Changed Crank Position Sensor, still won't start.

V

VSFiedor

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Hi, I'm a newbie posting, though I've been frequently gaining knowledge from this site and it's talented users. Thank you for the invaluable knowledge that could've only come from the stories told about problems solved.

I have a 98 LSC with 140K and I've owned it for 2 years and aside from having to fix the blend door I haven't had any problems.

One day the car stopped starting. Actually the day before it did start rather harshly - ran rough, then I shut it off. The next day it just cranked.I thought it might be the fuel pump so I checked the pressure - 38 psi.

I sprayed starter fluid in the intake and I got no change in engine response. I also pulled a plug and had my girlfriend crank the engine but I saw no spark.

I then replaced the crank position sensor since that is a popular problem but that did not change anything.

I unplugged/plugged in the cam position sensor but still nothing.

I then bought an Innova 3140 code reader but it said the [Mark VIIIs]computer did not have any DTCs stored.

I really thought I'd have this figured out by now but right now I'm at the point were I'll just start unplugging/plugging in all the sensors without much of a method. I'd really appreciate any advice anyone could offer.

Black 98 LSC
140K
 
46callaway said:
It might be the crank position sensor wiring, not the sensor itself.
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I agree. Anytime I change one of these sensors, I've learned to change the plug. You can get the pig tails from O'reilly. The cam and crack sensors use the same pig tail.
 
I thought about the crank position sensor wiring and that sounds like it could be the problem. It just scares me to have to replace the wiring since I don't know how far up the short exists.

I'll order the pigtails for both sensors. Thanks for the feedback.
 
HOTLNC, when you replace the connectors do you trace the wire to it source or do you splice it where it's convenient?
 
VSFiedor said:
HOTLNC, when you replace the connectors do you trace the wire to it source or do you splice it where it's convenient?
Click to expand...
The problem is the connector. I just splice the new one in as far back into the cable that is convenient. I've done a crank sensor only an inch or so behind the old one.
 
Very interesting problem. Unfortunately I don't think it applies to my situation. I haven't had any problems with my alarm and my car does crank. However, I have to mention that this whole problem began when temperatures dropped to 18 degrees and my drivers door latch froze to the point that it would not latch closed. I had to chain it shut for a few days until it was able to thaw at which point I exercised the mechanism and it began latching again. At the end of those few days I tried starting it and this is when the no start issue began.
 
Is there a starting sequence or flowchart that describes which systems are accessed or relied on in order for the car to start? Is there another set of sensors I should suspect as culprits in a crank/no-start situation?
 
If the engine is cranking, it's not an issue with the PATS.

Back to the basics: Fuel, air, spark.

Fuel - fuel pump, fuel filter, pressure regulator, cam sensor, injectors.

Air - air filter, MAF sensor, IACV, ACT sensor, throttle body.

Spark - crank sensor, coils, spark plugs.
 
Pulling at straws here, but have you gone thru and checked your battery and alternator output, as our cars do funny things when we have low voltage.
 
The first time I checked for spark I only pulled one plug, today I pulled all eight and had my girlfriend crank the engine. Every one of the plugs sparked so now I definately know I have spark. I put one of the plugs shallowly into the head (don't know what I was thinking) and ended up with some flames (which tells me I have at least some fuel.) During this time I had the air snorkle disconnected from the throttle body and the sensor attached to it disconnected as well.

The most important thing I learned was when checking for the basics (fuel, spark, air) be sure that each one exists or does not.
 
I measured voltage today and it was 12.14 from the battery.

My battery has been taking a beating lately as a result of the constant test starts. It has drained to the point that it won't crank then I jump it. I took it in and had it charged last week. I was told that it didn't seem that low but I had it charged anyway. Since then I have been jumping it every day I work on the car.

I was waiting til I found the reason for the no-start before I dealt with the battery. I figured once it starts I can let it charge and make a decision on whether or not it needs to be replaced.

Should I be paying more attention to the battery issue? My guess is that the battery is a symptom of the problem, not the problem itself. As satisfying as it is to replace a part so I know it's not the culprit . . .
 
The engine hasn't started in almost 30 days. It doesn't even try to catch . . .nothing, just turns.

Spark - I definately have spark as I visually tested each spark plug.
- I replaced the crank sensor and the harness
__________________________________________________________

Fuel - I have 38 psi at the rails as of this morning
-Small fire in cylinder during spark test indicates some fuel presence
-I replaced the cam sensor and its harness
__________________________________________________________

Air - I haven't conducted any tests.
__________________________________________________________

Battery - Installed an Optima from my other car.
__________________________________________________________

PCM - Reset PCM this morning by disconnecting battery for 2 hrs.
__________________________________________________________

Fuses - Checked all fuses and swapped relays.
__________________________________________________________

Neutral Safety Switch - Engine cranks at P and N, not at R, D, 1-3.
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Thoughts- Will the ACT or IACV keep the engine from starting?
- What is the liklihood that my PCM is bad?
 
Get your code reader out again and do a check with key on engine off for any codes. TPS might if voltage is not within spec. I would get yourself a DVD on the internet at the auction site they're pretty cheap and it should have the complete FOMOCO shop manual ans schematics and trouble shooting on it.
 
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Thanks for the response. The Throttle Position Sensor is 5v which falls in between the 4-6v range. I got the dvd and I have been using it but its only helpful up to the point where the breakout box is needed. The breakout box is needed to confirm that the PCM is bad. Here are the DTCs I captured:

Continuous Memory Codes
------------------------------
P1000

Key on Engine Off Codes
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P1116 Engine Coolant Temp Sensor Out of Self Test Range
P1711 Trans Fluid Temp Sensor Out of Self Test Range

It's difficult to know from the manual if these sensors are issues when flagged at the KOEO test (Since it is 25 degrees outside).
 
I tend to agree on that !! I know that Advance Auto can supply rebuilt engine control modules for our cars. They run about $300 with core. I'm sure that there are some cheaper sources. Have you tried Jamie yet?
 
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