Intermittent idle surge-increase

[dripley]

Dont throw the towel in yet on the ECM. I have had crazy temp swings on my truck for 10 or so years, most swinging low. Pretty sure its in the wiring and most likely grounds you cant just clean. I lost my ECM about 8 years ago and had surging, more pronounced that what you are seeing and the temp would peg on a cold start sometimes and sometimes not. Never saw it drop like yours.

 I have however seen similar drops before and after the the ECM was replaced. The surging returned about 3.5 years ago and stayed with me for a while until one day messing with the MAP sensor and for some reason it stopped and has not done it since. That was 6 months or so ago.  

 I dont have the answer to the problem but I am willing to bet it has nothing to do with the ECM, and probably not you sensor either. I have 3 to prove it was not mine. At least I will not have to ever buy another.

[Mopar1973Man]

On 4/20/2018 at 7:24 PM, Red Rambler said:

I was able to take some time today and put on my new nations alternator and do the ground wire mod.

 

I wish you would done just the alternator to verify the AC noise first then the ground wire mod.

 

I've got a few fears about this yet. The fact we never found the cause the diode failure for sure yet. So doing the ground wire mod might keep the noise from hoping in the ECM as quickly. So if we do the ground wire mod and have a failing alternator diode will it give you any warning or will it just torch off your ECM? 

 

This is a reason I'm looking for a solution to the diode issue first before resolving the ground wire issue. Still in all my truck ran 10 plus years without any mods and the alternator continue to function fine and no AC noise issues. Still, I'm going to hunt down the noise issue first. 

Edited April 23, 2018 by Mopar1973Man

[Alexio Auditore]

So could could his coolant temp sensor be the cause of his rough running truck?

[Red Rambler]

1 hour ago, dripley said:

Dont throw the towel in yet on the ECM. I have had crazy temp swings on my truck for 10 or so years, most swinging low. Pretty sure its in the wiring and most likely grounds you cant just clean. I lost my ECM about 8 years ago and had surging, more pronounced that what you are seeing and the temp would peg on a cold start sometimes and sometimes not. Never saw it drop like yours.

 I have however seen similar drops before and after the the ECM was replaced. The surging returned about 3.5 years ago and stayed with me for a while until one day messing with the MAP sensor and for some reason it stopped and has not done it since. That was 6 months or so ago.  

 I dont have the answer to the problem but I am willing to bet it has nothing to do with the ECM, and probably not you sensor either. I have 3 to prove it was not mine. At least I will not have to ever buy another.

I haven’t given up yet. I am hopeful that the APPS sensor will possibly fix my issue. But as Dieselfuture has stated, this is one fix that needs to be done no matter the case. I hope you are correct and it’s not the ECM. Did you pull your MAP sensor out or just unplug the connector? I might fire my truck up and crawl around it wiggling all the sensor connections. 

[Mopar1973Man]

34 minutes ago, Alexio Auditore said:

So could could his coolant temp sensor be the cause of his rough running truck?

 

Most likely not. 

 

Now if the coolant sensor was not tripping codes and was offset in normal range it will either raise or lower idle speed that's all. Since the coolant sensor is tripping an error code then the value is disregarded and normalized value is used in place to produce a idle speed number. 

 

You could disconnect all sensors on the engine except one (cam or crank - tach signal) and the truck will start and idle just fine without all other sensors present. 

[Red Rambler]

1 hour ago, Mopar1973Man said:

 

I wish you would done just the alternator to verify the AC noise first then the ground wire mod.

 

I've got a few fears about this yet. The fact we never found the cause the diode failure for sure yet. So doing the ground wire mod might keep the noise from hoping in the ECM as quickly. So if we do the ground wire mod and have a failing alternator diode will it give you any warning or will it just torch off your ECM? 

 

This is a reason I'm looking for a solution to the diode issue first before resolving the ground wire issue. Still in all my truck ran 10 plus years without any mods and the alternator continue to function fine and no AC noise issues. Still, I'm going to hunt down the noise issue first. 

Yes, looking back I knew better than to make more than one change at a time. That’s first day stuff for diagnosing. My hopes were that one of the two would fix the problem but no luck and I had the time and no kids so I just knocked them both out. I was also hopeful that if I fixed the alternator quickly than it wouldn’t take out my VP if it had already done damage to my ECM, however that might be bass ackwards. 

20 minutes ago, Mopar1973Man said:

 

Most likely not. 

 

Now if the coolant sensor was not tripping codes and was offset in normal range it will either raise or lower idle speed that's all. Since the coolant sensor is tripping an error code then the value is disregarded and normalized value is used in place to produce a idle speed number. 

 

You could disconnect all sensors on the engine except one (cam or crank - tach signal) and the truck will start and idle just fine without all other sensors present. 

This might be worth looking into and determining if it idles normal with only the crank sensor plugged in.  Would I then shut the truck off and begin plugging sensors back in one at a time? Would this throw CEL? 

I was rolling through Home Depot today, getting mulch and as you know people walk right out in front of you. I yielded and my damn truck had a snorting fit and I got a few looks, so needless to say I gotta get this fixed. It almost acts like it’s running out of fuel, however my fuel gauge never drops. Only my RPM’s raise and my temp gauge drops, it never raises above 180-190. 

Edited April 23, 2018 by Red Rambler

[Red Rambler]

@Mopar1973Man So I could unplug the below sensors and just leave the crank sensor plugged in and this would verify that my ECM is still good, given the engine idles fine? Would there be any issues with this throwing codes, or could i just clear them after with my OBD scanner? Thanks.

 

ECT

APPS

MAP

IAT

 

[Mopar1973Man]

Basically if you do the Blue Chip hot wire test will omit the entire ECM. The VP44 is powered separately and there is no connection to the ECM. 

 

As for the ECM if the APPS sensor is in "Idle Position" on the Idle Validation Switch (IVS) then the APPS sensor voltage is ignored and the ECM idle software is used. 

 

ECT does control idle speed on a cold startup. So if you going to pull this sensor I would do it after the truck is fully warmed up. I wouldn't want you to think you got a false positive. Colder temperature the higher the idle speed. 

 

MAP sensor has no effect on idle controls. Just like Edge Comp with a Smoke Switch it fools the MAP to full boost constantly. 

 

IAT only affects the timing of the injection pump. I would only pull this after the truck is fully warmed so not to get a false positive. Hence the MPG fooler switch holding 143*F IAT temp year round. 

 

All these sensors will throw a code of some sort being unplugged. You will need to reset all codes afterwards. The VP44 is smarty enough to start and idle by itself without an ECM. The only thing the ECM does at idle time is adjusting the idle speed and pump timing (cold engine and cold IAT).

Edited April 23, 2018 by Mopar1973Man

[Red Rambler]

I had a little time after work to mess with my truck. I had it running and went around and wiggled my sensors and upon wiggling my wires on my ECT sensor the engine would change RPMs and it threw a CEL light. The interesting part is it did not rough idle at all after doing this. It was cold upon doing this, took it for a spin and got it up to temp and came back home as slow as possible allowing it to idle as much as possible. My RPMs appear to be much more steady. Not exactly sure what that means other than a possible short. I am going to put a few miles on it and check for results. 

 

[dripley]

21 hours ago, Red Rambler said:

I haven’t given up yet. I am hopeful that the APPS sensor will possibly fix my issue. But as Dieselfuture has stated, this is one fix that needs to be done no matter the case. I hope you are correct and it’s not the ECM. Did you pull your MAP sensor out or just unplug the connector? I might fire my truck up and crawl around it wiggling all the sensor connections. 

I was going to swap in the old one and it broke so i ended up with old back in place. My surging stopped the day I did that and has not come back. Of course then I started having MAP issues. 

 Another thing on my surging, an APPS did NOT fix it. But my surging was different from yours.

[Red Rambler]

2 hours ago, dripley said:

I was going to swap in the old one and it broke so i ended up with old back in place. My surging stopped the day I did that and has not come back. Of course then I started having MAP issues. 

 Another thing on my surging, an APPS did NOT fix it. But my surging was different from yours.

Thanks dripley. I was messing with my wires today and the surging has stopped for now. I took a 40 minute drive. 20 there and back. On the way I had my MPG switch off, and on the way home I turned the MPG switch on. I used cruise control both ways and was logging live data on my OBD. At one point my temp dropped to 65 like it has been when my idle is irratic, however the RPMs did not change, this was in cruise. I am going to drive my truck and see if I can get the issue to duplicate itself. I am still not ruling out my temp sensor or something along those lines being my temp gauge zeros out and the way it acted by simply touching the wires today. 

[Red Rambler]

I drove my truck this AM to drop my son off at school and also drove it in to work. Roughly 30 minute drive, plenty of time to get up to temp. I did not experience any symptoms of my idle acting erratic. I did log the live data on my scanner and as seen below, during normal throttle the temp is dropping out. I am hoping my issue pertains to a faulty ECT sensor, or ECT wiring somehow. Since wiggling the ECT wires yesterday, the issue has not came back. I did order a new ECT sensor from Geno's Garage.

Below is my live data, as you can see, the temp drops even under normal throttle.

 

Time	ECT	RPM	Speed
1170.6	175	1687	63
1170.9	185	1684	63
1171.2	182	1679	63
1171.5	61	1679	63
1171.8	61	1682	63
1172.1	61	1696	63
1172.4	61	1696	63
1172.7	61	1697	63
1173	61	1697	63
1173.3	61	1697	63
1173.6	65	1698	63
1173.9	187	1699	64
1174.2	187	1699	64
1174.5	187	1699	64
1174.8	187	1699	64

[dripley]

That is similar to how mine has acted though mine has no where near the drop you are seeing. I have seen mine drop 15* or so in a few seconds and somes lower but not as quick or as large a drop as you are seeing. I am not seeing the wid swings anymore except on a rare occasion, very rare. This after messing with the wires as a whole in there harnesses. Not sure where to start on the individual wires.

[Red Rambler]

4 minutes ago, dripley said:

That is similar to how mine has acted though mine has no where near the drop you are seeing. I have seen mine drop 15* or so in a few seconds and somes lower but not as quick or as large a drop as you are seeing. I am not seeing the wid swings anymore except on a rare occasion, very rare. This after messing with the wires as a whole in there harnesses. Not sure where to start on the individual wires.

Same here, I am hesitant to go further than feeling/wiggling wires at this point. I am sure an after market wiring harness would fix a few issues, however that is extreme. For now I think I will look again tonight for obvious cuts in the ECT wire where it might be shorting out. The easier of the two, fix the wiring, or replace the ECT sensor, would be for me to replace the ECT sensor. I will do that and log live data to see if I am still getting these swings in temp.

[dripley]

You might want grab the wiring harness where it connects to the ECM. Squeeze it and move what you can. That has helped me with some of the issues of late. There is a splice in there that all the sensors share, very similar to the main computer splice near the VP. 

[Red Rambler]

1 hour ago, dripley said:

You might want grab the wiring harness where it connects to the ECM. Squeeze it and move what you can. That has helped me with some of the issues of late. There is a splice in there that all the sensors share, very similar to the main computer splice near the VP. 

Okay, thanks. I figured the wire would be buried somewhere in there, in a splice. I will do this tonight and trace down each wire to make sure they are not kinked anywhere, and in good shape. Wiring issues are no fun. Glad you got yours to quit by squeezing the harness

[mopar440cu]

I had the same issues with one of my companies 01 3500. I tried replacing everything from the ECT to all the other sensors and checking all grounds, the alternator and still nothing. So, I swapped out ECM's  from another 01 3500 I have and it cured the issues. I hope this helps!

Edited April 25, 2018 by mopar440cu

[Mopar1973Man]

Odd issue but does happen. Is it possible you have a pin push back and not making a solid connection at the ECM or the ECT plug? Like myself working with the Smarty Touch I couldn't get it to turn on at all. Come to find out after sending it back and have it tested. The Smarty Touch was fine but still didn't work on my truck this now points an issue on my truck. After getting the OBDII plug pulled out I found one of the SCI pin pushed back far enough to no longer make a connection with the OBDII plugs. After going around and double checking all the OBDII pins the problem is solved on my side. It is possible for a pin to pop out of the socket. 

[Red Rambler]

1 hour ago, mopar440cu said:

I had the same issues with one of my companies 01 3500. I tried replacing everything from the ECT to all the other sensors and checking all grounds, the alternator and still nothing. So, I swapped out ECM's  from another 01 3500 I have and it cured the issues. I hope this helps!

What all codes did you see when this happened?

49 minutes ago, Mopar1973Man said:

Odd issue but does happen. Is it possible you have a pin push back and not making a solid connection at the ECM or the ECT plug? Like myself working with the Smarty Touch I couldn't get it to turn on at all. Come to find out after sending it back and have it tested. The Smarty Touch was fine but still didn't work on my truck this now points an issue on my truck. After getting the OBDII plug pulled out I found one of the SCI pin pushed back far enough to no longer make a connection with the OBDII plugs. After going around and double checking all the OBDII pins the problem is solved on my side. It is possible for a pin to pop out of the socket. 

So far the issue has not happened again, after wiggling the ECT wires and straightening the wires directly above the ECT sensor. This could be a possibility as I do have the High Idle switch, but that was installed prior to winter, just seems like issues would have happened earlier on than this. Do you know of a good contact grease I could use to pull the plugs on all my sensors and spray them to coat them, and then plug/unplug them a time or 2 to ensure a solid connection?

[mopar440cu]

3 hours ago, Red Rambler said:

What all codes did you see when this happened?

 

I have 4 01's and had issues with them all and cant really remember the codes on that one. Sorry, but the new ECM stopped it.