Ok....So the car was fixed until tonight....My problem is that at idle the motor shakes and seems to be missing, then when you give it gas its weak. Like it won't pull a greased string out of a cats butt. It won't turn a tire over or anything....Here's what I know: Oil has gas in it, front four cylinders appear to be dead.....Here's what I have checked: fuel pressure is around 44-45 lbs, I pulled the plug off the front 4 injectors and the motor didn't run any different, changed the front 4 injectors for the back 4 injectors and nothing changed, Both oxygen sensors appear to be staying between 0-900mv, MAF reads between 7-9gps at idle, all plugs appear to have fire to them, along with all cylinders seem to have good compression, The left bank plugs are black while the right bank plugs seem fine.....That's all I know and I'm stumped.....Maybe regulator????

 

As Dave (speedy) pointed out to m just a day ago, the oil with gas in is is bad. Your engine cylinders are probably not firing yet still getting fuel, so your cylinders are "swamped." Speedy knows more about this than I do, so I would wait for him, but yeah there are some serious ramifications that result from cylinders which take damage from this. Speedy, input?

As far as the misfire goes, I have had one for the last few months since I got the car. Although I initially thought it was actually a ignition issue, I think it was actually clogged injectors, and fiddling with them greatly increased performance and stopped the same shake you describe. You definitely have fuel, so that is not something I would look at. If it's not compression, it's spark. The black plugs on the left bank indicate you are getting fuel, so....that further verifies this, although the right bank plugs are definitely strange. I would suggest replacing all the plugs first, but unlike me, label which cylinder they went in and save them for future reference.

 

Wow. You got some issues! Like I had tell you right?

How did you determine the front 4 cylinders are dead and yet only the left bank plugs look black?

My experience says SBC's will not run at all if they have 3 or more cylinders out. So I think you are incorrect about the number of cylinders out.

First, you have got to get the contaminated oil out of the engine.

I would like to know what the fuel pressure does right after the pump shuts off?????????

When you had the fuel rails up to switch the injectors, did you power up the pump to see what they did while pressurized?

I suggest you do a couple of things. First remove the fuel rails and power up the pump. You can do this with the fuel pump prime connector and not even power up the rest the car. It's near the PCM. Shove 12 volts in it. Pressure comes up. See what the injectors are doing with pressure behind them. Obviously you will confirm the pressure while you do this.

Remove the 12 volts from the fuel pump prime connector. Pull the fuel pump relay and crank it over with the plugs out to clear any fuel from the cylinders. It's a good idea to give each cylinder a table spoon of oil at this point through the plug holes. A squirt can works good for this.

Now put the relay back and have someone crank the engine over while you look at the fuel spray pattern from the injectors. The rails are still up at this point obviously.

When you did the compression test, did you disable the injectors? if not you may have gotten bad readings. You also need to have the throttle plates wide open.

Double check the spark. particularly on the left bank. However since all 4 on the left bank (I think that's what you inferred), chances are good you have a control problem which any number of people here can help you with.

Could be you have a problem with the diaphragm in the regulator leaking fuel into the intake but the pressure you indicated does not support this. Also, a leaking FPR usually puts fuel to the back cylinders.
Let us know what you find. I have to go to work.

 

Lol, I was gonna say something about the 4 cylinder misfire, but I figure you would be here pretty quick.

 

Ha yeah I know and its bout to go off a cliff, ugh.....first off let me say i rechecked my fuel pressure today, and initially it is at 45 lbs then over about 20 seconds it drops to around 37 lbs.....I had a regulator off a v6 camaro I put on it and it improved idle, but turned out to be a peice of junk, busted around the part that slides into the fuel rail.....So I'm probably gonna buy another anyway.....To answer speedy's question: I pulled the plugs and they are black, but I thought about it and the oxygen sensor went bad after I put those plugs in it.....So I went and got a new set, so ignore that part for now....The way I think I determined that the cylinders are dead is by pulling the retaining clip off of each injector and then pulling the plug away from the injector to see if it affects the idle of the car.....These didn't seem to affect it at all for the front four injectors, but the back four it did.....My dad also said its a miracle its runnin if only on 4 cylinders. So I will double check that as soon as I get a new regulator, assuming that doesn't fix it....I'm not to worried about the oil right now because I haven't run it hardly at all. I check my oil very frequently and any hint of gas I will change it, I burned up a cavalier motor like that one time.......Ok its gonna be probably turkey day before I can get back on it, but I will post updates if I get a chance to tomorrow.

 

I wouldn't worry too much about that 37lb fuel pressure. If I am right, that is pretty close to normal, so if it is a problem, it wouldn't be a horribly significant one. Rather, I would bet on something to do with the injectors or ignition instead. But yeah, that regulator may be causing a side problem, but I certainly wouldn't expect it to cause a 3+ (???????) cylinder misfire.

 

Never ignore a fuel pressure that is 15% below target....that might be at the limit of PCM correctability.

Since you won't get back to it until Thursday it'll give all time to think about it...

 

Are you measuring the fuel pressure with the vacuum compensation line attached to the FPR, or off the FPR? When the pressure was at 45psi, and at 20 seconds, dropped to 37psi, was the engine running?

Is there any sign of wet fuel in the vacuum compensation line?

 

I was measuring with the vacuum line on the fpr and getting those reading......I'm pretty sure that was wen the motor wasn't running, guess that could be fuel draining back into the tank......There was gas coming out of the top of the original regulator on vacuum attachment side........

 

Get the correct, healthy fuel pressure regulator on there before you do anything else.

 

Okay hold up guys. My apologies--I was assuming the car was running. HOWEVER, just to clarify for future reference, I thought that initial fuel drop after starting the car was completely normal and that fuel pressure was supposed to be 38-39 after starting and drop to 32lbs at WOT. Is this completely wrong?

 

With the engine running at idle, the fuel pressure WITHOUT the vacuum line connected should be 43.5psi. GM accepts anything in the range of 41-47psi as being within spec. When you reattach the vacuum line, pressure will drop proportional to intake manifold vacuum. With a stock cam, pressure will drop 6 to 8psi when the vacuum line is attached. With a more radical cam, the pressure drop will be less.

You also have to check the fuel pressure on the road, with the engine under full load - WOT/max rpm.

 

Okay, so at WOT what would be the expected fuel pressure? Was his 37lbs too low if the car were running with the vacuum on?

 

At WOT the vacuum line doesn't make any difference - there is virtually no intake manifold vacuum. You should not see any less than 40psi at max engine load.

 

that's extremely helpful.....I had to borrow a fuel gauge from a friend but I'm gonna go buy one along with a vacuum pump tomorrow so I can do that when I get it on.....I'll update Wednesday if I have time to work on it.....Thanks even though this wasn't aimed at me