I did a 5 speed swap on 2000 civic lx, and im still usin the auto tranny ecu. Now it seems like my gas mileage has dropped considerably! Like 15 miles a gallon or something....anyway, since im using the ecu for the auto, will that kill my mpg? Only difference is the tranny is now manual, and im not using like 3 sensors...does that matter?

 

Can anyone help?

 

Chances re you're driving more aggressively with the manual transmission. I can pretty much guarantee that you are. If you want your car to behave optimally in its new configuration, get the proper ECU. This is a no-brainer.

 

No, i havent, i shift at like 2k rpms give or take 100, and i go from 3th to 5th when crusing. I already know i need the right ecu, but i want to know what about the auto ecu with a manual car makes it run terrible? Nothing changes except for the couple tranny plugs being disconnected..

 

I'd look more towards the three sensors you decided to unplug - they're more the culprit than the transmission.

 

It was the solenoids for the tranny, the shift solenoid, and i think 2 others...so no one thinks the auto ecu is the culprit as well?still using auto ecu.

 

The fuel trim codes are the same between the ECUs, so the ECU isn't (entirely) at fault. You still should swap to the proper ECU, or modify yours (if that's even possible) to run correctly though.

 

I have p2e ecu, and im told obd2 are not able to be converted..ive been looking for a manual p2e, but no luck..i only find it on ebay, but i need the ecu now so i can drive home without filling up so many times..i always wondered why OP says use p2p ecu. Wont you get a cel for vtec soleniod, and the vtec pressure?? Lol

 

You use the ECU that matches your engine. Obviously, the engine in the OP uses a P2P. If yours uses a P2E, find a P2E. How long have you been looking for one locally? I'd be willing to bet if you had ordered one off eBay when you first started looking, it would be in your car already.

 

Yea, but see, im visiting my bro down south, and we have been looking for a sohc non vtec ecu ever since i got down..we checked facebok buy sell trade, craigslist all that. I knew ebay would have it, but my bro dont have his stuff hooked up, and neither do i...we only been able to find sohc vtec and dohc ecus, but around here, 4 door 2000 sohc ecus are almost non existant..lol

 

Knows he can get it off of Ebay. Doesn't get it off of Ebay. Problem remains unresolved. Have no idea what " but my bro dont have his stuff hooked up, and neither do i" because it isn't English. I see no mention of trying to contact and junkyards either because I find it HIGHLY unlikely that NONE of them have one.
Can't explain that.

 

I was referring to the paypal being linked, and i dont really have time to wait for ebay even if the account was hooked up because i need to get back home as fast as i can. And i havent checked junkyards. Your right, i havent really thought about it because my funds are really low at this point..anyway, no one really answered the question of will an auto ecu ruin gas mileage..jbpnoman shed little light, but still looking for definite answer.

 

You keep answering your own question. According to you the only differences from a previous configuration is the ECU and the disconnected plugs. So what else could it be if nothing else changed? Unless you forgot to mention something this is Basic Troubleshooting 101.

 

I just want to know for future references. Like does the auto think the car is stuck in a certain gear because the tranny is not hooked up to use a certain amount of fuel for a selected ger. Understand what im saying? If it is indeed the auto ecu giving me my issue, wHY is it happening. I understood long time ago i needed a new ecu to get rid of cel light lol

 

Same question phrased differently. Answer is the same. ECU and plugs are the only thing that is different and is the most likely cause of your issue at this point.

Why is it causing the change? Ask Honda. Ask the ECU. Does it really matter why? Absolutely NOT. Knowing why gets you what? Knowing why fixes your problem how? Knowing why gets your car running correctly how? There's nothing that benefits you or anything you can do by knowing this information that will resolve this issue. For future reference? Garbage. You plan on this happening again?

The only thing I would be worried about at this point is if you get the new ECU and it still does it. Then I would suspect the quality of the swap and if it was performed correctly. You still have not positively identified ALL the sensors that are unplugged. I'm willing to bet that there is information missing. Move on. Get the ECU.

 

Well it wouldnt hurt to learn why.. anyway thanks for your replies grumble and jbp.

 

Are you being tested on it?
Why does a Civic run differently after swapping transmissions, auto to manual, while using the same ECU? Compare and contrast the differences in gas mileage after doing such a swap. What would you do were you in the OP place? Knowing what you know, what conclusions can you make about this swap?

 

Im not being tested, but i am still learning, and i think it would good to know. And i would check everything that was changed, and if that checks out, i would get a manual ecu. My point was wondering if it is the ecu at fault, why would a missing tranny affect gas mileage, thats all..i understand evrything you are telling me.

 

this thread delivers

 

Elaborate?

 

It's a H-T classic. You know how to fix the problem, you just haven't bought the parts. You come here asking for advice for a problem you already know how to fix. We reiterate what you already know, and you still haven't fixed it. We only see it all the time.

 

have u double checked and acually checked the codes to make sure that the only codes u have are just the tranny codes not o2 sensor codes.etc....

 

dont the set idle rpms differ between manual and auto ecu's?
with the auto ecu i bet your idling a little bit higher than if you had a manual ecu. not enough to account for noticable gas consumption. i have done this swap in my old cb9..i started with the auto ecu, then went to the manual ecu shortly after..get the correct ecu.

 

I know the issue aleady guys, i was only asking if there was a reason as to why the auto wont work as good as the manual ecu, i knew to get the ecu for my car, i have obtained the right ecu.. i just wanted to know why, just to increase my knowledge, so when someone i know wants to do the swap, i can say, the auto wil work, but your gas mileage will decrease due to [reason still unknown]. Thats it guys lol, i searched all over trying to fine why, so i figured id ask here.

 

Yea, its only tranny codes man. I only want to know IF here is a reason for my gas loss.