p122 and engine surging

[dripley]

Several months ago I had the P122 with a cel. As it progressed I started experiencing engine surging. At first only 1, 2, maybe 3% as shown on my scan gauge. I lived with for a little while until I had a chance to try and diagnose it some. Some of you might know how much I enjoy diagnosing electrical problems and for any who does not I think I would rather have a root canal done. Any way I had pretty much determined that it was a bad apps sensor. I had a Timbo on the truck and was not completly convinced that it was bad. So I googled "apps/tps sensor and found a boat load on ebay for any where between $12 and $90. They all had the same picture and I ended up buying one for $16 bucks. I did this mainly to test with and see what happened. So I installed it and it worked. Surging gone, and no DTC's. Since I did not really trust the cheap apps that I bought, I went ahead and ordered a new Timbo. Put the new on when got it and every thing is great for about 15 minutes and the surging returned. Kept getting the 122 code intermittently  and the surge was approaching 8 and 9% on oddasion. Alternator VAC was about .03, the apps sensor voltage read OK thru the pedal range, nothing jumping around. So I put the el cheapo back in and no surging. But in a couple minutes it throws a P222 code with the CEL on. Cleared the code, started the engine and it is instantly back. I cleared several times but always came back instantly on engine start, but no surging. Idled beautifully. So I left it in and lived with the CEL lit and the code present. While it did not surge it was messing with the idle enough to disengage my E brake at times. That is the only way I could tell that it was still trying to surge. 

Fast forward to1 month ago while changing my oil I am looking at the ground cable from the passenger side battery to the block. Since I am in there I checked it and when I put a wrench on it the weight of the wrench turned it. So I took it off cleaned it up and reattached nice and tight. Over that past moth I started noticing the E brake is working all the time. So this past weekend I reinstalled the old Timbo apps and all is working as it should. No surging, cleared the 222 code with no return And have not seen the 122 code come back either. So I am assuming that ground is associated with the apps ? I have not tried to figure that part out on wiring diagram. 

I do appreciate all the advice I get from y'all but knew if I had asked when the problem arose I was not in a position to use the advice for a while and just rode it out till I got lucky Seems that ground did solve my problem. Stupid grounds. Too darn many to keep up with.

[IBMobile]

I think with that battery ground being loose you were running mainly on the left battery.  Think of all the other thing that get grounded to that battery/battery cable.  Doesn't the PCM ground there?

[dripley]

It probably was not helping anything. I know my PCM has a wire from the case to the fire wall. I did not add it, it came on the truck when new, I need to look at a wiring diagram but not tonight. It is nice to have it working right again,

[Mopar1973Man]

9 hours ago, IBMobile said:

Doesn't the PCM ground there?

ECM, PCM and VP44 ground...

[JAG1]

Thanks Dripley for the write up, interesting how you found it by accident. I had a similar problem on my first gen when it had it's first 200 k miles. Mine was only snug, not tight and showed resistance from dirt and corrosion.

Michael that grounding connector you are showing.... mine was not a very snug fit when I would pull it apart ea. time. I didn't like that on the electronic equipment so I chopped it off and soldered the wires together and put marine grade shrink tubing over it. Not saying everyone should do that, I just like good connections.

[dripley]

Guess I got to dig a little deeper. It started surging again today. No codes, and not surging a lot but still surging.

[Mopar1973Man]

Double check your wire tap and MAP sensor connection. I've had both do this. I've had my jam nut come loose on the Stealth Plate and making a weak connection for the wire tap. Then I just had a bad connection on the MAP sensor plug that caused a random up / down surge of power.

[dripley]

On 3/17/2016 at 9:30 PM, Mopar1973Man said:

Double check your wire tap and MAP sensor connection. I've had both do this. I've had my jam nut come loose on the Stealth Plate and making a weak connection for the wire tap. Then I just had a bad connection on the MAP sensor plug that caused a random up / down surge of power.

I will give that a try. I have the later model MAP sensor that requires an adapter pig tail. I still have the oe and dont think there is anything wrong with it. Might swap them out. I never had this issue until some time after I swapped the new one in. Not instantly after but some time after. Never associated the problem with the map or possibly the wire tap. Can you screw the stealth plate tap in too far and damage anything?

[Me78569]

If you really torque the wiretap down it could cause issues.  

[Mopar1973Man]

2 hours ago, dripley said:

Can you screw the stealth plate tap in too far and damage anything?

Yes. You can pus the screw right through the circuit board. Typically results in a broken corner of the circuit board and VP44 replacement. You need to check 12V at the tap wire with the key ON and not running.

 

2 hours ago, dripley said:

I have the later model MAP sensor that requires an adapter pig tail. I still have the oe and dont think there is anything wrong with it.

Most likely nothing wrong with the sensor but looking at connection that nothing is corroded or loose.

[dripley]

Thought I would revive this and update it. I still have the surging. I keep tinkering with the grounds and such and can make it go away for while. But always seems to come back. About 4 months ago I noticed the positive cable end on the drivers battery was cracked so I replaced it with a military style and low and behold it stopped, for about 6 weeks. Then started again and got pretty bad. Pulled up to a red light and it shot to near 9% then popped a 222 code and stopped surging for a few days. But as always it started again but not near as severe. At the time my batteries were pretty dirty and I was reading voltage across the tops so I took the cables loose and cleaned them up real good and it stopped again. That was 3 or 4 weeks ago and it has only surged a couple times. Last week end I installed some new injectors and had the batteries disconnected overnight. It has not surged since. It seems every time I mess with the electrical system it stops. I think most of these times I have had the batteries disconnected but not every time as I recall. So when it starts again I think I am going to just disconnect them amd see if that stops it. I understand that disconnecting them does not reset the computer but what could it possibly be doing to stop this surging from happening?

[JAG1]

On ‎3‎/‎18‎/‎2016 at 7:22 AM, Mopar1973Man said:

Yes. You can pus the screw right through the circuit board. Typically results in a broken corner of the circuit board and VP44 replacement. You need to check 12V at the tap wire with the key ON and not running.

 

 

Can you explain a bit more? Are you talking about inside the PDC box, that bolt you use to power the lift pump?

[dripley]

17 minutes ago, JAG1 said:

Can you explain a bit more? Are you talking about inside the PDC box, that bolt you use to power the lift pump?

That is the screw in the stealth plate that taps the VP. Not sure what bolt you use to power the lift pump. Mine is powered from the alternator.

[dripley]

Going to revive this. After many months of no surging it came back. This time after all the work I did on the front of the engine and replacing the bumper I had the batteries disconnected for 4 days. It started surging on the first or second trip I made and is still doing as of today. So my theory of disconnecting the batteries is out the window. Cant figure out what I did. The only electrical I touched was the batteries, fog lights, and the block ground from the driver side battery. 

 

No codes this time as of yet.

Edited June 14, 2017 by dripley

[Mopar1973Man]

Might do a voltage drop test of main cable wiring. I've got a feeling you've might have a rotten battery cable that you disturbed and created this issue.