Tuning a TBI big block
06-04-2013, 10:35 AM
#1
Tuning a TBI big block
I'm tuning my 454 BBC powered Suburban and have a few issues... For the guys who haven't read my build thread, It's around 9.7:1 compression with cleaned up iron heads and Probe forged dome pistons. Comp 266HR roller cam. Right now once it's warmed up it runs excellent even when I force open loop, that tells me the overall fueling is pretty close. It idles damn near as smooth as the stock dump truck cam. My problem comes from the fuel adders that are still stock.
I do have a WBo2 sensor, but as a double check, how do you read spark plugs with a black oxide body? Just go by what the insulator looks like?
What is a good cold start AFR? Is there a rule of thumb? With the stock cold start settings in the tune it's super rich, almost fouling plugs and black smoke rich. I've leaned it out about 15% and it's better, but I don't know how far I should go.
What about the acceleration enrichment? Just add or remove fuel there until it doesn't bog lean or rich when you mash the throttle?
Otherwise, it's pulling down decent MPG on the open road, responding to the AC requests without stumbling or stalling and overall the drivability is pretty good once it's up to temperature.
I do have a WBo2 sensor, but as a double check, how do you read spark plugs with a black oxide body? Just go by what the insulator looks like?
What is a good cold start AFR? Is there a rule of thumb? With the stock cold start settings in the tune it's super rich, almost fouling plugs and black smoke rich. I've leaned it out about 15% and it's better, but I don't know how far I should go.
What about the acceleration enrichment? Just add or remove fuel there until it doesn't bog lean or rich when you mash the throttle?
Otherwise, it's pulling down decent MPG on the open road, responding to the AC requests without stumbling or stalling and overall the drivability is pretty good once it's up to temperature.
06-05-2013, 03:25 PM
#3
PE delay and DFCO are disabled at the moment because I'm still tuning VE. I'm fighting detonation at 85 to 100KPa (2000 to 3000rpm) and my timing is only 10 degrees ACTUAL. It's a dog. I've been playing with DCR calculators and all of them are over 9.1 with the valve events of my current camshaft. I think I'm going to need to do a cam swap on this thing to get the DCR in line for pump gas.
On top of that I think something is up with my fuel PSI or my injectors, because every indication is that it's delivering way more fuel because of a mechanical issue, and I'm bandaiding it by lowering the VE table.
I can't upload the BIN, it's not an allowed attachment here.
On top of that I think something is up with my fuel PSI or my injectors, because every indication is that it's delivering way more fuel because of a mechanical issue, and I'm bandaiding it by lowering the VE table.
I can't upload the BIN, it's not an allowed attachment here.
06-05-2013, 05:30 PM
#4
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PE delay and DFCO are disabled at the moment because I'm still tuning VE. I'm fighting detonation at 85 to 100KPa (2000 to 3000rpm) and my timing is only 10 degrees ACTUAL. It's a dog. I've been playing with DCR calculators and all of them are over 9.1 with the valve events of my current camshaft. I think I'm going to need to do a cam swap on this thing to get the DCR in line for pump gas.
On top of that I think something is up with my fuel PSI or my injectors, because every indication is that it's delivering way more fuel because of a mechanical issue, and I'm bandaiding it by lowering the VE table.
I can't upload the BIN, it's not an allowed attachment here.
On top of that I think something is up with my fuel PSI or my injectors, because every indication is that it's delivering way more fuel because of a mechanical issue, and I'm bandaiding it by lowering the VE table.
I can't upload the BIN, it's not an allowed attachment here.
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