post #1 of Old 09-02-2013, 06:27 PM Thread Starter
Akumakis
Registered User
1991 YJ Wrangler 
 
Join Date: Sep 2012
Location: Kelowna
Posts: 9
On the table; a tricky one for the YJ experts:

2 years or so back, my 1991 YJ 4.0L started this habit of quitting after it runs for a while. Engine temp is nice and cool, and it'll happen in summer or winter, after about an hour of continuously driving. It happens faster after lots of uphill grinding, though it will quit on the highway if it's hot out. When it quits, it seems to just lose spark. Sometimes it would backfire (stopped this after the new air cleaner, below), and often I hear a "pressure release" sound, which I assume is back pressure in the exhaust. After it quits I wait a minute, then it starts and runs fine, but dies again a minute later. Once it starts this, it will run about twice as long as I let it rest. Up in the bush, if I kill the engine on downhills or stop every 20-30 minutes or so for a beer, it'll never quit, since it gets enough rest breaks.

I couldn't find an obvious solution, so I took it in to a general mechanic who had worked on the jeep. Not surprisingly, he couldn't get it to quit, and found nothing wrong. I drove until it quit, then limped up just as it died - he still couldn't figure out anything wrong.

I was in the process of doing some upgrades, so I expanded the process, did some research, and replaced lots of old stuff that could be the culprit. I though I had it beat last fall, but this summer it cropped up again.

- New stuff (since it first died). All high performance gear:
Coil
Spark plug leads
Plugs
Distributor
Air Cleaner
Fuel filter
Sensors: oxygen, intake temp, TPS (twice), crank position, water temp, oil press
Injectors
Battery
Header/Exhaust (never had CC within the issue timeframe)
Radiator/Thermostat

- Current Engine Codes:
12 - battery disconnected last 50 starts: yeah, I did.
33 - air con clutch relay: I don't have air conditioning.
15 - distance sensor or circuit - I understand this is due to an electric speedo. Doesn't fit the symptoms from what I see.
*24 - sometimes it shows, sometimes not. I've replaced it twice, once right after the jeep died. Died again 15 minutes later.

Whoever figures it out wins the Jeep Genius award.

Awaiting brilliant input.

Akumakis is offline  
post #2 of Old 09-02-2013, 08:23 PM
laybackman
Bikini Bridge Inspector
 
laybackman's Avatar
2010 JK Wrangler 
 
Join Date: Dec 2002
Location: Massachusetts
Posts: 6,876
Quote:
Originally Posted by Akumakis View Post
On the table; a tricky one for the YJ experts:

2 years or so back, my 1991 YJ 4.0L started this habit of quitting after it runs for a while. Engine temp is nice and cool, and it'll happen in summer or winter, after about an hour of continuously driving. It happens faster after lots of uphill grinding, though it will quit on the highway if it's hot out. When it quits, it seems to just lose spark. Sometimes it would backfire (stopped this after the new air cleaner, below), and often I hear a "pressure release" sound, which I assume is back pressure in the exhaust. After it quits I wait a minute, then it starts and runs fine, but dies again a minute later. Once it starts this, it will run about twice as long as I let it rest. Up in the bush, if I kill the engine on downhills or stop every 20-30 minutes or so for a beer, it'll never quit, since it gets enough rest breaks.

I couldn't find an obvious solution, so I took it in to a general mechanic who had worked on the jeep. Not surprisingly, he couldn't get it to quit, and found nothing wrong. I drove until it quit, then limped up just as it died - he still couldn't figure out anything wrong.

I was in the process of doing some upgrades, so I expanded the process, did some research, and replaced lots of old stuff that could be the culprit. I though I had it beat last fall, but this summer it cropped up again.

- New stuff (since it first died). All high performance gear:
Coil
Spark plug leads
Plugs
Distributor
Air Cleaner
Fuel filter
Sensors: oxygen, intake temp, TPS (twice), crank position, water temp, oil press
Injectors
Battery
Header/Exhaust (never had CC within the issue timeframe)
Radiator/Thermostat

- Current Engine Codes:
12 - battery disconnected last 50 starts: yeah, I did.
33 - air con clutch relay: I don't have air conditioning.
15 - distance sensor or circuit - I understand this is due to an electric speedo. Doesn't fit the symptoms from what I see.
*24 - sometimes it shows, sometimes not. I've replaced it twice, once right after the jeep died. Died again 15 minutes later.

Whoever figures it out wins the Jeep Genius award.

Awaiting brilliant input.
Unplug the VSS sensor plug from the VSS in the TC. You'll lose your speedometer. See what it does then.

Make sure the MAP sensor has good vacuum.

Do you know what was good about the good old days? I wasn't good, And I wasn't old!

Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....
laybackman is offline  
post #3 of Old 09-02-2013, 11:51 PM Thread Starter
Akumakis
Registered User
1991 YJ Wrangler 
 
Join Date: Sep 2012
Location: Kelowna
Posts: 9
I'll try the VSS trick. My understanding, however, is that this component regulates idle at stop - it shouldn't affect hot running performance at throttle.

A faulty MAP should send codes (never did), and a classic symptom should be rough running, which my jeep doesn't suffer from - it runs perfect until it dies, then perfect again after a rest.

All that said, I'll try these out and let you know...thanks.
Akumakis is offline  
post #4 of Old 09-03-2013, 12:46 AM
Fattynutzkin
Registered User
1988 YJ Wrangler 
 
Join Date: Jan 2013
Posts: 8
Sounds like a camshaft position sensor.

Is your fuel pressure within operating limits.
Fattynutzkin is offline  
post #5 of Old 09-03-2013, 07:09 AM
WDNewman
Registered User
1989 YJ Wrangler 
 
Join Date: Jun 2013
Location: Central Mississippi
Posts: 1,359
Quote:
Originally Posted by Fattynutzkin View Post
Sounds like a camshaft position sensor.
Sure does. If they are faulty, heat really works on them. Worth a check.
WDNewman is offline  
post #6 of Old 09-03-2013, 07:12 AM
laybackman
Bikini Bridge Inspector
 
laybackman's Avatar
2010 JK Wrangler 
 
Join Date: Dec 2002
Location: Massachusetts
Posts: 6,876
Quote:
Originally Posted by Akumakis View Post
I'll try the VSS trick. My understanding, however, is that this component regulates idle at stop - it shouldn't affect hot running performance at throttle.

A faulty MAP should send codes (never did), and a classic symptom should be rough running, which my jeep doesn't suffer from - it runs perfect until it dies, then perfect again after a rest.

All that said, I'll try these out and let you know...thanks.
#24 is the TPS DTC. But if the MAP sensor signal does not correlate with the TPS sensor that code can pop on.

Do you know what was good about the good old days? I wasn't good, And I wasn't old!

Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....
laybackman is offline  
post #7 of Old 09-03-2013, 08:00 AM
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit
Posts: 20,786
Akumakis, you posted your Jeep info in your thread, please put the info into your profile. It helps when you dont have to go digging to help someone figure out what is going on.
You need to see what is being lost when it stalls and will not start. You need to do some leg work first.

The speedo sensor will effect the calibration for decel. It can cause a no start without a fault code if the connector shorts. Repair the connector or replace the sensor.

You replace the TPS. It will set a code if it disagrees with the input from the Map sensor. The Map is usually not an intermittant sensor so it is a curious fault to be setting.

Clear the stored fault codes by disconnecting the the battery for a long 10 count. Check your codes to make sure you only have the 12,33, and 55. Get a pressure guage. Run the standard pressure test; 31 psi engine running, disconnect the vacuum line to the pressure regulator 39 psi, and bleed down it should hold more then 20 psi for 20 minutes. Take it for a drive and get it to stall out. Check your codes and see if the tps or any othe codes set. Check for spark at the plugs and see if you have spark at the plugs. Hook up your pressure guage to the fuel rail and run the pressure test. You will not be able to test the running pressure but ignition on it should be comparable to what you measure before. Post back the results.

We can get it figured out if you will do the leg work.
Que89YJ is online now  
post #8 of Old 09-04-2013, 06:33 PM Thread Starter
Akumakis
Registered User
1991 YJ Wrangler 
 
Join Date: Sep 2012
Location: Kelowna
Posts: 9
Que89YJ, that stuff didn't show up in the tablet version. Filled it in now, thanks.


And thanks to all for the ideas. I didn't even know about the camshaft position sensor...I'll dig into these as soon as I have Jeep time, and report back!

1991 Jeep YJ Renegade 4.0L
Akumakis is offline  
post #9 of Old 09-04-2013, 06:49 PM
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit
Posts: 20,786
Yeah. I posted to the forum admin. on the info. Same problem on my android app. Post back what you find.
Que89YJ is online now  
post #10 of Old 10-03-2013, 05:56 PM
The_Goob
Hell on Wheels
 
The_Goob's Avatar
1991 YJ Wrangler 
 
Join Date: Jun 2012
Location: Walcott
Posts: 4,404
Id sure love to see if you figured this out, since its exactly whats happening to my 91
The_Goob is online now  
post #11 of Old 10-03-2013, 07:09 PM
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit
Posts: 20,786
Amukakis any update?
Que89YJ is online now  
post #12 of Old 10-03-2013, 09:05 PM
DirtKar
I pledge allegiance.
 
DirtKar's Avatar
1993 YJ Wrangler 
 
Join Date: Jun 2012
Location: Nor Cal Sierras
Posts: 2,620
This is an interesting one... I sent him a pm requesting results, Que.

Quote:
Originally Posted by Anticanman

Come on by! It's easy to network locally when you join a 4x4 club especially when all the clubs in your state are united and invited to each other's runs. You meet poor folk like me or run into guys that own some of the big companies you only aspire to order from and drool when you see their products. The great uniting factor is that we are all jeepers at heart and are willing to help each other out even if its just a little. That's what the jeep wave is all about: community. The wave is the tip of the iceberg.
__________________
Luck Favours The Prepared
YJOTM JULY 2014
DirtKar is offline  
post #13 of Old 10-03-2013, 10:51 PM Thread Starter
Akumakis
Registered User
1991 YJ Wrangler 
 
Join Date: Sep 2012
Location: Kelowna
Posts: 9
The Continuing Saga of the Jeep Gone Wild

Tried a few things, but not the CSPS yet.

Testing for resolution is tough. It takes a while to heat up to the point of quitting, and we tend to stop for beers when out 4beer4ing. Even enough downhill seems to give it sufficient time to rest.

As I have time to try things and test properly, I'll keep posting on it.

Thanks, all.
Akumakis is offline  
post #14 of Old 10-04-2013, 12:37 PM
The_Goob
Hell on Wheels
 
The_Goob's Avatar
1991 YJ Wrangler 
 
Join Date: Jun 2012
Location: Walcott
Posts: 4,404
4beer4ing sounds fun, but I have a CDL so none of that for me
The_Goob is online now  
post #15 of Old 10-04-2013, 09:30 PM
linusb
Registered User
1994 YJ Wrangler 
 
Join Date: Aug 2009
Location: Lexington,SC
Posts: 1,838
I suggest VSS as well. I grenaded my TC once and as it was dying, the engine would stall and not restart from the VSS having gotten too hot.

VSS it does funny things to CPU and it will absolutely cause a no start condition.

You'll get a bad idle with it unplugged as well as a CEL code.

If that don't work, check your wiring. I recently had a hot stall issue that I seem to have elongating by routing large wire loom on pass side away from engine. I think I might have a bad wire and it was shorting against block occasionally.

1994 YJ Wrangler, 4.0, AX15, NP231, 35x12.50x15 BFG KM2s, 4" RC lift, 1" lift Boom Shackles, 1" BL, 4.10 gears, 8.8 LSD in rear and D30 Aussie Locker in front, on-board air conversion, Ramsey RE8000 winch.
linusb is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome