Hesitation at low rpm and fuel system goes to open loop

[Hyperman]

2012 Dodge ram with 208,000 kms. For the past year randomly around 1000 to 2000 rpm and 5th or 6th gear with MDS deactivated it just won't rev or build power be eventually it will drop a gear and about 10 to 15 seconds later just take right off. I bought a Blue Driver scanner tool. No check engine lights come on. Replaced air temp sensor and map sensor. Cleaned throttle body as well as swapped throttle body with my 2010 2500 and same issue. Noticed recently that I have a live mode on the Blue Driver scan tool and noticed when issue starts the fuel system goes into open loop and tool shows that I am at 100% engine load. This happens on level road or slight incline most of the time. O2 sensors seam fine. I have tried with MDS enabled and disabled with same outcome. I get no misfire counts on any cylinders. Looking for any kind of help. I took some screen shots when it acts up for you to see.

 

[OCDTech]

Bluedriver is rated very high, so i'm sure it has a way to watch the throttle position sensor in graph format. Key on engine off. Slowly press pedal down to floor, then slowly back, see if there is a smooth transition from low to high, if theres a studder... well there it is. May not be this, but easy to check.

Now i'm not familiar with where the tps is, so if its on throttle body, disregard, but my 05 Forester has like 3, two on the pedal, one on engine, they all have to correlate or here comes the CEL.

 

[Hyperman]

Thanks I will try that!

 

[OCDTech]

Thanks I will try that!

If there are multiple tps, you will need to find all/several graphs, possibly good luck. Whatever happens, let us know.

 

[Hyperman]

Checked everything with the accelerator and tps and everything seams fine. Checked same things with my 2010 and it reads the same. Is there a different reset for PCM other than removing battery cables for a bit?

 

[OCDTech]

Checked everything with the accelerator and tps and everything seams fine. Checked same things with my 2010 and it reads the same. Is there a different reset for PCM other than removing battery cables for a bit?

Disconnect put something over battery to prevent sparks connect the cables together either with a zip tie or piece of cable. Dont let them fall and hit battery. Do this for an hour or so then reconnect turn key on for 12 seconds or so then crank


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[chaten]

Hello. I have a 2010 ram 1500 with the exact same symptoms. Have you found any direction?

 

[chidychi]

I finally found a thread with my exact issue.... but no solution.

Checked everything with the accelerator and tps and everything seams fine.

Hello. I have a 2010 ram 1500 with the exact same symptoms. Have you found any direction?

Did either of you figure this out?

 

[chaten]

Mine was a combination of worn valve tips and pushrods against the rocker arms. Which I believe caused the knock sensor to retard timing. Changing those solved the hesitation for me. There's also a video on YouTube where corrosion in the ecm plug causes false knock sensor readings.

 

[chidychi]

Mine was a combination of worn valve tips and pushrods against the rocker arms. Which I believe caused the knock sensor to retard timing. Changing those solved the hesitation for me. There's also a video on YouTube where corrosion in the ecm plug causes false knock sensor readings.

Thanks for the quick reply!

Did you also happen to have a tick that went away after ( i assume) replacing the valves and pushrods? I just removed my valve covers with the expectation of seeing evidence of a bad lifter and was shocked to see all 16 springs working fine.

 

[chaten]

I replaced cam, lifters, valves, pushrods, and rockers. Cam and lifters showed no signs of failure but I made the mistake of listening to Google and changed them sincei was in. Tick never went away. I found that the original worn valves and pushrods were causing the tick (which was excessive lash)
As for changing my cam and lifters, that was a waste of time as the new lifters were cheap Chinese knock offs. So I reinstalled my original lifters. For the most part a cylender misfire code signifies lifter failure.
Long post but I chased Google diagnosis with the usual suspects and fixes ie lifter wearing cam, some people say change to expensive oil or viscosity change all a waste.

I'd also like to add that rock auto sucks and for pushrods, just go to the dealership.

 

[chidychi]

I'd also like to add that rock auto sucks and for pushrods, just go to the dealership.

Thanks again chaten. From what I can tell I have the exact problem you had. I'm going to pull the heads and take a look at everything, but I'm pretty sure it's the valves and/or pushrods.

Here's the thread that I started before I found this one:

5.7L bogging down under load and low rpm

Hi everyone. 5.7L with 66RFE I have a 2017 2500 slt with about 200k km (125k miles). I've searched the forums but haven't quite found my situation. About a year ago, the truck started to struggle climbing hills ( my driveway is a 300' hill with turns covered in ice and snow) . I parked it...

www.ramforum.com

 

[chaten]

Ive heard You could also remove the valve covers and let it run. Very careful put a little pressure on each rocker and the ticking may go away leading you to the problem. At least you might not have to remove both heads that way. If you put a stethoscope on the knock sensor or if you have a code reader that reads both knock sensor voltages worl help. It's convenient that you can leave the exhaust manifold on the head tho, but change the gasket and studs while it's off.