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Unread 05-05-2013, 12:18 AM   #1
franciscoapg
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1997 TJ Wrangler 
 
Join Date: Feb 2013
Posts: 14
TJ Cranks But NO Start!!

Hey guys, new member here. I have been wrenching on my newly acquired 1997 TJ 4.0 manual for some time now as I had quite a bit to fix. I have however, run into an issue I would really appreciate some help with.

As of yesterday, I have a no start issue on the Jeep. It cranks over very healthy but won't start. It briefly had an issue where it would stall out at idle a few times or after throttle input and it would take a few tries to start. The issue has now turned into a no start. Now this may be unrelated but when this was happening I got the common low oil pressure check gauges dash light telling me I had 0/very low oil pressure. I did however hook up an oil pressure gauge and found that my pressure is not a problem.

Onto the problem. As stated it cranks without a problem. I recently installed new plugs gapped to .035, spark plug wires, and the IAC. At first, I cleaned the original IAC with carburator cleaner and thought it my have been the problem for my rough idle/ stall issue and led to the no-start issue but cleaning didn't fix it so I installed a new one. Still nothing.

I have checked for spark which I am getting. the spark plug wires all arc'ed to the valve cover when turning over the motor.

I have attempted to put fuel in the throttle body and start it that way without success (I didn't have a friend to help so I poured a little fuel into the intake with an open throttle plate, allowed the plate to spring closed then poured a little more on top and feathered the pedal while trying to start it.)

As it looks like I am getting spark I'm confused as to why the fuel through TB didn't work - maybe I didn't put enough in or not a a constant rate?

Tomorrow I will be headed to pickup a fuel pressure gauge. I will find out if I have full fuel pressure at the rail.

I DO hear the fuel pump whine at startup.

I have pulled several codes off of the jeep.

I got 12 - for the battery wire to the PCM being disconnected - upon checking the terminal was loose and it was fixed.

Then code 17 for the car not reaching operating temperature within limits. This happened before the car progressed from stalling out to NO-start.

I also got Code 21 (twice) for the o2 sensors.

Then the NO-Start issue occurred

The IAC was cleaned/replaced

These codes where then cleared via a disconnect of the battery.

Then the next codes- 12 again, 25 for a fault in the IAC? 27 (three times) for
"Injector #3, and/or 4, and/or 5, and/or 6 output driver does not respond properly to the control signal." Then 42 for an ASD issue or fuel pump relay issue.

AS it stands after clearing the codes again I only have 12 and 25 that remain.

The relays all seem good. The ASD relay and fuel pump relay were switched with the known good relay from the horn. I am getting spark so I don't believe it is a crank position sensor? I believe the issue may be in the PCM. I will know about fuel pressure at the rail tomorrow and report back.

I appreciate your help in advance guys, thanks a lot!

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Unread 05-05-2013, 06:28 AM   #2
nankipoo
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1997 TJ Wrangler 
 
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As I was reading this long list I was ready to say ASD but then you said you swapped it. But being you said its giving a code related to the ASD then this seems the highest priority. Checking fuel pressure is a good thing to do , I am unsure if this ECU shuts down spark on the ASD or fuel but Im thinking its spark. If so then thats a odd thing as you say there is spark.

My advise find a mopar ECU practically any model any engine just so long as the plugs are the same. I had a 4 cly wrangler no start and used a v8 ECU off a full size dodge and it started then engine. It ran like crap BUT it told me the ECU was the problem.

Good luck
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Unread 05-05-2013, 11:05 AM   #3
durango-bob
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I would suspect the Crank position sensor. It sends a signal to the PCM so that the injectors and spark happen at the right time. You are getting a spark, but if it's at the wrong time the engine will not run, even if you pour gas in the throttle body.
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Unread 05-05-2013, 12:34 PM   #4
franciscoapg
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Deleted double post.
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Unread 05-05-2013, 12:37 PM   #5
franciscoapg
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Alright guys, headed out to buy and install the CKS then, hopefully it's as easy as that!
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Unread 05-05-2013, 01:36 PM   #6
franciscoapg
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Hey guys, the Crank sensor has been switched out, still cranks but doesn't start. The codes are still 12 and 25.
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Unread 05-05-2013, 01:44 PM   #7
franciscoapg
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Also, fuel pressure checks out at 42psi down to about 32psi while cranking. So I have fuel pressure at the rail but is it being fed through the injectors??
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Unread 05-05-2013, 07:47 PM   #8
franciscoapg
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Hey guys I have gotten one step closer to fixing this issue. I remembered the firing order from the distributor to the plugs was messed up by the previous owner. When I replaced the plugs and wires, I tried taking them off one by one but noticed that they weren't how the factory service manual says to route them. So I took all of them off and routed it according to the FSM for a 97 TJ. Well I took the plug wires and instead of the "right" firing order, switched them clockwise one spot over. After doing this (while doing this I also had the TB apart and cleaned it thoroughly including the IAC housing) I cranked her and now with some feathering of the throttle, she started up! It is hard to start but, it finally starts now. It will however, stall out again after a few minutes (if that) of running. After clearing the codes again, I STILL get 12 and the one that actually matters- 25. I'm having a tough time figuring out why I'm still getting the IAC trouble code after its been replaced and its housing has been cleaned. Also, why does the jeep run on the seemingly wrong firing order? I will attach some pictures of the factory firing order which I had originally set up the ignition with and then the order in which it starts now. I would really any insight, thanks!

EDIT:

The spark plug firing order that the Jeep ran with appears to have been correct - it seems I misinterpreted the first FSM as in reality the #1 cylinder plug wire terminal on the distributor cap isn't located as shown on the FSM's first diagram. Upon further research, I found a second diagram which showed the correct routing in more detail.
image-4280600164.jpg   image-3063970672.jpg   spark-plug-routing-tj-6cyl.jpg   spark-plug-routing-fsm.png  

Last edited by franciscoapg; 05-06-2013 at 12:38 AM..
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Unread 05-05-2013, 10:49 PM   #9
franciscoapg
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Quote:
Originally Posted by nankipoo
As I was reading this long list I was ready to say ASD but then you said you swapped it. But being you said its giving a code related to the ASD then this seems the highest priority. Checking fuel pressure is a good thing to do , I am unsure if this ECU shuts down spark on the ASD or fuel but Im thinking its spark. If so then thats a odd thing as you say there is spark.

My advise find a mopar ECU practically any model any engine just so long as the plugs are the same. I had a 4 cly wrangler no start and used a v8 ECU off a full size dodge and it started then engine. It ran like crap BUT it told me the ECU was the problem.

Good luck
In regards to the PCM/ECU, I don't have access to a PCM unless I buy one and really don't want to have to bite the bullet on one if that's not the issue. I'm thinking once again though, that unless the firing order is still a little messed up or the replacement autozone IAC was defective or I have a short in my wiring, then the PCM is my issue. Any ideas guys?
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Unread 05-06-2013, 03:39 AM   #10
franciscoapg
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Update: I confirmed via another source from the FSM that wiring the way I changed it to now is correct. That leaves iac issue, wiring defect, or PCM I would think.
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Unread 05-06-2013, 03:59 AM   #11
JPNinPA
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Are all your vac lines connected? It may be a vac leak.
Is it possible when you cleaned the IAC it was damaged? The plunger is sensitive and shouldn't be scrubbed.
Also when you replaced the IAC did the gaskets go on properly?
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Unread 05-06-2013, 10:16 AM   #12
franciscoapg
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Quote:
Originally Posted by JPNinPA
Are all your vac lines connected? It may be a vac leak.
Is it possible when you cleaned the IAC it was damaged? The plunger is sensitive and shouldn't be scrubbed.
Also when you replaced the IAC did the gaskets go on properly?
I'm going to check all vacuum lines and install another IAC. Maybe this one was defective. If that doesn't work, and I don't find a short in wiring should I just bite the bullet on a new PCM?
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Unread 05-06-2013, 09:43 PM   #13
franciscoapg
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Hey guys, the IAC replacement seems to have worked! The jeep starts easily now. It looks like the original replacement was also defective. Now that the car is running and driving I have code 21 which points to an issue in the o2 sensors. I want everything to be 100% solid so ill be fixing that.
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Unread 05-06-2013, 10:01 PM   #14
JPNinPA
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Try clearing it and see if it comes back. It could be set from all the starting issues.
Check the connections and wiring to both o2's.
Did you fave the manifold off?

If you replace the O2's use oem or ntk
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