LS-1 MAF translator vs ARC-2/ VPC

[set3422]

does fuel cut switch work for anyone? Turn #3 switch to On and still get fuel cut. Running about 24 psi with 630cc injectors. Highest PW captured was 24ms before bucking. Airflow signal stayed solid at 1606hz. So the only thing I can think of is the injector being overran. Any suggestions? Thanks.

 

[Motohead1]

umm yea 24 MS inj PW . I am perty sure 21ms is max. Id say your overrunning the injectors. I had the same issuew a few pages back but it was cause i was tunned super rich. The bucking is your injectors screaming for help.

 

[set3422]

Originally posted by Motohead1
umm yea 24 MS inj PW . I am perty sure 21ms is max. Id say your overrunning the injectors. I had the same issuew a few pages back but it was cause i was tunned super rich. The bucking is your injectors screaming for help.

Thanks for your input. Most definitely I'm running lean because trims (hi to lo) are at 124%, 100%, and 131%. I'm going to drop some 780cc this weekend and see if helps. Thanks again.

 

[NOSLO2PT0]

I guarantee you aren't overrunning your injectors. 1606hz is the MAX the ECU will ever see. Hell, you can flow that at 16psi on the stock turbo. Use the AFC peak/hold feature to see what your max airflow values are.

As for the injector issue, I'm running 660's w/Supra TT pump. I've got a base FP of 45psi. My AFC settings are -19 across the board, on PUMP GAS and 22psi w/an FP Green. i suggest you go retune the car before you drop even bigger injectors in there and have more issues.

Solve your current problems before you create new ones.

Mike

 

[set3422]

i thought 1606hz is the max the datalogger will see. The ecu is tabulated to handle more than 1606hz. If the airflow is causing fuel cut, I should see a drop in airflow signal during WOT. But then again I've ran my stock injectors to 33ms and wouldn't get any fuel cut. Thanks.

 

[Kevin Jewer]

Dont use the fuel cut switch unless you have an auxiliary fuel system. If you are using it without one, you obviously dont understand how and why it works, which is another reason not to use it. It will cuase you to run lean if you are running over the point that it clamps the signal. Ramchargers has already stated this, and its been discussed extensively in this thread.

 

[set3422]

I thought that was for the earlier version of MAFT (1.1???). Earlier versions would need TMO stage 2 and up eprom ecu for disactivating this switch and would leave it at north up (on) if you don't have the eprom ecu. I have a 1.3v. So this version should be the same as the rest of the versions? Better go turn it off now. Thanks.

 

[set3422]

one important piece of puzzle that I forgot to include in my fuel cut problem. All gaskets are checked for leaks by pressure testing at 30psi. My first set-up had the bov vented and never had fc issues. However once the bov was plumbed back to the compressor intake pipe (quicker spool), I noticed severe fc. i'm suspectiing by plumbing back the bov to compressor intake pipe would cause SOME of the airflow to be measured TWICE. How can this happen?? This can happen especially if you place the MAF close to the bov (say 4" away from the bov). I know the bov is place before the maf but I'm not going to get into the theory of intake and exhaust pressure wave (there's a thread on this somewhere). The injectors are being overran because it's compensating too much for the same amount of air that gets counted TWICE.


I'm going to disconnect the bov tube today and see if I would still get any fc. Or better yet relocate the bov further away from the maf. Thanks.

Originally posted by set3422
I thought that was for the earlier version of MAFT (1.1???). Earlier versions would need TMO stage 2 and up eprom ecu for disactivating this switch and would leave it at north up (on) if you don't have the eprom ecu. I have a 1.3v. So this version should be the same as the rest of the versions? Better go turn it off now. Thanks.

 

[natedogg]

As long as the MAF is upstream of the BOV, the air shouldn't be getting counted twice. Air that gets dumped through the BOV is of no consequence as far as the ECU is concerned. The fact that it gets picked up by the turbo again doesn't matter. Its all unmetered air from your IC and IC piping. The turbo is sucking the air from wherever it can and then blows it into the MAF. The MAF doesn't care where the air came from, it just counts it and dynamically calculates how much fuel you need at that particular instant.

Now if the MAF is downstream of the BOV different problems may arise because it will count all the air that gets dumped through the BOV when the BOV opens and richen the fuel mixture accordingly even though the throttle plate is shut.

 

[Kevin Jewer]

Even with the BOV venting before the MAF you can still run rich. When the throttle plate is closed and the BOV open, flow reverses. The hot wire MAF doesnt care about direction, it will measure that air in both direction. So people I know with the MAFT in blow through donfiguration are still having stumbling issues with vented BOVs. But its the best option we have so far, and I am installing my SARD bov with this in mind, hoping to minimize the problems when I later install the maf.

 

[natedogg]

The flow doesn't really reverse too much. Think about it for a second. When the throttle plate is closed and the compressor is still spinning, you have pressurized air between the compressor outlet and the throttle plate, basically inside the IC and the IC piping. The moment the plate closes the bov line registers vacuum from the manifold and opens the BOV. If the MAF is between the BOV and the throttle body then there is only a few inches of pressurized air back-flowing vs. the feet of de-pressurizing air flowing from the compressor outlet through the IC and piping all the way to the BOV but not through the MAF because it is on the throttle body side of the BOV.

 

[set3422]

Originally posted by natedogg
The flow doesn't really reverse too much. Think about it for a second. When the throttle plate is closed and the compressor is still spinning, you have pressurized air between the compressor outlet and the throttle plate, basically inside the IC and the IC piping. The moment the plate closes the bov line registers vacuum from the manifold and opens the BOV. If the MAF is between the BOV and the throttle body then there is only a few inches of pressurized air back-flowing vs. the feet of de-pressurizing air flowing from the compressor outlet through the IC and piping all the way to the BOV but not through the MAF because it is on the throttle body side of the BOV.

yup I'm referring to the air that's in between tb plate and maf that get counted twice. Thanks.

 

[eclipse2via]

Originally posted by set3422




Thanks for your input. Most definitely I'm running lean because trims (hi to lo) are at 124%, 100%, and 131%. I'm going to drop some 780cc this weekend and see if helps. Thanks again.

Trims are for closed loop operation only. Your WOT can be totally different, that's what the High knob is for. Here is a DC link.
http://www.ecanfix.com/~mdhamilton/dutycyclechart.html

The DC formula is: DC= IPW * MS / 1200

I would bet you're rich, not lean or need to have more fuel than 660's can give. I would adjust your base setting down one regardless. Then you can lean with SAFC or WOT knob.
Luck, Scott

 

[natedogg]

Originally posted by set3422



yup I'm referring to the air that's in between tb plate and maf that get counted twice. Thanks.

That small amount of air really shouldn't make any difference in how your car runs. I think you just need to spend some more time tuning it. Like Scott said try leaning her out some.

 

[Kevin Jewer]

Originally posted by natedogg
The flow doesn't really reverse too much. Think about it for a second.

Think about this for a second. I said above that people I know with the MAFt in blow through mode are having problems with it running too rich when the BOV opens. We can sit behind keyboards and theorize all day, but this is what is happening on actual cars. You are right in your assesment of what air it is flowing back, and this is why I am mounting the MAF close to the TB, to reduce the volum of air that will rush back towards the low prssure area that is the open BOV. Hopefully that will minimize the effect, but one of the cars having this problem mounted the maf right on the TB elbow. Its not nearly as bad as venting the BOV in stock type setup, but its worth mentioning.

 

[eclipse2via]

Set when is this occuring? Does it happen when you are still WOT or lifting? It sounded earlier in your posts like it was happening WOT.
Scott

 

[natedogg]

Originally posted by 95GSXracer


Think about this for a second. I said above that people I know with the MAFt in blow through mode are having problems with it running too rich when the BOV opens. We can sit behind keyboards and theorize all day, but this is what is happening on actual cars. You are right in your assesment of what air it is flowing back, and this is why I am mounting the MAF close to the TB, to reduce the volum of air that will rush back towards the low prssure area that is the open BOV. Hopefully that will minimize the effect, but one of the cars having this problem mounted the maf right on the TB elbow. Its not nearly as bad as venting the BOV in stock type setup, but its worth mentioning.

I hear ya. But, there are also DSM's running around in blow-through form that are running just fine. My buddy Kris for example - www.144mph.com . Its my belief that it just takes some tuning time. So as you see its not all theory...I helped tune his car as well as my own so I do have experience in both the blow-through and draw-through forms. Not saying I know it all, but I know enough to get me and 3 of my buddies running strong on different setups, different MAF's, and different turbos. Sometimes it takes a few hours of tuning to get things just right, but when the results come...ooohhh...its sweet. Just hope the results come before the cops come.

I am running in draw-through myself, but thats mainly because I'm using a 3.5" MAF and don't want to have a huge transition from 2.5" piping to a 3.5" MAF in blow-through setup. I'm lovin it. Can't wait for the drive home from work

 

[set3422]

Originally posted by eclipse2via
Set when is this occuring? Does it happen when you are still WOT or lifting? It sounded earlier in your posts like it was happening WOT.
Scott

WOT i would get fc. Alright I'm going to disconnect the bov tube and lean it out some more today. Thanks.

 

[Animosity4G63]

If anyone is looking for 2.5-3.5" couplers I found a supplier that will sell them directly to me. $20 ea. plus shipping email [email protected] I will try to post pictures soon.


Dj


BTW the only reason I post this is to help the DSM community im not selling these to make any proffit, I called every supplier for turbo's and turbo hoses in the US that I could think of and finally found them at a wherehouse.

 

[DeezNutsForYou]

I plan on using the stock 14b, and I was woundering how much benifit this would have for me. I tried to read through all 36 pages, but I got to page 6 or 7 and started seeing double. I plan on buying dejon tool's upper ic pipe that is ment for the gm maf. If I get this will the 3" impala ss maf fit. Or will I have to get extra silicone connectors. Also I have abs and cruise control will either of these be a problem. I heard you have to relocate your cruise, but about the abs. Dejon tool's sells a 2 1/4" pipe for abs cars, and a 2 1/2" pipe for non abs. And the pipe meant for the gm maf is a 2 1/2.

Thanks for any feedback. I definetely want to get this, as I was just about the buy a standard 2 1/4" hard pipe, and I figured this way I wouldn't have to buy another pipe later.

 

[DeezNutsForYou]

I'm pretty sure this is your car Animosity4G63. I think your the guy that I met at the OR/WA cruise/meet III. If I'm correct I was the guy sitting on your left. If not don't worry about it. But I'm pretty sure this is your engine bay. (And nice car buy the way, and it sounds as good as it looks.)

 

[Bohrn]

I don't remember a translator car at that meet. I'd have been all over it, being as curious as I am.

 

[DeezNutsForYou]

He has the blue 1g wih his hood up.

 

[Bohrn]

hmmm, musta been at a place I didn't go to.

I met in Portland Meadows(horsey track) and we went for a cruise around the area, up in the hills, Multnomah falls, hiway(95plus mph, yoiks) and to McMinnimans.

What'd I miss?

sorry to hijack an already huge thread

 

[Kevin Jewer]

Originally posted by natedogg


I hear ya. But, there are also DSM's running around in blow-through form that are running just fine. My buddy Kris for example - www.144mph.com . Its my belief that it just takes some tuning time. So as you see its not all theory...I helped tune his car as well as my own so I do have experience in both the blow-through and draw-through forms. Not saying I know it all, but I know enough to get me and 3 of my buddies running strong on different setups, different MAF's, and different turbos. Sometimes it takes a few hours of tuning to get things just right, but when the results come...ooohhh...its sweet. Just hope the results come before the cops come.

Well thats certainly good news. I'm just goig to set it up as well as I Can with all the "theory" in mind, and then hope I can tune it out later. I'm not terribly concerned, as I have been running vented to atmosphere for years with the 1g BOV (heavily moddifed to allow it), RFL (no brainer, but it leaks like a champ), and today a SARD. So I figure it can only get better There is no going back with the SARD anyway.