Ignition Frustration

TheGriz

TheGriz

Well-Known Member
Joined
Apr 6, 2005
Location
Raleigh, NC
I'm getting quite frustrated now...

So my 1998 TJ (4.0, AX15) engine died in the middle of the highway, engine turns over, but not fire.

1. Replaced the Crankshaft Position Sensor with an New OEM sensor
2. Replaced the Camshaft Position Sensor

Pulled a plug, turned over engine - No Spark
Checked for spark at coil - No Spark
Checked voltage going to the coil - No voltage
Checked Battery Voltage - 12.32 volts.
Fuel Rail pressurizes without problem.

Any help would be appreciated.

Used a scan tool and found this error:
P0351 (M) Ignition Coil # 1 Primary Circuit Peak primary circuit current not achieved with maximum dwell time.

I replaced the battery with one reading 12.50 volts, and the error code disappeared, but the engine still refuses to fire.
 
What made you replace the sensors? Is this coil over plug? Assuming you checked all fuses and relays , did you check that the timing chain/belt is still intact and has tension?
 
did you check the crank and cam sensors before replacing them? I hope your not replacing sensors without diagnosing first. Many many times i have seen good sensors get replaced by new (but bad) defective sensors. This introduces a whole new level of problems.

So we are dealing with ignition problems, the first thing i would check is the distibutor cap and rotor, or replace if you need a tuneup anyways.

After that the next thing to check would be the ASD(automatic shutdown) relay. The ASD supplies voltage to the O2 sensor heater, fuel pump, injectors and coil. You can check at the relay but it would be better to check for voltage at the coil to rule out wiring problems.

Once those questions are answered i'll have a better idea
 
I had no proof that the sensors were bad... just started replacing them out of frustration. I could easily go back and put my originals back in.

Not coil on plug. It's one coil pack leading to the distributor. I checked the ASD relay by switching it with the horn relay.

I put jumpers between the coil and it's connector, and I'm not getting voltage to the coil.

I haven't ruled out the timing chain. To check this I should pull the distributor cap again and turn over the engine. If the rotor turns, the timing should be intact right?

When I pulled the distributor the first time, I saw nothing out of the norm on the rotor as far as wear goes. It was replaced about 5K miles ago.
 
If it were the chain /belt, your motor would turn over really fast while trying to start, and if you have a chain, you should have heard an ungodly slapping noise.

If you don't have any power getting to the coil, you've almost answered your question. Keep tracing it back...... sha_ba_ may be on to something with that relay/fuse.
 
Checked voltage going to the coil - No voltage

Fuse, Circuit Breaker, broken wire?
 
I started pulling all the fuses and found a blown one. Replaced it and tried starting again. Blew fuse again.
It is a 20A fuse at F21. Any tips?

ai71.photobucket.com_albums_i135_sff5758_pcm.jpg
 
Eureka!

So... after pulling out the wiring diagrams:

The injectors, coil, and O2 sensors all run in that circuit. I had some buddies over and we began searching for something grounding out.

The O2 sensor on the header had frayed and was shorting out against the exhaust.

I'm glad that's over!!!! Thanks John and Scott!
 
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