96ZRDR

Thanks Hotwire, cylinder #3 is about 18% less from the rest. Cant remember what is the standard deviation that is acceptable when checking leak down.

You have dying cylinder, but it is not complety dead. Did you fix your knock sensor? You could always try a resistor? I think it is a 3.9k ohm resistor.

Later

Hotwire

I got the new knock sensor in, but haven't fired it up. had to pull driver's header to get to 1 & 5 cylinders to see if 3 was leaking into them. I am going to recheck my valve adjustment on 3 to see if it changes the reading, doubt it will. then i will probably pull the heads.

I have no clue what is killing #4, it's getting great compression, spark, fuel, air. what else does it need? I pulled the plug and cranked the motor over, it was getting fire to the plug.

i might pull the injectors and take it down to a buddy at the dealership see if they can test them, but seeing as how you already replaced yours, don't think that is the problem. maybe a flat lifter, flat valve spring, ecm??

do you have any type of programming in your car?

96ZRDR

I have PCM4less programming by ROOSTER (Alvin I think). My car wont run without it........

96ZRDR

Update:

Did a little troubleshooting this weekend and came up with the following results.

I began to test all my ground wires to see if there is any voltage on them. I found one.

There are 3 ground wires attached to the retaining bolt on the ignition coil. 2 are black and the other is tan with a white line. I tested them individually and found that both black wires are fine.

When I tested the tan wire, I found that there was voltage on the line, it constantly read a negative (-) number. I traced it back to the ECM and disconnected the harness connector and proceeded to re-test the tan wire. It was now fine.

This means that this wire is not shorted out, but when it is connected to the ECM it is. It gives me the same negative number with ignition on or off. I guess there is a short inside the pcm.

I then tested the same wire on a (2) 1994 Lt1's and it read as it should, just like the other ground wires.

I then tested it on a 1996 Lt1, this one has two wires like it, and they also tested out fine. No voltage.

Is it safe to assume that my ECM is toast?

Thanks

Hotwire

Sounds like it may be, let me get into my service manuals to see what that wire is for, and find out what the symptoms are for bad connections, ecm, etc. I'll check mine as well, going to be installing the crane cams HI-6 ignition and coil tonight, so I'll be messing w/ those bolts. Could just be the memory line for the pcm or something. I'll let you know.

What pcm connector and # pin is it?

I also did some troubleshooting and found my problem..

http://www.hpphoto.com/servlet/LinkP...44a3d652&size=
(Front of motor is top of pic, odd on left, even on right.. bird's eye view)

hmmmm... wonder what is wrong with my truck....

hehehe, after walking past it for the past two weeks glaring at it and entertaining thoughts of sledgehammers and pickaxes, I got up the nerve to work on it. I decided to start small, pulled the four bolts out of the fuel rail, removed the injector harness, and pried the rails up. bottom of the injectors looked spotless. damn.. so I said, well, after what everyone told me to do, check the injectors, I pulled #4 just to take a peek. HOLY HORNY TOADS!!! I had about a ounce of crap pour out over my hand and #4 is completely packed w/ rust and crap!! I guess from it sitting for so long the lines rusted up, then w/ the high flow from the v8 and high pressure, it knocked all of it loose. I cleaned them out yesterday very gently w/ a dental pick and carb cleaner, have put about 300 miles on it since!! You can't get me out of this thing, it is so much fun driving it around again, I also hooked up my tcc line so it's working, the gas gauge hasn't moved!!! it's great!!

96ZRDR

Hey man that is great news,.........man that is a load of crap in there. The engine must have been sitting down a long time....

ENJOY your newfound POWER!!!

Hotwire

alright, you have two tan w/ white wires coming out of the pcm on different connectors, Pin 18 on the red connector and pin 1 of the blue. They are both grounds for the PCM. They are both on the same circuit, 551, so they connect together somewhere in the harness before going over the motor to the driver's side head. (if you look closely you will see the numbers cast into the plastic)(don't know how familiar you are w/ the motor or electronics, sorry if I am talking down to you)

check both to make sure they are getting ground, one may be getting it, while the other isn't.

let me know what you find out.

96ZRDR

Is this for a 1993 ECM, just asking because I did notice two tan w/ white stripe wires on our 1996 Lt1 PCM connecting to driverside head on the coil bracket. But if I remember correctly our 2 94's only have one tan wire. What year is your motor?

The 93 only has one, but maybe there should be 2 ?!?

Anyways I will check that out, to confirm you are saying that two tan w/ white stripe wires are coming out of the ECM and join somewhere inside the wiring harness sleeve to make one wire and connect to coil the coil bracket?

Hey man, what service manuals are you using? Where could I get a copy of such manuals. Seems like they are very helpful.

On a side note: Do not worry of talking down to me, I learn as I go. I really appreciate your help.

Thanks

Hotwire

I'm using a 94 f-body manual.

It's a Helms Service manual, same thing the dealerships use.

You can go to www.helminc.com, click on do it yourself, follow the prompts, and get a set new, or sit around and wait for some used ones to come available. I always search all the f-body sites, ebay, yahoo auctions etc. (1994 or 94 service or shop manual) [don't fall for those cheap cds on ebay, get the real helms manuals] I did have a couple of good links for used service manuals, but my pc has crashed since then. New they go for $90 + shipping, but are extremely worth having. Usually if you have a ses code the manual will give you a complete explanation of what is happening, a flow chart to follow to diagnose, and different trouble shooting procedures, as well as interior, exterior blow outs, part numbers, part names, removal/installation procedures, wiring diagrams, circuits, you name it, they are awesome. haynes, chiltons, or anybody else cannot touch a helms. It will take a little bit to get used to the way they are laid out, i'm still learning on them, but once you get it down, they are like an extension of your hand. you can always go back and reference them whenever you have a question, that's why i was so broad with my problem when i first posted, didn't have the manuals.

I have two pcm grounds, but only one wire at the head. maybe they started bringing both wires out to avoid potential problems like this in 95, 96.

let me know if you need any other info man, hope I can help.

Hotwire

Hey man, get your's figured out? I have been driving the poop outta mine shaking down the rest of my problems.

Do you still have your old 24# injectors? I might be in the market to get some, might go w/ new svo injectors, trying to find some info on them.

i think that low cylinder is still causing me problems though, might be getting a little oil in the coolant as well. I want to pull the heads and replace the gaskets, gathering up all the gaskets I need right now, just neet to get the head gaskets themselves and i'll be ready to do it.

i ran the 1/8 in it last thursday, best time was 9.04 at 78 mph. also having a fun time trying to get my new laptop talking to my pcm through a usb to serial adapter. might have to drop the bux on a pcmcia card, but still working on it.

good luck.

96ZRDR

Hi HotWire,

Good Luck has not been able to find me just yet. I confirmed with another member of this board "Bud" that also has a 93' Vehicle.

He read the readings to me with the ignition key on, both grounds to IAT and MAP sensors.

He gave me:
.04 ohms (IAT)
.02 ohms (MAP)

I get different readings, dont know what is up other than the ECM. I get negative readings as in -1.7 ohms or so. Really strange.

Sounds like you have a low 14, high 13 sec truck!!!!! Can you confirm if you have coolant in your oil?

Watch OUT!!!

Hotwire

the negative reading on the ohm meter means there is voltage on the line, doesn't sound good. sounds like something in the pcm has shorted to ground, which means it's fubared.

maybe pull the eeproms and find another pcm? Anyone know what else he can do? get on ebay and look up ebay member name fparts. they might have a pcm that isn't that expensive. i've been running the 'yards lately getting stuff for the truck, i'll keep my eye open if you want.

and no, no coolant in the oil, just did oil change and it looked fine, there was a tiny bit of metal on the drain magnet though...
i am going to be pulling the heads soon, and based on what i see, may just install new gaskets, cc306 and 1.6 roller rockers. (just cashed in some stocks)