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  #16  
Old February 28th, 2019, 16:46
4x4JeePmaNthINg's Avatar
4x4JeePmaNthINg 4x4JeePmaNthINg is offline
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Re: P0122,p0171 having trouble getting engine running properly


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  #17  
Old March 1st, 2019, 01:36
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Re: P0122,p0171 having trouble getting engine running properly

I ran it again today before work, here is what the scanner reads once it's running bad.


I may try a new 02, some have said the body, which I have, do not work well with jeeps idk.
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  #18  
Old March 1st, 2019, 01:51
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Re: P0122,p0171 having trouble getting engine running properly

Quote:
Originally Posted by smokeyyank View Post
Leaks as in vacuum leaks? Smoke test is going to be your best bet on that. They do have DIY ways to make one.
I'll see what I can come up with this monday-tuesday. I feel like my stomach is in my throat everyday trying to get my only wheels going man. This has been quite the journey taking on a job like this for my having practically no experience with engines.

My hats off to anyone doing this regularly.
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  #19  
Old March 1st, 2019, 07:47
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Re: P0122,p0171 having trouble getting engine running properly

Quote:
Originally Posted by 4x4JeePmaNthINg View Post
I'll see what I can come up with this monday-tuesday. I feel like my stomach is in my throat everyday trying to get my only wheels going man. This has been quite the journey taking on a job like this for my having practically no experience with engines.

My hats off to anyone doing this regularly.
I hear ya man. Mechanical stuff I have no issue with but electrical things are a bitch. DIY smokers aren't hard to make. Just take some basic things and a compressor. Wish I knew more to help a out, but I'm even greener in this arena than you are right now!
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  #20  
Old March 10th, 2019, 22:14
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Re: P0122,p0171 having trouble getting engine running properly

First and foremost, I want to give a shout-out to Matt! He did a great job on the many "first time ever" tasks that went into this engine swap.

The stars aligned, the clouds parted, I was able to help another COLORADO CHAPTER MEMBER sort out some problems with his XJ.

The purpose of writing this out is to illustrate a systemic approach to diagnostics, that seems to be absent from many internet threads.

Drill-Down List:

Visual Inspection:
All electrical and vacuum systems hooked up, general condition?
Any loose or missing fasteners?
Any gaps, misalignments, or witness marks indicating loose assemblies?

Confirm Observations:

Matt had already confirmed the TPS Low and High Voltages were within prescribed limits. Without having specific knowledge of the software’s terminology, I wanted to do a “sweep” test on the sensor. Having some working knowledge of Rheostats and Potentiometers, and not having a DVOM with the capability of measuring for “drop out,” I brought an analog Ohmmeter. Alas! I could not reliably connect to the pins, so we opted for the OBDII reader. With the Key On, Engine Off, we checked the TPS for dead spots. The display did show two spots with no reading from the TPS, but, not at idle. The question remains: Are the dead spots the reason for the “TPS Low Voltage” code?

Since I am not familiar with the scanner software, I wanted to take another approach to the “Bank 1 lean” code set by the scanner.

While we tested the TPS, the ECU set another code, something about no signal from the CPS. Go figure!

Active Investigation:

After attaching a Vacuum Gauge to the manifold, and pressure gauge to the fuel rail, we started the engine. I noticed a slight misfire, and rough idle. The vacuum gauge registered 14” at idle, with minor, rapid, fluctuations. I thought this was a low reading, which could be an indicator of a few different problems. There were no sounds indicating mechanical problems inside the engine. I attributed the rapid fluctuation and low vacuum to the cylinder misfire. Fuel pressure was within spec, and consistent.

In an attempt to track down the misfire, we started by disconnecting the plug wires, one at a time, with the engine running. Each time, the rpms dropped, with no other changes. I touched each injector to find the solenoids cycling. In spite of Matt’s diligence in labeling and keeping the under hood organized, I wanted to try swapping injector connectors on cylinders 1 & 2, 5 & 6: No change. When we shut off the engine to swap the first pair of injector connectors, I did monitor the pressure on the fuel rail. After waiting 30 minutes, we had a slow and consistent 50% bleed down, which I believe is acceptable.

Through my process of looking for the big AHA! The scanner software on Matt’s had shut off a few times. At this point, I wanted to see the real time output from the oxygen sensor. Matt found the bar graph, with a voltage reading. As we watched, the graph went flat, the voltage went to zero, and stayed at zero. We had our smoking gun! When Matt pulled the oxygen sensor, it was covered with black soot.

After installing a new oxygen sensor, we started the engine to record the same low, unstable vacuum reading that we had already documented. I held the throttle open long enough to clear unburned fuel from the cylinders, no change. Time to look at the spark plugs.



All six spark plugs were covered with black soot, except where the arc was jumping from electrode to ground strap. All six plugs were properly gapped. All six spark plugs are platinum tipped, the manufacturer specified standard plugs. I wanted to do a compression test while the spark plugs were out.

Matt held the throttle all the way open while cranking the engine. While cranking on the first cylinder test, there was a strong fuel smell that was not present when we tested the rest of the cylinders. Results are as follows:
Cylinder 1-130 lbs.
Cylinder 2-130 lbs.
Cylinder 3-128 lbs.
Cylinder 4-135 lbs.
Cylinder 5-132 lbs.
Cylinder 6-130 lbs.

After recording the readings on my phone, I observed that all cylinders held their pressure until I released it.

At this point, we decided to install the used plugs from the old engine. We pulled the used plugs from the old engine, verified the gap and installed. The engine started easily and idled smoothly, the vacuum reading was more stable at 14”. As a cross check, I put the vacuum gauge on my engine: 14” vacuum. I guess that is all we can expect at his elevation.

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