94 ATX no start *UPDATE*

[TimboSHO]

Sometimes it starts and runs for about 10 secs, but usually doesn't even start. It cranks fine, and the tach works all of the time. The only codes I get are 116 and 636, which after searching are just due to it being 20 degrees out. The owner says that he was driving and it just died on him and wouldn't restart... no warning. The valve cover gaskets, plugs and wires were done recently, but he hadn't had a problem until now. Any ideas? Wouldn't the cam sensor throw a code? And if the tach works then it's probably not the crank sensor, right? I really don't like throwing parts at vehicles, but what else could it be?

 

[TimboSHO]

Anyone?

 

[kzoosho]

I dont know Tim . i may just have him replace the cam sensor and see what happens.

 

[94shoatx]

I would first clean the battery cables really good and reattach them. If that doesn't solve the problem I would suspect the crank sensor being bad.

 

[TimboSHO]

So you don't think it could be the cam sensor? I already checked the battery and connection. Terminals are fine and clean, no voltage drop between the battery and cable. When I get it started, I've tried revving it up a bit and holding it around 3K, but it still cuts off just the same.

 

[doclees]

Not enough info. Fuel pressure?

 

[kzoosho]

Not enough info. Fuel pressure?

plenty of that

 

[TimboSHO]

Not enough info. Fuel pressure?

I don't have exact numbers, but the fuel pump is working properly, and there is pressure at the rails. It's definately something electrical just because of the way it shuts off. There is no sputter or warning, even when the engine is revved. It just shuts down. What more info do you need? Is there any way to test either of the sensors?

 

[Aaron R.]

When it doesnt start does the check engine light stay on or does it go out? If it stays on the PCM is not seeing the crank signal. You should also check to see if the water pump is leaking on to the cranksensor. I am pretty sure the tac works off of the cam sensor but I am shure the cam sensor would NOT cause it not to start.
Good luck,

Aaron

 

[kzoosho]

When it doesnt start does the check engine light stay on or does it go out? If it stays on the PCM is not seeing the crank signal. You should also check to see if the water pump is leaking on to the cranksensor. I am pretty sure the tac works off of the cam sensor but I am shure the cam sensor would NOT cause it not to start.Good luck,

Aaron

that is incorrect

 

[TimboSHO]

We swapped in a known working cam sensor and still no start. Looks like a crank sensor after all. But I still want to know if there's any way to test it?

 

[kzoosho]

And what codes should the car be throwing that would tell us that it was the crank sensor. i did email rcm to overnight the crank sensor too tim.

 

[TimboSHO]

Alright, I have a new crank sensor in and still no start. Now instead of starting once in awhile and running, it doesn't start whatsoever. So what could it be now? I'm getting very frustrated. I have fuel, but no spark. Brand new CPS, working CID, what else is there? I unplugged them both and the tach still works as well. What else gives a tach reading? And there are still no codes as well. I really need help ASAP! Thanks!

PS. Yes, I gapped it to .03"

 

[hawkeye18]

Well if you're not getting a spark, then it's either (in order of signal) PCM, DIS, Coil pack, plug wires, or spark plugs. Make sure the DIS is getting a good ground to the intake. Make sure the wires are making a good connection. See if you can swap out a spare coil pack. If it just absolutely stopped working suddenly, it could very well be the DIS. I really haven't heard of DISs just up and dying, but anything is possible on these cars. Air, Fuel, Spark... those are the only three things that can cause a car not to start, and if you replaced the CKP and CMP already, then that's not it. I don't know what else can give a tach reading. It is possible that you got a bad CKP. Never trust that new parts are good! I have learned this lesson the hard way many times. Best of luck to you...

 

[TimboSHO]

Okay, I've gone through the testing procedure that rangerj has posted previously about testing CPS, CID, DIS, and coil pack.

Connect a DMM or LED test light between the PIP wire (DB Dark Blue) and the negative battery terminal. Then crank the engine. The test light should blink, or the DMM should read betweem 3 to 7 volts.

If NOT, the crank sensor, crank sensor POWER or GROUND, or wiring is faulty.

This tests failed with the old sensor and tests good with the new one (5.7V cranking, battery voltage with key on), but still no start.

SPOUT to DIS module.

Connect DMM or LED to SPOUT wire( Y/LG Yellow Light Green stripe) and negative battery terminal, then crank engine. You should get 3 to 7 volts or the test light blinks. If NOT, the control unit or wiring( including connection) is faulty. If OK, next test.

This tests out good (5.7V cranking, battery voltage with key on)

Connect DMM or LED test light between the IDM wire(GY/O Grey/Orange stripe) and negative battery terminal and crank the engine. Again 3 to 7 volts or the LED light blinks. If NOT DIS wiring or module faulty. If OK, next test.

Now this is where something is not right. On the GY/O wire, I only get .142V key on and .337V cranking. I checked the spout wire going into the DIS (Y/LG) and it tested the same as at the spout connector. Then I swapped out my working DIS on my 89, and i still got the same readings (.142V KO and .337V cranking). I thought maybe the 89 was different (since the wires going in and out are different), so I put one from a 93ATX on. Still the same voltages (.142V KO and .337V cranking). So if this is supposed to be 3-7 volts cranking, is there something I'm not testing right, or could both ATX DISs be bad, and my 89 not compatible? I'm really stuck now. I didn't go further in testing, as it did not pass this test, and I didn't see reason to go further.

Any knowledgeable help appreciated! Thanks!

 

[93rev2sev]

At this point what have you replaced?
Are you sure the DIS is grounded (bottom screws/manifold/firewall)?
Do you have a different coil pack to try?
Another DIS to try?
Is the engine cranking strong? weak battery could crank but too slow to trigger the crank sensor.

 

[TimboSHO]

At this point, I have replaced the CPS, CID (with a known working one) DIS (multiple times, with the same result).

I'm sure it's grounded because i noticed that the ground bolt (bolt that holds the strap from firewall to manifold) was not tight and I tightened it up before I even tested anything.

I could probably come up with a 3.2 coil pack and another DIS, but I absolutely hate throwing parts at something if there is any way of testing it.

The battery isn't very good, but whenever I'm testing it, I hook my running car up to it with jumper cables to make sure I'm getting enough voltage.

 

[Off Road SHO]

What about the two other bolts on the DIS's ground path? The crossover tube to bracket and bracket to rear plenum.

From the instantaneousness of the dying, I'm leaning towards a fault in the wiring between the fuse panel in the corner of the engine bay, and the computer, or the DIS.

Tom

 

[93rev2sev]

oh yeah, isnt there a pesky fuse that keeps blowing on these ATXs?

 

[TimboSHO]

What about the two other bolts on the DIS's ground path? The crossover tube to bracket and bracket to rear plenum.

From the instantaneousness of the dying, I'm leaning towards a fault in the wiring between the fuse panel in the corner of the engine bay, and the computer, or the DIS.

Tom

These bolts are tight as well. I checked all fuses and they are good. I guess I could try another DIS, but isn't it strange that 3 tested the same?

oh yeah, isnt there a pesky fuse that keeps blowing on these ATXs?

Isn't that the low coolant one or something causing a no-start? I researched that, but all fuses are good.