Engine Cutting in and out

95powersmoker · Mar 5, 2014

Hi guys,

Got a new issue developed after I had my trans rebuilt. If I am driving down the road and keeping constant throttle, my truck will cut in and out almost like it's going from in gear to neutral and back. This happens for a while and then drives normal for a while and then back. Right before I parked it last Friday, I also had an episode in addition to the cutting in and out where the truck threw a p1316 idm code and ran super rough spewing black smoke and not going over ten mph. I shut the truck off and restarted and it ran fine the rest of the way home except for some occasional cutting in and out. The cutting in and out only happens when under constant accelerator positioning and is not there when you are goosing it or at idle. I'm curious if my idm is on it's way or what. I haven't taken the idm out to see if it has water or is loose or what. Anybody ever seen something like this or have any ideas. Truck ran fine before the trans rebuild except for a lack of fuel pressure and the obviously crappy shifting.

golfer · Mar 6, 2014

95powersmoker said:
The cutting in and out only happens when under constant accelerator positioning and is not there when you are goosing it or at idle.

200% and larger nozzles will act that way when the ICP pressure is a tad high...

basically the higher the ICP pressure...at light load/pedal...the injectors can act like on/off switches...over & under accelerating the vehicle, making it seem super touchy.

have your tuner drop the ICP pressure a bit, and reduce MFD.

95powersmoker · Mar 6, 2014

I will get some data logging of icp and dc but when I looked at it before I parked it, they didn't look out of the norm. Also, I didn't have any issues of cutting in and out before the trans took a crap and I had put a few hundred miles on it with the injectors and tuning in before the trans pooped out. This issue is a recent deal. But I appreciate the idea and will get some data logging to send off to no limit tuning. If it is a tuning issue, that will be an easy deal.

golfer · Mar 6, 2014

did you get a lower stall converter or anything in the trans that would make the transmission 'transmit' more power or feel to the driveline?

ie..a stock, inefficient converter may not show the issue as much as an efficient converter.

what I'm describing is what I call 'trailer hitching'...

does it feel like a trailer on a hitch, pulling you back/pushing you forward with minimal pedal change? on/off/on/off accel/decel, etc?

if not, and it's literally cutting in & out...you should be able to catch that on a scantool by monitoring/logging CPS and/or ICP/IPR%

95powersmoker · Mar 6, 2014

I'm trying to get a list of exactly what was installed in the trans so I can pass that information on to the tuner. I'm not exactly sure as of now. But it definitely is literally cutting in and out, doesn't feel like a trailer behind me. Feels like the injectors all shut off and then back on and then off and back on.

duck fan · Mar 6, 2014

The P1316 code usually points to a UVCH coming loose. Pull your valve covers and check the plugs on both sides. Chances are one or both is backing out a bit causing intermittent electrical power loss to the injectors.

2000wa250 · Mar 6, 2014

Golfer, not to hijack, but what causes this trailer hitching you mentioned?

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95powersmoker · Mar 6, 2014

Peter@DP-Tuner said:
The P1316 code usually points to a UVCH coming loose. Pull your valve covers and check the plugs on both sides. Chances are one or both is backing out a bit causing intermittent electrical power loss to the injectors.

I was going to replace both sides to be safe. One side is ziptied tight and the other I broke the clip but still pushes on tight. It just seems that my issue is more than that though. The time it started spewing smoke and not wanting to move was definitely a feeling of a bank going down but the cutting in and out seems like it's more than a uvch plug coming loose. Because it only happens at constant/ light throttle, you can accelerate out of it and the truck doesn't skip a beat and idle is nice and smooth.

duck fan · Mar 7, 2014

Do you have it zip tied under the valve cover? I've seen people do that on the outside plug but under the valve cover is where you need to check in this case.

95powersmoker · Mar 7, 2014

Yep. It's zip tied on the outside. I'll pull the covers and check the under side to make sure it's all tight under there.

golfer · Mar 7, 2014

2000wa250 said:
Golfer, not to hijack, but what causes this trailer hitching you mentioned?

Sent from my SCH-I545 using Tapatalk

see post #2

95powersmoker · Mar 9, 2014

I got some data logging today. Also picked up valve cover gaskets and wiring. I ran a buzz test and it came back with an issue on the #5 cylinder. Definitely sounded faint compared to the others. Truck is still running rough and won't let go of the p1316 idm code.

duck fan · Mar 11, 2014

Definitely want to look under the valve covers.

95powersmoker · Mar 11, 2014

Peter@DP-Tuner said:
Definitely want to look under the valve covers.

They look fine both at the plug and under the covers. I am in the process of replacing both sides anyways. The gaskets have been replaced before but I will also change out the pigtails. Will report back once I'm done and hopefully that does the trick.

95powersmoker · Mar 19, 2014

Alrighty guys, I replaced both valve cover gaskets and pigtails. Haven't seen a ses since then. Still have the bucking/ cutting in and out when holding constant speed/accelerator position. It clears and pulls great under acceleration. I watched pretty close tonight on my way home and it seems like the tachometer stays constantly even when it feels like the motor cuts out and then catches back up. I'm at a loss. Any direction is helpful.

golfer · Mar 20, 2014

95powersmoker said:
Alrighty guys, I replaced both valve cover gaskets and pigtails. Haven't seen a ses since then. Still have the bucking/ cutting in and out when holding constant speed/accelerator position. It clears and pulls great under acceleration. I watched pretty close tonight on my way home and it seems like the tachometer stays constantly even when it feels like the motor cuts out and then catches back up. I'm at a loss. Any direction is helpful.

you need to monitor ICP pressure WHILE the truck is doing the on/off bucking deal...

mandkole · Mar 20, 2014

if you lockout OD and hold it in 3rd gear at similar road speeds does it still buck? wondered if it was throttle position or load sensitive

95powersmoker · Mar 22, 2014

Here is one that I got yesterday. I thought I recorded three but I guess the other two didn't save. I wish they had because the second one was bucking harder than it has before. This one I think is when I was driving about 40-45 mph until you see the rpms drop a little, i was coasting and then I had to speed up to about 45 again when you see the rpms go up. All while the OD was locked out.

I will take more today and make sure they actually save.

95powersmoker · Mar 26, 2014

Here's another datalog from today. I was doing about 50-55 in overdrive for the first little bit. It was cutting in and out pretty good. Then I coasted to about 45 and downshifted and physically locked out OD. Still bucking and cutting in and out. Then I slowed down to almost a stop, and brought it up to about 25-30 mph and it bucked pretty good a few more times and then I stopped the recording.

Thanks for taking a look.

golfer · Mar 27, 2014

can you try getting a log with (more) steady engine rpm? maybe include pedal position/volts?

looking over your log, I don't see anything standing out in the tuning...I was expecting to see a lot more ICP pressure....which could have caused the bucking.

is it bucking on/off/on/off...or is it a misfire...not critiquing anything just questioning.