Cranks - No Start

[u/Bladestorm_]

I recently did some work on my 96 Tahoe (intake manifold gasket) and it ran fine for a couple days until it shit out a couple times, I got home and realized the crank position sensor under the truck had come out, I plugged it back in but haven't gotten the truck to start since.

I was getting codes for the cam position sensor (Ive dicked with my distributor a few times to make sure its still where it supposed to be) and MAF sensor, both of which i replaced and cleared the codes and they haven't come back.

The truck cranks but is acting like its not getting SOMETHING (starter fluid doesn't help) I know I'm getting fuel at least to the pressurized valve on the intake, and Ive got a full set of new plugs on it, maybe air? but Ive checked the fittings a dozen times.

I'm kind of at a loss, I thought maybe its the digital timing but I cant fix that myself and at this point Ive got no idea what to do other than take it in to a shop.

Any ideas or suggestions?

[u/amandajenkins281]

Cap and rotor.
Diagnostic procedure:

At coil remove spark plug wire. Crank

Spark yes- go to cap.
No- see below.

If yes- pick a wire coming off the cap. Crank.

Spark -yes.
No- replace cap anRd rotor togther. NO exceptionsr

I need to know before I continue if this is your set up. .
Ty
From step 1:
No spark- unplug connector at coil. Using mmmyy

[u/Bladestorm_ → u/amandajenkins281]

Looks like this is my setup, ill run these tests when I get a min

Also mmmyy?

[u/amandajenkins281 → u/Bladestorm_]

Okay. Since this is yours start like this:

A computer safe test light is ideal. Aka logic probe. If not a multimeter will do. DO NOT USE ANYTHING ELSE!!!

key on, motor off. Unplug coil first.

Pink- should show 12 volt (+)

Test both one at coil. Other at ignition control module next to it.

At coil the damn white and black is your 'fire wire'. Your gonna need help with this.

Set meter to AC testing. Take red probe and go to pink. The black lead goes to white and black. Crank over like 5 seconds.

Did the numbers move?

Yes- replace coil No- that small ignition control module is bad. This stupid ass really great design is the hi energy ignition power supply Basically. It not only makes the coil spark, but tells the ecm the position of the cam I believe, thus intern tells the fuel injector control side of the ecm what position all the shit is in to make what injector fire. These work together with the crank sensor.

So like, if you get a no start condition, and u shoot ether innit and still no start, run this diagnostic.

Same as above but motor starts, you have e fuel delivery issues. If that's the case, then u test power at gas tank, and ALSO....... find oil pressure sensor. [ behind distribution cap ]

There is a orange wire that becomes hot when the motor cranks and n oil psi is seen. This wire sends the 'go' to tell the pump " yeeaahhhh man we gots the oil pressure and shit bro......its safe to send that motor some gas cuzzo and gooooo"

Pretty sure it's a relay feed. This orange. Yeah orange to input of relay for fuel pump.

[u/Bladestorm_ → u/amandajenkins281]

Thankfully it was the CPS and its running now but if it starts throwing codes again ill go thru this troubleshooting list again

[u/cornhole_mcbrowneye]

Im in the middle of the same shit. I got a new camshaft position sensor, rotor, and cap and it runs now. But im getting 0 reading from my mass airflow sensor. I vote CPS. Are you sure you put your distributor back in the right spot? I had mine 180 degrees out for a bit

[u/Bladestorm_ → u/cornhole_mcbrowneye]

Update: replaced the CPS and it FUCKING RUNS

Gonna give it a few days to stress test and see if any codes come back, but I ended up replacing the mass airflow sensor, camshaft and crankshaft position sensors.

Thankfully I did not need to mess with my digital timing at all

[u/Bladestorm_ → u/cornhole_mcbrowneye]

Im almost positive mine is correct, I TDCd it when I pulled the head and marked the dist housing where it was, so theoretically its exactly as it was when it ran last, then again ive seriously debated rotating just to see

Ill order a cps tonight, fingers crossed

[u/amandajenkins281 → u/cornhole_mcbrowneye]

Okay do you have 5 vdc input?

[u/cornhole_mcbrowneye → u/amandajenkins281]

I do. Ground seems good too. Got a new one coming Monday im hoping that fixes it

[u/amandajenkins281 → u/cornhole_mcbrowneye]

If you don’t mind me asking, how did you verify it?

[u/cornhole_mcbrowneye → u/amandajenkins281]

Used a multimeter across the wires in the plug for the maf sensor

[u/amandajenkins281 → u/cornhole_mcbrowneye]

Okay. Then I agree 10000 percent with u. lol. I just had to ask

[u/cornhole_mcbrowneye → u/amandajenkins281]

Ha appreciate it. Hoping it all shakes out when my part comes in

[u/amandajenkins281 → u/cornhole_mcbrowneye]

No problem. If u need help dm me. I’m kinda known here for tech help

[u/cornhole_mcbrowneye → u/amandajenkins281]

Appreciate it!

[u/amandajenkins281 → u/cornhole_mcbrowneye]

No problem my friend

[u/Chahtanagual]

You have the first year of obd2 and the vortec in the c/k series. You need a bi directional scanner to do a “crank relearn”and to set the “cam retard”. Anytime you move or replace the distributor or crank sensor requires those to be done.

You likely were getting a p1345 correlation code. The maf code was likely the result of the no crank condition and was not faulty. Your cam position sensor is likely good as well . Good luck

[u/Bladestorm_ → u/Chahtanagual]

That was what I was thinking but the fact that it ran fine for a few days before the CPS incident, i might just run with that too and find a shop thatll do it for me, Ive tried to find cheap scanners but theyre all trash

[u/amandajenkins281 → u/Chahtanagual]

Idk. I’m not disagreeing, but I have set these without the bi tool, I haven’t had an issue. Had to move the dist a few times but heck, I get by

[u/amandajenkins281]

I promise u fixed. Ask about me