MAF and Injector problems
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From: TEXAS
MAF and Injector problems Well I started dyno tuning this week with some help from some friends because I haven't done it before.
Little back ground. 383, 9:1, 50# injectors, 15psi ATI D1SC, MAF on blown side
I get to about 4600-4800 rpm and the MAF locks at 504grams/sec and right then the injectors stop at 21ms or so.
I wouldn't think that the injectors would be at 100% by that point, hell the car is only making 370hp at 4600rpm and 430ft-lbs of torque. (Still have a lot of tuning to do) So I wouldn't see how the MAF would be locked and the injectors too. I am getting belt slip and the blower is only putting out 9psi of boost at this point too, but on LT1 Edit everything just kinda stops and she starts leaning out really really badly, the a/f was going from about 11.8 to 12.5 to 13.2 to 13.8 and then I just shut it down.
What are you guys doing? I know the car has a lot more in it I just don't know how or what to do. We just starting manually putting in more fuel in the power enrichment mode at that point and it still wasn't helping.
We did take off the ATI inline pump and are just going with the 255LPH high pressure in tank unit because we think it was becoming a restriction so maybe that might help but I still don't know what to do about the MAF and Injector problem.
<small>[ August 26, 2002, 05:18 PM: Message edited by: 1LEThumper ]</small>
Little back ground. 383, 9:1, 50# injectors, 15psi ATI D1SC, MAF on blown side
I get to about 4600-4800 rpm and the MAF locks at 504grams/sec and right then the injectors stop at 21ms or so.
I wouldn't think that the injectors would be at 100% by that point, hell the car is only making 370hp at 4600rpm and 430ft-lbs of torque. (Still have a lot of tuning to do) So I wouldn't see how the MAF would be locked and the injectors too. I am getting belt slip and the blower is only putting out 9psi of boost at this point too, but on LT1 Edit everything just kinda stops and she starts leaning out really really badly, the a/f was going from about 11.8 to 12.5 to 13.2 to 13.8 and then I just shut it down.
What are you guys doing? I know the car has a lot more in it I just don't know how or what to do. We just starting manually putting in more fuel in the power enrichment mode at that point and it still wasn't helping.
We did take off the ATI inline pump and are just going with the 255LPH high pressure in tank unit because we think it was becoming a restriction so maybe that might help but I still don't know what to do about the MAF and Injector problem.
<small>[ August 26, 2002, 05:18 PM: Message edited by: 1LEThumper ]</small>
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From: College Station, Tx
Re: MAF and Injector problems Your MAF is maxxed out and so your computer doens't know you are getting in any additional air. At the RPM where your MAF maxes out you will need to add in the extra fuel required in your PE vs. RPM table. - your pe vs rpm table will look relatively flat/possibly sloped, until the point where you max it out - then it will take off at a steep angle.
To tune it properly you really need it on a dyno with a wideband.
Chris
To tune it properly you really need it on a dyno with a wideband.
Chris
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From: TEXAS
Re: MAF and Injector problems Yep she was on a dyno with a wide band.
We were adding in more fuel in the PE tables but the injectors still did not look like they were doing anyting.
I think some of the problem was with the ATI inline fuel pump and I haven't had it back on the dyno since then but it still starts leaning out really bad around that point. I guess I would have thought that the injectors would change more if you changed the Power Enrichment table.
A lot of this is still new to me so I'm not sure what all to do with it. Luckly I do have some help on here and here at Purdue.
So the MAF will always max its self out and from that point on you just do it in the PE tables? Some one had also brought up rescaling the MAF tables?
We were adding in more fuel in the PE tables but the injectors still did not look like they were doing anyting.
I think some of the problem was with the ATI inline fuel pump and I haven't had it back on the dyno since then but it still starts leaning out really bad around that point. I guess I would have thought that the injectors would change more if you changed the Power Enrichment table.
A lot of this is still new to me so I'm not sure what all to do with it. Luckly I do have some help on here and here at Purdue.
So the MAF will always max its self out and from that point on you just do it in the PE tables? Some one had also brought up rescaling the MAF tables?
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From: College Station, Tx
Re: MAF and Injector problems The highest MAF value the PCM can contain is 512g/sec - so it will max itself out no matter what - as for "rescaling it" you should make the transfer function reflect what the MAF is reading - and using a stock/non-ported MAF (which I hope you are) the stock table is pretty close. You might scale it by 104% to ensure negative l-trims, but rescaling it to increase range is futile as you still hit the 512g/sec wall.
You need a fuel pressure guage hooked up also to verify that you are maintaining fuel pressure - and you need a boost sensitive fuel pressure regulator - do you have one? (should raise fuel psi at a 1:1 rate with boost)
Chris Bennight
You need a fuel pressure guage hooked up also to verify that you are maintaining fuel pressure - and you need a boost sensitive fuel pressure regulator - do you have one? (should raise fuel psi at a 1:1 rate with boost)
Chris Bennight
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From: TEXAS
Re: MAF and Injector problems Yeah I have the stock MAF back in the car now. I do have a FP gage mounted in the car and we did notice the fuel pressure drop about 20psi around 5000rpm, This we believe was caused by the cheapo ATI inline pump being smaller than what is in the tank of the car (180 vs 255). The inline pump is now removed and if this doesn't work I'm just going to sump it and go with a big external.
I have a AeroMotive LT1 regulator that seems to be increasing at a 1:1 ratio right now. I am currently NOT using the ATI FMU that came with the kit.
The one thing I was wondering about rescaling the MAF tables is what will this do at low rpms? Will this throw the car into fits especially with as big of an injector that is in the car?
I have a AeroMotive LT1 regulator that seems to be increasing at a 1:1 ratio right now. I am currently NOT using the ATI FMU that came with the kit.
The one thing I was wondering about rescaling the MAF tables is what will this do at low rpms? Will this throw the car into fits especially with as big of an injector that is in the car?
