OBD1 1994 LT1. I have three warm/cold header tubes, and five hot, ie engine is missing bad. All The plugs come out with a soft soot which easliy wipes off.
I've checked valve lift-ok,compression 190-200 ok, spark - new plugs/wires/delteq, pcm checked on another car -ok.
Using 42# lucas, bought used, and D1SC blower.

Is there any way my old opti optical is dirty, and throwing a bad hi/lo signal to Delteq?

 

How do you know the condition is limted to "open loop" (cold start) operation?

 

It misses all the time, open or closed loop. By missing during cold start, I assume its not a sensor issue.

 

2 things if you think that is the case with used injectors. Move them to another cyl and see if it follows.

And not trying to be funny here: but i see you have the saviour to all lt1 problems the delteq. You may look at that system as a whole as most use DIY plug wires. Sounds more ignition related to me than anything.

and as an after thought are all of your intake connections tight?

 

I think those are 3 well thought out ideas.

I am currently switching the injectors around, to see if problem follows. I dont think it will as I already tried replacing 2 with my stock injectors and it made no diff.
I will next try replacing the 3 wires with some cheap/new off the shelf units from autozone?
The intake hasn't been off or touched-should be ok?
I did notice the egr was blown and am replacing but broke the oil pressure sender in the process, on order s/b in tomorrow.
will post results.
thanks

 

I got it started today.
Changing the injectors, and Delteq coils, anfd plug wires around yielded no improvement. The same 3 cylinders are cold.I checked 2 with a Noid light, and the light flashed, so the computer seems to be signaling the injectors ok.

Is there any way the optical part of my opti is dirty, and sending a bad hi/lo signal to Delteq????
What else can I check?

 

Did you pull a spark plug off of the cyinders in question to see if they are getting spark? That would be my first move.

 

Check your valve adj.
Do a compression test with all plugs out and on all cyls. Let the compression hit the guage 4 times on each cyl. Record all cyl's and if there is more than 50# between the cyl's check the valve adj on those that are low. You can do it open throttle or closed,open will give you a higher reading on all cyl's. That is not necessary as you are only wanting to establish a difference.

 

Compression is 190-215 on missing cylinders, s/b good enough.

There is spark.

All plugs are black and sooty.

Ichecked lash on one of three missiing cylinders, seems ok.

I also used a noid light to check injector signals, light flashes - looks ok.

 

What are the cyls that aren't missing check at????

 

Which cylinders are running "cold"? All on the same bank?

 

cylinders missing are 1,7,2. Three of four corners.
Do these cylinders have anything in comon? I believe the fuel injectors fire individually, not in batch? And the ignition using a delteq, should fire individually.

Tonite I replaced my new wires with another new wire - tested on cold cylinders, - no affect.

I've not checked compression in hot cylinders.

It sounds/runs like a car with timing chain off one tooth, but that would not give me 3 dead, they would all run bad. Wouldn't they????

 

Each injector fires sequentially. Each bank of the engine is managed independantly with regard to A/F ratio/O2 sensor feedback. If you had several cylinders running rich/cold on on bank, it would be a sign of misfiring on that bank due to some sort of faulty info from the O2 sensor. That's why I asked you which cylinders were cold. But since you have cold cylinders on both banks, I'd say there's a chance you have random misfires not related to fueling in one bank.

You Delteq actually fires two cylinders simultaneously.... one on the compression stroke and the other on the exhaust stroke (waste spark). Look at the coils and see how the cylinders are paired up.