Bog/Miss/hesitation under full throttle

[Ross]

My truck is acting like something really baaaad is about to happen. With the PowerMax on any setting above 3, the truck seems to bog, hesitate, make a "burble sound" and cough some white/blue smoke. It then overcomes the bog, and accelerates like usual, spinning tires, etc. The higher the setting on the PM, the worse the bog, until it feels like it's actually bucking. It can't be good for the engine.



With the PM turned off, i. e. , lower fueling levels, the truck runs fine, even at full throttle.



Here are some of my possible diagnoses:



Fuel starvation? My lift pump was strong 2 weeks ago.....

Injectors going bad? . . Can't stand the high flow without "bleeding"

Injector pump about to puke?



Any experience/advice is appreciated.

 

[LStanphill]

Hesitation with power upgrade

I used to have a Diablo Power Puck on my 01 and had similar problems (including the truck computer completely shutting down).



I have since removed the puck for a full refund. I later read an article stating the computer sensed too much boost from the turbo causing the computer to cut fuel. Some sell a brass ring that installs on the wastegate actuator to trick the computer...

Its sad when these companies quote so much research just to have it fail on you. .

 

[CUMINNTSTRKN]

Re: Hesitation with power upgrade

Originally posted by LStanphill

I used to have a Diablo Power Puck on my 01 and had similar problems (including the truck computer completely shutting down).



I have since removed the puck for a full refund. I later read an article stating the computer sensed too much boost from the turbo causing the computer to cut fuel. Some sell a brass ring that installs on the wastegate actuator to trick the computer...

Its sad when these companies quote so much research just to have it fail on you. .

i would disagree with you on this. it was your fault for not researching your purchase. as you found out the puck does not come with a boost module. but other products like the edge ez and the va do come with boost modules. at least you were able to get a full refund. you should try the edge ez.





jim

 

[Todd T]

If this is happening at full throttle it could be two things



fuel starvation or the speed limiter coming on.



at what speeds does this happen? and RPM?



have you checked your Fuel Pressure? do you know what you have at full throttle for FP?



PM or email me i will try to help you out.

 

[Ross]

Bog/Miss

Todd:



At the higher settings, it doesn't even take full throttle for the bog to occur. It is evident in every gear, especially 3rd, 4th & 5th. There's really not enough load/time spent in 2nd gear for it to occur. RPMs are anywhere between 1800 and redline (about the time boost builds).



Normally, my truck makes about 40 psi boost at full throttle in 3rd gear on up... .



I have been running TST boxes of various fueling levels for 2. 5 years, with the adjustable competition version on for about 14 months.



I've had the DD IIs in for 2 years.



The truck has 105,000 miles, although the problem has just recently surfaced.



I'm on my 3rd lift pump, and the current one check 12 psi/idle two weeks ago, although I haven't checked at WOT. Will do so ASAP.

 

[Jetpilot]

Ross,



Do the simple things first:



Check fuel pressure (might be filter or lift pump).



I am not familiar with TST products and installation but I would try and check all connections.



It could be the high pressure fuel pump, but lets hope not. I don't think it is injectors but I could be wrong... . Keep us posted, and good luck!

 

[Bigsaint]

Ross, if you check your FP at WOT and it's okay, then I'm not sure. That'd be my guess though, the TST Comp. requires a good amount of fuel. If you are still using the stock fuel lines/banjo bolts, you might need to upgrade to a less restrictive set up that allows for more flow. I doubt it's a connection, at least at the map sensor, unless you are getting a check engine light. If you tapped into the VP44 wire with the scotchlok, make sure you use some dilectric grease for a positive signal.



Mine is smooth unless I go above level 6, then I have a defueling shutter.



Scott W.

 

[RADdodge]

Ross

"Pillar Mounted Boost & Pyro; etc. , etc. ,"



I hope your etc includes a fuel pressure gauge! 3 lift pumps! I hope you voted in the "Lift Pump Survey!" I especially hope it's another lift pump. It's cheep compared to the injection pump. Jetpilot has a good suggestion. Bigsaint has a lot of fueling experience. If you don't have a permanent fuel pressure gauge, include that in your fix. Let us know the outcome.

 

[Todd T]

Ross, i would have to agree with Scott (Big Saint) if you have had the pm3 on the truck and this just started it would have to be along the lines of FP.



you really need to watch the FP at WOT. mine would suck the fp down to 2spi at wot before i drilled my banjos and replaced the line between the filter housing and the transfer pump.



now i have a good 5psi at WOT. on level 9



normally starvation feels like bucking and if its bad enough you will hear it popping.



you said you have the comp so it wouldnt defuel until 3000rpms



have you disconnected the speed limiter wire? on the 01 and up it will be effected by the pm on it. my truck would only go 85mph. with the wire hooked up.

 

[MikeR]

Ross,

Check your lift pump ASAP. This same thing happened to me month and a half ago... one week my lift pump was fine and the truck ran like a champ, the next week it was surging and loosing power on the top end especially with my PM3 turned on. I re-tested the lift pump to find out it took a complete sh*t within one week. I'm now on pump #4.



-Mike

 

[CUMINNTSTRKN]

Originally posted by Todd T





have you disconnected the speed limiter wire? on the 01 and up it will be effected by the pm on it. my truck would only go 85mph. with the wire hooked up.

todd



what speed limiter wire? i have never unhooked any wires and my truck will run up to redline in 6th, it's about 120mph.



jim

 

[Diesel Freak]

Re: Hesitation with power upgrade

Originally posted by LStanphill

I used to have a Diablo Power Puck on my 01 and had similar problems (including the truck computer completely shutting down).



I have since removed the puck for a full refund. I later read an article stating the computer sensed too much boost from the turbo causing the computer to cut fuel. Some sell a brass ring that installs on the wastegate actuator to trick the computer...

Its sad when these companies quote so much research just to have it fail on you. .

The brass ring does not do crap with regards to the ECM! All it does is defeat the factory wastgate setpoint.



You MUST use a boost module with the Puck. . if not, well you know.



FYI, I am only using 275's and a Puck... . WITH a boost module and I see 36 PSI on a regular basis.



Any fueling modifications however small will require a boost module to realize their full potential... if not, well, you know.

 

[Ross]

bog/miss

Big Saint:



When the truck rolled over 100,000 miles i. e. , no more warrantee, I cut all the PM harness wires and made hard-wired soldered connections. I also stripped the fuel pump wire and soldered it too. I am my own warrantee station.....



The truck has been running fine under these conditions, so I know that my PM wiring is not the problem (anymore). I'll check fuel pressure at WOT and report back to the group.



Thanks for all the input! You guys are great.

 

[Todd T]

Jim, I dont think the ETH's have the same problem. it has to do with a governor circuit on the trucks. it compares vehicle speed to fuel flow through the pump. the ECM will defuel if it reaches a set limit. IE: speed lmiter. its 115MPH or there about in a stock truck.



when i put the PM3 on my truck, for every level above 5, the speed limiter limit would lower. the worst is on level 9, it defuels at 85MPH no matter what. cut the wire and presto



i have mine on a switch inside the ashtray. you wanna talk about consistant ET's at the track use that, its like a block under the pedal. i would run through the traps at exaclty 85MPH with it to the floor.



plus you have an Edge box. it probably doesnt flow as much fuel at high RPM's



































that was just a wise crack dont flame me

 

[Steve St.Laurent]

Ross, what about the connection at the MAP sensor? Are you still using their inline plug? I had EXACTLY the same symptoms that you are talking about (bog, hesitate, burp, blue/white smoke - LOTs of it) at one point. My problem was that the inline plugs at the MAP sensor were not making good contact. What would happen is when the engine would move it would move that harness slightly and get the intermittent connection, once it was fully under power the connection would be good again and it would run fine. I talked with TST and they sent me a new inline plug, they said that they had some problems with the early MAP harnesses (I bought my first PM box in September of 99 btw). You can try a couple of things to see if this is the problem. First turn the ignition on without starting the engine, then go under the hood and move that harness around (both sides). In my case as the connection was broken and then made again the injection pump would click - it was easy to hear. I would guess that depending on which pin is making the bad connection that may or may not happen but you might try it. As a temporary fix until the new harness came in I used zip ties to hold the harness in place on the engine so that those connectors wouldn't move around under acceleration.

 

[Ross]

MAP sensor

Steve:



Yes, I'm still using TST's map sensor plugs, but I've redone/soldered all the single-wire friction plugs that connect the main harness to the MAP plugs. I'll wiggle the plugs as you've suggested and see If I hear the "click. "



So far, the problem is likely to be either

a) low fuel psi at WOT (lift pump)

b)MAP sensor contacts within the plug not making good connection:



I'll continue to trouble shoot and eliminate these possiblilities. I'll keep everyone posted.

 

[Bigsaint]

Ross, I see that you hard wired, good for you, eliminates alot. Pull the plug on the Map sensor and apply a small dab of dilectric grease on each of the 3 posts. If you still have the stumble, that should eliminate the map plug as the source. No codes or check engine lights, right ???



Scott W.

 

[Ross]

MAP Plugs..

Big:



That's correct, no codes or check engine lights. I'll do as you recommend. All I need now is a little time off from the job to do all this trouble shooting.



Jobs are SO inconventient!

 

[Bigsaint]

LOL, I agree 100%. When my last pump needed replacement, I parked the truck at home and had them pick me up for my TDY that day. It really killed me to not be home, lying in the snow and stones, getting diesel all over me while I exchanged the pumps. Hard to focus that night for sure, when I got home at 2315, I went right out and started the removal, wife doing this . Stayed up 'till 0130 soldering new connections and such, darn near stayed up another hour and completed the job. I hate it when the truck isn't 100%. Keep us posted.



Scott W.