OJ Avery

I have a 12 mp7 in a granite that I keep getting an intake manifold temp sensor code. Occasionally its active. The sensor has been replaced as well as the engine wire harness. Checked my connections and grounds, all good. I took a temp reading on the manifold, 110 and the ptt gave me 124. Thoughts?? Thankyou!!

The MP8 would have been a much better application here, but when you work for the state......

It is a shame. we have an 08 tractor that is mainly over the road and that truck has 225000 on it now with oe injectors. How they get used makes a huge difference.

 I did the injectors and it doesn't lose its prime overnight. Thanks for the input guys, I really appreciate it. This forum is gold to me as I work on DOT  trucks with little factory training. We've been given a decent supply of specialty tools so doing all repairs is possible but a little short on diagnostics. We've been using the graphite paste on all our injector jobs. We do probably more than average amount of injectors because of the truck use. They're plow trucks so they're over loaded with iron and salt and usually travel about 35-40 mph. we don't usually see a set go past 100,000 miles.

injectors are out, 2 of them show significantly more carbon than the rest. That's just a lot of $ for so little miles. Glad its not mine

Thanks fjh, I was looking for confirmation, just so low miles, a little hard to believe.

The 07 emission mp7 we usually see higher temps than that. 2010 emissions those temps are good. I'd say its not getting fuel to the 7th inj or the 7th injector itself.

We've experienced that the connector at the injector gets worn or the wiring becomes brittle from heat. Mack makes a replacement pigtail. Be sure to use oil/heat resistant heat shrink tubing. We've also done complete harness' .

I have a 2012 with a mp7 2010 emissions (spark assist) the problem I'm having is it looses its fuel prime over the weekend, sometimes overnight.  I replaced the fuel filter head and filters, one check ball was sticking. Still did it.  Replaced the "pressure regulator" on the return side on top of the head, still did it. Did an air in fuel test and it looked great. Did a warm hold function, that was good torque was 60ft# at idle. Did a cylinder balance test and #2 was off the most (+23), #6 was next at -20, # 3 -19. This vehicle only has 37k on it. But its a paint truck, really heavy and really slow driving. Do I have an injector leaking down causing it to loose its prime?

Soooo, been awhile. That unit did end up needing injectors. I did a power balance test and it showed cyl 1 and 4 being off. so when I pulled injectors 3 and 6 were really carboned . as far as the ambient air temp I found the wiring to be ok. we've experienced in the past weird issues with our Verizon gps unit that hooks right into our diagnostic port, so I unplugged that for now.

turckster, on the ambient air temp, I started checking resistance from sensor to bulkhead connector at firewall. at pin 1 I have .6 ohm. on the other pin I get a reading of 5 ohm and another pin in the block of 46 ohms. that tells me I've got a wiring issue.  

turckster, the ground circuit has 18 ohm resistance

ok thanks turckster, I understand possible injector issue with the regen often, even though it runs good, I have run into that before. what about the ambient air temp code? It goes active often. the sensor and updated pigtail have been replaced. I checked for continuity from the connector at the sensor all the way to the dash. I have continuity at the dash but its pretty high resistance, 114 k ohm. what am I missing with that? and the 2 wouldn't be related correct?

I have a 12 granite with a mp7(us10 emissions). its been in a couple times now. Has had most of the emissions components replaced. the code that keeps reoccurring is an active code for ambient air temp sensor. the sensor and pigtail have been replaced. The sensor reads correct temp in ptt. The other problem that has been on going is that its calling for a regen often. the last completed regen shows about 50 hours ago. soot level is at 130% dpf, 7th inj, egr, dpf, boost pressure/temp sensor, pre/post nox sensor have been replaced, and the ecm reflashed.... Last time in I did a def piss test and it was good. January it was having the same regen often issue.

the pressure, the volumes were good, it even had me testing def level sensor values. It guided me through a pretty thorough def system testing

yes the volumes were good, diagnostics even took me to the return side, that volume was good as well

ok thanks!! I haven't noticed and cracks but will be sure to look closely now

regen took care of it?? cleared code, drove, all good Why?? I also had another mp7 come in with same code yesterday, immediately took it outside and did regen, code gone?? I don't understand why this is happening, anyone have an explanation??

doing regen now

I have a 13 Granite with 10 emissions. active code spn 5246 after treatment scr operator inducement severity, fmi 0 data valid but above operating range. the ptt yesterday sent the tech to the scr test module, doser passed all 3 tests. then it said computer needs reprogramming. went to the dealer this morning, reprogrammed, no change at all except now it has the same code with a fmi 16, and that code is pending. every time we try to run the diagnostics it runs us to the scr test module where we find no problems. what are we missing here?? thanks

We have an over heat solenoid on our mp7's, idk if it comes on all. We've seen a no start condition caused by this

sounds like a charge air leak, did the dealer smoke test it? It should be pushing 39-42 psi

So I did the snap throttle test a couple times. the first time I did it the engine was cold and it let out a good sized puff of white smoke, then nothing. Shut it off, sat for about a hour and did it again, no smoke at all. Then I ran it in the bay for about 30 minutes to get some heat into it. It got up to about 170 and I tried it again and there was nothing. I did a warm hold function test which we've found to be handy when suspecting injectors and that was good. I'm not sure where to look next.  

The soot ratio was reset at time of replacement. What would a NOX issue be? It was suggested to me late yesterday by a dealer mechanic to do a snap test. I was told I should see a small puff of black, then it should clear up. If not the issue is probably injector(s) over fueling, which makes sense if the dpf soot levels are climbing quicker than they should. Thanks for the info on the rolling regen though, that will be useful! Also I got the turbo to hit #42 of boost a few times which the only other times I've seen it that high was bad injectors OR new turbo w/ new injectors.

Hi all. I have a 12 mp7 with US10 emissions that has some catalyst issues. Here's  what's been done. New DPF, 7th injector ,doser, doser lines, doser pump, doser coolant lines, EGR valve , EGR venturi and EGR differential pressure lines and sensor. Here's the problem. After a few days it calls for a parked regen. Driver does it and then in 10 miles or so it asks for it again. What I have done, ACM learned data reset (I don't know if that was done when doser was replaced) and an After treatment Injector Adaptive Factor reset. (again I don't know if this was done when the 7th inj was replaced). It came into the shop today with no codes. soot level was at 4%. I put 140 miles on it today, half country roads , half highway. Soot level is now 40%. I had the ptt hooked to it and it never showed a rolling regen. 7th inj was never activated. My biggest question is does any one know at what point (soot level %) will a rolling regen happen and at what point (soot level %) does it call for a parked regen? And why would it call for a parked regen with a new dpf?