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Discussion Starter #1
So, today was the day to dyno. The only problem was, it was a -22F feel effect last night and in the morning my car didnt want to start (even though it was on the trickle charger).

So I bought a new battery, installed it, drove the hour to the dyno and put it on. I noticed the check engine light was going on and off and the idle was stuttering when stopped.

I didnt check the code until after my first pull. But it was the 1222 code, Lambda, which also happened here when I disconnected the battery to install the test pipes.

Now my numbers are low for what I have done:




First pull was incredibly low: 250 wheel

I knew something was up, so thats when I hopped in and did the pedal test and came up o2 sensor.

Now the debate was whether to unhook the battery in hopes of resetting the DME and getting rid of the code, but possibly resetting and throwing the code again after I already drove 75 miles (95% highway cruising), or going again in hopes to have the car "learn" its power.


Well as you can tell, a few minutes later, without unhooking the battery, the car gained power everywhere - but still not where it should be.

We waited 5 minutes with random driving on the dyno, at different speeds and rpm, again, in hopes of "learning" the DME. It was the same peak horsepower, but now a loss of low end, but a decent chunk of midrange, as seen here:



Those overlap the two higher pulls.


..........



So, in short, I dyno'd 270 whp, 247ft/lbs on 75miles on a new battery while throwing the o2 code.

My question is, will my car eventually learn and get back to where it was running (flawlessly, 100kmh-200kmh in 12.0 flat) or do I need to unplug the battery again in hopes of getting rid of the o2 code in the DME?

Would the numbers be higher once the o2 is sorted out?

Help or opinions would be great

The car had about 50k miles on the rebuild with Schrick 280 cams and D'sylva chip by the way
 

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Not sure about the codes, but on full throttle the O2 sensor is ignored - the ECU is running in "open loop" mode, ie. it is fuelling according to the preset map in the DME - hence it doesn't (well, in theory, shouldn't) affect a dyno run on full throttle.

The O2 sensor is only used in closed-loop (part throttle) running to help the emissions.

That doesn't mean the DME isn't doing something else because it thinks the O2 sensor is dodgy incidentally, but on most cars it shouldn't matter.
 

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Discussion Starter #3 (Edited)
Well it has happened before. When the battery was unplugged, the CEL would flash.

It was only then when the car would feel stuttery and misfire, once the code somehow didnt register, the car ran tip top.

So something is messed up when you gain that much power everywhere without touching a thing.

EDIT: I thought 247 torque was pretty good, it looked like i was going to make good power until about 5750 rpm on the last pull. (2nd pic)
 

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AWOL, once corrected, your crankshaft power is around 320hp.

Guess those cams aint giving you much over the stock set up? I would imagine the stock cams must have a fair bit of lift and duration - how much more do your Schricks have?

That said, youve got quite a nice flat torque curve. Little bit of a dip at 4200, maybe this can be fine tuned out with that chip you have
 

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20BHP up from stock is still a reasonable figure from just a set of camshafts!

Plus, the car is making power right up to where the run was ended (7K revs) - you could easily explain the lumpy power by the fact the car is using a generic map and not one specifically mapped for the engine.

Not saying there isn't still something wrong, but it's not that catastrophic looking IMO ...

Is the cam timing spot on? Do you have adjustable cam pulleys?

I'm sitting here looking at my own graph and yours, but it's not telling me anything as I have a 3.8 ;)

All I will say is that my curves are far smoother, and that's not because of the print out, it's a very precise rolling road output and hasn't been smoothed.

Were any of the runs performed with a full wideband lambda sensor stuck in the exhaust? trying to deduce information from a dyno plot WITHOUT knowing what the air/fuel burn was like over the entire rev range is bloody useless IMO - get it back in the dyno and get the lambda plotted over the power/torque graphs and it will help explain what is happening .... I am of course assuming your rolling road tuner/operator has a wideband lambda for the exhaust, but i'd be very suprised if they didn't .... it IS after all how you tune a car.

Did you see any black smoke from overfuelling as the car was on the dyno?

Some food for thought there :)
 

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Discussion Starter #7
Well most chipped m5's alone are putting out 275wheel on dynojet's. I figured cams would net me another 10-15 wheel. So with my chip and cams I was shooting for the 280-290wheel range (actually predicting 283).

The first pull filled the facility with fuel. Peoples eyes were burning. The second pull the car sounded and rev'd much better when he gunned it, with less fuel smell.

Unfortunetely there lambda reader was broken that day and they had one a new one coming in the next day, but seeing as the car was feeling great the months prior, I felt doing a baseline pull was still okay.

Im still not pleased, but 247torque was beyond my expectations, hopefully the horsepower will follow suit once I figure out why my car is not running tip top
 

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While I know dyno to dyno comparo's are regularly useless, my '91 w/just an EAT Chip did 264/243 on a mustang dyno. I'd try and see if you can get Mark to work with you on a custom tune to really dial in the Shricks.
 

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Discussion Starter #9
I sent him a PM awhile ago pertaining to exactly that, if a retune for the cams would be a smart investment.

He said, "I have not made a chip specifically for those cams. I don't think much of a change is required, if any. Since the E34 M5 has a MAF, it reads the amount of air entering the motor and can compensate for it quite well. To properly re-tune it, I'd have to monitor the AFR with a wideband O2 sensor. There may not be any big difference in performance after doing that."

Im definitely going back to the dyno once the CEL code goes away, but Im just wondering if theres anything else I can do to find the power Im missing.

Compression is good, plugs are new, and wires seem okay.
 

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Well most chipped m5's alone are putting out 275wheel on dynojet's. I figured cams would net me another 10-15 wheel. So with my chip and cams I was shooting for the 280-290wheel range (actually predicting 283).

This member states most chipped M5s make 275 whp on Dyno Jet.

Dyno Jets read approx. 15 % higher than Dynamics.

275 dyno jet is approx. 235 whp dyno dynamics.

Another confirmation of my statements that stock M5s make 240-245 on Dynamics.
 

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