kevm14

Hi all. I've been directed towards this apparent wealth of knowledge for a long time, but never really investigated. I have read a couple threads and like what I see, so I decided to register...

Anyway, I have a 93 Caprice 9C1 with the L05 TBI 350. I had an opportunity to dyno my car (5 pulls) for $25. Here is a link to an Excel chart of one of my runs.

http://kmoore.res.wpi.net:8021/9c1/d...%20Run%201.jpg

You will immediately notice that the air/fuel is HORRIBLE when RPMs reach 3500. It gets way too rich for some reason. I have tried the $0.25 FPR mod once, but took it out many months ago (made no difference). I suppose I could have hurt the thing, but I kind of doubt it. Fuel filter was done a couple months ago. I have no muffler, but I do have the stock large cat and resonator. The cat may be contributing to the rich problem. I get fine MPG with the car and part throttle drivability has been improved since I disconnected the EGR vacuum control solenoid (was blowing my ECU fuse and disabling the car). I have a K&N air filter. Peak HP was about 155 but it SHOULD be more along the lines of 170-180 (rated at 205hp @ 4400rpm stock). Torque is perfect, rpm wise. Maybe 5-10 lb-ft too low, but nothing major.

You'll also notice that my HP peaks at about 3700rpm. I think the extra fuel is causing the problem. It seems that if the car was able to continue the torque band a little longer, it'd peak HP at a higher RPM as well as the actual value.

So has anybody seen this before? This car has run a best of 15.86 @ 85mph at New England Dragway (NOT cold weather). What I am not sure about is if it was running on 155 RWHP then or not...

I have run two bottles of injector cleaner through the system (two at the same time, with like 5 gallons left). That didn't do a whole lot. Right now, the only thing I can think of is the EGR solenoid that was messing up, causing the EGR to improperly recirculate gas at WOT, causing a rich condition. It's just that I've been driving the car hard a lot since disconnecting it and it just doesn't seem like I've gained 15hp. It DOES feel like I have gained part throttle torque, which is great for MPG, but doesn't help my top end. Actually, I LOVE the way it cruises now. According to my scanner, 20% throttle cruises at a steady 90mph with my 3.42. Pretty sweet.

My next plan in diagnosing the thing is to get a fuel pressure guage and see what's going on. It may be too high. Other than that, a clogged K&N (which shouldn't be clogged) and bad O2 are the only other things I could think of. Any advice?

I will probably be dynoing the car again on October 20th and we'll see what kind of torque & HP gains were from the EGR vacuum solenoid disconnect...

Thanks for entertaining my queries...

-Kevin Moore
93 9C1 350 TBI

V8Astro Captain

iTrader: (1)

Well if you got a scanner, what does the BLM and Integrator say?

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'92 Astro 350 TBI Edelbrock intake, MSD 6AL, 3.42's, 2.5" exhaust, Flowmaster 40 2 chamber, B&M 2nd stage shift kit, 255 60 R15 tires on AR-727's, Polished & Bored TBI, Custom EPROM in progress

kevm14

I meant to mention before that during extended highway cruise when the computer switches to that really lean mode, the O2 voltages are like 30-50mV. So it runs nice and lean when it's supposed to. The BLM and integrater don't really show a rich condition. Maybe once after a long trip, I caught BLM at 133. That's not too bad. I've also caught it at 126 though. I guess I should also try to determine if the computer is doing it on purpose or if it has NO idea that much fuel is being dumped in there...

-Kevin

Brent

iTrader: (1)

Where are those AFR numbers from? A wideband O2 or your scantool?

If they are from the scantool its nothing to worry about.

If thats from a WB O2 you could benifit from some Prom burning.

kevm14

My scantool talks to the computer...and the O2 talks to the computer. I can assume the O2 numbers are what I would get if I hooked a multimeter directly to it...or are you talking about the Integrator/BLM numbers?

-Kevin

Brent

iTrader: (1)

My question is, where did you get the Air Fuel Ratio numbers that are plotted on your graph?

kevm14

Oh, I guess I didn't really mention that. Sorry. Those numbers were from a wideband O2 up my tailpipe during the dyno runs...
Does that help?

-Kevin