Very Sluggish update

[93LS400]

Spoke with my mechanic and received the correct information about what has been completed/checked/replaced, what readings he is getting and what is not working properly:

1) Cylinders #1,3,5,7 dead.
2) Timing belt replaced-alignment good.
3) 30 Kilavolt spark at plugs.
4) 175 lbs compression per cylinder.
5) Good fuel pressure.
6) Changed computer.
7) Left rail and injectors changed.
8) Good injection pulse.
9) Fuel pressure in left rail good.

Cant figure out why four cylinders are not working properly.
Any help would be appreicated. Thanks in advanced.

 

[Pro]

when you say "dead", what do you mean? no compression? no spark? no fuel?

 

[93LS400]

It was indicated to me, that cylinders #1,3,5,7 were not operating (car is currently running on 4 cylinders #2,4,6,8) even though the compression, spark and fuel readings for these cylinders were what they should be inorder to make the car run properly. I believe part of the problem is that based on the test that have been preformed on cylinders 1,3,5,7 they should be working and their not.

 

[Peewee]

You either have a blown ignitor, blown coil, or faulty connection.
Easy fix.

 

[Muzza_NZ]

Peewee,
don't the ht leads cross over through to both banks from each ignitor/coil pack, so that would rule it out?

Would it be more likely to be a faulty +12V common for the injectors on one bank?

Muzz

 

[Zuffen]

Where was the injection pulse measured?

If at the injector and the meter ran to its own earth I would suspect a bad earth for those 4 injectors. If at the ECU you have the whole engine loom to worry about.

The ignition does cross feed from side to side so an ignitor shouldn't be it neither should it be a bad connection.

Could something be shorting out the ignition cables when the plasic covers are bolted down?

Lastly. How do they know it's the left bank? If they assume it's the left bank and not a mix of both we will all be barking up the wrong tree.

The best way to check is run it for a few minutes and see which cylinder is running by seeing how hot each exhaust port is. Carefull not to burn your fingers but just feel close to each exhaust port (I know it's a struggle to get your hand in there) to see which ones are cool. You could use a remote sensing thermometer.

If it's the whole left side the diagnosis you've been given is right.

If a mix of both sides Peewee would be right.

 

[Peewee]

Sorry, Muzza, you are correct.
I misread the post.

All 4 on one bank is strange, Injector earths is a possibility, but its earth through the ecu, so all injectors would affected.

Dropping drops of water on each exhaust port is a quick way of determining what hot and whats not.

Cam timing is another possibility that will knock out a whole bank.

 

[Peewee]

Could something be shorting out the ignition cables when the plasic covers are bolted down?

I've done that before, it only affected >4k rpm at >50% throttle.

 

[Pro]

All 4 on one bank is strange, Injector earths is a possibility, but its earth through the ecu, so all injectors would affected.

hence my question...!

 

[jgscott]

Distributor cover ?

 

[Lextreme II]

Is it possible problem might be in the ECU or ecu related (wiring, connectors)? Give us more details about your car before this problem occur..... like did u stall new electronic or got an engine wash or whatever.... details....

 

[KDog]

I would check that the injectors are getting +12V. The ground of each injector is switched by the ECU.

 

[93LS400]

Thanks for the input everybody. The ECU has been replaced (if that is that the computer located in the glove box area). It was replaced with a used one however. Mechanic thought it was a long shot that two ECUs want be bad. I'll check to find out were the injector pulse was measured. I will also find out about the injectors getting +12V. As far as the details about the car before the problem occured. The only major repair was a complete tune-up. (Wires,cap,plugs,rotor) That was 3-6 months before problem occured. Only routine checkups (oil change, tires, tune up, brakes, brakes, brakes). If I think of anything else I will post it. The curious thing for me is how fast this happened. It was within a afternoon, it was running fine that morning, sat for couple of hours, then I had to limp it to the shop. The car has been a tank up til now. Thanks again everybody. I'll be in touch.

 

[Lextreme II]

Could the one of the cam sensors is bad so would send engine info to ecu and then affect one side of the engine?

 

[93LS400]

Cam sensors have not been replaced. My mechanic was told by a "tech service line" that the cam sensors would not cause the problem. He believes the cam sensors would play a part in the overall system, but we haven't replaced the one controlling the left bank of cylinders yet. Could a faulty cam sensor cause the engine not to run on all cylinders? By the way the injectors are getting 12+ volts.

 

[Lextech]

If the cam sensors are bad it will set a code and check engine light.1 3 5 7 are the drivers side. Unplug those 4 injectors and check for 12 volts to 1 wire of each injector connector with the key on. All of the injectors have 12 volts with the key on or engine running, the computer gives each injector a pulsed ground to fire it. I have never seen an entire bank go out, I really have doubts that's happening. I would HIGHLY suspect 1 bad coil. Each coil fires 2 cylinders on each bank. Also since it happens at about 4000 rpm, check that the hood insulation is not sagging and blocking the air inlet slot for the air cleaner.