Back when I was contemplating modifying my 4.9 efi in a more serious way, I found a guy willing to crack the ecm open, as he put it. But that was a long time ago. I don't have the info anymore.
I've had several tell me they could do it. Not a single one would put their money where their mouth was.
Remember a few guys were successfully running megasquirt with n/a and turbo efi 4.9s.
I've heard several guys talk about running megasquirt, but don't remember ever seeing anyone do it. The turbo is actually pretty easy and doesn't require any tuning.
I been meaning to ask you, what are your plans for your built 4.9?
They have changed a lot the last few years. Originally it was just going to be the most efficient stock rebuilt I could do because until 3 years ago this was the truck we drove all over the country. When we got my wife her Jeep in 2011 we started taking it everywhere, so I decided to go a little farther. I'm shooting for about 10.2:1 compression and will probably end up with a Crower CompuPro Stage 4 cam With Harland Sharp 1.73 roller rockers, but the cam ultimately depends on what kind of flow I get out of the heads. I've got the Hedman headers on it now, but am upgrading to the Hookers for the new engine. I've got several intake combinations to try, but really am hoping to do a box upper on the stock lower with dual throttle bodies. I've got a lower I modified years ago to try as well as a single plane upper. It will all depend on what it likes best for power and road manners. Should do really well from just off idle to about 5000 rpm.
I think my real question, in regards to my situation. Is when emissions are bypassed, how does that affect the computers in terms of function, does it change the fuel end, does it change the spark end or does it do nothing?
On these computer I don't think it does anything. They just aren't smart enough to know the difference. I've been without any emissions since 1999 and it's never caused me any problems. With the stock injectors I still got the same mileage with headers as I did when it was stock. With 19lb injectors I lost a little mileage, but it runs a lot better, especially right after I have the batter disconnected. With the stock injectors it was terrible for about 150 miles until it figured out what it was doing.
I ran my 4.9 with no emissions and a check engine light for over a decade with no negative effects that I could tell, from mpg or performance standpoint. But then again, the whole time, Im wondering, what is really going on in the computer, when it sees there is no emissions. I mean, the lack of recirculated inert gas, shouldn't put the ecm out of its limits of understanding, I could see it using more fuel perhaps, if keeping the CC cooler was its intent, but it would have to base this on IAT, CTS and they are probably gonna read the same either way, only real change being the narrow bands O2s input. So I dunno.
These computers can't see any of that. All they can see is whether or not the solenoids are working. It can't tell if there is actually EGR flow, just that the valve is open or not. For the AIR system is just knows if the solenoids are plugged in or not. As far as running the engine, it just looks at the O2 sensor and adds or subtracts fuel to get what it wants.
What chip or piggy back chip companies are still around? I cant recall whom they were, superchips I think was one but rest I cant remember. Think there were only a couple more.
Superchips and Jet are the two I remember.
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Back when I was contemplating modifying my 4.9 efi in a more serious way, I found a guy willing to crack the ecm open, as he put it. But that was a long time ago. I don't have the info anymore.
I've had several tell me they could do it. Not a single one would put their money where their mouth was.
Remember a few guys were successfully running megasquirt with n/a and turbo efi 4.9s.
I've heard several guys talk about running megasquirt, but don't remember ever seeing anyone do it. The turbo is actually pretty easy and doesn't require any tuning.
I been meaning to ask you, what are your plans for your built 4.9?
They have changed a lot the last few years. Originally it was just going to be the most efficient stock rebuilt I could do because until 3 years ago this was the truck we drove all over the country. When we got my wife her Jeep in 2011 we started taking it everywhere, so I decided to go a little farther. I'm shooting for about 10.2:1 compression and will probably end up with a Crower CompuPro Stage 4 cam With Harland Sharp 1.73 roller rockers, but the cam ultimately depends on what kind of flow I get out of the heads. I've got the Hedman headers on it now, but am upgrading to the Hookers for the new engine. I've got several intake combinations to try, but really am hoping to do a box upper on the stock lower with dual throttle bodies. I've got a lower I modified years ago to try as well as a single plane upper. It will all depend on what it likes best for power and road manners. Should do really well from just off idle to about 5000 rpm.
I think my real question, in regards to my situation. Is when emissions are bypassed, how does that affect the computers in terms of function, does it change the fuel end, does it change the spark end or does it do nothing?
On these computer I don't think it does anything. They just aren't smart enough to know the difference. I've been without any emissions since 1999 and it's never caused me any problems. With the stock injectors I still got the same mileage with headers as I did when it was stock. With 19lb injectors I lost a little mileage, but it runs a lot better, especially right after I have the batter disconnected. With the stock injectors it was terrible for about 150 miles until it figured out what it was doing.
I ran my 4.9 with no emissions and a check engine light for over a decade with no negative effects that I could tell, from mpg or performance standpoint. But then again, the whole time, Im wondering, what is really going on in the computer, when it sees there is no emissions. I mean, the lack of recirculated inert gas, shouldn't put the ecm out of its limits of understanding, I could see it using more fuel perhaps, if keeping the CC cooler was its intent, but it would have to base this on IAT, CTS and they are probably gonna read the same either way, only real change being the narrow bands O2s input. So I dunno.
These computers can't see any of that. All they can see is whether or not the solenoids are working. It can't tell if there is actually EGR flow, just that the valve is open or not. For the AIR system is just knows if the solenoids are plugged in or not. As far as running the engine, it just looks at the O2 sensor and adds or subtracts fuel to get what it wants.
What chip or piggy back chip companies are still around? I cant recall whom they were, superchips I think was one but rest I cant remember. Think there were only a couple more.
Superchips and Jet are the two I remember.