Fuel economy down, soot up, power fine

flash7210 · **Posted:** Wed Aug 22, 2018 11:35 am

WWDiesel wrote:

casm wrote:

Interesting that you mention heat soak, though. If I drive for long enough (say, 20 minutes) to get the engine thoroughly warmed-up with the temperature gauge at the normal spot just left of centre, switch off, then come back 20-30 minutes later and turn the key without starting, the temperature needle will swing past centre about one-third of the way between normal and hot. Once started, it'll drop down to normal within 10 seconds or so as coolant starts flowing again. Classic indicator of heat soak, so you may be on to something.

That statement got my attention and concerns me! :shock:

I have never observed this on my Jeep and I live in a location where we can see 100+ ambient temps coupled with very high humidity.
On mine the temperature gauge always drops slightly or stays the same after I shut it off and restart it 10-15 minutes later even in hot sunshine and high outside air temperatures.
I don't have the OEM plastic engine cover in place, removed it years ago. Not sure if that plays into this or not?

Maybe your temperature sensor is bad? Might be worth a try to replace.

Just curious; Are there any others in very hot climates observing the phenomenon described by casm? :ALONE:

Cant say I've noticed that but I use a 180F thermostat.

I do notice heat soak at my IAT sensor but that doesn't have anything to do with the coolant temp sensor.
Typically my IAT, when cruising at a steady speed, is about 30 deg above ambient.
If the AC is on, then its about 40 deg above ambient.
So, on a 95 deg summer afternoon, driving with the AC on, my IAT will be about 135F.
After being parked for 15-20 min, then restarting, IAT might get up 155-160 (heat soak). But it quickly comes down once I start driving.

mass-hole · **Posted:** Wed Aug 22, 2018 3:43 pm

I've never noticed the coolant gauge swing right after parking briefly, it makes sense though as the coolant would have stopped flowing and the engine would still be hot. I know that if I am towing with my F150 and shut it down for a few minutes at a rest stop, the temp sensor will get hot enough that the electric fans will turn on right when I start it up again. They wont be on before turning it off.

WWDiesel · **Posted:** Wed Aug 22, 2018 10:20 pm

Drove around town this afternoon in 95+ degree heat. Made several stops and cut off engine while I went into some different stores.
Several ~10 minute stops and restarted Jeep and watched temperature gauge real close and it stayed right at 11:30 every time... :roll:

rancherman · **Posted:** Thu Aug 23, 2018 10:54 am

WWDiesel wrote:

Drove around town this afternoon in 95+ degree heat. Made several stops and cut off engine while I went into some different stores.
Several ~10 minute stops and restarted Jeep and watched temperature gauge real close and it stayed right at 11:30 every time... :roll:

What is YOUR shut-down procedure?

Several seconds of idle, then turn the key off, or is it immediate 'soon-as-vehicle-stops-rolling' dive out the door... key is in pocket? :seuss:

Seriously, I've noticed a heat soak rise on a vehicle that has entrapped air, or it's low on coolant. I feel there is a little 'auto thermo syphoning cycling' after shut down. It may not be much, but there is 'some'. Put an air bubble in the head, or lower coolant level , and this slight effect is disrupted.

I also agree that running w/o the 'top hat' helps let the heat from the turbo and exhaust manifold get away. Rather than just back-up into the head again. Heat flows to cold.. That aluminum head is a very nice heat sink.,, remind me, where is the coolant sensor located?

WWDiesel · **Posted:** Thu Aug 23, 2018 1:12 pm

rancherman wrote:

WWDiesel wrote:

Drove around town this afternoon in 95+ degree heat. Made several stops and cut off engine while I went into some different stores.
Several ~10 minute stops and restarted Jeep and watched temperature gauge real close and it stayed right at 11:30 every time... :roll:

What is YOUR shut-down procedure?

Several seconds of idle, then turn the key off, or is it immediate 'soon-as-vehicle-stops-rolling' dive out the door... key is in pocket? :seuss:

Seriously, I've noticed a heat soak rise on a vehicle that has entrapped air, or it's low on coolant. I feel there is a little 'auto thermo syphoning cycling' after shut down. It may not be much, but there is 'some'. Put an air bubble in the head, or lower coolant level , and this slight effect is disrupted.
I also agree that running w/o the 'top hat' helps let the heat from the turbo and exhaust manifold get away. Rather than just back-up into the head again. Heat flows to cold.. That aluminum head is a very nice heat sink.,, remind me, where is the coolant sensor located?

I always let it idle for idle before shutting it off for about a minute. I have never seen the temperature gauge rise past 12:00 when restarting a hot engine. :roll:

Engine coolant temperature sensor is located in thermostat housing, not in head as shown in Mopar parts diagrams. :shock:

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Grotsoldaat wrote:

casm wrote:

Update on this: lifting the Jeep appears to have fixed the problem.

So, it had too much ground effect. Now, when gravity effects it significantly less, fuel does not go porridge and burns easier. But the lack of gravity is making it unstable (steering), so you need to install a spoiler:

This response is my favourite one so far

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

WWDiesel wrote:

That statement got my attention and concerns me! :shock:

I have never observed this on my Jeep and I live in a location where we can see 100+ ambient temps coupled with very high humidity.
On mine the temperature gauge always drops slightly or stays the same after I shut it off and restart it 10-15 minutes later even in hot sunshine and high outside air temperatures.
I don't have the OEM plastic engine cover in place, removed it years ago. Not sure if that plays into this or not?

This really doesn't concern me too much - having spent close to 20 years in Southern California (including wheeling in the Mojave), it's not anything I'd consider to be out of whack. If the temperature didn't recover after starting up again, though, I would definitely be concerned.

Quote:

Maybe your temperature sensor is bad? Might be worth a try to replace.

It's possible, but what I'm reading via OBD pretty much matches what I'm seeing on the gauge. It could be a little slow to respond, I suppose, but at this point I don't have reason to think it's a goner - yet.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

flash7210 wrote:

WWDiesel wrote:

casm wrote:

Interesting that you mention heat soak, though. If I drive for long enough (say, 20 minutes) to get the engine thoroughly warmed-up with the temperature gauge at the normal spot just left of centre, switch off, then come back 20-30 minutes later and turn the key without starting, the temperature needle will swing past centre about one-third of the way between normal and hot. Once started, it'll drop down to normal within 10 seconds or so as coolant starts flowing again. Classic indicator of heat soak, so you may be on to something.

That statement got my attention and concerns me! :shock:

I have never observed this on my Jeep and I live in a location where we can see 100+ ambient temps coupled with very high humidity.
On mine the temperature gauge always drops slightly or stays the same after I shut it off and restart it 10-15 minutes later even in hot sunshine and high outside air temperatures.
I don't have the OEM plastic engine cover in place, removed it years ago. Not sure if that plays into this or not?

Maybe your temperature sensor is bad? Might be worth a try to replace.

Just curious; Are there any others in very hot climates observing the phenomenon described by casm? :ALONE:

Cant say I've noticed that but I use a 180F thermostat.

I do notice heat soak at my IAT sensor but that doesn't have anything to do with the coolant temp sensor.
Typically my IAT, when cruising at a steady speed, is about 30 deg above ambient.
If the AC is on, then its about 40 deg above ambient.
So, on a 95 deg summer afternoon, driving with the AC on, my IAT will be about 135F.
After being parked for 15-20 min, then restarting, IAT might get up 155-160 (heat soak). But it quickly comes down once I start driving.

You bring up a couple of good points.

I'm running a 193°F (IIRC) thermostat. Granted, 10°F isn't that much of a change from 203°F, but it is at least slightly cooler.

Having said that, I haven't been tracking IATs. It's kind of a Catch-22 right now, though - things are working normally, so even if I were to do that all I'd really be doing is establishing a baseline. Not that that's a bad thing, but it doesn't tell me what might have been happening previously.

Either way, I'll start tracking them next week. Not sure how much more in the way of triple-digit temperatures we're likely to get, but I'd kind of like to get some picture of what might be going on.

flash7210 · **Posted:** Thu Aug 23, 2018 9:17 pm

Quote:

Engine coolant temperature sensor is located on head, left side toward the rear. Item 34 in diagram.

No.
Coolant temp sensor is in the thermostat housing.

rancherman · **Posted:** Thu Aug 23, 2018 9:32 pm

flash7210 wrote:

Quote:

Engine coolant temperature sensor is located on head, left side toward the rear. Item 34 in diagram.

No.
Coolant temp sensor is in the thermostat housing.

is there one for the ecm, as well as the gauge on the dash?

flash7210 · **Posted:** Thu Aug 23, 2018 9:52 pm

rancherman wrote:

flash7210 wrote:

Quote:

Engine coolant temperature sensor is located on head, left side toward the rear. Item 34 in diagram.

No.
Coolant temp sensor is in the thermostat housing.

is there one for the ecm, as well as the gauge on the dash?

Same coolant temp sensor for both.
There is only one coolant temp sensor.

Grotsoldaat · **Posted:** Fri Aug 24, 2018 5:23 am

casm wrote:

Grotsoldaat wrote:

casm wrote:

Update on this: lifting the Jeep appears to have fixed the problem.

So, it had too much ground effect. Now, when gravity effects it significantly less, fuel does not go porridge and burns easier. But the lack of gravity is making it unstable (steering), so you need to install a spoiler:

This response is my favourite one so far

Naturally, as it is based in science and carved-on-a stone-level experience blowing things up as a combat engineer in the army. Next offered fix would have been called anti-tank-mine-treatment.

WWDiesel · **Posted:** Fri Aug 24, 2018 10:44 am

flash7210 wrote:

Coolant temp sensor is in the thermostat housing.

Flash is correct, temperature sensor is screwed into the thermostat housing, not into the head. Went and looked at my spare engine.
So Mopar diagram is incorrect, someone goofed! :banghead:

ROKTAXI · **Posted:** Fri Aug 24, 2018 4:18 pm

I don't have the OEM plastic engine cover in place, removed it years ago. Not sure if that plays into this or not?

Interesting. I don't live in a climate that has severe temperature / humidity issues. However, I find your comment interesting. What value does it have for you other than perhaps better ventilation. Perhaps less heat soak that effects longevity of plastic or rubber parts?

WWDiesel · **Posted:** Fri Aug 24, 2018 6:10 pm

ROKTAXI wrote:

I don't have the OEM plastic engine cover in place, removed it years ago. Not sure if that plays into this or not?

Interesting. I don't live in a climate that has severe temperature / humidity issues. However, I find your comment interesting. What value does it have for you other than perhaps better ventilation. Perhaps less heat soak that effects longevity of plastic or rubber parts?

I sincerely believe that it lets the engine breath better in respect to not trapping any radiated heat.
I believe I read several years ago by some other long time members of LOST to remove the plastic cover.
So mine has been removed for several years now. :wink:

ROKTAXI · **Posted:** Fri Aug 24, 2018 6:45 pm

Actually it makes sense that it helps in ventilation which in turn helps in longevity of various components such as rubber hoses and such. Never really thought much about it but understood that it was not a good thing to have excessive heat on some components. Anyway, just got done taking it off. I think the real only drawback may be more engine noise, but hey, I LOVE that diesel clatter. :SOMBRERO:

rankom · **Posted:** Fri Aug 24, 2018 7:20 pm

to get your fuel economy back , just remove v6 air box snorkel intake, i bet it will get better fuel mileage , i went back to oem didnt like v6 box. it was restricting air flow

WWDiesel · **Posted:** Fri Aug 24, 2018 10:22 pm

rankom wrote:

to get your fuel economy back , just remove v6 air box snorkel intake, i bet it will get better fuel mileage , i went back to oem didnt like v6 box. it was restricting air flow

Probably the best air intake would be one of those snorkels, but personally, I think they are kind of ugly! :ALONE:

carbcoma · **Joined:** Sat Oct 01, 2016 9:48 pm **Posts:** 86

WWDiesel wrote:

Dragging brakes can cause some loss of fuel mileage, but will not cause excessive black smoke when accelerating.
That is a huge sign of low boost or over fueling!

Do you have a boost gauge? It can tell you a lot.
Some other things to check are:
the small plastic vacuum line from the turbo vacuum modulator valve over to the turbo vane controller. One member found his had melted and / or cracked a few years back and it was causing low boost. See this older post:> viewtopic.php?p=682128#p682128

check stroke on turbo vanes and make sure there is no sticking going on that would prevent full vane movement.
check and make sure you have full vacuum at turbo modulator control station.

turbo modulator solenoid may be bad, you can test it by bypassing it temporarily.
These are the instructions:

Quote:

Turbo Vacuum solenoid test procedure

Failure of the vacuum reservoir solenoid (a.k.a. solenoid secondary runner valve per the parts fiche PN(PN 4606226AC) ) can produce several MIL/CEL codes and result is turbo boost problems. A temporary solution and diagnosis is to bypass that solenoid by rerouting vacuum lines as in the picture below:

By disconnecting the little hose from where the red arrow is and re-plugged it where the yellow arrow is (VAC port). If that solves the problem then leave the hoses in the new/temporary configuration and order a replacement solenoid. In the interim the vehicle may be driven; the CEL will remain until you replace the on/off solenoid. The only benefit that part provides is overnight storage of vacuum in the plastic reservoir so the turbo has vacuum immediately during the start. Without it you have a 2-10 second wait before the engine vacuum pump evacs the lines enough for the turbo vanes to move. Once the replacement solenoid is installed put the hose(s) back the way they were originally.

GDE's writeup for this says "By-passing of the on/off solenoid is very straight forward. Trace the vacuum line output from the black plastic reservoir to the input of the on/off solenoid. Remove this vacuum line and plug it directly into the turbo EVM on the port labeled "VAC". The turbo EVM is the one with the blue rubber isolator and vacuum line running directly to turbo."

Hopefully these pictures and diagrams will help: :SOMBRERO:

I ran this test bypassing the solenoid and noticed a big improvement . How do I replace the solenoid ? is there a guide or is it simple?
Thanks

WWDiesel · **Posted:** Thu Aug 30, 2018 12:40 pm

carbcoma wrote:

I ran this test bypassing the solenoid and noticed a big improvement . How do I replace the solenoid ? is there a guide or is it simple?
Thanks

Very simple to replace. Order a new one from IDParts or one of the other online suppliers.
Part No. 4606226AC :google:

https://www.idparts.com/vacuum-solenoid ... -3211.html

It is simple to replace, simply disconnect the hoses, disconnect the wire connector, and remove the solenoid, install new one and reconnect wire connector and rubber hoses.
Please keep in mind that this "Bypass Test" also bypasses the vacuum reservoir which may also be a problem if it has a leak or one of the hoses is leaking. :idea:

Fuel economy down, soot up, power fine

Who is online