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Discussion Starter #1
Long time lurker, first time poster. Here's the story. I bought this truck in January, all stock, 180K miles. Added a lift pump in May, lost the DPF, tuned with PPEI. Didn't block the EGR. First time towing our Toyhauler (around 8500lbs) I felt like I went over the wake up strips on the road a couple times. But there weren't any in the middle of the road. This was when I had my foot in it to get up one of these steep PA mountains. After about 2hrs towing we stopped for a pee break, I left the truck running.Got back in the truck on I 79 north, smooth fairly level road. I commented to the wife how nice the truck pulled. Of course, then the check engine light came on, and got Reduced Power message. Still running fine. I didn't want to stop on the interstate, so kept going to the next exit where we were going to get off anyway. Truck was running OK so we drove about 20 miles to the campground. Checked my Edge CTS2 for codes, low fuel rail pressure came up. DIC says Change Fuel Filter. Stock filter was changed less than 5000 miles ago, and lift pump was put on within last 2K. Cleared the codes, drove around the rest of the week, all was fine. Thought I felt the rumble under heavy pedal on the way home once or twice. Got a Race plug for the fuel rail, thinking that the stock FPRV was weak and popped open.
So. Next trip, felt the rumble again. Set the Edge to monitor fuel rail pressure, actual follows commanded just fine, no loss in heavy tow.
Set boost pressure PID, was at 20lbs last time I felt the rumble. Highest pressure that I saw was 27lbs. I don't know if the gauge could respond fast enough to the EGR valve blowing open, of if this is what it would feel/sound like if it did blow open.
Or, could it be the transmission? I changed to Transynd in March, doing the double drain method. Changed filters twice.
When not towing the truck runs fantastic, I have gotten over 20MPG with it on a long trip.
Anyone have any ideas?
Is it time to start shopping for another truck?
 

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Curious as to what hp level you was running while towing ?
27 boost is a little low IMO, mines max @ 31-32 with atp 40 hp towtune.
I do have a another EFI tuner same 40 hp TT it’s lucky to hit 27-28, that’s why I don’t use their tuning.
FYI, most EFI tuners do Rumble tunes unless you request a Hiss tune, but this is noticable while idling.

You could have EGR issues with this rumble, I’m pretty sure PPEI did a delete tune which would include the EGR.
It’ll still function, but I would try unplugging it, contact PPEI on this.
I had a similar issue when mine was first tuned I left my EGR functioning, when I blocked it the engine ran a little rough.

Then I remembered it was still plugged in, unplugging it cured the problem.
Your egr could be faulty now and either needs to be replaced or blocked.
If you block it, unplug it.
 

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Discussion Starter #3
I was running the #2 tune. 60HP tow tune. Just to be clear, it's not a constant rumble, more like a burp. and that's about how long it lasts. I've never had the truck in the #5 tune, usually drive in#3. I'm wondering if it could be the torque converter, but wouldn't it throw a code?
 

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Are you using towhaul when towing ?
If not then start, always use towhaul when towing anything.
If you mentioned this, sorry I missed it.

As far as a code that depends, pay attention to your tack(rpms).
If the rpms is jumping up like maxed out redlined in between shifts when this is happening that’s a good sign of trans troubles.

Are you manually shifting or just putting it in drive when towing ?
If drive, don’t, manual shift and select 5th gear to lock trans out from going into 6th.
RPM’s on flat 1800-2100 grades 2200-2800, 3000 for short burst getting up that steep grade.
Mines happier @ 2100 on flats.
 

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Discussion Starter #5
Yep, using tow/haul. Tach is not jumping when this happens. Usually just put it in D. In the mountains here there is little chance of going fast enough to reach 6th gear speeds. It has gone into 6th once or twice on a slight downhill grade, but that doesn't last long. I keep an eye on tranny temps, last trip they didn't go over 185. This only happens under heavy pedal pulling a hill. Next tow trip I'll try manual 5th and downshift sooner with the - button.

You know, it's almost like a rev limiter on an ATV. But it's over so quick when it happens it's hard to check all the gauges.
 

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I think you’ll find using manual to stay out of 6th gear and keep the rpms up somewhere near my suggestions, you’ll find works quiet well.
My guess is your lugging the engine (low rpms) and when you try to Getty-up-n-go, pretty much the issues your explaining will/should go away.

Next time check your rpms when in 6th gear, probably in the 1500 -1600 range, not good when towing.

Did you get the turbo brake with your EFI tune, to help with engine braking on grades when towing ?
If so, when going down grades and the turbo brake kicks in you’ll have a rumbling sound.
You have the CTS2 select the turbo vane position sensor for a pid to view.
Lower right corner of my CTS2.
0% opened all the way - 100% closed
 

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Discussion Starter #7
Yes, it has the turbo brake. Sometimes a little more aggressive than I'd like. I have the turbo VPS on as well as EGT.
 

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The EFI turbo brake functions best when using towhaul.
In towhaul the converter is locked after the trans shifts into 2nd gear.
The turbo brake function kicks in above about 1800, when you let off the throttle it starts the engine braking.
When the rpms drop below around 1800 some maybe 1600 the engine braking kicks out.
You can test this when empty/solo, select TH and manual shift like maybe 3rd or 4th gear, get the rpms up above 2000, I’ll usually get them up to about 3000 when testing, then let off the throttle, you’ll get a all of a sudden feel like you just dropped a anchor, until it kicks out everything is back to normal.

When it’s functioning you’ll see the VOPS is about 95%-100% closed when the TB kicks out it should be well below 100%.
As soon as you touch the throttle it kick out.

When empty and your not using towhaul you should never feel it functioning.
What’s considered to aggressive having something that helps braking when towing.
Now a big rig with a Jake brake, that’s aggressive but your also trying to stop 80,000+ lbs.
I’ve run my ATP tune since around 2011, 40 hp tow tune with turbo brake 24/7 365.
NO tune switching with the chance of doing something stupid, single tunes.
 

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There’s really not a WOW difference between regular tunes and tow tunes.
Try a lower hp tune similar hp to your TT, providing it doesn’t have the turbo brake, then tow with it.
After you get the feeling you’ve just about lost control lost your brakes and smell burning brake pads going down that steep grade, you’ll luv the turbo brake.
 

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Discussion Starter #10
I don't really like the 1st tune on my dsp5. It's a 30HP stock/economy tune. Makes too much rattle for me and doesn't get any better fuel mileage. I think i"ll just leave it in #2(tow/60HP) it feels pretty good there. I don't need to race around and I try to take it easy on equipment.
By aggressive, I mean as I was descending a hill, with my foot on the brake, the tranny kicked down into 4th then 3rd and was revving the engine around 3k. Not used to hearing that! Putting my foot back into it to get it to upshift made a lot of rattle. I was so rattled I took it out of tow /haul to release the turbo brake. Still not used to it after coming from an Avalanche 2500 with the 8.1.
 

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That’s one reason to manual shift, your under control, you still have to watch the rpms and down shift when needed to control the speed a little.
Drop a gear to slow down, on my motor home (gasser no engine braking) on steep down grades I have to go into them in 2nd gear, and try to keep the speed under control.
3000 is pushing it IMO, but sometimes a must, on my MH 3500-3800 at times down grade, then tap the brakes to slow down a little.
On my Dmax when towing and coming up on a down grade, I’ll slow down enough to drop it in 3rd gear, maintaining 2600-2800 rpms then go from there.
Approaching a down grade in 4th would be going a little fast for my heart, and is pretty risky for you, your family and anyone around you.

This is how the turbo brake/engine braking functions.
At least now when you hear the rumble look at the % on the turbo vane sensor.
The reason I suggested to tow in a tune with out the TB, then you might learn to accept that it’s a great option to have.

I towed something for over 40 years for a living, it’s not something you can just put it in drive, crank up the juke box and just relax like you can when driving solo.
Of course if you had a driver to do all the work and thinking then you could.
 
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