MayDay!! - Hard Accel Killed Idle

[AnotherOldJeepGuy]

OK, I did the TPS adjustment.  It was off by what seems to be only a little, but I don't really know what a little really is.  The ref voltage measured at 4.74V so the target output was 3.934V (83%).  It initially measured 4.04 (85%) but I got it adjusted to 3.93 bumping to 3.94 occasionally.  I don't know how much damage 2% can do.

 

Also, Before I did this I went around again and wiggled hoses, and noted a change when I wiggled the hose to the MAF.  When I noticed that I looked and found a crack.  It is entirely possible and I think likely that my wiggle is what caused this crack since I have wiggled and looked at this line multiple times and did not see a crack.  Either way, I cut out the crack and patched it.

 

So with these 2 things along with everything else done so far the idle is pretty good although still a bit louder than I remember.  It might be almost normal but it I feel like it is still shaking a bit.  But it's close.  And also the stalling I was able to do repeatedly earlier by just slightly moving the throttle at the TB off the resting position, is no longer happening.  So improvements are being done.  BUT, it still doesn't accelerate smoothly and my guess is the power assist is still not there at low RPM.

 

With the improvements so far I repeated the water test because I know for a fact I found leaks this way and fixed them in the past, I could not induce any change in RPM at all spraying from the top or the bottom.  There may still be an exhaust manifold leak but if there is it's out of sight and not something I can hit with water and cause anything to happen.  And I can't get it out of my mind that yeah, a bunch of little things have been fixed, but I can't imagine how any of these things fixed so far could have in any way been caused by the acceleration/brake/turn maneuver that I did, it makes no sense to me.  Well, the fact that I was able to tighten the manifold bolts slightly (1/4 max but probably not that much) could maybe have been them getting loosened by a jolt, but the rest I just don't see as a result of that, and especially not all of the things at the same time!  Which is still a good argument for an issue with the exhaust manifold or gasket that I just can't find. !!

 

 

Edited Tuesday at 02:30 PM by AnotherOldJeepGuy
"the stalling I was able to do repeatedly earlier by just slightly moving the throttle at the TB off the resting position, is no longer happening" is not true, see quoted post 5/26 9:30AM

[AnotherOldJeepGuy]

7 hours ago, Gojira94 said:

If you pull the vacuum line off the FPR and plug it with your thumb (the line, not the regulator itself) normal response would be a dip in RPM/ slight bog as it started to chew on more fuel at 39-ish psi instead of 31-ish at idle. If there's no change, that would be a clue.

So since I witnessed no change when I plugged this line, and that suggested a clue, what does that clue suggest?

[Gojira94]

4 hours ago, AnotherOldJeepGuy said:

what does that clue suggest?

Check fuel pressure at the Schrader valve. Idling with the FPR vacuum attached it should be 31psi, minimum 28. With vacuum off the FPR and vacuum line capped with your thumb it should read 39psi, minimum 35-36.

 

If you still have the fuel pump ballast resistor hooked up, make a shunt from 1/4” male spade connectors and a bit of 14ga or minimum 16ga to bypass it and see if your pressures improve after the test above. If they’re really low, the pump may be dying or the plumbing inside the tank may have an issue that’s weakening fuel flow.

[AnotherOldJeepGuy]

Crap, another tool I don't have!  I'll check to see if any of the local auto parts places loan or rent something to measure vacuum with with a fitting that works at the Schrader.  I do still have the ballast resistor, but have been considering replacing it because the ceramic outside is cracked.  I expect the resistor is still connected just it's house is cracked.  But since I am going to disconnect it maybe I'll go ahead and replace it at that time.  The journey continues.... thanks @Gojira94 for all you time yesterday!

[AnotherOldJeepGuy]

14 hours ago, AnotherOldJeepGuy said:

the stalling I was able to do repeatedly earlier by just slightly moving the throttle at the TB off the resting position, is no longer happening

This is NOT TRUE!  It is more complicated but perhaps what I noted this morning is helpful.  It IS TRUE that pulling throttle just off resting position doesn't cause a stall, IF THE EGR PLUNGER DOES NOT MOVE.  BUT, if the EGR Plunger does move, it still stalls.  So back to the issue that the EGR moves sometimes, and sometimes it doesn't, when I rev up RPMs.  This perhaps means something to folks that know stuff!!

[Gojira94]

You should be able to rent a fuel pressure checker from your local parts house and return it for a full refund afterward.

 

And... more homework if you're up to it...

 

1) Pull the oil dipstick and see how it smells. If it smells like raw fuel and the oil feels thin, we'll want to know that.

 

2) Pull the plugs and see if any look/ smell different from the rest. "Good" will have a white to light tan ceramic insulator, light deposit on the ground strap, possibly with a slight color change about 1/2 way up, very light and even black around the end where the threads are and clean center electrode. Some evidence of age-related oil deposits may be expected and not that big of a deal at the moment.

 

3) consider Cruiser54's distributor indexing tip at some point. Marginally set/ unknown ignition timing can compound driveability issues.

[AnotherOldJeepGuy]

I have not tried to track down a pressure tester yet but I did the quickest one, pulled the dipstick.  I don't particularly smell anything from it.  It is slippery but could it be "a little thinner?", I can't really judge that.  If I hold the dipstick up horizontally with the wide side vertical the fluid slowly begins to accumulate more on the bottom, nothing drips off, that's about as much as I can say about it.

 

[AnotherOldJeepGuy]

It's starting to rain but I pulled the easiest to get to plug before getting wet.  I am thinking the experts can maybe make something out of just this one to start with and I'll go further after the rain.  I looked in my records and I put in new plugs, rotor, dist and wires back in Jan and at that time Jeep was very happy.  I'll note in case it is useful that this plug was not very tight.  It wasn't finger only removal loose, but it took almost no effort to "break" it loose.

 

[Porquer]

From that plug, it looks like you’re running rich.

[AnotherOldJeepGuy]

I cleaned that plug up pretty good.  Took out the next one and it looked exactly the same.  My plan was to take all of them out one at a time, note if any looked different, clean each one up as good as I could and put them back it, and see if anything changes.  Unfortunately the 3rd one I removed the ceramic top broke, so that plan doesn't really work anymore so I'll be getting some new plugs.  I am expecting 1 of 2 things to happen, assuming they all look the same:

1.  The black plugs were blacken by the driving since the time of "the incident", and just maybe all the things fixed at this point will result in running well once all the black plugs are replaced with clean ones.  This will be the lucky  outcome.

2.  Nothing will change and the problem remains as it was before this exercise and I'll still be down.

 

 

Edited Tuesday at 10:18 PM by AnotherOldJeepGuy
Forgot to mention that the 3 I removed so far looked exactly the same.

[Gojira94]

If the oil was getting heavily fuel contaminated, the dipstick would stink of raw gas. Sounds like you're ok there, so you likely don't have an 'internal' fuel leak making it dangerously rich. However, I agree with Porquer that the plugs show very rich/ sooty, with the ceramic insulator completely blackened. I'd still go ahead and see what your fuel pressure is with the ballast resistor both hooked up and bypassed, it's just good to know.

 

Bad news is you're definitely over-fueling, likely something with an exhaust leak near the O2 sensor as stated previously. The increased loudness, even after a muffler change, indicates either your exhaust manifold is indeed cracked where you can't see it, or possibly the donut gasket to the downpipe is blown.

 

Hard to say for sure on marginally ok spark timing possibly adding to the mix of woes, but let's set that aside for the moment until we know more about fuel/air.

[AnotherOldJeepGuy]

Thanks @Gojira94, @Porquer.  Since I broke a plug I'll go ahead and replace it, there's not a lot of choice on that one.  For the others, a pic of one cleaned up is below.  I'm thinking cleaning and reinstall is good enough at least for now, the plugs were all new in Jan.

 

I'll be calling the local auto places today to see if a fuel pressure checker can be borrowed or rented so that data point can be added to the collection.

 

As for the elusive yet suspected leak, perhaps the soapy water test (the one used to find a tire leak) might work at least at the donut gasket?  Not sure access/visibility is really good enough for that test elsewhere, but maybe I can do it at the donut.

 

 

[AnotherOldJeepGuy]

If I don't find a loaner, would this from Harbor Freight work?

https://www.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html

 

 

[Gojira94]

That's for lower pressure, 4-12psi (carbs). This one ($29.99) would work:

 

https://www.harborfreight.com/fuel-injection-pump-tester-58760.html

[AnotherOldJeepGuy]

Finished with removing and inspecting plugs assignment .  They all looked the same.  I cleaned them all and put them back in (well new one for the one with broken top), no change in how the truck runs.  Planning to get my hands on some kind of pressure measurement gear tomorrow.

[89 MJ]

That thing is running very rich. 

[AnotherOldJeepGuy]

How would running rich be noticed?  What kind of performance issues might be noticed if the engine is running rich?

[Gojira94]

14 hours ago, AnotherOldJeepGuy said:

How would running rich be noticed?

 

Poor fuel mileage, hesitation or backfire/ pop on acceleration, lack of crisp throttle response, sooty/ fouled spark plugs, shortened O2 sensor life, fuel poisoning of the converter, running cooler (or hotter) than normal, fuel contamination of the oil (washes the rings, accelerates cylinder wear), dramatic increase in HCs and raw fuel smell in the exhaust, to name a few...

[AnotherOldJeepGuy]

19 minutes ago, Gojira94 said:

to name a few

That's "a few" ! lol

 

[Gojira94]

Let's take a stab at something that's been bugging me. The main vacuum feed for HVAC, CAD, cruise and vacuum tank. Anything downstream of that could introduce a really big vacuum leak you wouldn't detect spritzing water or starting fluid around the intake. Put a vacuum cap on the fitting circled in red and see if it makes a huge difference. Call it a 'slaps forehead and exclaims "I coulda had a V8!" moment.

 

[AnotherOldJeepGuy]

I will definitely give this a try tomorrow and post what happens.  I got sidetracked today with appointment so I haven't gotten the vacuum tester yet either, but hopefully tomorrow.  Haven't tried my soapy water test yet either so plenty of what-ifs on the list to do.