International Full Size Jeep Association
Home Forums Reader's Rigs Tech Library Trail Stories FSJ-List
International Full Size Jeep Association  

Go Back   International Full Size Jeep Association > Tire Kickin' > General FSJ Tech

Reply
 
Thread Tools Search this Thread Display Modes
  #21  
Old 09-25-2020, 12:38 AM
DarkMonohue's Avatar
DarkMonohue DarkMonohue is offline
Shakes hands with danger
 
Join Date: Jul 01, 2012
Location: PNW
Posts: 1,090
Quote:
Originally Posted by wiley-moeracing
The dual plain is a mute point if the injectors are injecting directly into the valve area like most new vehicles do. A dual plain will be beneficial when you have a aftermarket injection system with a injector set up on top of the intake.
I am going to have to disagree. Fuel distribution aside, the dual plane offers a big advantage in throttle response and cylinder filling at the speeds these things see. The Pro Flo system uses a race manifold with short, fat runners and a huge open plenum compared to the longer, smaller runners and much smaller (partially due to being divided) plenum that a street oriented dual plane manifold uses. The advantage may be more a result of smaller runners and plenum than of being a dual plane design, but the point remains.

That's all I want to say here in order to avoid derailing the thread any further.
__________________
'85 J20 Old Man Truck, bought @ 65K miles - not great, but better than walking.
Member, FSJ Prissy Restoration Association
High quality junk here: intro thread and slow build thread

Did you know? Willys is just Willis spelled differently, but pronounced the same. Neither Willy nor his apostrophe are involved.
Reply With Quote
  #22  
Old 09-25-2020, 07:25 AM
wiley-moeracing wiley-moeracing is online now
350 Buick
 
Join Date: Feb 15, 2010
Location: arizona
Posts: 1,289
Would be happy to discuss further in private messaging, but agree to leave this off this post.
Reply With Quote
  #23  
Old 09-25-2020, 08:04 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Thanks both for your input on that, it's something I wasn't aware of and will look into further if/when the time comes!

DarkMonohue, I'm impressed that you've heard of Santa Pod. Funny enough, I was actually there two weekends ago in my Wagoneer, not racing though!

Santa Pod Night by Brynjaminjones, on Flickr


I do have another issue I've spotted in the past few days related to fuel consumption, but probably not worth its own topic.

The fuel line into the front of my 2150 is definitely leaking gas. It's a steel line going into a brass fitting.
Gas is weeping along the threads of the steel line, so I don't think it's a leak from the carb body itself.

I've got it nice and tight but it won't stop. Any idea what can be done?
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #24  
Old 09-25-2020, 09:14 AM
wiley-moeracing wiley-moeracing is online now
350 Buick
 
Join Date: Feb 15, 2010
Location: arizona
Posts: 1,289
Replace the gas line or remove and cut off the end a re-flare it.
Reply With Quote
  #25  
Old 09-25-2020, 03:39 PM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Thank you. I've taken it off and found a little nick in the mating surface. I've sanded the surface smooth so hopefully it should be good now.


In other news, I think I've finally found why this thing is using too much gas!!!

I was playing around with it this evening, and decided to take the top off the carb and test how much vacuum it took to open/close the power valve.
I noticed straight away that the power valve in there didn't close as far as the one I've got on the shelf when vacuum was applied, even though they're supposed to be identical parts with the same rating.

I took the carb off and removed the power valve. Look what I found!

Broken Power Valve by Brynjaminjones, on Flickr


I don't know how well you can see in the photo, but the body of the power valve was splitting in half around the threads!
I remember when I installed it, it felt like I'd over-tightened it a touch so I left it as I was too scared to take it back out. It all makes sense now!

I applied vacuum to it, and even with it closed I could blow right through it.

That, on top of the fact that this power valve doesn't fully close, must be why I'm using a little more fuel than I'd have expected.

The funny thing is that because of the way it had failed, it held vacuum just fine so it seemed like nothing was wrong with it.

I'm not expecting miracles on the MPG front, but I should hopefully see a small improvement.
I'll report back after I've run a tank of gas through it
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #26  
Old 10-10-2020, 02:29 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
I've now put a tank of gas through it and we're up to 11mpg, mixed driving. That's getting closer to what I was expecting so I don't think I'm too worried now, not that that will stop me from obsessing over it!


The only concern I still have is about a slight hesitation that it now has on throttle tip-in. I'll describe what's happening...

When started from cold, it fires right up and idles great. Blipping the throttle brings it straight down to a lower idle and I can drive straight away.
The issue is that there is a hesitation on throttle tip-in when driving gently. If I accelerate harder it's barely noticeable at all, but of course I try not to do that on a cold engine.

Once the engine is completely up to temperature it pretty much completely goes away, but this takes somewhere around 10 minutes so isn't exactly quick. The choke fully opens in around 3 minutes so I don't know if it's choke related or not.

If I stop in a store for 20 minutes, when I restart the Wagoneer the hesitation comes back and will stay for another 5 minutes or so until the engine gets all the way back to operating temperature again.


Because there is no hesitation when the engine is FULLY warm, I assume that rules out the accelerator pump?
I thought it might be the choke cover setting, so adjusted it to stay on a little longer. It has improved the hesitation but also makes it run a little rich and lumpy after a couple of minutes. I feel like it might just be masking the issue.
I also thought about the choke pull-off, but surely that only affects it for about a minute before the choke starts moving?

The fact that this issue has come about since replacing the broken power valve suggests to me that the previous artificial rich condition was hiding this tuning issue, so I think it's a lean stumble rather than a rich one.


Any help on this would be much appreciated! I'm getting very close to having this thing dialled in - I've been driving it on propane for the last 3 years so have never driven it on gas long enough to discover these issues!
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #27  
Old 10-11-2020, 07:29 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
I think I may have this sorted!

I removed the accelerator pump yesterday and noticed the "button" was lightly corroded.
I've cleaned it up with some emery cloth to make it nice and smooth, then reassembled.

I didn't think it would do anything, but the last two days I've not had any hesitation problems at all!
It still drives a little "flat" when the choke is active but it's not a real hesitation. I guess I can't expect a carbureted engine to drive like fuel injection all the time!

Operating the accelerator pump by hand it seemed fine before, so I guess the corrosion must have been stopping it from moving smoothly with small throttle openings.
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #28  
Old 10-12-2020, 10:25 AM
rang-a-stang's Avatar
rang-a-stang rang-a-stang is offline
Administrator
 
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 3,713
Awesome!! Well done!!
__________________
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
Reply With Quote
  #29  
Old 10-13-2020, 11:57 AM
MysticRob MysticRob is offline
232 I6
 
Join Date: Nov 26, 2019
Location: Boise, ID
Posts: 155
Just a quick FYI in general for MPG figures on any car, go to fueleconomy.gov and punch in the specifics on the vehicle you want to get MPG figures for. I've looked up many vehicles in the past and they're always very accurate. The powers that be a few years ago finally tweaked the algorithms to give MPG results based on real-world driving habits, not the make-believe figures we could never achieve (i.e. 55 MPH speed limits, etc).

Using a 1991 GW, your MPGs should be close to 10/11/12 for local/combined/hwy mileage.
Blame that on 4500 Lb weight, only 3 speeds in the ancient transmissions, and good old inefficient carburetion.
__________________
1988 Jeep Grand Wagoneer / Baltic Blue & Tan
2008 BMW 535xi Wagon / Deep Sea Blue & Tan
Reply With Quote
  #30  
Old 10-16-2020, 07:49 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Thank you, it does give me some more confidence in my tuning to see that I'm actually getting the exact quoted figures!


I've now started playing with yet more stuff - I'm trying to reconnect the EGR.

I tested it by pushing up on the diaphragm whilst idling, and it nearly killed the engine (as I think it should).
I then hooked it up to vacuum and raised the rpms. I could feel the diaphragm moving so it looks like it might be working properly!

The only problem is that it has now introduced another part-throttle flat spot. Should I install a delay valve to help with that?


My other concern is about the CTO switch. I don't have any of these switches that still work, so I've hooked the EGR straight to ported vacuum.
Will this cause problems when the engine is cold?
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #31  
Old 10-16-2020, 09:29 AM
babywag's Avatar
babywag babywag is offline
out of order
 
Join Date: Jun 08, 2005
Location: Land of froot loops and cukcoo-nuts, CA
Posts: 9,770
yes, egr should only be active when engine is fully warmed up.
get a cto, or leave it disconnected.
__________________
Tony
Reply With Quote
  #32  
Old 10-16-2020, 10:14 AM
rang-a-stang's Avatar
rang-a-stang rang-a-stang is offline
Administrator
 
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 3,713
I just bought a brand new CTO from my local McParts store. It was pretty easy for them to find. I ordered this one:
https://www.autozone.com/engine-mana...earchText=E907
Right after I installed my new one, I found my original working one in my parts stash. You can have it for shipping if you want. It is pretty small so I think getting it to the UK would not cost that much if you cannot find one there locally for cheap. My truck is a 79 so my vacuum routing may be a little different.

When I was running a carb and EGR, I had a big flat spot off idle, after warming up/CTO opening, too. Again, I am a 79 so I am probably slightly different than yours. There was a part I had to get that had about 3 different names but I called it a vacuum dump valve. On my vacuum diagram it was called the VSD Valve. It mounts between the EGR and intake manifold and senses exhaust pressure and modulates the EGR vacuum signal to do away with that flat spot. I believe a vacuum delay would do away with your flat spot but the dump valve seemed to be a better solution. The down side to the dump valve: they are IMPOSSSSSSSSIBLE to find. It took me a good 2 years to find a working one. I am willing sell mine to you but I think you would be better off trying a vacuum delay valve first.
__________________
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
Reply With Quote
  #33  
Old 10-16-2020, 02:16 PM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Thanks both for the help!

Rang-a-stang, that's really kind, thank you!

I actually think I've found a CTO that will work. The dual CTO on the heater hose has two ports that hold vacuum perfectly. In the morning I'm going to warm it up and see if it switches properly.

I've been browsing vacuum diagrams and it seems some years use the front CTO for EGR but others use this rear one, so if it works hopefully it should do what I need.

If not though, I'll definitely be interested in that one you've got, thank you
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #34  
Old 10-17-2020, 06:53 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
I've tested my CTO this morning and it works great! Doesn't allow any vacuum through when cold, allows full vacuum with engine warm, and doesn't leak at all.

I've now hooked my charcoal canister up to this as previously it went straight to ported vacuum.
Once I've got a delay valve for the EGR I'll get that hooked up too.

I'm also considering having the delay valve in front of the charcoal canister too, as it might help richen up the initial throttle tip in momentarily, but I'll see how I get on with just EGR first.
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #35  
Old 10-21-2020, 02:36 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
I've got a little more update on this:

I've temporarily hooked up the EGR without a delay valve, as they seem almost impossible to find.
Both the EGR and the charcoal canister are now hooked up to the dual-CTO so they don't come in until the engine is warmed up a little.

I drove it about 30 miles like this yesterday to test.

As expected the throttle response is now very poor, so overall drivability is definitely worse.
I expect a delay valve will go a long way towards fixing this, but it still generally feels a lot less powerful when going up hill at part throttle.

Is that normal with EGR, or a sign that something else is off?
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #36  
Old 10-21-2020, 03:59 PM
rang-a-stang's Avatar
rang-a-stang rang-a-stang is offline
Administrator
 
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 3,713
no, that is not normal, something is off. You should not even really notice EGR is working when it is working. Hopefully that is the delay valve.
__________________
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
Reply With Quote
  #37  
Old 10-21-2020, 04:09 PM
DarkMonohue's Avatar
DarkMonohue DarkMonohue is offline
Shakes hands with danger
 
Join Date: Jul 01, 2012
Location: PNW
Posts: 1,090
Under part throttle and moderate load, the engine will require a slightly greater throttle opening with EGR than at the same power level without EGR, but it should be a minor difference. Not sure you'd notice it by SOTP.
__________________
'85 J20 Old Man Truck, bought @ 65K miles - not great, but better than walking.
Member, FSJ Prissy Restoration Association
High quality junk here: intro thread and slow build thread

Did you know? Willys is just Willis spelled differently, but pronounced the same. Neither Willy nor his apostrophe are involved.
Reply With Quote
  #38  
Old 10-22-2020, 01:09 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Thanks both, it's definitely changed how it feels to drive. My girlfriend was with me and after 5 minutes of driving asked "what's wrong with her today?"!!

I actually found a delay valve in my drawer of junk yesterday. It only delays by a second or so but I'll try it out until I can get one with more of a delay.
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
  #39  
Old 10-22-2020, 11:32 AM
Brynjminjones's Avatar
Brynjminjones Brynjminjones is offline
258 I6
 
Join Date: Jun 11, 2017
Location: Derby, England
Posts: 331
Well I placed an order the other day for a NOS random vacuum delay valve from eBay. It was the only one I could find of any kind in the country.
It said it was for a '70s Ford Fiesta and didn't have a proper picture.

It arrived today and although the packaging says "Made to European Ford specification", it's actually a made in USA part almost exactly like what the Wagoneer would have come with!


I applied a vacuum to it and found it takes about 20 seconds to go from 0 to full vacuum. A bit more delay than I need but I don't see that being a problem.

I've fitted it to the Wagoneer and driven around town, and it's driving great! Admittedly, with a 20 second delay, there probably aren't too many times EGR will come in around town, but I'm hoping this will allow it to work properly whilst cruising.

I've still got another very slight hesitation (wouldn't be noticeable to a passenger) sometimes that I think is linked to the charcoal canister. I've now added my 1 second delay valve to that to see if that sharpens up my throttle response a touch.


I'm starting to see light at the end of the tunnel with all this tweaking!
__________________
1991 Grand Wagoneer - Hunter Green. All stock. Rebuilt 360 with Melling MTA-1 cam.

1998 Cherokee (XJ) 4.0
1997 Grand Cherokee (ZJ) 4.0
1974 Ford F100 390
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Basic 4BBL carb questions crispyboy General FSJ Discussion 3 07-03-2012 10:16 AM
How can the MC2150 carb run rich? Kevin718 General FSJ Tech 11 11-22-2005 01:43 PM
Where should my tranny get worked on? jgarcia2 General FSJ Tech 10 03-25-2004 06:36 PM
1991 wagoneer pwrwgn General FSJ Tech 1 11-08-2002 04:15 AM
Gaskets on EM of 1991 Grand Wagoneer Thom General FSJ Tech 5 07-31-2001 03:13 AM


All times are GMT -6. The time now is 11:07 AM.


Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
corner corner