02 SL2 Injectors not pulsing

[RB56]

I parked the Saturn in my driveway, the next day went to start it up and would not start.

• Starter turns engine but no fire.
• Dash lights normal and Security light does not stay on or blink.
• Engine will fire if starting fluid sprayed into the air box.
• Fuel pump powers up when key is first turned on.
• No obd codes.
• OBD II Live Data shows RPMs at 0 even when engine starts with starting fluid.
• OBD II Live Data shows trottle position sensor reporting accurately.
• Battery at 12.8 volts.
• Verified that all fuses good.
• Bypassed the Fuel Pump relay, still no fuel at cylinders.
• Tried spare key.

Seems like the computer is not sending the signal to the injectors, but can't figure it out.

Any suggestions would be appreciated.

[billr]

Check if the fuel pump comes back on when cranking. After key-on, wait several seconds until the pump stops after the "priming" pump cycle times out; then crank and see if the pump comes back on. It may be hard to hear (while the engine is cranking) from inside the car, so having a second person help you is an easy way to listen. There are ways to check for this electrically, of course, but really more effort than just grabbing a buddy.

If the pump does not come back on while cranking, then that, coupled with the no injection pulses and lack of rpm reading hints strongly with a problem in the CKP sensor circuit. It does seem odd, though that no trouble-code is being set, so post results of above checking and let's keep talking...

[fdryer]

It would be extremely difficult for anyone to hear a fuel pump run while starting. The best way to know if a pump runs is to connect a fuel pressure gauge to the fuel test port on the fuel rail where injectors are plumbed in.

RB56, if the engine runs on starting fluid, this tells me the pcm and crank sensor are working. Did you check for a blown main injector fuse that supplies power to all injectors? This may be either a fuel or injector issue. Fuel pressure requires a fuel pump but injectors are pulsed by the pcm with injectors supplied with 12v power at ignition on time. Each injector has its ground electronically switched by the pcm to pulse at the appropriate time. A blown injector fuse simply kills injector operation.

[RB56]

Thanks for the suggestions so far.
Additional info:
* Fuel pressure test shows 45 psi during start attempts.
* Pulled the spark plug wires off the coil packs one at a time. The 1-4 never arc'd during key-on or start attempt. The 2-3 arcs one time when key is turned on, but not during start attempts.
* Took the ignition module to Autozone for testing. The ran the test 7 or 8 time and the ignition module passed every time.
* I pulled the spark plugs out one at a time and got no spark during start attempts. From this I conclude that the "firing" I got from starting fluid was "dieseling."
* There was no fuel on the spark plugs when I pulled them.
* Compression test on cyl 1 was 135, on cyl 2 was 140.
* All fuses have been tested and verified good.
* Changed the CPS. The old one was 873 ohms, the new one was 950.

What would be the next step?

[billr]

I don't think it was dieseling, I have never had that happen (except a hot engine, idling fast, and it was with just gasoline). How big a gap are you trying to get the spark to jump when looking for it at the coils? If you have done the compression test reasonably proper, those figures are pretty low. What were the other two cylinders reading? How about the 12V power to the injectors, is it there while cranking? Does the fuel pump come back on while cranking?

[fdryer]

1-Under normal circumstances, spark is never generated with ignition key in the ON position. Spark is generated only when the crank sensor sends timing signals to allow the pcm to operate fuel pump, injectors and ignition. Technically, spark occurs only when the engine is started or running. The same for injectors.

A valid spark test requires disconnecting all plug wires from both coils, after noting firing order. If crank sensor and pcm are operating, spark should occur across both coil towers.

2-Is the new crank sensor seated all the way in? One or two members neglected to seat their sensors because the O-ring was difficult to work into the hole, resulting in a larger gap between the crank sensor tip and crankshaft machined teeth; failure to have the sensor completely seated caused the same no start/run problem.

3-While fuses were verified, the pcm, injector and ignition fuses may need to be checked again. Either substitute with replacement fuses or try a different method to ensure 12v goes across each fuse; some blade fuses have exposed electrical tabs on top to allow voltage measurement on both sides of the fuse. Connect negative probe to chassis ground and use the positive probe to check each metal tab; 12 volts should be seen on both tabs. One tab not showing 12v means either the tab is covered by plastic or the fuse is faulty.

4-Intermittent spark and lack of injector pulses seem to point towards possible pcm failure. Intermittent spark and lack of injector pulses (no fuel on spark plugs) or intermittent engine running from starting fluid doesn't make sense. Possible ground issues? The battery has two major ground connections; battery cable negative connects to a chassis stud and the chassis connects to the engine block. Both connections need to be checked for corrosion or loose connections. In addition, pcm ground should be checked. Normally, pcm has its own ground wire connection among the wire bundle so checking to see if any water damage occurred may hint of corrosion to pcm ground.

While icm bench tests may prove fine, this doesn't rule out wiring problems on the car, connections to the icm. Check and verify the cables and terminals for signs of damage and corrosion. Wires can break at their crimped terminals or anywhere in the insulation. A continuity test may be needed for each wire.

Another possibility may be missed timing. A worn timing chain slipping will cause mistiming and poor compression. Mechanical timing coupled with problems in the EFI system can be double or triple trouble.

5-What's mileage?

6-Does the security light turn on at ignition ON time then turn off?

[RB56]

The fuel pressure test was 45 psi throughout start attempts.

The reason I assumed dieseling is because it only does it if I spray starting fluid. If I spray gasoline in I get nothing. It doesn't start even with the starting fluid, only shakes like a dieseling engine.

Also, like I said there is no spark at the plugs during start attempts (which I had not confirmed before the original post).

I didn't do the compression test on all cylinders because I was just trying to confirm that the timing belt/chain was ok. I will test again and include all cylinders. What is the acceptable compression range?

If I am getting no spark, and the plugs are not wet after start attempts would that point to the ckp sensor circuit? If so, what would I test next?

[RB56]

Response to fdryer:
1. With the spark plug wires removed from the coils, only one single arc is noted and that is when the key is turned to the on position, and occurs between the 2 and 3 towers.
2. Crank sensor is seated all the way.
3. Fuses in the fuse block under the hood verified by multitester touching each side of the fuse against the battery ground.
4. Clarification that engine doesn't start with stating fluid...only diesels. I only checked the ground to the frame below the battery. I will look for the pcm ground and check it. Can you give me an idea where to look? I had not thought too much about grounding because the starter spins up strong.
Timing: How do I test?
5. 83000 miles
6. The security light comes on when the key is turned on and goes off after a few seconds. (My very first gut feeling when this started was "security")

[fdryer]

Fuel pressure is not in question. Injector operation is and is a direct command from the pcm. In order for the pcm to make injectors operate, Passlock must not be activated (please answer questions), flashing during starting. Passlock must turn on the security light at least once at ignition ON time then turn off. Does it turn on and off?

'Dieseling' on four stroke engines cannot occur on fuel injected systems. When you witness dieseling, spark and fuel are involved to create dieseling. Actual dieseling on diesel engines occurs with greater compression (20:1) without spark as the very high compression and injecting diesel fuel creates combustion. older carbureted engines can 'diesel' due to carbon deposits on pistons and leaking carburetors never shutting off fuel from hot engines boiling fuel into overflowing the carb and entering the cylinders. Dieseling gasoline engines rarely occur and yours is not the exception. Fuel and spark is occurring despite your findings because spark is occurring. Maybe not perfectly timed but spark is occurring, intermittently.

Here's a brief synopsis of electronic fuel injection. The crank sensor must send precise timing pulses to the pcm when the engine is started or running. No crank sensor output = no pcm operation. No pcm operation = no fuel pump at ignition ON time or during starting/ running, no injector pulses and no spark.

When cranks sensor timing signals are sent to the pcm the pcm responds by turn on fuel pump, initiates ignition for spark and pulses injectors.

[RB56]

Thanks for your reply. I will test the wires from the CPS to the PCM first as soon as I can...hopefully tonight or tomorrow night.

I did answer the security light question...
It comes on when the key is turned on and goes off after a few seconds.

I used the term "dieseling" to try to describe what the engine was doing when trying to start after spraying starting fluid. I didn't look it up but I thought dieseling might be possible with "starting fluid" at the car's compression psi.

As I said, nothing happens when I spray gasoline in the intake and try to start. So there is a difference between spraying starting fluid and spraying gasoline. But definitely no spark at the plugs when I pull them out and test one at a time (and no wet plugs).

[fdryer]

My apologies as I was up all night replacing front struts (a first for me) and a do over to correct a mistake. I can now say what not to do when replacing struts.

While there may be a difference between starting fluid and gasoline, the difference is starting fluid is more volatile and it's this characteristic that makes it great for the occasional hard starting when less ideal conditions occurs. It's also expensive when scaling up to gallon costs. The chances of spark occurring more likely with starting fluid is the main reason it's used in winter hard starting scenarios. You disconnect power to the ignition system, the connector to the icm and try starting again with starting fluid I'm guessing the engine won't run at all.

Something is missing and the reason I made a list possibilities. Some are easy to check while others require removing the cam cover examine the timing chain and timing. Compression should be around 185 psi for a worn engine but several members with very low compression are still running around albeit with less power.

[RB56]

I will definitely try the starting fluid with spark plugs disconnected and let you know the results, and also redo the compression test. Hopefully I can do it this evening.

[RB56]

Got some additional testing done...
1. Removed spark plug wires from all cylinders. Sprayed my ether based starting fluid into the intake, and tried to start. Sure enough dieseling occurred. My conclusion is that the ether diesels at a lower compression than gasoline or diesel.
2. Compression tested all cylinders. The results for cylinders 1-4 are as follows: 185, 190, 200, 185 respectively. This time I decided to buy a compression tester. Previously posted measurements were from one I had rented one from Autozone (which was apparently not reading correctly).
3. Tested injector pulses for cylinders 1 and 2 with NOID light and got nothing.

I am pretty convinced now that it is either wiring between CPS and PCM, PCM ground, or bad PCM.

I hope to get into the wiring this weekend.

Any other ideas would be appreciated.

[billr]

Well, I gotta admit I am really surprised that it would diesel!

Have you checked to see if the fuel pump comes on when cranking? If it does, then that would preclude the CKP circuit, but if it doesn't that would be the "third strike" against the CKP... If you can't hear the pump run, or can't get to the pump connector to check for voltage, go to the pump relay socket and see if the relay coil drive becomes active.

[fdryer]

I too am surprised the engine can run without spark on starting fluid.........my guess is compression is helping ignite ether(?).

Now that compression is back to normal (from a faulty loaner), ignition and injector operation (both controlled by the pcm) need to be analyzed. Injectors are controlled directly by pcm but spark is indirect. The pcm controls spark thru the ignition control module to generate high voltage spark. Below are two diagrams that can help.

[RB56]

billr,
The fuel pressure at the rail is about 45 psi when key is first turned on and during starting, and I can hear the pump start up using a stethoscope in the trunk over the pump. I'm not sure if it starts up again during start attempts.
Should it run during starting if the pressure in the rail stays constant due to injectors never opening?

fdryer,
Thanks for the diagrams. I plan to go through the wiring this weekend.
If I am able to verify continuity between the CKP sensor and the PCM, is there a voltage I should see on those wires during starting if the CKP sensor is working?

[billr]

The fuel pump should always come back on when cranking/running is detected via the CKP sensor.

The fact that pressure stays up after the initial "key-on" pump run is unimportant. Ideally, fuel pressure should stay up for many minutes after that key-on pumping if no injector pulses are commanded. But, many systems will drop, anything from just a few psi to near-zero, and it won't prevent the engine from starting or running.

It is important to determine if the pump comes back on as that may be conclusive info to determine if the CKP circuit is OK. As pointed out above, the injector pulses depend on good CKP, but the ignition is debatable. So, the pump is the "third opinion".

In retrospect: I am usually using starting-fluid on small lower-compression engines; either flat-head or with compression releases, sometimes both. That may well be the difference in what we have experienced!

[fdryer]

I've never checked crank sensor output when mine failed soft (intermittent). After replacement the engine started up as of nothing ever occurred. Bench tests with a multimeter showed resistance rising as heat from a heat gun heated it. It never occurred to me to try measuring voltage output of scoping it when I had the opportunity. Technically, output will be generated as a piece of iron (screwdriver tip or shaft passes by) with an AC voltage, rising as metal is passed by quickly. Whether you can measure this on a multimeter or not is questionable. I presume wiring is intact but you never know.

The pcm is working insofar as controlling the fuel pump because the pump signal is used twice; turning on pump for two seconds at key on engine off time and during starting/engine running.

[billr]

^^^

"and during starting/engine running."

That's the key bit of info that I don't think the OP has confirmed yet.

[RB56]

billr,
I will check if the fuel pump comes back on after the initial 2 seconds, during a start attempt. Since it won't start and run I can't check it at the running state.
Thanks.