Truck Won,t Start

[B5967]

I have a 97 Chevy C1500 5.7R engine that was rebuilt less than 2 yrs ago. The truck started hesitating, then missing and then started to backfire all in 5 miles, the only code P0300. Replaced CKP sensor with no start, then the dist (pulled to check gear, OK but replaced anyway) again with no start. Check for fire with no results, so I replaced Ignition module, no start and replaced coil with no start. Checked the wiring from ECM to each sensor, A OK, Checked pink wire, have power, also checked fuses under hood. After trying to start I get P0336, P0338, P0339 and P1361. Any place else should I be looking and/or checking. Also I checked the fuel pressure and its around 55-65 psi while cranking.

 

 

Oh, I am still not getting any fire from the coil.

This maybe a clue, When checking for a spark, I would get one spark when the battery will not turn the engine anymore, the last romp.

 

I have read a lot of the topics that sound like mine but the conclusion are something I already checked.

 

Please help before I do something ILLEGAL~!!

[B5967]

I was reading my Haynes manual and it said to check the CKP sensor reference voltage (yellow wire). THe voltage is suppose to be 5 volts but I'm getting 17.7 volts. What does this mean?

[Debo511]

What is the battery voltage when you are measuring 17.7 volts????

[ChevyTech77]

ECM.

[B5967]

Oops, The voltage was AC, the ECM converts this voltage to a square sine pattern,as i am told i am not an electrician. So to answer your question, the battery was at 11 1/2 volts on the purple wire.

 

Yea, everything I have checked seems to point to the ECM. Since I work 6/12's and at night, its hard to work on the truck. Also the truck is in the parking lot here.

 

It has been a good truck for over 13 yrs. Stranded me three times, transmission under warranty and twice in the last year, distributor gear and this one.

 

A reman ECM plus programing, I'm looking at $250+ depending where and who does it.

[B5967]

Well, I was hoping someone would come up with something new or a fresh idea. A friend of a friend of a friend said that maybe I have a couple of wire touching in the harness, I will check that when I get the truck home.

 

Question? Has any one ever heard of a tone ring/reluctor wheel going bad? Just shooting in the dark hoping to hit something, I really hate to buy an ECM and the problem is still there.

[B5967]

Update. I tried to start ti using starter fluid, it did not try to start. So I bought a used computer, again it didn't want to start. I sprayed some starter fluid and it tried to crank. So now I am thinking because of the backfiring, that something in the fuel injection is burnt. When I rebuilt the engine, I upgraded the fuel injectors to the snyder type system, with wires not poppet valves.

 

Question: How can you test the injectors to see if they are working?

[B5967]

Well it seems that this has stumped a few people out there. Well I have another question.

When testing an CKP sensor, what should the voltage be when the vehicle is not cranking?

 

Everything I have read, checked and double checked points to the CKP sensor. This is the third Borg Warner I have installed ( warrantied) and before I take this one back, I want to check to make sure it is it. As I said earlier, I am getting 17 volts AC on the signal wire (Yellow) with just the key on and when cranking. I have check the wires visually, the continuaty(?), the grounds, power leads and I checked each Connector on both ends. I unplugged the computer, plobe the CKP wires and touched every terminal going into the ECM to see a cross link, none.

 

I have read on here about the knock sensor going bad causing the the ECM to retard the timing and add more fuel. Is this possible on start up?

 

Please I need all the help I can get, Its going on 5 weeks now.

[B5967]

This is the last update as I finally got the darn thing running.

 

I like to say thanks to those who helped me, but I can't because no one did.

[txab]

So what ended up being your problem?

[B5967]

Well, it was two bad Borge Warner CKP sensor. I have another BW CKP sensor mow but from a different batch, works great. That sensor is the most important sensor of all. It tells the computer were # 1 TDC is which in turn controls the sparks, timing and fuel. As ya'll can tell, I didn't get much help here so I spent more than I had too. If you start getting random missfires, Check the Dist. gear and if good, check CKP sensor. Use the Chilton repair manual, Its has more detail in it.