on graph) Different load values? a Dyno puts more or less load on a car.. so it would stand to reason that it's not going to be exactly the same.. without a log it'll be impossible to tell exactly what was going on or what load cells you were hitting.
4) Would Boost stay the same with a slipping clutch? Depends on how bad the slippage is.. if it did indeed "start to grab again" then I'd say yeah it slipped a bit but nothing like completely letting go. again... See above.

I mean at this point be grateful your car is still drivable and you discovered the weak point in the system.

 

[kjlinwi]

Oooh Boy, I love it when someone thinks their getting the spoon out! Now it gets fun.

Your numbers above.

1. It slipped at 3850 rpm. If your worried about destruction, that's where you stop. Not at 5k. But nice of you to decide what others are doing for them.
2. Why do another pull? To figure out what's going on. See the attached picture of a dyno from a dumped clutch. Here's the spoon. That's diagnostics. Approach the problem and see what's going on, don't assume. The attached dyno sheet looks like clutch slip as well, but it's not.
3. Here's another spoon for you. Answering a question with a question isn't an answer, its a WAG. Especially when I posted another dyno chart of an actual clutch slippage with no AFR change. Unlike you, I'm not assuming anything. I'm asking lots of questions and working to learn and understand how it all applies on a dyno. No maybes here.
4. More maybes.

Final point, it's my wife's performance car. They break because they are built beyond what they were designed for. We run the risk of breakage anytime it steps on a dyno or we push it on the street or this coming spring when she takes it to the strip. If it breaks when testing and doing diagnostics, well that's just the way the wrench bounced. But avoiding the testing and diagnostics isn't the way to understand what's going on or fix a car.

 

[1990TSIAWDTALON]

Give us a datalog so there can try to be some help here. Try to duplicate the clutch slipping, however that may be, but put some different loads on it.
Theres no way I could tell why it went lean if I didn't have data (testing) to look at.

 

[kjlinwi]

I agree that's a good idea. I'll try and get one in the next few days. Besides RPM, MAF and Map and TPS what other things do you think would be relevant without too much data?

 

[Vegas Smith]

A couple things you're not considering:

1) You're blaming the operators for not shutting the car down at 3800 instead of 5k. It actually takes time for the human brain to take in information and make a decision to shut the run off. 3800-5000 rpms takes about 1 second in real life; that's about as fast a reaction you can hope for. Sure, they could have done another run but when the clutch blows up guess who you'll be blaming when they told you they already suspected clutch slippage on the last one? Why did you idiots blast the car again if you knew the clutch was slipping! I'll sue!

2) Although your AFRs dip, it doesn't appear to be a giant dip. For example, it appears to lower from about 12 to 11.3 during the run. That seems fairly natural to me. I think you've got all your answers and now you need to buy a new clutch from TMZ.

 

[rEclipserGST]

I am ASSUMING you did not pay any monies during this dyno experience? Since they did only one pull & you have no log.

 

[kjlinwi]

I'm not blaming anyone. I wish they had called me and I would have told them to run it again on the dyno at higher RPM. BUT, hindsight is always 20/20 and I understand what your saying. The gradients for the AFR are tough to figure out on the chart. The bottom of the chart states that AFR had a range of 13.2 - 11.3. I agree not a huge difference but it mirrors the event at 3850 rpm so it is worth understanding what it is. Especially when I have spent days looking at dyno charts of other cars with known slipping clutches and their AFR doesn't change.

I myself, would have run it up to the 7500 rpm limit to see what the chart shows. I would have also done a couple of different pulls at different acceleration curves, but that's just me and how I'm wired.

My wife and I are actually talking about renting out a dyno in milwaukee for me to work on and see what I can learn from it.

I completely understand that a NEW part just means that it had Never Ever Worked and my new clutch may be junk. But I need to understand everything that's going on before I throw more parts at it.

Such as, I'm also debating whether the lightweight flywheel was such a good idea given that it can cost you shift rpms on lower power cars (which my wife's car was built to put out 400hp at the flywheel and I think qualifies for that). But again how do I know that without playing with numbers and comparing them? Lots and lots to learn and think about.

 

[kjlinwi]

No, I paid full price for the dyno tuning.

 

[rEclipserGST]

 

[1990TSIAWDTALON]

I'm not blaming anyone. I wish they had called me and I would have told them to run it again on the dyno at higher RPM. BUT, hindsight is always 20/20 and I understand what your saying. The gradients for the AFR are tough to figure out on the chart. The bottom of the chart states that AFR had a range of 13.2 - 11.3. I agree not a huge difference but it mirrors the event at 3850 rpm so it is worth understanding what it is. Especially when I have spent days looking at dyno charts of other cars with known slipping clutches and their AFR doesn't change.

I myself, would have run it up to the 7500 rpm limit to see what the chart shows. I would have also done a couple of different pulls at different acceleration curves, but that's just me and how I'm wired.

My wife and I are actually talking about renting out a dyno in milwaukee for me to work on and see what I can learn from it.

I completely understand that a NEW part just means that it had Never Ever Worked and my new clutch may be junk. But I need to understand everything that's going on before I throw more parts at it.

Such as, I'm also debating whether the lightweight flywheel was such a good idea given that it can cost you shift rpms on lower power cars (which my wife's car was built to put out 400hp at the flywheel and I think qualifies for that). But again how do I know that without playing with numbers and comparing them? Lots and lots to learn and think about.

Lightweight flywheels have there place but even I think I need more weight to launch my car. I run an ACT lightweight, 11 lbs I think, and I would be happer running the stock heavier flywheel that stores more energy. Food for thought and my profile car is well into 500 hp. My clutch gave at 515 tq so I had to do some retuning until I replace it.
Some of my experiences.

 

[19gsx91]

Oooh Boy, I love it when someone thinks their getting the spoon out! Now it gets fun.

Your numbers above.

1. It slipped at 3850 rpm. If your worried about destruction, that's where you stop. Not at 5k. But nice of you to decide what others are doing for them.
2. Why do another pull? To figure out what's going on. See the attached picture of a dyno from a dumped clutch. Here's the spoon. That's diagnostics. Approach the problem and see what's going on, don't assume. The attached dyno sheet looks like clutch slip as well, but it's not.
3. Here's another spoon for you. Answering a question with a question isn't an answer, its a WAG. Especially when I posted another dyno chart of an actual clutch slippage with no AFR change. Unlike you, I'm not assuming anything. I'm asking lots of questions and working to learn and understand how it all applies on a dyno. No maybes here.
4. More maybes.

Final point, it's my wife's performance car. They break because they are built beyond what they were designed for. We run the risk of breakage anytime it steps on a dyno or we push it on the street or this coming spring when she takes it to the strip. If it breaks when testing and doing diagnostics, well that's just the way the wrench bounced. But avoiding the testing and diagnostics isn't the way to understand what's going on or fix a car.

Given your general demeanor perhaps you should sell the dsm and go buy a subaru. You've been given things to consider and instead of taking any of it into account and reporting back to us.. you're questioning our knowledge while googling (I hope nobody uses bing) other cars that have clutch slipping problems.. but every car is different. every setup is different. you can't just look up other examples of different setups in an effort to prove your point. that is not YOUR clutch. "slipping clutch" is such a broad term that you will probably never find anything that actually has comparable data to your specific circumstances.

If you're sour about the dyno fees then ask them for a discount if you were to return with the clutch fixed. I really don't understand what other information you expect to gather. I mean this really isn't that difficult.