Intake over heating

Whiskey · **Posted:** Sun Feb 16, 2014 11:53 pm

Hi folks,

My jeep once again is throwing a curve ball at me, and baseball isn't my game. Very sporadically over the last two weeks my intake temp has out of the blue been jumping up to between 95 and 170, three times after going up a long steep hill but also twice after leaving the grocery store on flat ground. The two times it did it when leaving the store it had been running perfectly on the way to the store and once I had been "playing" in a nice open snow covered parking lot for 10 minutes prior and the intake never went above 50. Talking with a (semi) diesel mechanic friend of mine tonight he thought it may be a sensor going out, I don't think that's the case though because the engine is acting consistent with the intake temps I'm getting. It's acting and exhibiting the signs of not getting enough air. The other day when it was acting up the intake temp was high as soon as I started up (about 95 I'm guessing), which it wasn't that hot when I shut down (approx 20 minute elapsed time). I proceeded to drive maybe 1/5 of a mile to my next stop and it was surging the whole way (about 3-10 psi boost and no more than 35 mph), parked went inside for probably 20 minutes, came out got Torque running on my phone and kept my head out the door to listen to the engine on start up, fired up fine idle was higher (770 vs 760, it's always 760 when warm), let it idle for 1-3 minutes to see what it was going to do, and it did something. Something actuated, it sounded like a switch or a valve of sort moving. The intake temp went from 95 down to 50 in 20 seconds or less and the coolant went from 114 down to 109 in just a little longer time. I've had to idle the thing a lot this winter and am wondering if it's catching up to me now and the turbo vanes or actuator are sticking. Does this sound logical to those who have had dealings with the turbo/vacuum system? The other idea someone had is that the thermostat is dead and is sticking closed, I don't buy into that very well since the intake is getting hot and not the engine. If not these two, does anybody have suggestions? I should also add that there hasn't been any codes thrown.

toy_vw · **Joined:** Sun Aug 04, 2013 2:50 pm **Posts:** 35

have you actually measured the intake with say an infared temp gun to confirm? could be a sensor? or thanks to our EGR system....could be a plugged up intake manifold...not sure where our temp sensor is..but are you getting any faults pertaining to air intake temps or boost faults?

it requires a lot of restriction on the air intake to bring temps up this crazy...and typically youll see combustion/exhaust temps climb..not intake temps.

also...when your "pressurizing air" it will get hot...hence why we have aftercoolers up front...

Im gonna say its a sensor aswell...especially how you say its fluctuates all over...

Whiskey · **Posted:** Mon Feb 17, 2014 1:25 am

As far as I know the MAF sensor and MAP sensor are the only two in the intake system, I could be wrong though I'm still learning this thing. One thing I forgot to mention is the problem typically clears itself if I put it in second and let the engine fight gravity down the hill that has initiated the problem. Hopefully I get out of work early enough tomorrow to puck up a laser thermometer. It's not throwing any codes and I've ran an inspection camera from the intake to the air box and air box to the turbo. So unless the aftercooler is plugged that leaves the the 4 month old turbo hoses or something in the manifold. I still think it has an air flow issue, it's acting identical to when I accidentally blocked off the intake.

dthdcrd · **Posted:** Mon Feb 17, 2014 11:12 am

FWIW Check your air cleaner element. I just recently saw someone who let their element go so long it started to fall apart and block the intake. It had also gotten wet and this made it decay. When they applied more throttle it would suck the dilapidated filter element against the intake tube and when the let off the throttle or drove more conservatively the element would stay in place and not block off the intake. Sometimes it's the simple things....

Hexus · **Posted:** Mon Feb 17, 2014 11:42 am

Also your fan clutch is probably shot if you haven't renewed it. You would most notice it under heavy loads, I.E. up and down hill.

Saying your intake is overheating doesn't make sense, there's nothing up there but antifreeze, air and oil, all the combustion happens below the head. Possibly a faulty Thermostat as well.

How many miles on it? Timing belt done? How's your coolant level, any back pressure after running?

flash7210 · **Posted:** Mon Feb 17, 2014 7:12 pm

So you are monitoring intake temp using Torque on your android phone?
The intake temp is taken from the MAP sensor.
Sounds to me like you either need to clean your MAP sensor or replace it.

How are your boost pressure readings? Are they erratic too?

Whiskey · **Posted:** Tue Feb 18, 2014 12:07 am

I stopped at O'Reilly's tonight and picked up a new air filter, the old one wasn't terrible but I figured what the heck. While there had them look up a MAF and MAP sensor just to see what it would be if one was out, and I found out (as flash7210 stated) it is in fact not a MAP sensor but a Manifold Air Temperature sensor. After finding this out I went back to my apartment and pulled the thing out and cleaned it. It was far dirtier when I bought the Jeep than it is now, it's only been a little over 3,000 miles since I cleaned it last. Also while I had Torque running I took a laser thermometer to different parts of the engine to see if I could find anywhere that had the same temp as what my phone was reading, nothing matched or came within a reasonable range. Everything was either hotter or colder. We'll see what happens tomorrow. Boost jumps around some, but it's directly proportional to the engine surges. For the way it's acting my money is that MAT sensor.

Also Hexus, it just rolled over to 165,200 today, coolant is good, and I haven't done the timing belt but when I inspected it the belt was in good shape and showed no signs of wear or damage.

toy_vw · **Joined:** Sun Aug 04, 2013 2:50 pm **Posts:** 35

You cant judge a belt by it looked good with no wear and tear...wheres the tensioner needle pointing? And if your uncertain..at least replace the belt if anyrhing...3 or so hours taking your time and you can worry a little less

Whiskey · **Posted:** Wed Feb 19, 2014 12:24 am

Cleaned the MAT senator last night. Still got hot intake readings today but it did seem to run a little better. A new sensor has been ordered.

Whiskey · **Posted:** Sun Mar 02, 2014 10:51 pm

I went out to do some running around town today, jeep ran fine like it has all of this week. Was driving for about 5 minutes and realized I forgot something at my apartment, so I turned around and went back. Got back, shut down, was inside for a few minutes came back out, started back up and could tell right away the intake air was hot (or sensor says it was). Sure enough 89 degrees, it was maybe 40 when I shut down. So I proceeded to put the new MAP sensor in, and behold... it read the same temp. :5SHOTS:

So my next idea is there might be a resistor or other component in the line that has gone bad and is causing the voltage to be higher than it should be and giving the ECU a erroneous readings or the ECU itself is a little squirrely. Anyone have some suggestions? Or a wiring diagram for these things?

flash7210 · **Posted:** Tue Mar 04, 2014 9:48 am

The only resistor in the MAP/MAT circuit that I know of is in the sensor itself.
It works like this:
High resistance = low temperature reading
low reistance = high temperature reading

If the sensor is giving you a unusual or intermittent high reading then I would say there is a
problem in the wiring. Like maybe the wire's insulation is worn off and shorting out against
something, creating a brief period of LOW resistance.
If a connector or wire were corroded or loose, that would give you high resistance.

If its not the sensor or the wiring then I would wonder if your OBD reader is working properly.

Whiskey · **Posted:** Tue Mar 04, 2014 11:22 pm

Alrighty now we're getting somewhere!! Thank you flash, that is the information I needed. Hopefully I get out of work at a decent time tomorrow and can take a good look at the wires, and hopefully that is the issue and I can find it.

Whiskey · **Posted:** Sat Mar 15, 2014 3:54 pm

Finally got some time away from work and rang out the wiring between the MAT sensor and the ECU, and found nothing. I followed the Jeep trouble shooting manual for the the electrical and everything. I compared the resistance of the old MAT sensor IAT pins to the new sensor and they match up perfectly and respond to temperature change identically. flash I wish it was just the OBD, but the engine is acting accordingly with the temps I'm reading. The boost is reading fine for how the engine is acting. If I put my foot into it I can still get 15-18 psi. Since the electrical seems to be working my next question is what is the device just after where the CAC hose attaches onto the engine? I'm assuming it regulates the air flow in some fashion, has anyone heard of that getting stuck? That's the only thing left I can think of. If the intercooler was plugged I wouldn't get any boost pressure correct? And if the fan clutch was out I would be getting high coolant temps too correct? Let me know what you all think.

dkenny · **Posted:** Sat Mar 15, 2014 4:08 pm

don't foget the sensor near the air filter...
its not the map nor the maf..
there is another sensor..check the air box!

-dkenny

papaindigo · **Posted:** Sat Mar 15, 2014 4:12 pm

That's the FCV (flow control valve); inside looks a lot like a gas carburetor choke butterfly. It's electrically operated and has a plastic gear so if the gear strips yes it can get stuck. IIRC when the ignition is off it's open. Others can explain it better than me but it has something to do with balancing boost and exhaust gas flow thru the EGR to the intake.

The butterfly can be removed by removing the screws with no harm.

Whether it has anything to do with your issue I have no clue.

Whiskey · **Posted:** Sat Mar 15, 2014 6:52 pm

Just came back in from pulling the CAC hose off and looking at the FCV, 1. It's almost St. Patty's day, it should be warmer than this. 2. The valve seems to be to be spring loaded to the open position, so there went that idea of it getting stuck. Something I saw that I'm not sure what to make of is there is a thin film of very adhered soot on the engine end of the CAC hose. It runs down about to the elbow of the hose then stops. Has anyone else seen this?

flash7210 · **Posted:** Sat Mar 15, 2014 10:49 pm

OK, wait a minute.

Isn't the MAP sensor downstream from the EGR valve?
If the EGR valve opens, won't intake temp go up?
Could this mean that the EGR valve is the problem?
Or could this mean that the intake temp is normal for a functioning EGR valve?
And whatever problem you are experiencing is not related to the intake temp?

My EGR is non functioning so I can't really compare intake temp with you.

Whiskey · **Posted:** Sun Mar 16, 2014 12:12 am

The EGR very well could be the problem, I really have no idea at this point. However I don't think that the EGR opening would be causing this. It ran perfect up until about 2 months ago. Just to recap here is what I'm experiencing on a normal day vs. a cranky MV day.

Normal:
*Intake temp between 28-47 degrees F. At temps between -10 and 30.
*No engine surging.
*Boost pressure at idle between -0.1 and 0.1 psi.
*Plenty of power and get up off the line, can put my foot into it in 5th and go 50-65 without the slightest thought from the transmission of down shifting.

Cranky MV day:
*Intake temp will rise from 35-40 degrees to 95-104 in as little as 1 mile, aprox 3 miles to 170 on flat ground or hill. This happened once from a dead cold start, 35-104 in 1.2 miles. Usually stabilizes between 120-144.
*Intake temp can be above ambient and coolant temp even after sitting for 12+ hours. Example March 9th I took a screen shot, coolant temp 37.4 F, outside air temp 39-40 F, intake temp after sitting more than 12 hours 42.8 F. The high for the day was only 42 and that was about an hour later.
*Intake temp will sporadically spike under normal driving conditions. Will go from 46>60>75>95 and so on and will not come back down even if stopped and shut down.
*Can be running fine, be shut down and intake temp will rise. In a 20 minute period can rise from 35>95 when it's -10 outside air temp.
*Engine surges when driving, sluggish and surgey off the line and can idle ruff.
*Boost at idle is between -0.3 and -1.1 psi, can get 15-18 psi if demanded of the engine but very slow acceleration compared to normal.
*Intake temp will go down briefly when engine is motored to push cool air into engine, but immediately spikes back up to high temp when motoring is stopped.
*Intake temp has spiked almost constantly since it's warmed up, 35-50 F.
*In cooler weather (20 and below) hot intake could be resolved by putting the jeep in 2nd and letting it coast down a big long hill (8-10 blocks). Has not worked since the temperature has risen.

papaindigo · **Posted:** Sun Mar 16, 2014 9:38 am

I'm reaching/speculating/making things up but:
1. try unplugging MAF (top of air box outlet) which will trigger a CEL but will also disable your EGR. Does issue go away? If so pull and clean EGR (viewtopic.php?f=5&t=59352&p=659410#p659410 and viewtopic.php?f=5&t=62495)
2. try the boost pressure solenoid bypass (viewtopic.php?f=5&t=70602&p=757348&hilit=boost+solenoid#p757348). It might be possible that it's intermittently not working properly which clearly would cause poor acceleration and might mess with intake air flow enough to mess with intake temp. If problem goes away replace solenoid (PN 4606226AC)

Wild guesses but free checks.

WWDiesel · **Posted:** Sun Mar 16, 2014 11:23 am

To add to what others have suggested:
Try blocking off the EGR valve with a metal plate where it attaches to the EGR valve. :wink:

Simple to make, dimentions here: viewtopic.php?f=5&t=76576

If you must keep your EGR valve in service for Emission Testing, I have a good used one and cooler available that I just removed from my motor when I installed the Weeks101 elbow kit. It was working just fine when I removed it. PM me if anyone needs one. :SOMBRERO:

If you do not need it for Emission Testing, simply leave it blocked off, remove the butterfly plate out of the FCV and unplug the MAF. NOTE: There are tunes available on Squeeto's post to fix the CEL by doing the FCV/EGR delete. :BANANA:

Intake over heating

Who is online