sam

Im sure someone can help. I cant think of were to start looking. Hopefully someone experienced something simillar and solved the problem


It is a 5.0 TPI firebird.

It runs like crap and then at some times it is a beast. When bad it hesitates to rev pass 3000 revs and if it does it does not have the power that it has when running good. I checkled for error codes and non have been set.


It run so rough at one point that when rolling in neutral I pressed the gas to rev it ands it reved then died on me


Hours later it ran great. After that back to crappy mode.


I think I have condensation in some electrical parts but where? any sugestions?

Feels like it runs better when it starts to warm up good.

Thanks

Samer

Toehead

did you try running it in the dark and looking for llighning along your wires/disty cap? That is where I would start.

yzinger1

kinda sounds like you may have water in your gas,have you changed your fuel filter?as for the water in the gas ,get some denatured alcohol from your local hardware store,and pour half of it in the tank ,have atleast half a tank of gas.this will get rid of the water.as for the fuel filter ,it would be a good idea to change this either way.if you have water in the tank its in the filter also.i really hope this helps jimmy

sam

Thanks

Today it is running perfect... But I will check as you suggest, in the dark when it starts to act wierd again GREAT TIP!!

Fuel pump is new and fuel is just been filled up so any water should be minimal. but I will try the additive.

Does the computer have its own ground? I was told it could be a grounding problem? The casing is under the dash and lose but it is plastic so it cant be the grounding

thanks,

Sam

sam

running like cra again, probably can be out run by some old broken down 1.3 L mazda.

I checked at night and no lightning as far as i can tell.

Thanks,

Sam

yzinger1

sam ,there is a ground on the back of the engine where the transmission bolts to the block,both sides.you said the fuel pump is new ,is the fuel filter?,may be partially clogged enough to hurt fuel flow after running it gets clogged badly .then after it sets debris settles enough to let enough fuel pass to run fine for awhile. trouble shoot the fuel system first,then go to the electrical.fuel is easier.hope this fixes it .trouble shooting is nooooo fun!!!later,jimmy

sam

Sorry man, I meant fuel filter is new, fuel pump is probably stock and original

BUT I have a new edelbrock pump going in soon, hopefully that will make a difference.

i am droping the car off at the mechanic for diagnosis. Ill let you know what it turns out to be. I just dont want to do the trouble shooting, just the fixing when the fault is found

thanks,

Sam

yzinger1

hey man i dont fault you for that ,if you will let me know what it was, thanks,jimmy

Toehead

I'm interested too!! I would lean towards some sort of ignition system/ sensor problem that has an intermittent short...

sam

turns out a bad spark plug and much lower pressure in that cylinder than the others. So time for new engine soon.

Is it best to run with the injector unplugged on that cylinder?

Thanks

Sam

sam

Let me clarify, Cyl # 3 had 25 psi less than the rest/highest. The spark got covered in oil and crap. So it was not firing strong......

It runs great now. Burning out everywere hehehe.

Q) Is 25 PSI or is the limit greater? How bad is it really? Should I run thicker oil to make it last a bit longer?

I will probabl;y change engines in the summer

Thanks

Sam

PhLaXuS

I believe the spec is each cylinder should be between 100 & 150 PSI with a maximum variance of 20% from the norm for your engine. I doubt heavier oil will help much, but it's worth a shot. Depends on a few factors.

sam

dont know if it was a good idea but I added engine restor ( a blue oil additive) and I feel a difference. maybe just in my head though as i have no evidence hehe

Vader

Thicker oil may be the problem, not the solution. Most additives (Lucas, Restore, STP, etcetera) are only polymer additives in higher viscosity petroleum oil. That almost never helps anything but the companies selling that garbage. If an engine is really gone, additives like that may allow it to limp along without getting 10 miles per quart, but it's no "fix"by any measure.

Multi-viscosity oils with a poor inherent viscosity index and loads of polymers to compensate for that (like Pennzoil/Quaker State used to be) tend to create heavy carbon deposits around rings and in ring grooves within a couple thousand miles. Sticky, nasty, coked, dirty rings won't seal, and will show as low compression. Years ago, I used Pennzoil GT religiously, until I started tearing down those engines that used it - most at 100K miles or less. I never went back. The correct viscosity oil, changed regularly, may actually improve your situation. Synthetics may even more help in the long run.

FWIW, 25 PSI differential really isn't unusual. The percentage difference is more important. Keep good quality, clean oil in it, and it may get better. It certainly can't hurt. At the least, if you've already lost a ring and/or bore, you may save a crank.