Anyone know what the differences are between these 2 ecms? is one better than the other?
Trying to figure out what ecm will get me passed the smog natzies in California without a air pump.
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Anyone know what the differences are between these 2 ecms? is one better than the other?
Trying to figure out what ecm will get me passed the smog natzies in California without a air pump.
Whether one is better than the other can be debated, but FWIW, I recently swapped a truck that was originally equipped with a 299 to a 7747, and after tuning ran much better than the 299 did with some tuning, though there was a bad O2 sensor, that I couldn't disable in the 299. The 7747 has been hacked to death and is well known for it's inner workings, so tunablity is a bit better on the '7747 than the '299, IMO.
Ahhh, ok. I thought I may have found my golden answer to why some gm trucks here in Cali have air pumps, and some dont from the factory.
Thanks!
They are both the same type ECM, neither is better or worse. Like Six Shooter says the 7747 has just been worked on more so better documented. Plugs right in. But 299 has soldered in netres chip and 7747 has plug in netres chip. Both main chips are the same. So you would need a 7747 that came with your engine, then tune main chip, or leave stock main chip.Quote:
Originally Posted by jameslleary
Problem in CA is you can't just pass emissions. If anything has been changed from stock factory part then it has to have a CARB certificate. If any emissions device is removed it fails. I have not dealt with them in person in 20 years and it was horrible back then as it was only done by State Government Employees. I've heard now that mechnics in shops can do this. Much better to have a human being, but they have to protect their license.
I think the only issue to ECM change would be if they plug in and scan the ID would need to be correct. This can be done to 7747 chip to match your factory origanal chip. But if vehicle is noticably missing pieces like air pump, your dead in water.
James,Quote:
Originally Posted by jameslleary
In my efforts to keep my truck Californicate smog legal, I have found that depending upon the year and weight of the truck there are different smog rules. My 87 4x4 is a federal truck (I think ) and looking at my mechanics required smog equipment for it, there is no smog pump listed. Since you live in an "enhanced smog test" area, you will have to prove it was built as a federal vehicle to get away with no smog pump. Look at the original BCC from your truck and use BCCFind here on this forum to determine if it was.
I am fully aware of the Smog laws in CA, I have done many conversions that have been state certified. This is a switch to TBI from TPI, I am preparing for the Certification. The donor truck was a 91 gmt-400 K1500 truck, without AIR, but the ecm was missing. I did find a few emissions labels for Cali, that do not specify AIR. My current BCC is ASDU.
Also, Mark, where would be a good place to post a datalog for you wizards to look at? Its a Tunerpro log that I did this morning, since I was able to get my PC going yesterday. My BLM sits around 115 or so at idle...I am used to seeing 124ish, but that was on the TPI setup I previousely had That Dave was helping me with.
Thanks Guys!
Not trying to lecture you on smog rules James, I know you know them well, just trying to answer the question. The answer seems to be based on weight and california or federal build (but then again I have been wrong before) ASDU comes back as a Federal prom. I also think that about then ( 91 gmt-400 trucks) is when they started doing away with smog pumps and just using diverter valves.
115 does seem really rich at idle. This is going in your Burb right? What size injectors are you running, and how much have you tweeked the prom?
Nah, I know you know Jim...LOL!Quote:
Originally Posted by jim_in_dorris
I am running the stock 55pph, stock chip. I do have a supersucker throttle body spacer, and my fuel pressure is at 13 psi.
Exhaust is all new, single cat, 3" walker quietfolow system, new manifolds. The spray pattern looks good on the injectors, but I may still send them out to witch hunter at some point for some freshening up.Going as factory as possible, save for the spacer.
I did post a datalog on my Target Idle thread...on the iPad right now, or I would post it here.
ASDU seems to be the only Bin I can find, is there a specific one for California?
Also looking for a diverter valve if anybody has one in the junk pile...just incase I need to put the AIR pump back on.
here is the link to the 7747 BCC's with some of the california BCC's
http://www.gearhead-efi.com/Fuel-Inj...Information-42
If your going to mail injectors look at Mr Injector, he has a banner ad here. His shop is up the street from me and does fine work! Less then others...
http://www.mrinjector.us/
I'll take a look at your log in AM.
The 747 is a direct plug and play replacement for the 299 I did the swap on my 92 k1500 more than 10 years ago. I still have the 299 I need move to a good home.