Jake 1 Posted June 12, 2022 (edited) Thanks for letting me join. I recently purchased a 2009 Honda rancher 420. Latest drove it seemed good but didn’t notice it going from nuetral to 2nd gear. The only issue he said it had was the switch for auto/ esp needed changed and that he put a new fuel pump and computer since his boy hooked up the battery backwards. So the issue is that the old computer part number doesn’t match up with the one he put in it. When I hook up the old one it won’t start but it goes into auto and esp says there is a 1st gear not running though. Any ideas would it be just the wrong computer.The new computer won’t let it go into fully auto but it’ll start it and runs fine but just goes straight to 2nd gear. But the old one won’t start it but with the key on it’ll go into esp with 1st gear and auto it’ll say drive but kicks it back into nuetral. Edited June 12, 2022 by Jake Share this post Link to post Share on other sites
jeepwm69 7,751 Posted June 13, 2022 Welcome aboard. What part number is the new computer? The DCT’s have lots of electronic stuff on them and if anything is off they don’t work right Share this post Link to post Share on other sites
Jake 1 Posted June 13, 2022 (edited) # 38770-hp5-a51 was the number on the new one. #38770-hp7-ao4 is the old one.Thanks for the response And it also has a FMF exhaust with the programmer. Aren’t you suppose to leave the programmer hooked up or can you take it off and run it that way cause my boy has a trx 700 and I thought he said he left his hooked up. Just wondering if that would cause an issue. Thank Edited June 13, 2022 by Jake Share this post Link to post Share on other sites
jeepwm69 7,751 Posted June 13, 2022 Your new ECU is incorrect. It's for the ES (electric shift) models, while you have an FA (automatic) Rancher. First thing you're going to need to do is put the proper ECU on there. PSN has a used one for $200, and they stand behind what they sell. New looks to be $300-up. https://www.powersportsnation.com/honda-rancher-420-fpa-10-pgm-fuel-injection-unit-38770-hp7-a04-37084.html Share this post Link to post Share on other sites
Jake 1 Posted June 13, 2022 Thanks man I got one ordered and I’ll post once it comes and hooked up. Again thank you Share this post Link to post Share on other sites
Jake 1 Posted June 16, 2022 Well got the new one hooked it up and everything works. The gear switch motor sounded a little noisey don’t know if that’s normal but I did open it up and thought I read there should be grease in it but it was bone dry. Another question is there is a HMF exhaust on it and the guy gave me the optimizer with it but it’s not hooked up. Does it need to plugged in to get the best performance with that exhaust on. Thanks 1 Share this post Link to post Share on other sites
jeepwm69 7,751 Posted June 16, 2022 Eh, probably not just for a muffler. I did a 500 top end on my wife's 09 DCT when I did the rebuild. I added a Weisco programmer at the same time and honestly I think I wasted my money on it. I've seen too many people who slapped the 500 top end on a bike without the programmer who had zero problems doing it that way. The fuel injected vehicles tend to not need the tuning that the carb'd rigs did for performance "add ons" I'd run it without the programmer and check the plug frequently to see if it's running lean. If it is, put the programmer on. I don't think bolt ons like an exhaust and programmer do much if anything on these single cylinder Honda utility engines. Share this post Link to post Share on other sites
Jake 1 Posted June 16, 2022 Ok thanks just wondering I know it not a machine made for speed and stuff but I got a trx 700 that has one and that one is hooked up. Again thank you very much Share this post Link to post Share on other sites
jeepwm69 7,751 Posted June 16, 2022 1 minute ago, Jake said: Ok thanks just wondering I know it not a machine made for speed and stuff but I got a trx 700 that has one and that one is hooked up. Again thank you very much Well if you already have the programmer, I guess you might as well hook it up. I still have mine hooked up on the wife's rig, just not sure it really does any good vs stock, but once you've paid for it, makes sense to use it! Lol Share this post Link to post Share on other sites
Fishfiles 20,147 Posted June 16, 2022 Something to think about , I hear guys talk about having to do a oxygen sensor delete on the 420 when you have a custom exhaust or it is snorkeled , don't know much about that other than have read it , as I don't have a 420 or a fuel injected model Share this post Link to post Share on other sites
jeepwm69 7,751 Posted June 16, 2022 1 hour ago, Fishfiles said: Something to think about , I hear guys talk about having to do a oxygen sensor delete on the 420 when you have a custom exhaust or it is snorkeled , don't know much about that other than have read it , as I don't have a 420 or a fuel injected model Don't think the O2 sensor came about till 2014-2015. Not one on an 09 420 for sure, which is what OP has and what the wife's is. Share this post Link to post Share on other sites
