Bad misfire, engine doesnt want to crank, certainly wont run, shakes, etc. Just started running bad one night, and got worse over the next hour and I had to have her towed home.

Replaced coil/ICM. No change. Opti is 2 months old. Plugs/Wires check out okay. No access to a laptop or a scanner, and I'm fresh out of ideas. The car's running absolutely horrid if I can get it to run at all.

 

What do you mean by won't crank??? Are we talking about a starter issue as in it won't rotate as well as a running problem? Does the oil smell like fuel?
Let us know right away. If so, you could be flooding. But for the moment let's assume it's not.

As far as your running problem, you may have a spark issue but my feeling is, fuel is more likely. So rule it out first since it is easy to deal with. If you're dealing with fuel, the most likely is the pump.

My first suggestion is relieve all the pressure at the fuel rail. When you do, look carefully at what comes out. If all looks good and you relieved all the pressure, now cycle the power on engine off and then back to off several times and either put a fuel pressure gage on it or try relieving the pressure again to see if it built up pressure. You really need to check it with a gage though as it may look like it has enough pressure but in reality it may be too low.

If all that looks good, the next thing to rule out is injector pulses. Check to be sure with KOEO that all the injectors have 12 volts. If not, could be one of the 2 injector fuses is blown. If that's ok and the noid light shows a problem, the first thing to check is grounds to the PCM. Remember that 12 volts goes directly to the injectors and the PCM fires them by supplying ground.

Hope you find something and let us know if you need more ideas.

Dave

 

Getting fuel and spark. Fuel rail is good, pump good, oil clean. I'll doublecheck the grounds in the morning.

Edit: Grounds are good and intact.

By wont crank I mean doesnt want to crank when it turns over. It'll fire, but when it does, its missing. Have a few cold cylinders, and a few hot ones. Remember, it was running fine, then went to @#%# real fast. If mine wasn't two months and a thousand miles old, I'd replace the opti.

 

Well the cold cylinders make it easy now. Need fuel, spark and compression. Assuming you have spark and fuel as you said. Check compression on the cold cylinders. If compression is low on the bad cylinders, check the rockers first. But I doubt it's a compression problem. I would compare the spark at the suspect cylinders to the good ones adjacent to them. Swap out wire and plug if necessary. If spark looks good. Check injector pulses. You said fuel rail looks good and fuel pump looks good. Not sure how you checked but you didn't mention pulses. Just process of elimination.

 

To me, crank=turning engine over with the starter. You have a no-run scenario (as in "cranks, but won't run" as a lot of car manual diagnostic trees state).

It might help to know what cylinders are cold or don't appear to be firing. That could correlate to a blown injector fuse. There are two of them, powering four injectors each.

 

Interesting. Fuses appeared intact, but I'll go double check now.

 

Fuses are definetly intact. The second cylinder back on passenger side, and the frontmost one on the driver's side are not firing I know for sure. Is it possible I spun the crap out of the opti and damaged the rotor? I turned it pretty high not long before it started acting funny.

 

You said getting fuel and spark. Are you or not? Check to see if the injectors are getting 12 volts then check for spark. Then if you have to, get a noid light. Last, check compression but doubtful you have to go that far.

 

Did the search and didnt come up with anything. Where do you test the injectors?

 

Use a pin to back probe the connectors at the injector body. The pink wires are hot with KOEO. If you have an OBDI, the injectors 2,3,5 & 8 are on one fuse and the rest are on another.

If they all have 12 volts, check the injector pulses with a noid light. I like this one from Lisle
http://www.lislecorp.com/tool_detail.cfm?detail=379
It has a long wire and a suction cup to stick it to the windshield so you can check them alone.

 

Excuse me since i'm not familiar, KOEO? I'm guessing you just probe the inside of the injector plug?

 

Key on, engine off

im having a bitch of a problem with my LT1 doing about the same ****, and I know I have spark, fuel and compression and all kinds of ****.

 

This would be my guess.

 

Indeed. I'll pull it out tuesday and see.

 

If the screws seem to have come loose then take and blue locktite ALL the screws in the replacement before install.