DAVECS1

The car is a 2001 Corvette Automatic. Has TSP long tubes, X-pipe, Corsa exhaust, and Fast 102 intake and 90mm throttle body.

I've tuned a number of Lsx engines, with various packages. Jet, HP Tuners, and EFI live. This car I am using HPTuners.

First off the car runs great, almost like OEM, but with a noticeable idle, at about 800 RPM. The part that concerns me is the VE table. When I started tunning the car I was getting 17 and up AFRs on both widebands (one for each bank) and the narrow bands were not crossing. The car was surging pretty bad. I was not concerned as I know, larger aftermarket cams with tighter LSAs (112 in this case) will have this effect and unburnt fuel can make O2 read a false lean.

So I started decreasing the VE at idle as I normally do with aftermarket cams. The was no improvement, and the car was having trouble staying lit especially going into gear. I checked my airflow for IAC starting point again and it was relatively low at 2.3 or so. I then opened it up a bit which did not help. So I put it back to my original values.

I then put the car back into closed loop with, no timing correction ad set the timing values to an absolute 26 degrees. The WB and came back to 14.7 and the narrowbands started crossing and the car idled extremely smooth almost stock. I watch the injector opening time and it had increased from 3.1ms to 3.4 ms.

So with that data I figured I would add some fuel to the VE table. SUre enough things got better. To get the engine back to 14.7 or better at idle in closed loop though, my idle VE table values are in the mid 90s!

with that being said with STFTs turned on and timing compensation reactivated I am getting about 3-0 percent correction on fuel and the car runs decent everywhere.

These idle values just do not seem right. I am kind of thinking there is a vacuum leak, BUT even with this cam my idle KPA is in the low 40s which would seem about right if not high, and backing down the IAC will make it stall. Though I have noticed in gear the the car goes up to 60 kpa and it does not take much to get to 100 KPA when revving it.

Any ideas, opinions, or other tid bits of info appreciated.

BLK02WS6

iTrader: (2)

What injectors are in it and are the injector tables stock or have they been altered?

DAVECS1

Stock injectors and injector tables

sweet-94z28

iTrader: (30)

Did someone at one point get some stock 1999-2000 26# injectors in it? Have you verified fuel pressure?

I've never seen that before and I've done quite a few heads/cam and cam only cars. Sounds to me like something is amiss. What is the VE at lets say 5600 RPM at 90-100 KPA? That cam should be 50-55ish at idle and like 105-110 on the high end.

Maybe post the tune and a scan as well.

DAVECS1

mid 90s to about 105, My ve curve looks like a sideways U. Fuel pressure is good 48 at idle and 60 at WOT. The injectors are stock as my old man has owned the car from new.

sweet-94z28

iTrader: (30)

PE enrichment at ~1.140? Any knock retard on the scanner at WOT?

Another thing to try as well.... start the car, warm up and let idle for like 10 minutes. Pull a plug and look around the base. See if it's sooty. Just an idea. The wideband should be picking that up though....

DAVECS1

PE enrichment at what IAT or RPM? I have about 15 logs that are about 15 minutes or longer. Only blip in the knock retard I have seen is instances were I have gotten into the traction control too hard on a dusty surface. Most all of my runs are free from any timing being pulled.

I am leaning towards a vacuum leak, but I find it odd I was able to tune it out.

BLK02WS6

iTrader: (2)

That is what I would look for... you can tune them out, have seen that before...

joecar

If you have the stock FPR then this is incorrect.

DAVECS1

Well I took the Fast 102 Intake off tonite. Installed new port seals and put silicone around the perimeter seal of the intake, for the two halves. Then I rubbed down the injector O-rings with silicone gel and did the same to the port seals. Then used loctite on the bolts that joined the two halves of the intake.

After reinstalling the intake. I ended up having to take 80-90 percent of the fuel out. I am tempted to start with a stock tune, but I will take a couple swings at what I have as many of the other tables are close.

Long story short, it was an intake leak, however small. If you are seeing wacky VE values at idle, check your intake.

DAVECS1

Got another question. This is my first auto vette. It is the A4 with a 2.73 rear end I believ and a stock stall. I have the car sounding and running pretty stockish at idle, unfortunately. It makes some good noise when you stomp it though.

My question is, should this car be exhibiting any cruse control feeling. When you let of the brake it gets to about 10 mph with no gas pedal. My idle trims are less than 1 lb/hr. the idle trims shut off once it starts rolling and the ETC goes to 13 percent and it goes down the road about 1100 rpm. I zeroed out the throttle cracker down low and it helped a little.

Timing is about 27 degrees when this is happening. Was thinking of taking it down a couple degrees and see what happens, just not excited about getting the ve reset and the redoing the raf tables