The Jeep Guru – Page 24 – Jeep Performance Improvement Ideas

November 15, 2015November 16, 2015

2015 XJ List Fall Crawl

Harlan, KY

Once again, the XJ list met for its semi annual outing in the Harlan, Ky. We had to change campsite this time due to Rock Buggy race scheduled at the new race track in our normal camping spot. We stayed in spot 4 instead of 3 at Harlan County Campground. This might have been a nice spot out of the wind but recent logging had made it a muddy mess with barely enough room for tents and tow rigs.

We made the best of it with big fires each night made with scrap left from the loggers. As usual, the stars were amazing under the dark night sky of the back country. While the view was not great, being in the cove blocked the worst of the wind.

On Thursday, we had a small group and took a run at Mason Jar. We made an interesting observation that this group had only manual transmissions. Normally we have about an even mix of autos and stick shifts. However, in this group, everyone got to exercise their left leg.

The Toyotas played on the big rocks at the entrance while the XJs took the scary and still challenging left line. Took us about an hour to get the first fifty feet into the trail. We soon picked up the pace and noticed the trail has changed dramatically over the last ten years. Places that were hard are near impossible but there are new passages that have their own challenges. We all took various lines just to see what they were like.

Neal had a break in his air system so he had to run most of the trail with open diffs since his ARBs require pressure to lock. I got hung on a rock and needed a short tug with my winch. However when I got the cable good and tight the winch failed. Would not go in or out. I was seriously stuck until Frosty turned around and gave me enough of a tug to release the clutch and free the winch.

We made it back to camp just after dark. We built a huge fire to ward off the cold and clean up some of the logs.

Friday we had a few more rigs. We headed up trail 15 and had lunch at the helicopter pad. We played on the White Tail climb until Brian broke his rear yoke and had to be rescued. He drove back to camp in front wheel drive via the paved road stopping at a junk yard to get parts along the way.

The rest of us headed to lower rock garden and made a few passes on the beginning. Frosty and Dean played on the waterfall near rail bed and Frosty ended up breaking an axle shaft.

We then hit Fish Fossil. I had to back out of this trail last year so I was excited to lead the group in this time. Still with no winch, I was determined to make it. Neal’s expert spotting helped me get over the little water fall in the middle. However the long climb at the end was rutted too deep for my 33″s. I had to try to straddle the ruts. My first three attempts had me sliding into the ruts and having to back down. We finally sent a winched jeep up to give me a tug.

I hit it again and this time held on almost to the top. Just a few feet from the top I slipped into the rut again. More throttle from my 4.7 storker motor was probably not the best choice but I was giving it a go. Then there was a snap and the left front wheel stopped turning. Thinking it was just a U joint, I tried again. Then the front wheel gained LOTS of camber.

I accepted the cable and as I was drug to the top the wheel was separating more and more from the Jeep. The lower ball joint was gone. Is was nearing dark so while the other made their way up the hill, Evan made a rally racer run taking me back to camp to get the trailer. We made the long drive around the mountain to come in form Evarts.
With lots of help and some ratchet straps I got it on the trailer and made the long run back around to camp.

I figured I was done for the weekend and even wondered how I would get it off the trailer when I got back to the shop. In the daylight I saw it was just a ball joint and not the axle C. Scott had his ball joint press and as a group we had all the tools I needed. I picked up some ball joints from the parts store in Harlan and an hour later I was back on my wheels ready to ride. Thanks to all who helped me wrench, hammer and press the new parts into the damaged axle end.

We headed up the trail 45 which has become quite a challenge in its self. It took awhile to get every one to middle fork. We then decided to take the easy way (20) to lower rock garden. Along the way one jeep took a bad line through a wash and ended up on its roof down an embankment.

We spent the rest of the day recovering the Jeep and getting it back to camp. This extraction was an amazing feat of team work and recovery skills. No one was injured and the XJ made it way back to camp on it wheels. It ran most of the way but having lost most of its vital fluids during its long time upside down it suffered some drivability issues. We got back to camp just after dark again.

We made our usual delicious steak and potato boats. After that there was wood chopping demonstrations and other “manly” games.

Once again the events of the weekend showed me the benefits of good friends and working as a team. These are the reasons I enjoy wheeling with this particular group.

October 20, 2015October 21, 2015

Lexan Rear Hatch for Porsche 944

In order to improve the aerodynamics of our Porsche 944 ChumpCar racer, we decided to add a Lexan hatch. The ChumpCar rules require all glass other than the windshield to be removed. For our first race, we removed the glass and ran just the hatch frame. After looking at the other 944s racing against us we decided to add a Lexan hatch like they had.

We ordered the material from Five Star Race Car bodies on the advice of one of the other teams. This is the same material sold by Porsche specialty shops for about $100 less. The material surprisingly comes rolled up in a small box so shipping costs were reasonable.

Since we already had the glass out of the hatch we were able to start right away. Removing the glass from the hatch frame is challenging and requires a lot of patience. I have seen youtube videos of people breaking theirs out but they still had to deal with all the little pieces in the channels. I used an oscillating tool to cut the bonding material and carefully removed the glass. I had a heat gun for some places but mostly where the bonding material was cut, the glass lifted out.

We began by laying out the screw holes making sure there was no more than ten inches between holes. We paid extra to have the material cut to the size of the original rear glass. We may have been better off buying the oversized version as ours was just a little smaller than we would have liked.

We marked and drilled all the holes in the perimeter of the frame. Then we set the Leaxan in the upper groove and pressed it into place. We then carefully drilled through each hole into the Lexan. I found that if the bit ran too fast, the material would melt rather than drill and would refill the holes when the drill bit was removed. After a few holes I had the technique down. The biggest trouble we had was finding the right place to drill the holes. The best spacing away fort eh edge of the window put us in a ridge on the inside of the frame. This caused some of the holes to be angled which gave us trouble later.

We used a hand brace and a large drill bit to cut the counter sinks. We used the screws provided in the mounting kit from Five Star. The kit seemed a good value as it came with the right screws, locking nuts and a drill bit.

Due to the way the nuts hit the back of the frame, the ridge caused the nuts to not seat right. We ended up using a cutting tool to notch the frame at each of the screw holes so the nuts could sit flat. This also allowed us to use the shorter screws in the kit allowing the hatch to fit better when back on the car. Notching the frame took away some strength but once careful handling allowed us to get the Lexan mounted without it bending. Once the Lexan was in place the rigidity returned.

We added the two required one inch wide aluminum strips over the hatch and bolted them top and bottom. We then put all the rubber trim pieces back on the hatch to cover the holes and retain the look and function of the original spoiler.

The new hatch is very light weight and looks nice. We hope the performance improvement will be worth the cost and two weekends of work required to make the swap.

September 29, 2015

Jeep XJ Stumbles and Stalls

Jeep XJ stumbles and stalls

For quite a while now Jenny’s 1992 Jeep Cherokee has had a stumble or hiccup while driving. We have tried changing a lot of parts to make it go away. New crank sensor, fuel pump etc.

On her last off road adventure the stalling got so bad as to be dangerous. At one point the Jeep would not go into reverse without stalling. It became very noticeable that whenever the engine shifted positions it would stall.

We checked all the wring connections that could move and they all seemed fine. We were close to ordering a new distributor.

We made one last investigation and found that moving the main harness that comes from the firewall to the engine would stall the engine. There are no connectors in this bundle so it was a bit of a surprise to find trouble in this loom.

I pulled off the cover and cut off the tape. I began pulling on individual wires to see which one caused the stumble. We soon narrowed it down to the green wire that was spliced to six others.

This turned out to be the power wires for the six injectors. The factory crimp was covered in heat shrink and looked in good condition. Even after removing the heat shrink, there was no visual indication of a problem. However tugging on the wire caused the engine to stumble or stall.

To repair, I cut out eh splice and stripped back the wires. I tinned them with solder. I added a short section of wire and soldered all seven wires to the new piece. I then covered it with tape to insulate.

The engine now runs smoother indicating that even when it was working some injectors were not always firing. So far the hiccups on the interstate are gone and there have been no stalls off road.

September 28, 2015September 28, 2015

Passat Coolant Leak

Passat coolant leak

For months now I have been struggling to find a coolant leak on my 2000 V6 Passat. The leak has gotten so bad that I can no longer drive the car.

The leak appeared soon after I replaced a cam tensioner. However the leak was on the opposite head than the one I removed. I assumed the leak had something to do with parts that were disturbed by removing the head.

The leak was at the back on the engine dripping off the driver’s side of the bell housing. Access to this area is very limited due to all the stuff that comes in here.

I removed the intake manifold and noticed that the two water lines to the throttle body were cracked. I could not see any holes but I replaced them anyway. This change did not help the leak.

I was finally able to track the source by dusting he entire area with baby powder. With the powder in place, I was able to see where the drip came from. I saw it was from the coolant pipe at the back of the engine; however I was still not sure of the exact spot.

I removed the manifold again and used my brake pressure bleeder to pressurize the system. I attached to one of the tubes that goes to the throttle body and blocked the other one with a plug. So I was able to see the drip coming off the quick connect from the heater hose.

I was able to pull the clip and work the hose off the tube. I tried cleaning it up and brushing the metal part. But it still leaked when pressured up. On closer inspection I found, that the O-ring inside the quick connect was flat and hard. I priced the new lines and decided to give a try at refurbishing this one. I was able to use a pick to pluck out the old O-ring and then match up one from my kit.

I cleaned everything up well and put the line back in place. I pressurized the system again and this time it held. I left for a bit and the pressure was still on the system when I got back.

Not to get it all back together and give it a test drive.

September 21, 2015

Renix no spark

A few weeks ago I went to start up Scuffy my 1988 XJ and it would not start. The starter spun but the motor would not start. A quick check showed no spark.

I suspected a broken wire but I did not see anything obvious. I began with the usual suspects and checked the connection for the CPS and the ground wire by the dip stick. These both seemed fine.

I then went to check the distributor wiring and found a wire pulled out of the plug. I am not sure this was before or after I unplugged the connector to check it.

I decided to then drag the Jeep into the shop for better diagnosis.

I put a scope on the CPS and it read the correct 500mv. However the wire looked in really bad shape so I ordered a new one. I also ordered a new distributor since the wires were falling out of the connector.

When they arrived, I installed them and expected the engine to fire right up. No such luck. I still had no spark. I hooked up a test light and confirmed the injectors were firing so the computer had to be getting its input signals. Just to be sure, I cleaned the C101 connector at the firewall anyway.

I then started to focus on the coil. I removed it from the ignition control module and tested it. It made a spark out of the system. I pulled the ICM and took it to autozone to be tested. The tech seemed to be unfamiliar with the test procedure but he eventually figured it out and declared the unit bad. He happily sold me a replacement.

I installed that and again no spark. I began to suspect a faulty ECM output. I checked the trigger wire which is yellow and could not detect any pulses. I used a test light to simulate the pulse at the ICM and sure enough the coil would fire.

I was really dreading puling the ECM from under the dash because my racing seats and roll cage make access difficult. However, I needed to test continuity of the yellow wire from the ECU to the ICM.

I began on the engine side since it was easier to access. I began pulling off the wiring harness cover and running my hand along the yellow wire. I soon found where it had been chewed in two.

I quickly spliced the wire and the other one near it that was also cut. The Jeep started right up.

I did leaner several things about the Renix system that I did not know before. It has several differences from the Mopar controller I am more familiar with.

The CPS (crank sensor) on the Renix system has two wires while the Mopar has three wires. The Renix CPS generates a voltage due to eh starter teeth passing the sensor on the flywheel. There is a missing tooth where the coil fires.

The Cam position sensor in the distributor has nothing to do with firing the coil. I have trouble wrapping my head aroun dhti sone but it seesm to be true according toe h Renix control manual. The cam sensor signal helps the ECU determine which of the missing teeth is for Cylinder 1. If the compute can’t get a reference signal it just makes up something. If it guesses wrong, the engine will still run just not as well as if it guesses right. So maybe my broken distributor wire explains why sometime my engine would feel off power and others times run fine.

The Renix coil is fired by a transistor pack under the coil. This pack gets a 12V pulse from the computer when it is time to fire the coil. Timing, dwell etc. are all controlled by the ECU.

The Renix injectors get a 12V pulse to fire and use a common ground wire for all six. The opposite is true for the Mopar that feeds all six with 12V and grounds the one that it wants to fire.