Sporadic delayed starting

[coolwind57]

On 6/17/2018 at 9:46 AM, cruiser54 said:

Good idea.

 

On 6/16/2018 at 2:35 PM, Ωhm said:

Check the hose between the manifold and the fuel pressure regulator for fuel. Possible small leak on regulator diaphragm.

 

Cruiser, Ohm:  I rented a fuel pressure gauge today after work.  I think we're good as far as fuel delivery.  33-34 instant spike when key is turned on and 30-31psi at idle.  Pull vac line to regulator and I get 38psi.   Leak down was bad, but I'm not convinced that my very-used rental gauge was sealing 100% at the shrader valve.  I lost all pressure within 5 minutes, slowly but steadily.  Again, I think I had a bad seal at the valve.

 

We can now assume that the instant spike of fuel pressure on KEY ON/ENGINE OFF mode would eliminate the possibility of a early fuel starve scenerio, right?  Especially since engine starts are typically better when the engine has had at least a half-day of cool-down.

 

Perhaps I'll now move on to the electrical equation of the problem...

I'm going to stick the new distributor in maybe tomorrow if I find the time.   I apologize for my poor little pea-sized brain, but what's up with distro indexing?  What causes the need to do this?  I am assuming that things wear/loosen and begin to migrate out of spec over time, maybe, requiring a realignment of distro gears with engine firing?  If not, then didn't the factory get it right when they developed location of the alignment tab?  Would I need to do this tab cutting with a brand-new distributer?

 

Purpose of new distributer install is to eliminate the possibility of faulty sync signal generator & pulse ring.  Thanks for helping me, everyone.  

[Ωhm]

12 hours ago, coolwind57 said:

Would I need to do this tab cutting with a brand-new distributer?

Engine timing is a function of the CPS sensor location and the crankshaft trigger wheel. Using this signal, the ECU will determine when to fire the coil for base timing or any advance timing needed for any engine demands. No need to rotate the distributor housing/cap. Indexing ensures that the tip of the rotor, which does rotate, is correctly positioned for the number #1 tower on the distributor cap. Rotor tip should just be pulling away (trailing edge of rotor tip) from the #1 tower. Cylinder piston #1 must be on TDC of the compression/power stoke. Once rotor tip is set, the signal generator/pulse ring (SYNC sensor) will also be in its correct position. So again there is never any need to move the distributor housing/cap and should be installed using the distributor housing locking tabs.

[cruiser54]

Distributor indexing explained
For clarification though, that’s not a cam sensor inside the Renix dizzy. It’s there to fire the injectors sequentially with the firing order. You’ll never notice if it went bad because the ECU will try to “guess” where it is and does a heck of a job at it.

As for the “timing”, it is controlled by the ECU. Ever notice how wide the tip of the rotor is? Try and wrap your head around this:

When the ECU yells “Fire” to the ignition control module, where is the rotor in relationship to the dizzy terminal? Not to the terminal yet? Past the terminal too far?

What happens to the spark/secondary ignition strength when it has to jump the Grand Canyon in comparison to shooting from a rotor tip?

Use Tip 12 first to guarantee you’re on #1 TDC.

 

Now, if you read my Tip 13, you would see the importance of indexing a Renix dizzy......

[coolwind57]

1 hour ago, cruiser54 said:

Distributor indexing explained
For clarification though, that’s not a cam sensor inside the Renix dizzy. It’s there to fire the injectors sequentially with the firing order. You’ll never notice if it went bad because the ECU will try to “guess” where it is and does a heck of a job at it.

As for the “timing”, it is controlled by the ECU. Ever notice how wide the tip of the rotor is? Try and wrap your head around this:

When the ECU yells “Fire” to the ignition control module, where is the rotor in relationship to the dizzy terminal? Not to the terminal yet? Past the terminal too far?

What happens to the spark/secondary ignition strength when it has to jump the Grand Canyon in comparison to shooting from a rotor tip?

Use Tip 12 first to guarantee you’re on #1 TDC.

 

Now, if you read my Tip 13, you would see the importance of indexing a Renix dizzy......

So it's NOT a matter of the wear/age causing some minor rotor misalignment from it's desired spark plug post terminal? 

 

I suppose my question should had been this:  Are we modifying (cutting a locating tab on a distributor) to correct worn and out of adjustment parts or because Jeep didn't get it completely right at the factory to begin with?  I am getting the purpose of it now, but at what point did a need to do this procedure develop? 

 

If Jeep didn't get this right from the start, then I should index (which involves the cutting the locating tab) this brand new distributor I'm fixing to install, right?  

 

[coolwind57]

11 hours ago, Ωhm said:

 No need to rotate the distributor housing/cap.

 

11 hours ago, Ωhm said:

Once rotor tip is set, the signal generator/pulse ring (SYNC sensor) will also be in its correct position. So again there is never any need to move the distributor housing/cap and should be installed using the distributor housing locking tabs.

Perhaps I'm not following how one sets the rotor tip without rotating the distributor housing/cap.  Cruiser's Distributor Indexing instructions, step #11:

 

11.  Reinstall the distributor cap with the cutout “window”. Rotate the distributor housing until the trailing edge of the distributor rotor tip is just departing from the #1 spark plug wire post terminal.

 

 

[Ωhm]

Sorry, I never realized step 5 has you cutting off the tabs. This allows for dropping the distributor in the engine only aligning the oil pump driving shaft and setting the rotor tip approximately, or if your lucky, exactly where it needs to be. If your rotor tip is within a tooth or two, moving the distributor housing can make up for this difference.

It is possible to do this without cutting off the tabs, but three (3) things need to happen all at once.

1. Oil pump driving shaft must be aligned.
2. As the distributor gear is dropped into the engine, the rotor tip will rotate with the distributor driving gear and must end up just leaving the distributor cap #1 tower, when distributor cap is reinstalled.
3. Distributor housing tabs show the hold-down bolt hole between both tabs.

This is not a easy task, but it is possible. Its your call.
 

[coolwind57]

I just installed the brand-new distributor and performed Cruiser54's method of indexing.  I took photos and will do a write up on this tomorrow.  Apparently, I did everything correct...the new distributor slipped down just fine, aligned with oil pump and using the window method, I got her indexed correctly, it seems.  She fired up and ran just fine.  Could be the placebo effect, but it did seem to idle smoother and I thought I was detecting slightly lower rpm too but I'm not 100% sure.  

 

All of this was a new experience for me:  finding TDC, marking cap/wires, removing/installing new distributor, etc.  I'm feeling pretty dang proud and I praise God I didn't screw anything up.  

 

I'm anxious to see if the new distributer (with a new synch sensor inside) will have a postive effect on my delayed starting problem.  Should find out in the next couple of driving days.

[cruiser54]

They were wrong from the factory......

 

We worked hand in hand with JeepTech figuring this out at our dealership. 

 

This is an important procedure.

[coolwind57]

33 minutes ago, cruiser54 said:

They were wrong from the factory......

 

We worked hand in hand with JeepTech figuring this out at our dealership. 

 

This is an important procedure.

Wow.  That is freakin' amazing.

 

I'm not convinced that a new distributor and indexing solved my starting issues.  I started my engine twice this morning and she started relative quickly but it usually gives me fits when i shut down and restart more frequently after the long evening/morning rest.  I swear it seems to idle better, though.  Second start this morning--although not so prolonged, had me smelling fuel a bit.  I'm thinking fuel delivery.  

 

 

[cruiser54]

You 100% sure the throttle body to MAP sensor hose isn't compromised somehow?

 

CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY TO MAP SENSOR HOSE FIX

JANUARY 23, 2016 CRUISER54 27 COMMENTS

The Renix throttle bodies have a strange and failure prone connector on the side where the MAP supply originates and then runs up to the MAP sensor located on the firewall. This hose/pipe assembly is no longer available for purchase.

The real kicker here is how critical this line is in supplying the correct vacuum signal to the MAP, the most relied upon sensor for the ECU to read regarding air/fuel ratio. Any cracks, melted spots, or loose rubber connectors can cause major starting and driveability issues.

There’s a simple fix though. All that’s required is a 1/8” NPT tap, a new throttle body gasket ( Napa FPG 60742 ), a vacuum fitting (Napa 05703-B102), two vacuum elbows (Napa2-670), and a length of new plastic piping (Napa 2-672).

Remove the throttle body and take it to the workbench.

Using an oiled tap along with a driver, carefully thread the lower of the 2 holes of the throttle body where the old fitting was plugged in. Don’t go too deep. These are pipe threads.

Flush the hole with carb cleaner and inspect for any left over cuttings.
This is an excellent time to do a complete throttle body and IAC cleaning.  See Tip 11.
Take the vacuum fitting (05703-B102 ) and apply a LITTLE bit of thread sealer on the threads only. I prefer Permatex #2 but almost anything is fine.

.

Carefully screw the fitting in until snug.

Install one of the vacuum elbows on the MAP sensor so it points toward the throttle body, and the other vacuum elbow on your new throttle body fitting so it points up to the MAP sensor.
Cut a length of the new plastic tubing (approximately 13 inches) to fit between the vacuum elbows and install it making sure there is enough slack for some engine movement. Route it according to the photo. We don’t want any rubbing or chafing with engine movement.  Not a bad idea to use some contact cement or Gasga-Cinch sparingly on the tubing to elbow connectors.

Revised 2-06-2016

[coolwind57]

16 minutes ago, cruiser54 said:

You 100% sure the throttle body to MAP sensor hose isn't compromised somehow?

 

No, I'm not. 

 

I used a small soft copper line to replace the broken, brittle stock plastic line, but I re-used that rectangular rubber grommet thing that sticks in the side of the throttle body. 

 

 

This worked for me wonderfully in the past, but I do like your method better.  My copper tubing is stuck inside the grommet and the grommet is pushed inside the orifice of the TB as securely as I could get it.  There's a possibility that the rubber may be blocking my copper tubing or I have a leak at the grommet/TB contact area.  I'll surely check this after work today.

 

Thank you Cruiser54 for continuing to share your thoughts on this issue.  That mind of yours must have constantly-turning gears within.

[coolwind57]

On 6/22/2018 at 8:43 AM, cruiser54 said:

You 100% sure the throttle body to MAP sensor hose isn't compromised somehow?

Well, I'm 100% sure now.  All good but it did not solve my delayed starting problem.

 

This morning, engine fired to life only after about 1 second!  But this is rare.  It sat for a full day of non-use.  Its when I start it throughout the work day that the excessive cranking happens (and fuel odor).

 

My plan of attack at this point is to:

1.  Remove and thoroughly clean throttle body and AIT.  Then reindex TB butterfly. I'll go ahead and and check for a properly set TPS.   I did all of this back in December, by the way.

2.  Replace my CPS with the original one that I still have in my garage.  It's not been modified to allow for timing advancing like the currently one.

3.  Not sure what to do with fuel system, but I may fiddle more with my fuel rail and injectors.. Figure out a way to better test my injectors if it means removing them and fuel rail.

 

I'm choosing these steps because I am at a loss and can think of nothing else to try.  

 

Always enjoy your thoughts and input, fellas.