Cranks but wont start, 93 DOHC

[AL]

ICM Operation:

The DIS module monitors the crank sensor signals and based on these signals sends a reference signal to the ECM so that correct spark and fuel injector control can be maintained during all driving conditions. During cranking, the DIS module monitors the "sync pulse" to begin the ignition firing sequence, and below 400 rpm the module controls spark advance by triggering each of the three coils at a pre-determined interval based on engine speed only. Above 400 rpm, the ECM controls the spark timing through the module (EST), and compensates for all driving conditions. The DIS module must receive a "sync pulse" and then a crank signal in that order to enable the engine to start. The DIS module is not repairable. When a module is replaced, the remaining DIS module components must be transferred to the new module."

 

So what I am getting is the ICM monitors the crank signal and then tells the ECM what the crank sensor sees and the ECM controls both spark AND fuel??

[AL]

Also, What is the sync pulse? I havent heard of that before... I looked in the index of my FSM and there is nothing about it...

[AL]

BUMP

[AL]

So today I push it into the shop, and go to hook up the computer to the crank sensor wire and boom it fires up after about half a second of cranking, well I didnt have the power steering fluid in so I turned it off... I added the fluid, cranked it over and it started again, Idling at 2500, It then idled down to 1300 or so... I had to put the airbox on yet and add some more coolant so I shut it off again and put the airbox on and added coolant... Go to crank it over and it wouldnt fire... Let it sit for 5-10 min. Still wouldnt fire... So I push it back outside and decide I would head back to school after work and see if it will start... Sure enough, I tap the key foreward and it fires right up... Idles down to about 1300 and I let it start burning off all the degreaser... After 4-5 minutes of it running, I notice I hadnt put my coolant overflow tank on, So I turn it off, Put the tank on, and go to start it and it would only crank, Not fire... HELP

[Crazy K]

hook the computer back up and see what happens?

[AL]

By computer I meant a Sun 450 which will tell me exactly what signal each wire is sending or recieving...

[AL]

IT RUNS!!!! AND DRIVES!!! AND ACTUALLY STARTS!!!!! WOO HOO!!!! I disconnected the crank sensor wires to the ICM the ICM to the ECM wires and cleaned the connections and added dielectric grease, I found the 02 sensor wire disconnected and connected that and it seems 100% minus the SES light being on for code 42, EST Malfunction, and the oil pressure guage reads 80+ all the time

[AL]

Ok, I go to pull it out of the shop and it decided to not fire... I checked fuel pressure and I only get fuel pressure one out of about 10 times I turn the ignition on... Hmmm

[AL]

When rolling the key forward, the fuel pump doesnt prime unless it feels like it... The relay doesnt even click sometimes... And sometimes it will prime, but not pump fuel while cranking... There has to be a bad connection to the pump somehow

[White93z34]

check the fuel pump relay / change oil pressure sender.

[AL]

I changed the relay, I will clean the connections to it tho... They are all dusty

[ns87]

When the pump doesn't prime.....does the check engine light turn on with the car "on"? This sounds identical to my old CS so far

[jman093]

x2 on the oil pressure switch. If you have a scanner, make sure the ECM can see that switch closing shortly after you start cranking.

 

 

When the pump doesn't prime.....does the check engine light turn on with the car "on"? This sounds identical to my old CS so far

 

No check engine for an inop fuel pump.

 

[AL]

I will check that oil pressure switch... As for the check engine light, I will check but I am pretty sure it comes on every time the key is rolled forward because it has a constant code, code 42 for EST failure