After reading and searching I believe that I need to adjust my MAF tables to allign my BLM's. I tuned with the constant to get most areas in line, but certian cells are still rich while others are lean. I am not sure how to find the address of the cell in correlation to the MAF tables in Tunercat. I am using datamaster to datalog. I am not very confident in my ideas though.I have posted a CSV file of a quick run. Can anyone could look at it and maybe tell me if I am heading in the right direction. I don't want to do the wrong thing. If anything else jumps out with a red flag please comment as I am new to most of this and learning by experience but trying to keep notes as I go.The columns also look a lot more organized in microsoft excel.
Thanks, Jay

http://www.moates.net/files/6)%20Mis...%20datalog.csv

 

Would that explain the fluctuation in my short term counts??? They seem to be all over the place

 

I looked at your file a while ago then got busy and didn't respond. . .

Anyway, have you done anything to the engine or MAF? Maybe intake system?

Because as you said the INT is all over the place. In some areas it drags the BLM to the lower limit, while in other areas the BLM is high.

The short term (INT) moving around is normal, but not to the extent shown in the data log.

RBob.

 

Hi RBob, thanks for the response. As far as the MAF it had the screens removed before I bought the car. The engine is a 355 with a 10.5:1 compression ratio, ported plenum, SLP runners with the divider wall removed another inch and fully ported to 1.63" and the base was also ported to match the runners and ported heads. There is a lot of work on the 083 heads/valvetrain. I also have a ZZ4 cam with 1.6's on the intake and 1.5's on the exhaust, LS1 injectors, headers and exhaust. The Walbro 255LPH high pressure fuel pump is new as well.

I have been able to get rid of all my knock, the only time I get any retard is when the car shifts and the tires will break loose. The small cam I hope I have tuned not too badly as it idles like glass at 750 when warm. I am still trying to find out why I have a terrible idle/stall on initial start up when cold tho..I notice I can only pull about 180 gms/sec on my MAF. As suggested I checked the ground to the MAF and the correct supply voltage as well.

I am happy with my settings for the injector constant and the offsets. I have changed the timing tables but I think for the good. They just need to be ramped a little neater. Its just the constant BLM fluctuation from rich to lean in certian cells.

Am I on the right path by wanting to adjust the MAF tables or should I be looking at a new MAF first???

 

I looked at my slightly rich idle for starters and was wondering if you scale the entire MAF1 table or just certian parts of the table??? I have been searching as to how to isolate a certian cell in datamatser and then calculate which maf value in tunercat it refers to.Do I need to use hexidecimal calculations to do this??? I understand the part about the last value of a lower table must be carried through to the following upper table.

It seems I come across posts like the one above and then it makes me realize I am not sure of what I am doing, but more importantly WHY I am doing it. I am sure some of you read this and roll your eyes but if anyone has a little time and some knowledge they would like to share I am all ears.

 

razor, just due to the fact that the MAF screens are gone you will need to re-calibrate the MAF scalar tables. This is required as these tables no longer match what the MAF is flowing and reporting.

Another problem is the twisted air cleaner/ductwork used on the Firebirds. Without the MAF screeens the air flow through the MAF will be turbulent.

As for "I notice I can only pull about 180 gms/sec on my MAF" check the maximum MAF vs RPM limit table. If it is up against the limit you probably need to raise them.

OTOH the MAF just may be bad. Only 180 gms/sec is low.

Back to the MAF scalar tables and what they are. The six MAF scalar tables are used to convert the analog voltage output of the MAF to an airfow in gms/sec. IOW they are the calibration tables for the MAF. If the MAF has been changed (such as de-screening or gutting) then the MAF scalar tables are no longer in calibration and need to be changed.

RBob.

 

Well the first problem I should try to address is the grams per second issue. If I CAN get the MAF to actually read something over the 180g/sec then I will throw some more coal on th fire and address my MAF tables. If I can't then I will beg/borrow/buy another one with some screens and start from there.

Jay

 

Well I borrowed a friends MAF to try out. The only unfortunate thing was he had the screens removed as well. The car only pulled 192gm/sec. Where do I start to look??? Is it something in my APYU bin??? Is it with the 6e definition file??? Would it be my ECM???Could a lower TPS reading affect anything???
I am scratching my head now. Just because the screens are removed that should not affect the data that bad would it??? I noticed the BLM's were not up and down from 128 as much. For the most part they were a little lean in certian cells which would make sense because my 1st maf table was modified trying to adjust to my MAF's values.

I attached another CSV file of the datalog.

http://www.moates.net/files/6)%20Mis...ay27difmaf.csv

 

I am not sure of what to tell you. The cal you mention APYU, does not appear to be what is running for this data log. The data log shows too much timing for it to be APYU. Also notice that each time the throttle is wacked open the O2 dips down, the timing increases and the knock counts start upward.

The second instance of WOT is terrible in this regard (around record 840+). Up to 15+ degrees of retard with a very slow decay.

It looks like at idle (no MPH column, so hard to tell if really at idle) the BLM (long term) fueling is high (149). that may mean there is a small vacuum leak after the MAF sensor. Any unmetered air will do this.

RBob.

edit: almost forgot, I only see 5 frames per second of data. Should be able to get up to 11 frames of data per second. IIRC this is a setup parameter for Datamaster. Worth it to go as high as possible.

 

I was using my last bin with his MAF. On my car with my MAF and that bin I was only getting 2-4 degrees with my MAF.

The bin was APYU but the car was a dog with the spark tables and AC Delco R43TS plugs. On R45TS plugs it liked less timing. With the 43's I needed the extra timing earlier to give it some life at part throttle. As for WOT I just took a few degrees out of my upper tables. This did nothing for knock. So I editied another bin trying to quelch knock with more fuel. It seemed to knock more. Thats what the datalog states anyhow. I thought more fuel will stop knock???

I increased my sample rate and adjusted the Maf tables to get cell 1 and cell 2 in line. THAT seemed to actually work to a point. It still needs more tweaking but it yielded results. That could be the first thing that has How do you post MPH in a datamaster CSV??? They have a MPH ratio but that comes up as 255 in every colunm?? Jay

Less Timing
http://www.moates.net/files/6) Misce...ppertiming.zip

Less Timing and increased PE/MAF tables
http://www.moates.net/files/6) Misce...ppertiming.zip

 

My MAF reads low still. I don't think it got over 175gm/sec on the last two datalogs. That still bothers me. I will try to find someone with a known good MAF with screens and try from there.

And RBob you mentioned maybe a slight leak past the MAF??? I inspected everything by removing and re-installing the entire air ducting and throttle body. It all looks good. The only thing I can see as a source is my shark nozzle for my nitrous. I can test that tomorrow.