5POINT9

Need some good advice.

Some time ago, I bought a new hot juice. On hot level 5, it would buck and miss and cause some injector low voltage codes as soon as the throttle was hit hard. Called edge and sent it in for eval.. haven't heard back yet, BUT..

Found a good deal on a PPE (not hot) downloader in the mean time. Tried performance level. All good. On extreme, it will do something similar with the throttle is mashed hard and quickly. Doesn't set codes, but feels similar to what the edge is doing.

Ok so..

1. Maybe fuel filter? The filter does not have that many miles on it, but my truck sits a lot. It probably has 500 miles on the filter, but the truck has sat for 6+ months with little usage. I have an extra filter, so I will probably switch that out while I wait for you pros to help diagnose!

2. Fuel pressure at idle is 16psi, but I only have an underhood gage for my Walbro setup. I can't tell what the fuel pressure is under heavy throttle. Also, my TS MPD monitor is in for repair , dead on arrival. So I can't tell what the rail pressure is right now.

3. When trying to diagnose the juice, I pulled the rail pressure banjo off. Wet inside, and it flowed a little at idle when I started it. I was told that being wet doesn't always mean that the rail pressue valve is bad. What do you think? If I buy a new one, where is a good place to buy one (not at dealer).

4. Any other ideas? What would cause popping/bucking under hard immediate accel when downloaders/chips are setup to kill mode?

Thanks! Off to change the filter!

5POINT9

Oh.. two more things. This is with the VA OFF the vehicle. Also, if I roll on the throttle, the power is smooth with no noticable hiccups.

Thanks!

5POINT9

well.. wasn't fuel filter

Asher

Your not the only one in this boat... I get the same problem when I set the TM on my smarty to lvl 4 (least TM).... I really think it has something to do with timing because if I stay in it, it comes to life. But what I have done is set the TM to lvl 1 (easier to drive anyway) and problem gone...

I don't feel it is a FP issue because just like you, rolling into the throttle will not cause it and it pulls hard all the way up (where is should starve for fuel)...

I suspect my tone ring mod has something to do with it, but it really seems like the truck is "miss firing" due to too much timing...

5POINT9

Well, let me know what you find!

Rail pressure gage should be back soon. I hope. Any others with ideas?

Did some more driving around. Strange. You would think that if it was fuel starving it would happen more when doing a long hard pull, not right after you stomp on the pedal??

Plus, ha ha, I forgot to shut the drain off on the fuel canister. Needless to say, it came gushing out with a vengance. If the truck uses more fuel than what I saw coming out of there, then it's time to sell it!!

I've had a lot of different programmers on this truck. I might try to reload the stock ("orginal") and try to reload the extreme. It only seems to pop (big-time) in first, maybe an occasional pop in 2nd. Nothing after that! Plenty of smoke through the whole pull would show me that fuel is available??

greg_bingham

when you're hitting the throttle down low you're draining the rail and the revs(pump) aern't there to satisfy demand like they are when you're rolling??

Greg

5POINT9

Good question.. maybe.. maybe a pump "expert" could tell us if the pump volume is rev dependent? It's hard to believe that I am draining the rail instantly though.. will keep looking!

AK RAM

I get the same thing when mashing the pedal hard and quickly, whether from a 60mph cruise in overdrive (to pass someone) or stomping on it at a stoplight. I never really get the "bucking" per say, but it feels like a very hard miss, sometimes twice in quick succession, as soon as RPMs start to come up after mashing it. I only get that when I use an aftermarket plug-in box that extends duration like the TST, X-Power, VA C3.2, etc (never tried a Juice), regardless of whether they advance timing also (as the VA does not). It is specific to plug-in duration modules for me. Being stacked or not with a programmer makes no difference. I get it with a plug in module by itself, or stacked.

If I am running just a downloader by itself, I never have that problem, whether BullyDog, Smarty, or whatever. The popping you see with Smarty is not really related I don't think. It feels different, sounds different, happens under different conditions, and at very different RPMs.

Rail drain is never an issue for me. Definitely not a factor when this happens on my truck.

5POINT9

It's funny cause I never had this issue before. My last setup was diablo RKL & VA3.1. No issues! At this, by sotp, felt a lot stronger and hotter than what I am running now.
Got the hot juice and started having issues. Popping, missing. With the juice, however, the truck would stumble and pop, then nearly die for about 5-6 seconds. The truck would come back to life but set injector voltage codes.
Now with another downloader (ppe - again NOT hot), I am having similar issues. The PPE does not feel super strong, so I can't be draining the rail if my pumps are good.

Asher

I have to agree, I really can't imagine that it's draining the rail, just way to fast. I really feels like some parts of the engine are trying to respond faster then the rest and then it all catches up after a second and takes off...

I never had any issues with my MP-8, and never even after my smart was stacked, but only when I load up the least TQ management setting. Like I said just going back to any setting less then lvl 4 TM doesn't make the truck do it so I am really chaulking it up to too much fuel / timing advance. Even with the smarty on lvl 7 and my mp-8 100% I don't get it (unless it's on TM lvl 4)...

Personally I haven't really looked into the problem / cause, I don't feel the need to win any dyno events, or tweak time slips at the race track... I just want a lively truck that is a little quicker and pulls a little better then the stock truck beside me, so I just increase the TM and I'm happy (just don't run lvl 4)...