Netwrkengeer

Hello this is my first post here so I will introduce my self before I burden you guys with my problem.

First off My name is Robert and I live in Farmingville, NY
I own a Black 94 Z28 with the Following mods
De-screened MAF
Tb by-pass
Fan Switch
Moroso CAI
Jet Air-Foil
Free Ram-Air
Flowmaster cat-back
Trans-Go shift kit
BMR Control Arms
BMR Torque arm
LT4 knock module
160 degree thermostat
Use only Mobile one synthetic

My car has been really great with plenty of HP but just recently it has been backfiring and has a real loss of power and horrible throttle response under 2500RPM. But only backfires when it warms up.

I have done a few things to try and fix this problem.
For example
Replaced All Plugs and wires (Used Di-electric grease)
Replaced Fuel Filter
Replaced Intake Air Temp Sensor
Replaced PCV
Replaced Air Filter (Oiled air filter as well)
Cleaned Throttle body with Carb Cleaner
Cleaned the Diodes in the MAF with Electronics cleaner
Used Octane booster
Used Fuel injector Cleaner
Checked Fuses and Battery
Disconnected battery for about 10 hours to reset the Computer
Disconnected the MAF and ran engine
Disconnected EGR Valve and ran engine

Well I'm still having the problem and every mechanic I talk to suggest replacing something different I don't want to have someone replace many expensive parts because they are not familiar with the LT1 engine. Some things I have been told to replace.

EGR Valve and Vacuum solenoid
O2 Sensor
Fuel Pressure Regulator
Map Sensor
MAF Sensor
Coolant Temp sensor
Ignition control module
Intake air control valve

If there is any way you can help it would be greatly appreciated.

Thank you,
Robert

Crazy95Z

Is it throwing any codes? Or have any stored in the pcm? Autozone can usually pull them and tell you what they are. If so, I'd replace whatever they tell you about the codes. Then come back here and post if that doesn't fix it. We really can't give any more than possible guesses without more information.

Compstall

Scanned for any codes? How old is the opti?

dreamer1q

Sounds like what mine did when the coil was dying.

hammersz28

Hey dude, sounds like your opti-crap is going out on you. If I were you I"ll go with the the delteg system, because you never know what you may get with a new opti-crap, it"s a crap-shoot. I replaced three optis in two years on my 94z . I know it's a little more expensive, but take my advice, you won"t regret it.

BUBBA

I'd opt for the inexpensive things first. If you still have the originall 02 I'd seriously consider changing it, since if bad it could booger your cat. JMHO

Netwrkengeer

I'm not sure about what codes it is giving me yet but will soon.
If it is the O2 wouldn't the check engine light come on?
I remember with the impala ss there was a recall item for a similar problem does anyone remember this. I think it was the EGR.

Netwrkengeer

Hammer how is the Delteq, do you notice an increase in HP ect...

phinger23

stop trying to chase down all them mexicans in farmingville and your car will thank you! j/k
im from franklin square (nassau county)
since your cars older, no no on the autozone scan...too old.
your opti may be going...but try a new coil to start, and check your fuel pressure.....but im gonna go with ignition.
how many miles are on it?

Compstall

It ain't too old what're you talkin' about. It's OBD1, wasn't THAT long ago.

phinger23

yea, and any AZ i been to dont read OBD1 cars.

hammersz28

I can't say that I've noticed any horsepower difference, but my baby does rev like a ****.

Netwrkengeer

Miles = 95,000

Hammer - How was the install, how does it run off the opti and what did you do with the wires, obviously the stock cable won't run to the valve covers.
Do you have photo's?

Also does the Delteq have the secondary spark on the exhaust stroke?

kevm14

It has to, since there are only 4 coils. It's a "wasted spark" type system.

I have the same issue, just not as bad yet. Under 2500rpm, when warm, throttle response and torque in general is pretty pathetic. Turn the A/C on and it gets REALLY bad. The car will actually sort of buck and surge as it accelerates, making me look like a bad clutch operator, but it's not the driver...I think it's also related to the fact that, on a good day, my car can't do any better than 22 or 23mpg. It should be closer to 26. All of our (near-stock) cars should.

MyTMous

Cheap stuff first.
Fuel filter and Coil( Coil is like $18 at AZ)

if that doesn't do it Opti, "the key is it gets worse when it heats up"

that is an opti clue.

I went through 3 "new" ones before I got a good one.
check them out real well. I got mine from AZ with a lifetime warrentee.