I installed the REV300tvs kit a few months back and everything seemed perfect with the car. I've had the lotus parked the last few weeks, and then a friend came to visit over thanksgiving so I took him out for a drive in it.
When I last drove it a few weeks ago, the air temperature was around 70 degrees or so. During that time, my A/F was spot on between 11-12.5 : 1 at WOT (depending on load, etc) and it didn't seem to move around much. During that time I didn't experience any strange noises or any hesitation at any RPMs.
This week it's been down in the 30s outside. I let the car warm up for a while to get up to temp, and then took it out for some aggressive driving. Everything seems fine in 1st and 2nd gear (although it blows the tires away so it's hard to notice any engine noises / issues), but when I was on the highway doing 3rd gear pulls, I noticed there was a slight hesitation around 6k rpms. If I go WOT starting at 5k, it will hit 6k, pause for a half/quarter second, and then continue accelerating. When I hit over 7200 rpm or so, the engine tone switches completely and it doesn't sound right at all. It's a hard sound to describe, almost like it switches from the normal engine sound to a high-powered vacuum cleaner.
I also noticed that the a/f ratio has gotten slightly leaner now. When I go WOT, it hits around 13.5 : 1 at first and goes maybe to 12:5 : 1 at higher rpms. When it starts making that noise over 7200, it seems to hit down to 10:1 or so, although it's hard to tell if that's happening when I release the throttle or if i'm bounding off the rev limiter at that point.
For reference, the car is stock besides the rev300tvs w/ koldfire tune and ST muffler. Car has 9800 miles on it.
So my questions are:
1. Would the drop in air temperature cause the car to go leaner overall since it's presumably making more power from the colder air? I have an 05 so there is no AIT sensor to adjust the tune for the colder air. Or does the 30-40 degree drop in ambient temperature not affect the car much once the engine is warm on a non-intercooled car?
2. What could cause that brief hesitation around 6k rpms? The tone of the engine doesn't change at that point, I just noticed that it hangs that for the split second before screaming past it. Maybe a small amount of clutch slip and then it catches at 6k?
3. Any idea why the tone of the engine would change so dramatically over 7k rpms? Could detonation cause a big change in the tone of the engine? Or maybe spark blowout? Or possibly valve float? (although I'm not sure why that would have suddenly happened when it got colder out)
4. What is the actual redline (where it cuts spark) of our engines with a Koldfire tune on the rev300tvs? And what's the realistic redline for our engines with the same setup (where I should shift to stay out of the danger zone)?
Thanks!
When I last drove it a few weeks ago, the air temperature was around 70 degrees or so. During that time, my A/F was spot on between 11-12.5 : 1 at WOT (depending on load, etc) and it didn't seem to move around much. During that time I didn't experience any strange noises or any hesitation at any RPMs.
This week it's been down in the 30s outside. I let the car warm up for a while to get up to temp, and then took it out for some aggressive driving. Everything seems fine in 1st and 2nd gear (although it blows the tires away so it's hard to notice any engine noises / issues), but when I was on the highway doing 3rd gear pulls, I noticed there was a slight hesitation around 6k rpms. If I go WOT starting at 5k, it will hit 6k, pause for a half/quarter second, and then continue accelerating. When I hit over 7200 rpm or so, the engine tone switches completely and it doesn't sound right at all. It's a hard sound to describe, almost like it switches from the normal engine sound to a high-powered vacuum cleaner.
I also noticed that the a/f ratio has gotten slightly leaner now. When I go WOT, it hits around 13.5 : 1 at first and goes maybe to 12:5 : 1 at higher rpms. When it starts making that noise over 7200, it seems to hit down to 10:1 or so, although it's hard to tell if that's happening when I release the throttle or if i'm bounding off the rev limiter at that point.
For reference, the car is stock besides the rev300tvs w/ koldfire tune and ST muffler. Car has 9800 miles on it.
So my questions are:
1. Would the drop in air temperature cause the car to go leaner overall since it's presumably making more power from the colder air? I have an 05 so there is no AIT sensor to adjust the tune for the colder air. Or does the 30-40 degree drop in ambient temperature not affect the car much once the engine is warm on a non-intercooled car?
2. What could cause that brief hesitation around 6k rpms? The tone of the engine doesn't change at that point, I just noticed that it hangs that for the split second before screaming past it. Maybe a small amount of clutch slip and then it catches at 6k?
3. Any idea why the tone of the engine would change so dramatically over 7k rpms? Could detonation cause a big change in the tone of the engine? Or maybe spark blowout? Or possibly valve float? (although I'm not sure why that would have suddenly happened when it got colder out)
4. What is the actual redline (where it cuts spark) of our engines with a Koldfire tune on the rev300tvs? And what's the realistic redline for our engines with the same setup (where I should shift to stay out of the danger zone)?
Thanks!
