hey guys... i just put a gsr swap into an ls, and im having a problem with the vtec. I had a gsr b4 so im familiar with the way the car drove. This swap is giving me a problem. check engine light is on and vtec does engage... but not nearly as noticable as i know it should. I;ve had a few people look at it.. and still not a clue. the shop that put the swap in didnt get an engine harness, instead tampered with the wiring. I was upset but the guy is known for his work. I dont wanna put any names out there, but I am curious, could the wiring be a problem? He did hook up a s300 to it, so he could check out the check engine light, and vtec hit HARD. I have a gsr (p72) on there, so idk if its that or could it be the wiring? I am just confused cuz with the other ecu there was no problem whatsoever. Pls if you have any ideas, it would greatly help. also the knock sensor isnt plugged in... could that have somethin to do with it? maybe its restrictin the engines performance? idk just throwing things out there...

 

For the millionth time, vtec should NOT hit hard. It should be a smooth transition and if it's hitting hard there is definately something wrong anyways. You could always get an OBD2 tester and pull the codes to figure out the problem. Perhaps if all else fails, you could just get the correct harness GL

 

ya if its not wired correctly on the ls harness vtec wont engage or you will have a problem with the ecu, so he put a hondata s300 ecu and cleared the check engine light and it engaged vtec HARD as you say but not as much with the stock gsr ecu? well i think its because maybe that ecu had a whole diffrent map that made the car feel faster i think the stock ecu is fine and it felt like that cause its stock and or somethings wrong with the wiring get a obd2 wire harness and use the stock ecu.gl

 

yup.

do you have the stock IM? if so, thats why vtec doesnt kick as hard as you want. gsr mani has the butterfly(dual stage) in them. vtec opens at 4900rpm(noticeable but not as much as one stage, b16/itr) and then pulls at 5400rpm(i think). so thats why you dont hear a huge changeover. gl.

 

change im and get type r cams if u want it to kick in harder

 

by hard i wasnt talkin about like somethin crazy as if there was a lot of work done. The transition just isnt the same as i had on my previous gsr. It doesnt pull all that well either. 3rd isnt nearly as strong (so it feels), it just seems to be losing power early around 6500-7000 rpms. It might not kick hard but there is a difference when vtec engages. I think im just goin to try and get the engine harness, the only pain in the *** is that I would have to get a new vtec solenoid. the check engine light was due to a knock sensor and tps sensor, we replaced the tps, but i just found out that the knock sensor isnt even connected... I just want to get this damn thing running right and strong...

 

hey, sometime its just the motor. what i'm saying is that some motors are gifted and some arent. i see this all the time. my cousin swapped a gsr into an eg and he cant beat my integra gsr. i'm not saying i'm a better driver, the motor didnt run as well. also, we both pretty much had the same bolt ons too. just race it and find out.

 

i guess i can do that... its just weird being that the car was completely different wit the s300 in. i have no bolt ons, just a port and polished head lol soo I dont understand how the ecu made that much of a difference... we will see wat happens.... thanx to everyone that replied.

 

ecu is the brains of your car man. ecus make ALOT of difference. thats why tuning is soo important. tuning can give you 15+ more hp. i thought you would know since you swapped in your own motor. a stock ecu has stock air/fuel ratio but with s300(any tuning programs) you can change them at different points of the powerband or increase them. change the vtec point where its best for a specific motor. theres tons of other stuff too. people suggest everytime you mod your engine you get a tune, because it changes the engine either by sucking in more air, pushing out more air, so you need to compesate it by tuning. but not everyone has the money or time to tune it everytime they upgrade. cant believe you dont know bout this...

also thats prob why your car feels weak...your head is ported. its trying to suck in more air but the stock IM and intake is holding it back. take off the top part of your intake box(just three screws) you'll definetly feel the difference and the vtec will be alil louder. get bolt ons and your car wont feel as slow.

 

2 things....

did u do a compression test on the car to see how healthy the motor is?
and
i know if theres not a knock sensor wired up it will retard ur timing. i remember when mine wasnt hooked up, and then i got a new sensor, but it didnt really affect the performance. it was all in my head lol