Dalee1104 Posted November 28, 2016 Share Posted November 28, 2016 Hey guys, I've searched around some of the forums and haven't found any with the same issues I've had so I figured I would take a stab in the dark. I have a 97 legacy gt, I've put a lot of work into the engine and the car itself. For a long time I've been trying to chase this issue with not having its full power. I've driven other legacies with the same engine and everything and they feel pretty nimble and light on their feet, but not mine. I have a good torque reading all the way up to about 3k rpms and then it goes away. My car still climbs, just slowly, hitting highways speeds takes awhile with it acting like this. If I shift early such as before I hit 3k than you don't feel the drop in power. With this I thought it was the knock sensor looking around. I lose power right around 3k and start to gain it back after 5k. I relocated the knock sensor to see if this would change anything at all and sure enough it doesn't. I've had my fuel and intake system gone over by a shop and they washed out my injectors as well. My fuel pressure reads within factory readings. I'm lost as its not throwing a check engine light either. Any help and insight would be greatly appreciated. I'm running the ej25 engine on regular fuel octane (ran 89 for awhile, no changes either so back to 87). If it's any help, sometimes the car just feels a lurch like a large loss in torque but keeps going, although it's not nearly as hard as a misfire while driving, it's still enough to cause your passengers head to Bob around and usually occurs right around 3k Link to comment Share on other sites More sharing options...
twisty Posted November 28, 2016 Share Posted November 28, 2016 IIRC the 96-97 ej25d required 91 octane fuel. i can definitely feel a difference in my 96 GT with 87 vs. 91. it took a while for the tune to adjust tho when i first got it, the guy had always put 87 in it. a few tanks later it was a different car tho. Link to comment Share on other sites More sharing options...
Dalee1104 Posted November 28, 2016 Author Share Posted November 28, 2016 Really? I've read that the engine build before these used 89 and then they went to 89 but never heard of 91. Then again that was Wikipedia. Are you just running with the factory ecu? No chips or anything? Should I just try 91 for a few weeks? Link to comment Share on other sites More sharing options...
twisty Posted November 29, 2016 Share Posted November 29, 2016 mine is pretty well bone stock. no add ons or anything. when i open the gas door there is a note (sticker) in there about using premium fuel as well, my ej22 cars dont have that. Link to comment Share on other sites More sharing options...
choover1101 Posted November 30, 2016 Share Posted November 30, 2016 Could you have the 96 ej25? Peak hp tq was at 2800 rpm according to the stickies. Sent from my SAMSUNG-SGH-I747 using Tapatalk Link to comment Share on other sites More sharing options...
twisty Posted November 30, 2016 Share Posted November 30, 2016 peak tq is about 3k rpm, peak hp is at like 5800 rpm or somewhere around there. mine is a 96, and at just about 3000 rpm the car gets peppier, not slower. just checked, its 2800 and 5600 respectively (according to wiki). either way, peak torque doesnt make the engine lag, and using 87 oct wont make it lag either. it will ping and such, but without something else being bad there shouldnt be a huge flat spot with no power at all. youve had the fuel system worked out, but what about the sensors/ electrical? have you checked the wires/ coil to make sure they are in spec? how do the plugs look? is the MAF clean? how clean is the throttle body? does the trans make any noises when this is happening? can you feel or irregularity in the engine firing sequence? Link to comment Share on other sites More sharing options...
choover1101 Posted November 30, 2016 Share Posted November 30, 2016 Thanks for the fact check Twisty. I misread this post. http://legacygt.com/forums/showthread.php/second-generation-usdm-legacy-engines-219372.html Link to comment Share on other sites More sharing options...
Dalee1104 Posted November 30, 2016 Author Share Posted November 30, 2016 I've mostly rebuilt anything top end on this current engine, replaced plugs and wires, throttle body cleaned, injection system cleaned, recently checked out the knock sensor, fuel system cleaned so the engine is really well. Current update, I filled up with premium. I never had a sticker saying use premium and read many different things online about 87 or 89 octane so i've tried both with no difference, not knowing I should use at least 91. Then I read some more and some more research and I guess it's just a rule of thumb that subies like high octane fuel. Here premium is 92 octane and that actually made a world of difference guys. Ever since running the 87 out and getting some 92 going through the knock sensor isn't an issue, my power ban is much more linear, increasing with rpms, torque is great. Honestly that's the key, running high octane and my engine is loving it, have enough power to break traction in 2nd gear if I floor it hard enough Link to comment Share on other sites More sharing options...
Dalee1104 Posted December 2, 2016 Author Share Posted December 2, 2016 Oh and twisty the 87 was causing it to ping but that's what the knock sensor was picking up. As the knock sensor picked up the ping it would cut my power almost as soon as I hit that power ban. Replacing a knock sensor is no use without using the correct fuel lol Link to comment Share on other sites More sharing options...
twisty Posted December 2, 2016 Share Posted December 2, 2016 lol true, but usually that would have been across the board, the pickup of power after 5k was what confused me Link to comment Share on other sites More sharing options...
Dalee1104 Posted December 5, 2016 Author Share Posted December 5, 2016 Honestly that could have just been me over analyzing like I always do with the car lol. Glad that just the gas solved the issue, thank you guys! Link to comment Share on other sites More sharing options...
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