Problems with FAST

[Whut]

Can anyone offer any advice or check my tune out?

Last year I thought I had it moving forward until I blew a water pump at the end of the season and just let it sit for the winter. I put a new water pump in and took it out last night to the track.

Last year I was battling a rich problem, I was slowly (didnt want to blow it up) leaning it out but for some reason it seems to have taken five steps backwards. At hot idle my o2 is correcting the max pull out it can and my actual o2 is still sitting in the 9's, possibly richer. I sat and watched as the tail pipes spewed raw gas as the idle surged a bit. I made a few passes before I could no longer blame carbon build up as the culprit.

The first pass I ran a 12.16 and watched my knock gauge light up like a Christmas tree. I wasnt at WOT and let off after half track. The second pass was a 12.73 with less knock. I had made some changes I couldnt remember to the tune so I went back to an older tune I had that I was running mid 11's on, albeit rich, it was still faster. With that tune in I ran a 12.38 with no knock and the car launched so hard my rearview mirror shot off the window. At the end of that run the car felt like it was running flat at the big end. This was a problem I felt last season on the last couple of passes I did before I noticed my water pump was shooting coolant out. Now it seems the car is chugging so much gas its just flat lining at the big end, it also backfired so I buttoned it up and went home.

The car runs, it just runs like garbage. I lost my job so the car is in a friends garage for now. I am still new to tuning with fast so if anyone has any input for me I would greatly appreciate it. I am going to try and get over there this evening to mess with it a little more.

If anyone would like to see my tune and some logs just let me know and I can either attach them or email them.

The main problem is how rich its running. It also has a slight tipin stumble and starts like garbage. When it does start it seems to get a big rich spike. Its almost like the car thinks gas is heroine and just keeps wanting more no matter what I do to change it.

Please help!

Oh, this is FAST classic, not XFi.

 

[Turbo Loyd]

Please upload your gct file, with some information about your car. You may have to zip the file to upload. This will make it easier to see what is going on.

If you have logged any run that will be a big bonus.

 

[Whut]

Thanks for the reply. I have put my tune along with one pass from last night here, Index of /FAST There is also a log with pretty much the same tune from last year when I was able to run an 11.51.

My car is an 87 Grand National. Stock 109 block bored .20 over with JE pistons, Carillo rods, BMS stroker crank, Billet caps, FMIC, TA-51 turbo, 72 lb injectors. If you want more info just ask.

FWIW I unplugged each injector one at a time and noticed only enough difference in the AF to show that one hole was dead. I also pulled out the o2 sensor and cleaned it off with some MAF cleaner spray. It was full of carbon but the spray got it clean. Plugging it in and letting the car go into closed loop showed no change. Also, I unchecked FAST from going into closed loop, no change with that either.

 

[Turbo Loyd]

Under "View" select from the dropdown "Cranking/Afterstart Fuel Tables, the select "Afterstart vs CTS" which brings up the Afterstart Enrichment vs Coolant Temperature table

It continues to go up the warmer the engine is. It should be at zero when the engine is warmed up

Will take a look at more of the tables when I get back home tomorrow evening

I'm not an expert, but this is an obvious problem. The real expert with these files are busy getting ready for the GS Nationals right now

 

[Whut]

Really? Are you looking at the file in Ccom XFi? If so, that would be the problem. My buddy runs XFi and looked at my files, I got a frantic text message wondering how I hadnt blown up yet. Once we compared a few tables we realized that looking at a gct file from FAST Classic in the XFi application will produce some odd results.

With that said, when I look at my After Start vs CTS it progressively goes down, never to zero but it does go down as the temps go up.

 

[Chuck Leeper]

"With that said, when I look at my After Start vs CTS it progressively goes down, never to zero but it does go down as the temps go up."
That may be why you are seeing no change from CL to OL. Unless aft start is at zero, no cl.
If I'm looking at the correct GCT file, you have tps idle at 12%..Should be 1 more than key on engine off, or the ecm thinks you are no longer at idle...If that 12 is good, then disregard.

 

[Whut]

Its at zero now starting at 140 degrees. I will go down even more if I have to (temps wise that is).

Thanks for the suggestions. Tomorrow is supposed to be really nice so I hope to get some ideas and see how the car reacts to them.

 

[HighPSI]

The Afterstart vs CTS does not have to go to zero at a certain temperature. Once the car fires, it will look up this table to determine how much afterstart fuel to initially use. This fuel enrichment will decay out at the rate specified in the AFTER START DECAY VS. CTS graph. If you are having trouble getting your ECU to go into closed loop because after start fuel is being applied for too long, reduce the after start decay vs. CTS settings.

 

[Chuck Leeper]

Decay is..

The Afterstart vs CTS does not have to go to zero at a certain temperature. Once the car fires, it will look up this table to determine how much afterstart fuel to initially use. This fuel enrichment will decay out at the rate specified in the AFTER START DECAY VS. CTS graph. If you are having trouble getting your ECU to go into closed loop because after start fuel is being applied for too long, reduce the after start decay vs. CTS settings.

still @4.3% @ 264*F... Don't think that will work, will it???

 

[HighPSI]

Shouldn't be an issue, as long as he waits for it to decay out.

 

[Turbo Loyd]

Really? Are you looking at the file in Ccom XFi? If so, that would be the problem. My buddy runs XFi and looked at my files, I got a frantic text message wondering how I hadnt blown up yet. Once we compared a few tables we realized that looking at a gct file from FAST Classic in the XFi application will produce some odd results.

With that said, when I look at my After Start vs CTS it progressively goes down, never to zero but it does go down as the temps go up.

Thanks for pointing that out. I did use the CCom for XFI. Will have to make a note to keep the file sets seperate and remember which program to use, when I start using the XFI system.

Also the information about "After Start Decay vs. CTS" does reduce the enrichment after so many crankshaft turns is good information to learn as well.

 

[Whut]

I played a little more with it today, modifying the After Start and Cranking Fuel and the car starts a lot better now. I just learned how to tell if the o2 is shot about an hour ago so I will have to check that next time I can access my car and its not raining.

I got the starting issue almost worked out and its no longer spewing plumes of raw gas from the tail pipes. Now I am thinking my o2 is screwed up as the car at idle is in the 11's for AF. When I get on it, it goes up to 15.94 (I think the leanest it can read?) and seems to sit around there. Even with ADDING fuel in the VE Table it still shows lean but the correction is PULLING OUT 25% of the fuel so basically they are working against each other.

Such a puzzle this car is. One minute its super fat the next its super lean. In any case, I feel I am getting closer to the actual problem and resolving some other issues on the way.

I love this forum.