Erratic AFR / Mapdot, Noise issue?
 

Morning all

Ive recently noticed that my wideband hasnt been acting its usual self. Normally when crusing and in the "tuned" areas of my map is tends to sit +- .2. Ive not driven the car for a while and i recently replaced the alternator belt ( was slipping and screeching ). now it seems that in my logs my MAPdot and AFR are much more irratic. Im still using MAPdot for AE so i first noticed when it was cyling from 15.0 to 13.xx in a cruise situation.

Does that attatched log look like electrical noise to someone that would know?. Ive checked that the batter connections are clean and tight, the ground on the exhaust side of the head and the one on the intake side aswell. Is there one im missing that might have came loose / ive broken while doing the alternator belt?. I have a miss at idle, could a possible miss at higher loads cause a simular thing, not that ive noticed one.

Im guessing electrical noise as while sitting in the same VE cells my AFR in some logs is changing by up to 2 points.

Thanks
Scott

PS Ive still really only autotuned the areas i hit while going to work so most of my VE is untouched

What is the tps doing? I had mine jump around a lot because the tps was jumping around a lot. The short term fix was some wd40 in the connection at the tps. If you do not have variable tps you can discregard this post.

90-93 and a ms1?

Sorry my details were poor, its a 90 with a Rev MS2. Ive just got an inline fuel filter to stick on the map line. I dont think this will "fix" my problem but it should help it a little. It seems that the noise is worse at specific RPM (2400-3100).

Is it possible that my MAP line is vibrating at this rpm causing the MAP to be noisy and in turn screwing my afr?. that it the train of thought im on currently anyway so ill be making sure that my MAP line is secured and not pinched and add the filter and see how i go. Some times my map / fueling acts like normal so im hoping its just some vibration and not an electrical noise issue.

Thanks for any input

PS, no VTPS atm im hoping to buy the one thats up for sale ATM, being in Tasmania getting anything locally / finding correct part numbers and buying online is a PITA.

Put in the Filter and it seemed to have stopped the baddest of the map issue from the quick test i did, ill have to do some more to be sure. I still think something else is going on, does anyone know if i could have knocked a ground loose when working on the alternator?

You map does not seem erratic to me at all. Having said that, you def need the TPS. MAPdot is is just a bandaid if you don't have a TPS, it is not a proper solution.

The 3.3.0b alpha release and onwards now have a new MAP sampling method that averages an over sampled set of values. Result is much smoother and less erratic map.

I've added this method to the TPS sampling and got a similar good result too (for TPS) and both and much more are available in FW MOD 2.4.4

G

Grant, good stuff.

Is your sampling synchronous with crank position?
Due to IM pressure pulsing from the intake valves, in theory it's best to sample say, every 45* of crank angle and do a 4 point running average (which works out to 180* running average).

Having said that the 2-pole RC filter I put into my AEM with a total lag time of 40 ms is working very well at getting rid of the IM pulsations.

Im currently still just using the firmware Rev sent to me :) im no totally sure what one it is. Rev is it a custom firmware of yours? would you recomend trying a different one?. I think i might leave it as is for now and grab a VTPS as id rather not mess with the MS2 too much

Been playing a bit, ive installed a vtps and decided to give updating my firmware a bash from ms2extra 310serial ( i beleive that this is 3.1.0 ) to 3.3.x when its released / stable version. im having simular problems with TPS dot while at steady state sometimes spiking to 60 while other days i can have my threshold set at 40 and not have any trouble while traveling the samew roads. Im hoping that the newer TPS sampling will help smooth this out. Is a Threshold of 60%/s high or low to most people?

The latest mod 2.6 contains TPS over sampling and averaging plus tpsDOT moving anchor support. These together allow you to run a clean 10 TPS threshold without any false triggers. Simply awesome!

G

that sounds awesome. ill have to read about how to do my firmware. i dont think i need to mess with a boot jumper becuase im already on the msextra firmware but unsure about unplugging coils, infact i woudlnt know what to unplug if i do need to lol. Should there be any issues changed from 3.2.1 to 2.6?.
Cheers

Try this firmware first... And follow the docs.

http://www.msextra.com/forums/viewto...p?f=91&t=44289

OK a quick over view :).

I downloaded the firmware and the release and copied the gslender verions files over top of the others. Saved my tune to pc so i could compare before and after incase of any table corruption, unplugged ingniter altho i have the invert start mod done so shouldnt have needed to. Flashed firmware without issue. Loaded up TS and updated the ini in existing project. pushed my tunerstudio config to the ms.Caliberated tps/afr/clt/mat, taken my lappy inside and confirmed all the settings are identical to my old one ( apart from the new features ).Plugged igniter back in.

Have i missed anything obvious before i try firing it up?

Cheers
Scott

Nope. Sounds 'bout right.

G

Mate where is aus are u?. im in Tazzie and if im ever near you i need to buy u a few beers!.

Started up car and while everything isnt exactly how it was its either better or something that i thought "ah its probibly this nothing to worry about". my idle has always been ok for a while then would oscilate +-150rpm and rubbish. Literally spent 5min on it and turned on adaptive PID reduction and its best its ever been. I admit i need to read etc, but without understanding fully PID let alone the option i enabled ive got the best idle and the most stable Idle AFR ive ever had im stoked, i know it much get heaps better with understanding and proper tuning but honestly its at a place now i could never revisit it and not care.

TPS noise is gone with default setting of 2.5% and 65MS. this is something ill need to work on, it works great but seems that my tpsdot is happening a considerable time after the tps movement has happened. Im guessing this could be due to my lag factors being at 50 for tps, setting that to 100 i think should help.

I had an issue that is hard to exaplain. When taking off / changing gears the car would "bog" / "go a bit jerky" / "omg that guy doesnt know how to drive a manual" type feeling. Seems 90% gone from my short test drive.

Thanks for the hand holding also, its much appriciated!

Cheers
Scott

I'm in sunny QLD. So if you ever venture up this way, yell as I'm sure to be keen to grab a beer!!

As for your car, glad my MOD worked so well... that why I wrote it.. cause I was unhappy with the outcomes of the standard MS2 code.

G