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04 CTSV 500rwhp, 96 FTS-V T56 previously, 95 T56 Impala SS
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433 Posts
Discussion Starter #1
Ok... Well, some of you may know that I've been chasing a running rich problem pretty much since I bought this car. I figure I'd post the question here though, and we can go at it again.

So it runs rich. Really rich. And I've replaced just about everything at least once. With the gears and tranny I have, I should be getting AT LEAST low 20's MPG on the highway, but I don't. I drive mostly highway (85-90%) and I average 18MPG per tank. My normal highway speeds are 75-85mph, but at 80mph in 6th gear, that's only 1850rpms with my 3.73's (I'll be switching to 4.56's as soon as money allows). I normally drive with a fairly liht foot too. But that doesn't really effect my mileage, on the tanks that I beat the shit out of the car, I get low to mid 18's, when I drive like yo mama, I get mid to high 18's, or MAYBE low 19's.

Here are my mods, at least what I can think of that would relate:
Custom intake with 7" S&B filter
TB Airfoil
Chevy ZZ3 Cam
Proform 1.5 roller rockers
Tri-Y headers
Bosch platinum plugs
No cats
True duals, 2.25" with h-pipe
T56, 6 speed manual trans
Stock Z28 Clutch
3.73 gears with Eaton posi
OBD-1 conversion - custom program

Things I've replaced:
o2's with new GM units. twice
MAF sensor swapped with known good one
Cleaned and rebuilt TB
New plugs (3X! 2 sets Bosch platinums and 1 set NGK TR55 coppers)
New Wires (twice. 1st Taylors, now Magnecore)
New optispark
New coil
New 6 speed GM EGR
New GM 6 speed EGR solenoid

There are no exhaust leaks. Car SMELLS rich. Like real bad. Your eyes will tear if you are driving behind me. Worse when warmed up. Not so bad when started cold. Keep in mind it has done this since before I started modding it.

I have a feeling that it has a bit to do with the program, but do not think it is totally the problem. I am not very familiar with the programming yet, so I cannot comment on it. I can send the file to those who may be familiar. The base program was dyno tuned on another zz3 car with similar mods, so I would assume it is close.

I am working on getting Tunercat and Freescan working on my laptop.

So... Any suggestions?
 

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04 CTSV 500rwhp, 96 FTS-V T56 previously, 95 T56 Impala SS
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433 Posts
Discussion Starter #2
Oh, and I should add, I run 93 octane gas (required for my programming) and I go to the same pump at the same station 99% of the time...

According to Datamaster on a friends laptop, I get no knock retard anywher in the RPM range, but that's all I remember from that...
 

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'05 XLR
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1,698 Posts
Have you checked/replaced the coolant temp sensor? That can occasionally cause some problems with fuel mixture without throwing codes.

How about the injectors - any chance one or more are not functioning properly?
 

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Registered
04 CTSV 500rwhp, 96 FTS-V T56 previously, 95 T56 Impala SS
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433 Posts
Discussion Starter #5
the Sandman said:
Have you checked/replaced the coolant temp sensor? That can occasionally cause some problems with fuel mixture without throwing codes.

How about the injectors - any chance one or more are not functioning properly?
Oh yeah, forgot those. Both have been replaced. :) Both coolant sensors, the one in the water pump AND the one in the block...

And it got newer injectors with the cam. They had miles on them, but low miles out of a spectactularly maintained Impala...

Thanks for the thoughts though. :)
 

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04 CTSV 500rwhp, 96 FTS-V T56 previously, 95 T56 Impala SS
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433 Posts
Discussion Starter #8
the Sandman said:
Could there be a problem with the fuel pressure regulator, or a restriction in the fuel return line causing increased fuel pressure?
Both possibilities. I'll look into it. I was under the impression that the FPR's in these cars never fail. But it can't hurt to try. I think I have a spare one, actually. :)

Oh, new fuel filter too...
 

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53 Eldo, 54 CDV, 74 FWB 96 FWB (sold),1998 STS(sold), 03 ESV
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755 Posts
Put some high flow cats on there and then see how it is. I removed the cat on my 1983 Firebird and now the exhaust smells really gasey and basically stinks.
 

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Eldo1953 said:
Put some high flow cats on there and then see how it is. I removed the cat on my 1983 Firebird and now the exhaust smells really gasey and basically stinks.
I had the same problem on my 99 towncar and all it was, was a faulty oxygen sensor. Sounds simple, but maybe.......
 

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'05 XLR
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1,698 Posts
miishmiish said:
I had the same problem on my 99 towncar and all it was, was a faulty oxygen sensor. Sounds simple, but maybe.......
He said he changed those twice (he didn't say it twice, he changed them twice :D ).
 

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04 CTSV 500rwhp, 96 FTS-V T56 previously, 95 T56 Impala SS
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433 Posts
Discussion Starter #12
Well, I bought another Coolant sensor for the water pump. Gotta put it in.

I also contacted my programmer again. Hopefully he can lean it out a bit. We'll see!

Thanks guys! :)
 
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