Need help - engine (ECU?) problem found during dyno

[iwantanatom]

So, a quick bit of background. My atom is one of the very early atoms (originally was MyerFire48's car). I sent it in at the start of the year to brammo to get it upgraded to "the latest of everything they had figured out". This included the new air intake routing and supposedly the latest ECU tune. I finally got around to getting it to the dyno to check how this worked out.

This is a 245hp / stage 2 car. Car was run on a dynojet, 90-95deg ambient, sea level, one fan blowing on the radiator, 4th gear,  91 octane CA "summer formula" gas. As you can see and as was felt by the tech, there was some problem above ~5500 RPM. I also asked him to take the first run into the fuel cutoff (but not above 7000 rpm - strangely, he said that he did not hit the fuel cutoff at 7000rpm??) His opinion was that the ECU should be leaning out the engine about 5000 to fix this, and he strongly advised not taking the engine above 5000-5500 until this was worked out. I asked if there was something else, ie run on race gas, high temp, etc. and he felt this was just ECU tuning of A/F ratio was the only fix. For the first run the water temp started at 180 and was up to 210 at the end of the run. In the second run we started at ~195 and aborted when the water temp hit 215.

So, does this make any sense? Certainly I don't want to do any damage to the engine. Any thoughts on the most painless, low cost, low risk way to fix this? Getting to a certain HP result is not important to me, I just want to make sure that engine is running well.

[bolus]

what did he think the problem was?  that looks like a pretty typical atom curve to me ( though Im no expert)

Cheapest way to improve the tune would be to get a used Cobalt ss 2006 ECU ($50-100), get a base tune from darth or me (free), bring it to your tuner and use hptuners to get exactly what you want (? price 200-300 maybe?).  The Atom ECU is not tunable by HPtuners. 

[bolus]

oh, the rev limit is 7200 I think in the base tune

[iwantanatom]

I don't recall his exact words, but he felt that the HP curve should be smooth (not lumpy) as you can see above 5000 RPM. He pulled up a copy of a honda atom that they had done a few years back (I think it was also posted here somewhere) and the HP curve was very smooth (of course apple to oranges). If I look at the other dyno plots of the other ecotec engines posted here, I don't see anyone else with the lumps, they just flatten out at higher RPM. He felt the engine was not running smoothly at high RPM (I'll call him on Monday and get the exact words) and felt running the engine there would do damage pretty quickly.

[DarthChicken]

You need to get a datalogger on that car.  Find out what the actual A/F is, and also what the timing is doing.  That looks VERY lean to me, and that bumping around is probably the ECU pulling timing like crazy. 

Make sure there is no air making it into the engine that isn't metered by the MAF sensor.  The sensor is down tight, the hose clamps at the throttle body are tight, etc...

Nice to see that car again, I saw it when it was being built a couple years ago.

[iwantanatom]

Thanks Darth. I checked the air intake and clamps and I can't find a leak.
I am looking at how best to get setup for datalogging.
It looks like the exhaust only has the one mount for stock O2 sensor - I assume this is a narrowband sensor and is used by the ECU so it can't be disconnected without effecting operation?
The dyno test guys just used a separate sensor shoved into the exhaust output for AF monitoring, but for drive around testing, obviously this won't work.
Is the only thing to do get an wideband O2 sensor and get a second mount installed in the exhaust? Or just datalog off of the OBD2 -- just record what the stock sensor is reading?
(What are people using for datalogging? hptuner? Innovative motorsports OT1?)

Also, I took the car out on the freeway at 65degF ambient and ran it up and down at 5-7k RPM and did not hear or feel anything (no stuttering or hesitation, sounded fine as well) and water temp stayed at 180degC. I wonder if the stock ECU tune is just not right for very high temp operation??

[DarthChicken]

I just pull the stock O2 sensor (and unplug it) and put a wideband in their.  HPtuners to lock advance, knock, and I pull in data from an LM1 wideband into the hptuner logger software, so its all right there in one spot.

Sitting on a hot dyno with minimal airflow is hard on an engine - big fans or not.  You're probably just fine as you are.

[Myerfire48]

Man....its like watching your stripper girlfriend dancing for a rock star...

[DarthChicken]

That's ex girlfriend..... 

[Myerfire48]

yes very ex... umm that I dont hang out with anymore.  or ever talk too.  kinda like the car which I miss even more.

[iwantanatom]

Okay, so freeway run, 70degF ambient, datalogging from ECU using innovate motorsports OT-1 over OBDII (so, I not sure if it is decoding everything correctly.) I have not hooked up the wideband AF yet -- need to get/find a wrench which lets me unbolt stock O2 sensor.

1- Does timing advance vs MAP/MAF/RPM/Throttle look reasonable?
2- The logged ECT matched the WT shown on the dash, but the IAT is bouncing all over the place. I assume it is a OT-1 ODBII decode problem, but maybe it is real (cable/sensor problem)??
3- datalogger information for speed is not working. Is the speed information going to the stock ECU/OBDII accessible?
4- what is the magic tool to make it easy to unscrew/unbolt stock exhaust O2 sensor?

If it helps,
13:55-14:03: 1st gear acceleration onto freeway
14:03-14:05: 2nd gear
14:05-14:14: 3rd gear
14:14-14:15: double clutch downshift to 2nd
14:15-14:40: 6k-7k RPM runs
14:40-14:43: 3rd gear
14:43-: 4th gear?

I did one run into fuel cutoff, I believe that was 14:35 run. I'm am pretty certain that cutoff occurred at 7200 RPM, so I'm not sure why that doesn't seem to appear here.

Thanks again for the help!

P.S. Rob- Let me know if you need some alone time your ex - we can probably arrange something!