I recently installed a Cobb AP and I use the stage 1 93 octane v401 map. so far it feels great the car pulls better than stock and feels a good bit faster. my only question is I seem to bit hitting fairly consistently 26 PSI of boost and even spiking up to 27 occasionally at WOT. other than that AFR seems good (as far as I know) at about 11.5-11.8 at WOT and I have yet to see any knock. The car is stock other than a drop in perrin filter. The 27 PSI boost seems a little high to me though. Should I be worried about that? or maybe try a different map? I love the way the car feels now compared to stock but I'm just a little concerned I'm going to ....blow something the F*** up.

 

I think the stage 1 map is suppose to be used on a stock car however many of us have added a few mods without issue. But technically if it is not stock, you may run into discrepancies.

Are you using a wideband or the cobb ap to measure boost? I am not sure how accurate the ap boost gauge is. My cobb ap would show around 9 when at idle. At the same time my wideband would show 20.

Send your 3rd gear pull to Marshall at marshall.glasgow@cobbtuning.com. get him to look over your numbers for you. Occassional knock is ok as alot of the time it is just phantom knock. I can't tell you about the AFR as I don't know what it should be according to the cobb ap. My AFR would always read between 10-12. And as for boost you definitely need to watch for over boosting. I don't believe I was having an issue with it, but you should keep an eye on it.

 

Ken - Widebands don't measure boost, they measure AFR. The AP boost gauge is very accurate, it reads directly off the 3-bar MAP sensor.

Drilling - Your boost level sounds fine as long as the engine isn't knocking. Keeping using that good BP 93-octane available up there and you'll be fine!

 

thats what I have been using for fuel, BPs 93 octane, I remember being super happy when I found out they had 93, everyone else around here is 91 or 92. Yeah so far no knocking at all when I look at a couple logs I've done. sooo... fingers crossed..

 

My bad. That's what I meant though. Fixed

It still shows a way different reading though. Around 8-9 vacuum on the AP while at idle and about 20 on the AEM boost guage. I am not to sure if the AP vacuum (boost) reading max's out at -8 to9 or something. Or if the calculations are different (perhaps the AP value's are displayed in half).

So those with an AP and aftermarket boost gauge, both you values are pretty close?

 

I never found any gas worth a damn in MN besides for BP's. No reason to cross your fingers unless you start using some other fuel. If you do have to use something below BP93, just make sure you flash on the Stage 1 91 map.

 

You're comparing two different values. Below zero, boost gauges read in/Hg whereas the MAP sensor is still reading psi.

 

Gotcha! But above 0 is accurate when comparing the two?

 

Correct, at/above zero they're both reading in psig. Note: there may be slight differences due to atmospheric calibration values, this is to be expected and not something to be concerned about. To see this variance, turn your key ignition on but do not start the vehicle, ideally both should be reading a perfect 0.0 but that is very unlikely.

 

Well, I did some more checking on my way home from work this morning looking more closely at the knock sum. I did a few 1st, 2nd, and 3rd gear pulls at WOT. sorry, I'm new to all this the larger number in the middle will read 1 or 2 under full boost and then the smaller numbers in the bottom constantly said 0/4. Is this ok, should I tune down to 91? and what exactly do these numbers mean? been trying to find info but can't dig any up.

 

0/4 is your min/max knock values. The 1 or 2 would be your real-time values. Sounds to me like you're running fine; 1-2 is nothing to be concerned about, especially on such a basis setup.