: Running an OBD-II computer with 4BT



mooktank
10-17-2007, 03:33 PM
I am planning my next swap and there's a possibility that it may be more illegal than my last one.

SO.

Anyone have any insight into how to build a computer/circuit than someone could plug a scanner into and pass emmissions testing?

I can only imagine the system uses electrical readings to make sure the engine is healthy. If you could replicate these with a computer and make it discreet enough, you could pass with a diesel...

For "off road use only" of course.

Blueflame
10-17-2007, 04:49 PM
I,m not sure that would do you any good. We don't have a inspection here in Okla. (at this time). From what I understand in the states that do they use a 4 gas analyzer with a probe placed in the tail pipe. Some places also do a visual inspection to make sure all required smog equipment is in place. I expect that Okla. will go to an inspection any time now. It has been up before the state legislature the last 2 years but has been voted down so far. This last year the Oklahoma new car dealers association has really been pushing for it and money talks. I would hate to do a conversion on any late model vehicle right now. I'm just hoping my 64 IHC will slide by when it passes. But I suspect that since the new car dealers are involved now that it will be all about getting older vehicles off the road. Ill get off my soap box now.

IHWillys
10-17-2007, 05:28 PM
Here in northern Colorado the emissions testing that had been in place for 20+ years on gasoline powered vehicles is now gone. No testing required on any gasoline powered vehicle as of January 2007. Diesel vehicles still get tested.

Ken

Crza1
10-17-2007, 05:59 PM
The ODB-II system uses the vehicles on board computer to verify all sensors are reading in the proper range. No gas analyzer. This is vehicles 96 and newer I believe. Not sure about tricking it.

averagef250
10-17-2007, 06:58 PM
The megasquirt aftermarket EFI controller is built to run an engine, but a neat little accessorie for the meqasquirt is the stimulator board which is a circuit board that's sole purpose is to hook to the computer and make it believe it is hooked to a running engine for the purpose of testing and troubleshooting the megasquirt computer.

I use a megasquirt computer and a stimulator board on my gas injector flowbench to flowtest injectors and check spray patterns under any operating parameter.

I don't know what EFI system you're looking at fooling, but it's likely not very feasible unless it's very early EFI. The only system I'm really familiar with is Ford EEC-IV. EEC-IV is 1980's technology and it's very, very, very smart. EEC-IV self diagnostics are extremely complex and monitor all aspects of the engine, even engine speed and fuel rates in relationship to vehicle speed, feedback from egr and air injection valves activating, etc. These inputs can be faked easily with resistors to make the computer run correctly without emissions, but it will still trip trouble codes in the EEC, even though the check engine light stays off.

The simplest closed loop MPFI computer is smarter than you are. I don't think it's feasible to fake one out for the sake of emissions testing.

Blueflame
10-17-2007, 07:59 PM
Here in northern Colorado the emissions testing that had been in place for 20+ years on gasoline powered vehicles is now gone. No testing required on any gasoline powered vehicle as of January 2007. Diesel vehicles still get tested.

Ken

What does the testing consist of ? What years does it apply to ?

nhdiesel
10-17-2007, 08:14 PM
I can't speak for other states, but here in NH the only testing is a PC plugged into the OBD data port. As long as the vehicle has no pending engine/emissions codes (no Check Engine light), it will pass.

A trick is to use a different vehicle for the test. The tester enters the VIN into the PC manually, then reads any vehicle he wants. Of course this requires you to know the tester, and have him be willing to do this. Then again, just having a vehicle with a swapped in diesel will require the same, because he will know that the diesel isn't OBD-II.

This is, of course, illegal. I justify it because the diesel will get far better mileage, and put out less emissions, then the "legal" engine it replaces. And that is, afterall, the point of emissions testing, isn't it?

Jim

mooktank
10-17-2007, 09:07 PM
I can't speak for other states, but here in NH the only testing is a PC plugged into the OBD data port. As long as the vehicle has no pending engine/emissions codes (no Check Engine light), it will pass.

A trick is to use a different vehicle for the test. The tester enters the VIN into the PC manually, then reads any vehicle he wants. Of course this requires you to know the tester, and have him be willing to do this. Then again, just having a vehicle with a swapped in diesel will require the same, because he will know that the diesel isn't OBD-II.

This is, of course, illegal. I justify it because the diesel will get far better mileage, and put out less emissions, then the "legal" engine it replaces. And that is, afterall, the point of emissions testing, isn't it?

Jim

I was reading that MA (my state) is now checking computers to make sure they match the vin. I will probably just do a '95 to avoid the OBDII scandal since I think the dyno tests are over soon. Hopefully tailpipe tests are gone too and it will just be OBD which is the rumor goin round right now.

nhdiesel
10-17-2007, 09:56 PM
Most computers aren't VIN specific (don't record the VIN of the vehicle) so it would be impossible to check. Thats why you can buy a PCM off ebay, plug it in, and drive the vehicle. It all boils down to the shop that actually does it.

On the same subject, I am going to attempt to wire up a vehjicle "simulator" to use for vehicles that have issues that won't pass the state's test. It will basically just be a powered PCM with some sensors, and some sensor simulators (to fool the PCM into thinking its a running vehicle), that I can plug into the PC. There are so many stupid things that will cause a vehicle to fail. Some examples are:
-Many late model GMs use the cig. lighter circuit to power the data link connector. If the cig. lighter blows a fuse, the vehicle will fail emissions (even though the PCM is working fine). This is easy to fix, but wouldn't be if there was a wiring issue somewhere else in the circuit.
-My brother in law had a bad A/C fan in his '02 Dodge 1500. This blew the A/C fan fuse, which set off the check engine light. He brought it to the dealer, not knowing what the problem was (I wasn't around), and it cost him almost $400 to fix the A/C fan, allowing the truck to pass inspection.

These are just two examples, but they show what I'm getting at.

Jim