FR-S Seems Slower Than Normal?
 

Hey guys! This will be my first post to the forum, and I'm hoping some of you will be able to help me out with some potential problems my FR-S may be having. I bought Skylar about 6 months ago and she currently has 33k miles on her and an MXP Comp RS exhaust system. Automatic transmission as well (I know, here's my man card). I guess I didn't do quite enough research before I bought the car, because for about 4 of those months, I was filling the tank with regular 87 octane. I never heard that it took 93, nor did the dealership mention it to me. I noticed the car getting slower and things started to just not feel right, and that's when I started researching and found out I needed to use 93. I've been on 93 now for about 2 month and things feel better, but the car still doesn't feel as quick on its feet as it did the day I brought it home. When doing hard accelerations, the revs don't climb smoothly, but rather intermittently, as if the engine is struggling to get up to red line. Also, when I shift manually down into first when I'm slowing down, the gear change is delayed and sometimes the car will jerk and there will be a clunk from the transmission. Sometimes this same thing will happen shifting down to 4th at about 55mph, but usually its just going down to first. Last thing is that there is a whine coming from what sounds like the engine bay or transmission that is most prominent in 3rd gear at 3500rpm. This started happening shortly after I switched back to 93 octane. So I guess my questions are which of these things are normal for the automatic FR-S and which are cause for concern? Also, what damage could I have done by running 87 for those 4 months and should I try unplugging the battery for a night so the ECU can reset and re-learn itself? It's been pretty cold here for the last month but I'm not sure if that would have a significant effect on the car. I did a lot of research on all these things but could not find much useful information, so I'm sorry if some of these topics have been discussed on other forums that I didn't find. Thank in advance, everyone!

You bough the wrong car
2L2R

Yep disconnect the NEG terminal. I dunno if this trick applies to newer cars but older cars it works. Someone here will chime in but check out the software tuning thread it may help

http://www.ft86club.com/forums/forumdisplay.php?f=88

Try the ECU reset but if you still have concerns take it to the dealer (if still in warranty) or a shop and have them check it out.
Although guys will try there is no way to actually diagnose if you have a problem much less what that problem could be over the internet.
There is a TSB for a reflash of the auto tranny control modules that could help.
Unless you had some knock going then there isn't really any damage that running the 87 would cause. If you had serious knock and kept pushing the car then you could have some damaged internals. Again that can not be checked over the internet.

The weather may have some play on this too. Cars don't run worth a damn in very cold weather and from what I read, cold is taking its toll. I did the same as you, put different octane in but only a lil over a month. We don't have cold weather much but I really didn't noticed any difference. I don't think you really could have done any damage, just fill it up with 93 91 whatever you can get from now on

This could all just be weather related. Mines a manual and till it warms up its all bitchy and pissy. Today its 45 I think so it shouldn't be grouchy

Once the engine is warmed up it doesn't matter if it is 50 or minus 50 out. It will run exactly the same. Was minus 12 here yesterday and mine ran the same as it does in August once it warmed up. Now the interior creaks, clicks, squeaks and rattles you get at that temperate are a whole different matter.

Your engine control unit adapts to the changes of octane running through the engine. I honestly have made 4000 mile road trips in the car on 87 and when i get back home i put 93/91 one back into it and its fine and over 80,000 miles of 87 into a supercharged mercedes that called for nothing but 91/93 and never had a problem.

I have heard from many engine mechanics that 87 has absolutely NO lasting negative effects on the engine besides temporary reduction of power and torque while it's in the tank.

But there are a lot of guys on here think its a cardinal sin and a slow death of the 86 to put 87 into the tank.

Would absolutely love it if some professionals in the field could clear the air when it comes to this.

:cheers:

Do not read in an angry tone

How about the engineers that built the car and state in the manual that 93 is preferred and a minimum 91 is required?


They did not say 91 is required but it is OK to use 87 if you so choose.
I am not for one second saying it will wreck the engine but if there was severe knock from using it then it a possibility.

Thank you guys. There was never any engine knocking, so it shouldn't be damaged then. I will try the ECU reset tonight and if things don't get better, I will take it to the dealership. I'm just trying to avoid that at all costs because I hate anybody touching my car but me. But whatever it takes to get her running well until the LS swap...

Ok you bring up knock but do we know we get knock at 87? The ECU is a smart piece of work that pulls back the engine to prevent knock.

It would be interesting to run a datalog while running 87 to see if there actually is any.. i'm sure someone on here has done that.

Isn't there a sticker inside the fulel filler door that says PREMIUM unleaded fuel only?

Doesn't it actually pull back the engine AFTER it detects knock? In other words, there some knock must happen before the ECU adjusts the engine, so it only can prevent more knock?

Ahh that's a good point, that could be so. See i'm still trying figure this out myself.

There probably is one someplace yes. I only bring it up as a possible not as a given. I would hope that the ECU would prevent any issues and under normal driving it would almost be guaranteed that it would. Hard driving on the other hand could be a bit of a gamble to trust that it would all the time. They require high octane for a reason and I don't think I would want to trust the ECU to protect my engine for a prolonged period. That isn't even taking the retarded timing and resulting loss of power into the equation.