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Amedee
Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 24419
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Replaced head gasket on 2004 Grand Cherokee and now have a

Customer Question

Replaced head gasket on 2004 Grand Cherokee and now have a 'no start situation'. Have spark, fuel, compression. Vehicle briefly back fires out of intake and then smells heavily of fuel. Please advise! At a complete loss
Submitted: 1 year ago.
Category: Jeep
Customer: replied 1 year ago.
Both Cam sprockets are V8 up. Cylinder #1 sparks at TDC, matches marker on crank indicator. Check engine light is on but shows no codes on reader. Will also flash occasionally. OFF, ON, OFF, ON, OFF, ON also shows no codes. The 'no key' light comes on but then shuts off when key is being turned. Thanks in advance.
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Amedee replied 1 year ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. Please accept my offer and call me now.

Customer: replied 1 year ago.
I did not know there was an extra charge. Can we first start on this problem first via email and then move to a phone call should the need arise? Thanks Amedee?
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! YES, we sure can.

Expert:  Amedee replied 1 year ago.

Let me ask you this, if you disable the fuel system, does the engine start and run using starting fluid?

Customer: replied 1 year ago.
Great suggestion, and just tried it and got the same result. A muffled back fire at first and then nothing. It did at least not smell like fuel but that was because we had turned off the injectors. Very eager to receive next suggestion. Thanks Amedee
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! If the engine does in fact have spark but does not run on starting fluid (after disabling the fuel system), the engine is simply out of time. Hands down.

Expert:  Amedee replied 1 year ago.

So, basically, we need to figure out of the ignition timing is off or if the valve timing is off. Does that make sense?

Customer: replied 1 year ago.
Obviously not the news I was hoping for. What about a crank or can sensor. The engine ran prior to us changing the head gasket but we put the head back on with the cam sprocket in the wrong position. Then we adjusted the v8 logo to be back to 12 o'clock position. We did this without removing the timing chain cover. Is it possible the idler is not in the correct position? Can it move while the Cain is still tightly attached to the other cam from the crank? We have spark but think that something could be wrong with the timing in the computer or one of the sensors?
Expert:  Amedee replied 1 year ago.

Very good question. I will explain..

Expert:  Amedee replied 1 year ago.

Because you have spark, no.. the problem is not going to be the cam or crank sensor..

Expert:  Amedee replied 1 year ago.

YES, the problem is caused by the valve timing being off or incorrect. This basically confuses the computer causing the ignition timing to be off.

Expert:  Amedee replied 1 year ago.

The computer is not firing the ignition system at the right time because of fualty inputs. The cam and crank signal inputs. However, it is not the sensors. The signals from the cam and crank sensor out of sync with eachother because the valve timing is off.

Expert:  Amedee replied 1 year ago.

Does that make sense?

Customer: replied 1 year ago.
Fair enough. Then is it possible that the computer needs to be reset? Could it be that I did not put the starting fluid in properly or effect the system by unplugging the fuel injector and pump fuses. There is a no key light that comes on and also have a flashing check engine light with no codes. Again, this ran prior to the head gasket change. Your assurance is greatly appreciated..
Customer: replied 1 year ago.
Could we have demagnetized the cam wheel? How can we correct the valve timing issue?
Expert:  Amedee replied 1 year ago.

Reseting the computer will not get this thing started.. at least in my experience. However, you can sure try. In addition, replacing the computer will not help either. The new computer will act the same way.. again, it is because of the faulty inputs to the computer. What do we know about computers? Garbage in, garbage out. Thats how they work. YES, the cam or crank trigger wheel can in fact be damaged affecting the inputs to the PCM. This will affect the signal coming from the cam or crank sensor as the engine is cranking over.

Expert:  Amedee replied 1 year ago.

So, what you need to do is pull the front cover apart and double check the timing marks and the cam trigger wheel for damage.

Expert:  Amedee replied 1 year ago.

That is your next step.

Customer: replied 1 year ago.
Incredible advice. Will get back to you shortly after we dig deeper...
Expert:  Amedee replied 1 year ago.

Sounds good. Good luck!!!

Customer: replied 1 year ago.
even though the indicator on the harmonic balancer is lined up and both v8 logos are on top, we still need to take off the timing cover to ensure the timing is accurate? I guess since our timing on the cam sprocket was off. We used zip ties to secure the cam timing chain to the sprocket and then put it back together but noticed the timing was off a couple degrees when we compared the V8 logo to the mark to then white mark on the harmonic balancer.
Expert:  Amedee replied 1 year ago.

Here is a picture.

When the number 1 piston is at TDC, the cam marks should look like this..

Expert:  Amedee replied 1 year ago.

In addition, even if these timing marks are lined up correctly, the camshaft(s) could be out of aligment with the crankshaft.

Expert:  Amedee replied 1 year ago.

For example, if one of the camshaft sprockets has spun on the camshaft, the timing marks will be dead on and the cam will be out of rotation in relation to the crankshaft. That is why you hear the combustion happening from the intake or exhaust when trying to start the engine.

Customer: replied 1 year ago.
How is it possible for the camshaft sprocket to spin on the camshaft when there is the notch on the camshaft that goes into the hole in the sprocket? The crank is firing the spark plug at TDC, this means that the timing is right on the crank correct? Also, is it possible that the cam is 180 off even with the v8 on top?
Expert:  Amedee replied 1 year ago.

That is why we should talk on the phone. We could have covered all of this by now. Anyway, to answer your question, the dowel pin between the camshaft sprocket and camshaft could have broke or sheared causing the sprocket to spin on the camshaft. The ingition timing is not off in relation to the crank. It is off in relation to the cam(s)

Customer: replied 1 year ago.
let's talk on the phone. You have confirmed your value. What time works for you?
Expert:  Amedee replied 1 year ago.

I can talk in about 10 minutes. Does that work?

Expert:  Amedee replied 1 year ago.

Going to log off now. Please accept my offer and call me.

Customer: replied 1 year ago.
Sorry Amedee, I cannot talk until later this evening. 4 or 5 hours but have a thought. If we put pliers to our cam magnet trigger wheel, or hit it with out magnetic bolt grabber, would that cause a no start situation?
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! I have been visiting a family member in the hospital. YES, anything that can damage or affect the signal going back to the computer (cam or crank signals) can cause a no start condition like you are describing.