Well I have a 97' k2500 burb with the 6.5l, truck runs great other than one small problem. When I try to pick up the idle up past 1000 rpms the engine rpms race to a red line. No matter how slow I try to bring them up or how hard I try to hold it steady it does that same thing. Also notice the same problem when driving also. Of course it is less noticeable at lower speed, however it was extremely noticeable (I mean annoying) while trying to drive on some icy roads this weekend. At highway speeds when I back off the throttle a little it jerks the truck around like someone turned on an engine brake. I check for trouble codes and found a few codes that have set and are not active at the moment. P0122, P0216B, P0251A and P1214. These code cover the APP and the timing/cam sensor of the IP. I know that the PMD is the cause of a lot of headaches and problems for this engine. I checked the engine grounds, connectors and wiring harness going to the IP & PMD. All looked fine. All of the problems with the PMD that I have found seem to be related to a no start. After my inspection of the harness I noted that this truck still has the original PMD and IP. Any thoughts?

 

A bad PMD will cause runaway on a 6.5 what is the age and location of PMD now if it is still on the IP you need to get a new one and do a relocate out of engine compartment and behind the front bumper ASAP

 

X2 on the PMD relocation.

 

PMD has a 96' date on it and is still in original location on IP. I have been leaning towards the PMD being the problem however the one code for the cam has to do with the Optical sensor on the IP and I have been curious about it being a problem also. Any recommendations on where to acquire a quality PMD and relocation kit?

 

Multiple deals on fleabay lately,with lifetime warranty,I go for a thick heat sink some of them look pretty cheap made.

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Fleabay.

 

DPI I believe it is in Memphis are reputable as are there products

 

angelofishes on ebay is also good.

Go with the PMD since you should carry a spare anyways,but I would address the APP code first-it's what tells the ECM what amount of throttle input there is.

Sometimes a PMD will throw IP codes.

P0122 APP Sensor 1 Circuit Low Voltage

P0216 Injection Timing Control Circuit

P0251 Injection Pump Cam System

P1214 Injection Pump Timing Offset

I doubt the IP is original with those codes?

 

No the date code on the IP has a 1996 for the year. I am the 2nd owner and I spoke with the original owner and he has not had not had it replaced. The P0216 and the P1214 are the old codes that were not active when I purchased the truck back in July and have not come back since being cleared in July. The other 2 codes came on once also, this weekend and have not come back either. I was fighting with icy streets and short trips bouncing from store to store Christmas shopping. I plan on looking at the APP a little closer just after the weather warms up a bit. I need to make a tee for the harness so I can hook up my scope to it to see the if there is a dead spot in any of the sensors. The first time I notice the problem I took a brief look at the APP and did not find anything the seemed to out of place. After not finding anything with the APP I took the truck out for a highway test and check to see if I could determine if the runaway problem could be the APP. I found the truck still had the same drivability problem with the cruise activated. The APP is not used to adjust the rpms while the cruise is on. So I ruled that out as the cause of the problem.

 

The timing codes indicate that the IP has been fooled with location.

 

So as to these pesky trouble codes they were paired in two separate instances the first set (P0216B & P1214) were there before I bought the truck in July. The second set (P0122 & P0251A) was set last weekend while Christmas shopping and jumping from store to store and fighting icy conditions and with this horrible throttle problem, all within a couple of hours. So I checked the APP with the scope this evening and found no dead spots and the voltages are ok. The P0122 was the first of the trouble codes and it looks to be just a one time code. The P0251 code diagnostic chart has you check for cam ref missed. The value on the chart is 8, the scan tool listed 0. So the next step stated that it was intermittent and to look at any lower codes that were set. As to timing code I was looking at the diagnostic chart for the P0216 and in the second step the engine is to be held at 1500 rpms and check the timing with the scan tool. I can't hold the rpms at 1500, as soon as I try to bring the rpms up and make it over 1000 rpms the engine rpms runs away. I have to get this runaway engine under control before I can address this possible problem. The P1214 code said to fix any lower codes, and reset the timing offset. Clear and check for code setting again. I suspect that these codes that have only set once are similar to the ones I have seen on the Caterpillar equipment I work on. We see codes that get logged one and never again. I also have seen one problem act up causing the machine to throw other codes while it was misbehaving.