Tuning issues... Please help...
Thread Starter
Teching In
Joined: May 2021
Posts: 16
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From: Clermont FL
Tuning issues... Please help... So I recently did a heads and cam swap on my 1999 Camaro SS. The car is at a reputable tuner in Central Florida. Getting the car tuned has been a nightmare it seems. Here is the mods recently added and I'll explain further.
PRC 227 heads
Texas speed torquer v4 cam
Fast 102 intake and throttle body
New melling high volume oil pump
Fuel injector clinic 40 lbs injectors
Texas speed 1 7/8 headers to offroad y-pipe and magnaflow
Texas speed 100mm MAF and fast toys 104mm airbox lid
Brand new timing chain and gear, new cam sensor etc
when the tuner enters the info into HP tuners for the injector size and MAF size the car will not run. When he enters the stock parameters then it runs. He had to tweak around that to get the air/fuel ratio correct. The car dyno'd today 430 hp and 364 torque. This is on a dynojet. My question is what would be causing this issue? Bad ECU? Just doesn't make sense. The tuner said himself the numbers seem low. Could this be because the computer doesn't know what to do or does the tuning software completely bypass this in a sense?
The car previously was tuned at hawks performance in SC and on stock heads, Torquer V2 cam, original Fast 78 intake and throttle body, pacesetter longtubes etc the car made 401hp and 379tq
At this point going to way better heads, bigger cam and intake etc I gained 29hp and lost 15 ft lbs of torque. I'm kinda confused here.
PRC 227 heads
Texas speed torquer v4 cam
Fast 102 intake and throttle body
New melling high volume oil pump
Fuel injector clinic 40 lbs injectors
Texas speed 1 7/8 headers to offroad y-pipe and magnaflow
Texas speed 100mm MAF and fast toys 104mm airbox lid
Brand new timing chain and gear, new cam sensor etc
when the tuner enters the info into HP tuners for the injector size and MAF size the car will not run. When he enters the stock parameters then it runs. He had to tweak around that to get the air/fuel ratio correct. The car dyno'd today 430 hp and 364 torque. This is on a dynojet. My question is what would be causing this issue? Bad ECU? Just doesn't make sense. The tuner said himself the numbers seem low. Could this be because the computer doesn't know what to do or does the tuning software completely bypass this in a sense?
The car previously was tuned at hawks performance in SC and on stock heads, Torquer V2 cam, original Fast 78 intake and throttle body, pacesetter longtubes etc the car made 401hp and 379tq
At this point going to way better heads, bigger cam and intake etc I gained 29hp and lost 15 ft lbs of torque. I'm kinda confused here.
I assume your tuner uploaded the values found here?
Did he change the MAF table to reflect the lager MAF? If he has not the car would not run. I would begin by making sure the data supplied from the injector manufacturer is entered correctly AND multiply the whole MAF table by 1.5. This should get the car to start and he should be able to handle it from there. I've never had good luck getting the car to idle using a 100mm cartridge style MAF on a P01 PCM (as found in 99-02 F-Bodies). I've had much better luck going speed density. Now I have no problem getting a P59 PCM to idle with a 100mm MAF.
Are you able to post a copy of the tune?
Did he change the MAF table to reflect the lager MAF? If he has not the car would not run. I would begin by making sure the data supplied from the injector manufacturer is entered correctly AND multiply the whole MAF table by 1.5. This should get the car to start and he should be able to handle it from there. I've never had good luck getting the car to idle using a 100mm cartridge style MAF on a P01 PCM (as found in 99-02 F-Bodies). I've had much better luck going speed density. Now I have no problem getting a P59 PCM to idle with a 100mm MAF.
Are you able to post a copy of the tune?
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Does it at least run in Speed Density? Those mods shouldn’t be a problem for that PCM. And no, it doesn’t bypass anything. The calibration is flash memory. Whatever the values are the computer will command, within the hardcode limits of course.
I would have him work up a solid SD tune before engaging with that larger MAF. The PCM will read the MAF perfectly fine, however you may have increased instability at low RPM due to changes in the air tract.
He can also do a MAF baseline after getting the SD tune on point by simply plotting dynamic airflow on the MAF freq table. From there you just copy it straight over.
I’m kind of wondering why he didn’t start with VE in the first place. I always do that first if the end calibration is meant to be a blended model. You should also be able to use your actual injector data too.
If later you want to use the MAF, and you still have problems at idle, just go ahead and do an open loop idle tune and set the dynamic disable up to 4K. Should work fine.
I would have him work up a solid SD tune before engaging with that larger MAF. The PCM will read the MAF perfectly fine, however you may have increased instability at low RPM due to changes in the air tract.
He can also do a MAF baseline after getting the SD tune on point by simply plotting dynamic airflow on the MAF freq table. From there you just copy it straight over.
I’m kind of wondering why he didn’t start with VE in the first place. I always do that first if the end calibration is meant to be a blended model. You should also be able to use your actual injector data too.
If later you want to use the MAF, and you still have problems at idle, just go ahead and do an open loop idle tune and set the dynamic disable up to 4K. Should work fine.
