sharpe

1000 RPM roll. Nail the accelerator. Nothing.

It bogged down until it got to 2500 then spun. Across all of my RPM range the car has gained a huge amount of performance, but under 2500 RPMs it is still a dog. Won't even spin the tires.

With the paycheck I got today I went and got two new O2 sensors. I sure hope they do the trick.

If they don't, I guess I will take it to another shop that can check the fuel pressure. Maybe it is a weak pump. Maybe it is a weak coil. I don't know.

This is making me sick... literally.

sharpe

But, if it was a weak coil, it would be weak throughout the RPMs; it wouldn't have a place where all of a sudden it "woke up" (2500 RPM), right?

Would O2 sensors also have this symptom? Why is it so dead under 2500?!

10 seconds

Wouldn't bad 02's set a light? but if they are bad that could affect your performance. PS: coils have more affect the higher in rpm's you go,usually.

Pneumatic_Tire

If all that didn't help fix the initial problem, I'd be starting to wonder about internal problems. Have a compression test done on the engine. Other wise, good luck. Your camshaft may have had enough. Before condeming the cam though, see if you can have the lifters adjusted within specs.

Need4Camaro

... $165.... for ALL that....on a V8.... and it's costing me $225 just to change ONLY the Plugs...for a V6...


For 10 Seconds information, a minor tidbit...

There was a write up on O2's that sometimes they go bad and DON'T send a code or SES light. This causes a HUGE mishappen that eventually leads to your car running rich and leaving fuel deposites that are enough to clog up your exhaust, coughing it up your vents instead of your pipes... Not cool unless you like falling asleep while behind the wheel. It's a real slow process though.

I kind of disagree with the "Coil" statement too, being a weak coil effecting only Higher RPM ranges... Trust me they can affect just about anywere in the RPM range and leave some parts unharmed or just barely affecting it to the point you wouldn't even notice. This doesn't mean that if a Coil's bad that it can't or won't hurt the whole RPM range, it just means they can be quite various. My dads 98 3.8's Coil bit the dust and it would rock and ride rough as hell up to 30 MPH... and after that it was just plain fine... it turned out it was the coil and we didn't have problems since...

I'm not sure how much they are for you or if you require different one's, mine were about $25... RELATIVELY cheap considering some alternatives... Even if this doesn't work, atleast you're sure you got some good coils in there and that definately helps ignition. Oh yes.. another thing about coils. DON'T trust their appearance on the outside, even if it looks PERFECTLY clean and shiney on the outside metal connectors, they could still be bad. I've run into cases like that several times.

sharpe

Well, I do smell gas/exhaust fumes sometimes when I really get on it. I already bought them ($50 apiece), so we'll see if it fixes the problem. If I have fuel deposits in my exhaust, where will they be and what do I need to do to clean them?

Also, I have no idea how long this car has been without an air filter. The car does see dusty gravel roads regularly. I am well aware that driving without an air filter is a huge mistake; that's why I ordered the SLP CAI. But, the damage could have already be done, what ever that is. Might the intake need cleaned or something? What all could this harm? What do I need to do in this regard if the O2 sensors don't fix the issue?

Cams can just get "worn out?" I'll read up on how to adjust the lifters. I may come back on another thread to ask for more instruction if I don't think I find enough information.

sharpe

Before I go any farther, let me stop and thank all the people who have offered me good advice and helpful opinions. I really appreciate it. Thanks.

Here is a pic of my poor car. She thanks you all for the help as well.
http://www.bridgeportleader.com/94z28.jpg

Chenzz

I have a 99 z28 ls1 m6 and I had a similar problem with mine where I would have nothing and then have a jump and then die down again. I went through the whole process that your going through now and none of it helped at all. The problem turned out to be in my fuel system. People kept telling me it was the fuel pump. So I changed it to a Walbro 255lph pump and that didnt help either. Truth be told, and Im not sure if u lt1 guys have the same setup, but GM really screwed us with the sending unit.

The fuel system contains 2 fuel regulators, 1 in the engine bay(?) and 1 in the sending unit. The 1 in the sending unit cannot be replaced. you have to replace the entire sending unit. Most likely ur problem is the check valve in the sending units regulator and therefore not enough fuel pressure is reaching your rails.

check ur pressure and if u guys have the same setup this could be the answer to ur whole problem.

Let me know
Good Luck
Vinny

sharpe

Thanks, Vinny. I'll be sure and check my fuel pressure as soon as possible, and definitely before I buy any more components like coils, which are next on my list if changing my O2 sensors doesn't help.

I don't know if I have said this before, but my car even sounds doggy down low.

Andrew04ME

It's hard to imagine that after reading this entire thread that no one has mentioned the optispark. I would give the Opti a little more chance of being the culprit than "a worn down cam." If i were you, i would find a way to have your car scanned. If you have a laptop (a regular PC would work too) you could buy a cable from AKM ($90) or www.mastach.com ($45). Download some free software (Freescan or TTS Datamaster) and you could retrieve data that you could copy and paste in lt1 tech or something and let others help you figure out the problem. This would also be a good way of retrieving codes that may be present but haven't tripped the SES light. You may also find a little more help in the lt1 tech section. I could almost guarantee that someone in there has had a similar problem to yours.

Running without an air filter would cause particles, dust, etc to eventually reach the combustion chamber. In the long run it's very possible that it could lead to issues with your intake valves, and even cause wear in the cylinder bore. This could equate to increased oil consumption and loss of compression, which would hurt power.

Return those 02's for now and take the money and get it scanned!

Need4Camaro

If I remember correctly, it would be around the Cat or in several cases, in it. I forgot to be honest. If you're running without a Cat, check where it used to be and see what you can find.

I strongly agree...

sharpe

Can I buy an optispark and replace it? I have a laptop, an Inspiron 8100 that's only a year old. I went to mastach.com and had a look. I would be scared to do it, but I would try. Still, if optis go out, then I would rather just replace it than spend money and time on diagnosing the problem. The car has 118,000 on it. I'm going to replace the O2 sensors and have the fuel pressure checked, but I will try replacing the optispark first and then the coils before trying to adjust the valves.

sharpe

Holy crap! I did a search for "opti" in the LT1 board... There were so many people that have my same precise problem, no power between idle and 2500 RPM.

Damn, now I need about $450 for a new one...

Andrew04ME

Do a search for Jason Cromer. He's a parts guy at a dealership down in Florida. He's usually cheaper than wholesale. If you don't want to deal with him try www.gmpartsdirect.com. They are cheap, but charge an arm and a leg for shipping. You should pay no more than $300. If you have a laptop, just buy a cable from mastach.com. They send you directions on where to plug it in. The software is free and couldn't hurt to have.

Here is a good write up on opti replacement.

http://www.streetillusionsracing.com.../opti/opti.htm

Silvershark

Keep us updated. You will figure it out.