Yesterday we installed the GSC 272i/264e cam combo in my 2005 MR. All in all the power production and delivery is excellent. I am left with a somewhat lopey idle however and I am curious as to whether anyone here has a similar combination and has been able to successfully tune the idle to run more smooth.

On another note, thanks to MalibuJack et al regarding the boost cut posts from last week. We went to open loop and that issue is officially gone. Now I am just throwing an overboost CEL on a regular basis(using a Hallman Pro). Not too sure if that is something I can avoid.

Thanks for any assistance,

Technov

 

I have yet to install my GSC 272 intake/exhaust cams, but i can tell u that using adjustable cam gears will help smooth out the idle. I'm not sure what the best setting is, but im sure someone will be able to help u with that. Hope this helps a little!

 

To get my HKS 272s to idle better, I adjusted the cam gears to -4/-1 (I/E). I also made my 0% load timing, 20deg from 750-2000 and added 30% fuel in the same load sites under OLF.

 

You will definitely need the cam gears to get the idle a little smoother! How is the over all car running?

 

Before the cam gears and Utec, it died all the time.
Since, It's died maybe 2-3 times (in six months).
When I switch back to map 0, it barely runs (at idle), even with gears.
Cam gears are good, but unless you get an "idle fix" flash, or tune with a Utec it'll idle like crap and die alot.
AEM EMS can be tuned the best, but you lose your user tunability and the knock safety threshold drops.

 

The aem can set any knock threshold you want as so can the utec. I wouldn't say lose user tunability, but make it a lot more complicated.

 

Not to bash, but my idle is a littly lopey, but i don't have issues with the car stalling on me. I don't have the same setup, but I was able to set my cam gears to -3/-3 on my 264/272 combo. The car pulls like a freight train, and no issues on stalling. I had more stalling issues when I was just running the utec and hks rs intake before I started tuning. Just my .02

 

Ok.. here's the trick..

Try to get your fuel trims from hunting and it won't stall....

Look at your idle MAF reading, and look at an OBD-II scanner, look at your fuel trims..

1) Set your base idle to around 1000rpm and try to get it so it rarely drops below that
2) Watch your short term and long term trims, try to keep them as close to 0 as possible, -11 seems to work best on my car, at idle -11 equals about 36-38hz..

Basically depending on your setup, your MAF reading at idle may read anywhere from 17-44hz, anything outside of 30-36hz will result in your trims being way out of range, and can cause the car to hunt and stall.

You'll still have a lopey idle, but it will be very smooth and stable..

Ok.. how do you do this?

Well, on my car, its easy, my blowthrough MAF sensor "bottoms" at an adjustable level, I have it set at 36hz which provided the best idle, on a stock MAF sensor, you can try to find a device that clamps the low value so it never goes below a set point, or play with the 0% column so at 1000rpm the idle hz is about 36, at 1500 its about 44hz (with the throttle closed) and below 1000rpm (250,750, etc..) you alter the maf frequency DRASTICALLY so it is bumped to around 30-33hz if it drops that low, what that should do is in most circumstances, your trims will end up in a decent range, but if the engine speed drops, instead of leaning out, it will richen up, and smooth the idle out a bit and the idle speed will raise again..

Hope this helps, I don't have this issue because I have stock cams, but I did have a MAJOR idle issue with the blowthrough sensor, and discovered this trick to keep the trims in check.. If you can eliminate it from going out of range, the trims won't reset, and the engine should no longer stall.

 

Oops.. Let me translate what I just wrote..

In most cars, the idle airflow is low, so you end up adding 30% fuel from 0-750rpm, and 15-20% at 1000rpm approx.. watch your UTEC logging and try to target the MOD MAF frequency so it remains at around 36hz whenever the engine is running at 750-1100rpm the car should no longer hunt and run very smoothly once the trims stabilize, it will "Find" 14.7:1 all the time..

If you have oversized injectors, rely on your fuel trims using an OBD-II scanner, and adjust it until it is less than +/- 11% (the closer to 0 the better)

Reset your ECU, start the car, it should start up and run smoothly afterwards..

In order to tell if you got everything working ok, turn on your A/C to max, if you have it set right, the compressor should load the engine, and the AFR's will likely go very lean until it learns, but the RPM's shouldn't change much..

 

In the end, if you have cams and injectors, the trick is to keep your idle mixture from hunting, which means keeping your fuel trims in range, thats all there is to it.. if your idle drops, you want the UTEC to bump the MAF reading up a bit...

IT turns out that the blowthrough sensor took me months to get the MAF curve replicated EXACTLY as the stock MAF would respond, but the Pro-Flow setup, has a minimum airflow reading (when airflow drops below that point, it reads a particular value no matter what) this actually is a great thing if you have a cammed car, since your not relying on unstable airflow due to a heavy compressor wheel or cams with alot of overlap to measure your idle airspeed.. and it still functions correctly in closed loop since the afr's are still correct at idle.

 

Oh, and that CEL code 246?? (Overboost) happens to me every time I run my car WOT.. basically the turbo is spooling faster than the MAF expects it to.. its actually normal and isn't much you can do about it besides using the UTEC boost control and keeping it low until your at higher RPM and load site above 10%

 

I have the 264-272 combo and have perfect idle. In my timing map I have ecu for the 0 column, seems to work out very nice.

 

god mine is terrible i dont know what to do the utec is confusing hehe