dryad001

iTrader: (27)

After a few days of letting the ECU learn the new system the trims were on the lean side. My guess is the added air that was going into the motor.

I had to drop the Injector scaling quite a bit and figure out some new latency values. I have Precision 780's with them scaled to 612 and a 14v latency of .490

So far so good. I have had the car up to about 20psi for a short pull and everything is looking good so far. Write-up is coming along slowly but should be done in a few more days.

MalibuJack

iTrader: (5)

It takes time to get the curve to match the stock MAF, the setup I have currently is even more difficult to get just right, which is why I'm switching to the ECU+.

There was another development in my setup though, I was told that the MAFT Gen II supports the analog ford MAF I already use, so I want to give that a try before I switch to the GM sensor. My experience with the ford and gm sensors, is I generally like the Ford (hitachi style) sensors a little better due to their stable output, and less finicky about humidity and condensation on the sensor.

dryad001

iTrader: (27)

The only thing Im having trouble with right now is the start-up. I let the car warm up past the "L" and put it into gear and if there is any type of load on the engine it goes lean and wants to die, but if just at idle out of gear it runs fine. It takes about 500ft of this type of driving for it to clear up. After that it runs perfect.

I do have the start-up enrichment turned on, could this be the problem? Im trying to look at the wideband while this is happening but Im wondeing if the car goes pig rich and the Ecu is trying to dump a bunch of fuel...

Or I think it could be the light spring in the Tial BOV (7lb) With this spring the valve is open at idle and cruise. Could be the movement of the piston is too fast that the Ecu can't compensate quickly.

Any ideas?

MitsuJoe

iTrader: (133)

My ideas is the GM MAF is very poor at cold startup or hard weather changes. It is a solution but using a Ford MAF is much better as Jack already pointed out.

MalibuJack

iTrader: (5)

You probably have to log the MAF frequency, TPS, and AFR to be sure..

I actually found that my car would idle poorly if the DV was partially open, this was due to very low airflow through the sensor, and it would be inconsistent since the vacuum at idle would vary (Engine load, EGR valve opening, etc..)

Start by turning off the Enrichment and see if it gets better.. Then re-enable it, and start with small steps to tip-in..

When my car is cold, it sometimes would "tip in lean" when I would start from a standstill, after it was warm, it would go away. You could raise the minimum temp for closed loop to force the car to go into open loop all the time, and adjust the fuel maps until it doesn't tip in lean any more, that should help alot, then lower the temp for closed loop back to normal.

Also there are baro and temp compensation tables that may come into play so look at those. I never had to touch mine, but my current setup does have an AIT sensor.

MalibuJack

iTrader: (5)

I found the Ford sensor did most of this stuff "better" but all hot wire sensors have a bit of trouble when you first start the car as the ambient temps in the pipes are "lower than normal" and takes a bit before it comes up to operating temp. Karmann sensors dont suffer from this..

Its more obvious when there is no AIT sensor to compensate, so the sensor reads somewhat incorrectly until the air temps in the pipes rise.

The way I used to work around issues like that was to make sure the idle frequency was always 37hz no matter how cold it was.. You can do that in the proflow setup, and I'm pretty sure you can do that with the MAFT also. ECU+ has this feature built in as a configurable option, as does the MAFT GEN II.

Smogrunner

iTrader: (5)

Subscribed. If anyone else is about to do this setup, I have one for sale. It is a brand new, in the box, MAF Translater and a 3.5 inch GM MAF sitting in my garage. I was going to use it on my car but decided not to. Original instruction manual included. Let me know.

BiFfMaN

iTrader: (3)

i got a question.....

what if you opted to go with the upgraded GM MAF sensor instead of the stock unit.

i have heard of some improvments in the upgraded MAF design, like the sensor has been injection-molded out of a polymer that rejects heat better than the OE metal sensor. There are a few testimonials out there claiming that they got improved performance from this better flowing design. The first downside i see from this is cost of the upgraded unit.



Not trying to hyjack....but was thinking of trying the same thing later down the road.

MitsuJoe

iTrader: (133)

The MAFTPro was not designed to use the aftermarket MAFs designed for higher flow. Stick with a stock GM MAF for results.

BiFfMaN

iTrader: (3)

ahhh ok....i figured since they were plug and play units the feedback voltage and reading would match..thanks.

MalibuJack

iTrader: (5)

You would likely spend quite a bit of time getting the curve dialed in so it outputs correctly to the ECU.. Its not impossible to do (I've done it) but it takes some time since it flows differently.

dryad001

iTrader: (27)

Exactly what I have noticed. Although the idle and cruise Hz reading are mirrored from stock MAF to the GM unit the entire injector scaling has to be re-done.

I've switched the min coolant temp for closed loop to 100 from 7 and see if that will help a bit more, hopefully the engine will be at normal operating temp...

Im trying to figure out what the MAF scaling actually does and what the value is. My guess is g/sec

BiFfMaN

iTrader: (3)

cool cool,

Only reason i asked was a few conserns of mine if i made the swap. the biggest one would be the accuracy of the sensor its self. Location is a big key IMO so not to be effected by outside variables, like radiant heat from the engine (effecting the heated element), vibration ( could be a factor ) or lastly contamination.....in the event i keep the stock/catch can PVC system...ie blow-by. The aftermarket version offered better accuracy and protection (insulated) as the stock unit has just the screen. just trying to be carefull.... sorry i follow the 6 "P's"....proper preparation prevents **** poor performance.

but yah keep this going, i been reading a few of your write-ups on this MJ...lets keep this up.

03whitegsr

iTrader: (8)

Does the EVO MAFT show unstable airflow measurements at higher airflows when used in blow-thru mode?

The DSM version has issues with a very rough signal output when used in blow-thru mode above about 40 pounds/min of airflow. This would be on the upper end of the stock turbo and may not be noticed without a cam upgrade, but should be easily reached on an upgraded turbo and cam motor.

Guys that run into this problem have noted that the A/F ratio also varies with the MAF signal variance.

dryad001

iTrader: (27)

Cold start issue resolved. Now we moved onto a rich tip-in. I have an idea how to get rid of that. Either raise my injector scaling, or start to mess with the accel enrichment tables.



I just want to say how mouch of a learning experiance this is. I finally get to see first hand on how the slightest change to any parameter reflects performance to the car. WOT should be a brezze to tune once I get to that point. But first I want a driveable car instead of just a power monger with crappy in between driving. I do a lot more partial throttle acceleration than I do at WOT.