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Question about modern obd2 systems


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Howdy all, I havent posted here in ages. I still have my Z but its been parked for a few years now. Kinda lost interest and got into other things. Hopefully interest will come back as it has in the past.

 

Anyway, that's not why I am here. I wanted to get a honest answer about the course modern engine/vehicle control systems have taken over the years. I understand automotive wiring and EMS systems quite well but I have very little experience with stock systems past the 1990's. Recently I bought a 2003 Dodge Dakota with a blown 3.9 V6 and I was having a hard time finding a replacement so I opted to drop in a 5.2 because they bolt right in. (same mounts, same exhaust, same bell housing)  Sounds easy enough right? WRONG!   I knew I would have to swap out the PCM for a V8 one. Research told me that I needed one from the EXACT same year and it had to be a Dakota, NOT a Durango or a Ram. Ok, I lucked out and scored a PCM from a 03 Dakota 5.9 for $50  (there is no 5.2 in a 03) I added two pinouts for the extra two injectors and it fired right up, then died a second later with the security light blinking. 

  From the research I did I kinda figured this would happen. These vehicles have the PCM coded to the vehicle and if the VIN numbers and mileage dont match you're hooped. Only the dealer has the ability to reprogram the VIN numbers. Having no choice I towed the truck to the dealer on my flatdeck trailer. I asked to get it reflashed on the trailer because it sounded a whole lot easier than unloading a truck that won't run. I got the flash done and the truck ran with no CEL's or security light, both transponder keys were working I was quite happy. I towed it back home and unloaded it, after the tires started to spin the ABS light started flashing. Turns out the axle ratio and tire sizes have to be programed in too or the ABS module will get a error. Back to the stealership....     they wanted to charge me twice but after some bitching they did it for no extra cost. I was happy again...  until...

  Backing up a bit it turned out the 5.2 I got was in rougher shape than I had hoped and decided to do a complete rebuild before the initial install, obviously I removed the distributor so once it was up and running again I knew I would have to set the timing properly. I went online to find out how to put the PCM into diagnostic mode to set the base timing. Turns out the base timing is set in stone when you put the ring gear on. The adjustment on the dizzy however does effect the fuel injection sync. The method of doing this is to put is on a scanner (and not a cheap one)  What does this mean?   FFS! back to the freaking stealership again???   I have never seen a vehicle that makes you so dependent on going back to the dealership! It has certainly turned me right off from Dodge.

 

My question is...  I don't have much experience with newer cars so is this just a Dodge thing or are the all like that now? If it's only Dodge I am guessing its because of the time they spend in bed with Mercedes. I know German vehicles have computer control in every aspect of the vehicle. Can I expect to see this kind of crap in say a 05-10 Toyota, Honda or Nissan?  The reason I am asking here is because I don't really want the opinion of Dodge fanboys on a Dodge forum.

 

Thanks for any replies.

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Im a Nissan Tech, this is what new cars have been going towards since 2000. Nissan doesnt monitor the gear ratios like that.  If you were to do an engine swap in one of these. You need the wiring harness ecm, bcm, key antenna. Kind of like when guys put the 350z or 370z engine in an old Z. If you use the Nissan wiring harness, you need all those components. Then bring it in so we can program the system for the key. Nissan as others should, Have a rolling code system for starting. Never uses the same key starting signal, makes them harder to steal.

No distributors in the later years, cam and crank sensors. Time the engine chains and gears correctly. it will start and run.

 

This is usually why people just try to get the engine running on a standalone system to avoid the hassle.. If the car doesnt have to go through emissions your in business.

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Essentially all new cars, are a rolling network  of computers.

With MATCHING (engine, trans, sensors,etc)  hardware.

Software updates are common, and Vin specific.

 

Swapping components/modifications is now a difficult, if not impossible task for the DIY crowd.

It is an uphill battle you are unlikely to win. 

 

Play with the old stuff, leave the new stuff alone, unless you buy engineered for the application items,

have deep pockets, lots of time, etc,etc,etc........

Good Luck.

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You can still certainly play with new cars but it takes a slightly different skill-set. If you are scared of computers, then it's surely not for you!

 

Nissan doesnt monitor the gear ratios like that.

 

Have you ever swapped diff ratios on a Nissan/Infiniti, e.g. 370Z/G37? It will definitely throw codes and possibly disable cruise control. Only way to fix that would be if you had access to the TCU and could change the necessary parameters...

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"You can still certainly play with new cars but it takes a slightly different skill-set. If you are scared of computers, then it's surely not for you!"

 

 

Well I've done plenty of custom wiring and played around with standalones enough that I am definitely not scared of computers. However if you are dealing with codes that only the dealer has access to you are up the creek without a paddle. It is also hardly worth it to spend thousands of dollars on a scanner that comes with a limited amount of keys and likely needs a update every time you want to look at another make. Or better yet becomes obsolete before you had a chance to use it a dozen times. 

 

This whole prospect of this new direction cars are taking makes me a sad panda....

Edited by GrayZee
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Leon, I haven't swapped gear ratios in a G37 or 370z. I was reffering to the OP's Engine swap question. What i would say is. if i put a larger set of tires on the rear of a 370z I dont think the abs light would come on. Changing tire sizes is similar to changing gear ratios. Personally I would never be concerned if a cruise control code popped up after doing a diff swap though.

But if the vehicle was 4wheel drive the abs light or trans will have a code. Brand new tires on the front, worn tires on the rear. Will cause the light to flash. Toyota trucks do the same thing.. Nissan does not give techs access to changing parameters for diffs and transmissions and or tire sizes. But if the car had to go through emiissions that code may turn the check engine light on. If it turned on the ABS and Slip lights i definately wouldnt be concerned. OP wanted to swap engines.

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I lament my 90 Dually isn't newer so I could use TunerCat through the OBD interface.

The new powertrains are great, and the computers  are hackable to allow you to tailor things the way YOU want them....

 

AND, as VW has recently showed us, with a few quick keystrokes everything is back in line for "The Man" and  his "Central Scrutinizing Process"...

 

My bud did a swap of a 94 Camaro into a 74 Camaro. Man, sweet! That TunerCat Studio is like a standalone. Turn off this, turn off that, reprogram for differential gearing... And everything works together like a newer car!

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I lament my 90 Dually isn't newer so I could use TunerCat through the OBD interface.

The new powertrains are great, and the computers  are hackable to allow you to tailor things the way YOU want them....

 

AND, as VW has recently showed us, with a few quick keystrokes everything is back in line for "The Man" and  his "Central Scrutinizing Process"...

 

My bud did a swap of a 94 Camaro into a 74 Camaro. Man, sweet! That TunerCat Studio is like a standalone. Turn off this, turn off that, reprogram for differential gearing... And everything works together like a newer car!

 

Precisely!

 

Our shop recently developed a turbo kit for the Subaru BRZ/Scion FRS. Tuning was all done on the stock ECU. The kit went through extensive emissions testing and is CARB-legal.

 

Playing with new cars isn't impossible, and with the internet nearly everything is at your fingertips should you choose to search for it! For those things that you just can't figure out, you'll just have to go the old-fashioned way and make friends with someone at the dealer. ;)

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