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Chris
Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 13771
Experience:  Jeep Certified Master Tech
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1999 Grand Cherokee, 201K. Just replaced the transmission

Customer Question

1999 Grand Cherokee, 201K. Just replaced the transmission solenoids and replaced the catalytic converter yesterday (had a non-qualified model). Runs great, even in 100+ heat. Smog test failed twice yesterday before and after catalytic converter replacement; NOx readings over 1,200. Clearly high combust. temp issues. Recommendations?
JA: Sometimes the difference between passing and failing a smog test can be just a few quick repairs. Luckily, the mechanic I'm going to connect you with will have just the information you need to get this fixed fast. How many miles are on the car?
Customer: 201,500
JA: Are you hoping to fix this yourself?
Customer: no; will take to certified mechanic, but am hoping for some suggestions and to keep this under $300.
JA: OK! The Jeep Mechanic will help you with the diagnostics so you are sure to get this fixed right. Is there anything else important you think the Jeep Mechanic should know about your Jeep?
Customer: nope
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Jeep Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Jeep
Expert:  Chris replied 1 year ago.

Hello and welcome to just answer. I am a shop foreman and a California smog tech. Is this a 4.0 L straight 6 engine in your Jeep?

Chris

Customer: replied 1 year ago.
NOx readings were over 1200, both speeds, with brand new catalytic converter. Tested in Sacramento yesterday, air temp 102.
Expert:  Chris replied 1 year ago.

Ok, I thought so. That engine is notorious for high Nox.

Expert:  Chris replied 1 year ago.

Here is what I recommend :

Expert:  Chris replied 1 year ago.

Get a bottle of Sea Foam engine treatment and perform a decarbon procedure by slowly pouring the product into the throttle body while the engine is running. Follow the instructions on the bottle.

Expert:  Chris replied 1 year ago.

Then shut off the engine and let it sit for about an hour. Now get a spray bottle filled with water and with the engine running at an idle, spray the water into the throttle body for about 5 to 10 minutes. Now go out and drive the Jeep onto the freeway performing several wide open throttle sessions.

Expert:  Chris replied 1 year ago.

Another thing to do is to run premium fuel and add a bottle of fuel injector cleaner to the tank. Doing these things will help reduce high combustion temperatures and reduce Nox.

I hope that this information is helpful and if so, please take a minute to rate my service today.

Thank you!

Chris

Expert:  Chris replied 1 year ago.

Hello? Did you receive my answer?

Expert:  Chris replied 1 year ago.

Hello, justchecking back to see if you received my answer. Let me know if you did or did not. I can send it again if necessary.

Chris

Expert:  Chris replied 1 year ago.

If my answer has helped you, please help me by leaving a rating or accepting my answer so I may be credited. Rating or accepting my answer does not cost you extra. It allows me to be credited for my work. Please rate or accept in a positive way. You can ask follow-up questions after you rate or accept.

Thank you!

Chris

Expert:  Chris replied 1 year ago.

I sent you a phone call request. Accept it if you would like me to call. If you do not, let me know and I will help you out using this chat format.

Chris

Expert:  Chris replied 1 year ago.

Hello? Was my answer helpful? Are you still here?

Chris