I find it fascinating we all here have the exact same problem.. before I could never find anyone to relate with as far as this goes because no one else had the problem.. Im thinking of taking it out to the mechanic I know.. there aren't any big shops here so I don't really know if he will be able to fix the problem besides throwing parts at it like everyone else is doing.. but everyone who solves the problem PLEASE post what you did it will make everyone very happy

 

Same problem for two years. Bogging and surging when it get to normal running temp. But my tends to start reving on it's own I hope one day this problem will get fix for all of us. It really hurt the value of the car. However I love my Z28 and wont give it up for nothing






94 Z28 Teal w/T-tops
BMR strut tower brace
1LE elbow
Moroso CAI
Car sound hi flow cat
Magnaflow cat back

 

mine too

 

Mine is fixed.

Wires.

I've replaced my opti also but my problem was wires. If you have a bunch of miles and years on an opti, it could be corroded from the rotor inside arching for years, just like a distributor rotor.

Good Luck

 

I think I'm going to start with a plug wire change considering it needs to be done anyway and hopefully it will solve the problem. If not, then I'm going to take it to a shop for a diagnose. I'm excited that I'm not the only one! If anyone else fixes the problem, let us know asap.

Thanks!!

 

tell us how the wire change goes for ya.. right now id buy a 500 dollar wire change if it fixed the problem =O i love my car

 

The car runs fine when cold. When the engine warms it starts running bad. When the car is cold a higher percentage of fuel to air is supposed to be sent to the cylinders than when it warms up. When the engine warms it requires a leaner (less gas) mixture. The MAF or computer is not making the adjustment when the car warms up. It is supposed to lean the mixture as the car warms. You might be able to re-program this for your modified MAF. I am sure modifying the MAF without changing anything else may have mucked things up. If the computer is sensing more air it may likely be dumping more fuel also. Not so much of an issue when the car is cold or going WOT, but initial take off, perhaps. I have experienced this with carburated bikes when the needle for fuel is adjusted to high. Everything is fine whilst it is warming up, but once it gets warm it stumbles from take off, a result of too rich of a mixture when the throttle is initially depressed.
I think that is the problem. A previous post said putting in a fan switch cured his problem. Well, it allowed the engine to run cooler requiring a richer mixture.
Just my two cents, but me thinks it is a lean vs rich issue that perhaps could be programmed away.

 

When the car goes into closed loop operation, it is going to run like crap if the fire is not at the spark plug.

Raw oxygen goes to the o2 sensor and the o2 sensor tells the PCM to add gas to compensate for the Oxygen it is sensing. Therefore you are running rich. Mine was doing this to where the back of my car was covered with carbon spots comming from the tailpipe.

I still think it is a wire problem. Make sure the wires are contacting good where it enters the opti and where it goes onto the plug. look anywhere where the wires gets close to the block or anytype of ground.

And don't be afriad to buy new wires.

D Moss

 

when your car bogged down, do you have your AC on??

 

It bogs when the AC is off but is even worse when it is on.

I was thinking that the MAF might be a problem for that very same reason. I'm going to change my wires hopefully this weekend. If that doesn't do it, then I'm planning on buying the stock MAF that that one guy is selling here on the forums. If that doesn't do it... then I'm stuck with an extra stock MAF and am going to have to dish out more money for a diagnostic Oh well, we'll eventually get this problem solved

Oh and as far as my cooling goes... I have a 160 degree thermostat and I just replcaced my waterpump. My temp never gets hot, just warm. My cooling system is perfect. The bogging just mostly occurs when it's hot outside, the egine temp is just a little warmer...

 

hrmm when I bought my car the water pump had just been replaced and there was a 160 thermastat in it already.. so im guessing the people before me had a few goes at trying to fix it..

 

I remember reading a blurb about how a ported MAF makes the computer think that the engine is sucking in something like 20% less air and acutally reduces horsepower unless the computer is reprogrammed for it. This was because the center bar accelerates the air around it and past the sensor. The is even a file for LT1 edit that is supposed to compensate for that. I don't know if that is causing your problem but, with the MAF being 20% off, it can't be good. High flow aftermarket MAFs that do not have the center bar are calibrated to funtion correctly. Do you know anyone that has an lt1 that you can borrow their MAf from

 

Z28Chick, I kinda skipped throught this forum reading most of the replies. You said this problem existed before the water pump went out. There is a weep hole at the bottom of the pump. Mine was leaking onto my opti and my opti went out before I realized the water pump had gone bad. The problem you describe is the problem I had as well. I replaced the opti and the water pump and it cured my problem. In almost every case, when the water pump goes (if it leaked onto the opti for any length of time) it usually takes the opti with it. One other thing you might check that I don't think was mentioned is the coil wire going to the opti. Pull it off and check for corrosion. This wire is notorious for problems.

 

I don't have one I can borrow but like I said that guy is going to sell me one for $50. I do agree with you though. I don't think it's a good thing to have a ported stock MAF.

Delsoto, I'm pretty sure it was not the leaky waterpump that would've made the opti go bad because this propblem began 2 years ago and the waterpump just recently started leaking. I noticed it right away when coolant was being flung all over my engine If my opti were to have gone bad 2 years ago, then it probably would've been from when my old friend washed the underside of my engine.

I'm leaning toward my opti spark being bad so I'm going to kinda need a 'how to' on how to replace it. Like I said earlier, all I know about the opti is the little info I have heard. I've never seen it and I don't know where it is and so on... Think one of you could e-mail me instructions or something?? Thanks!

AZSarah84@netscape.net

 

you have mail....