Hey guys, I'm looking for some advice here as I surely am not an expert on the subject. I have a 2002 L. Has A LOT of mods. Built engine, Stage 3 heads, cams, LT's, Kenne Bell 2.3L. My fuel setup consists of twin Walbro 255s, 60lb Inj, SCT 2400 MAF but I'm using the stock rails, regulator, and the relay is still being used as well as the stock resistor. My problem is only during WOT I experience what seems like some sputtering/missing/hesitation. It only happens during WOT and full boost is reached. I have searched the forums and I know new plugs could fix it, as well as new coils and a fuel filter change. But I jumped all that and did a pressure test for now. At idle I get a solid 39-40psi, and when the engine is revved and up to WOT it only sees a max of 50 psi. So...I removed the pump relay and used a jumper to give the pumps full volts from idle. With that done at idle I see a solid 60psi and when revved I see a max of about 75psi. All this is with the vacuum still attached to the stock regulator. I'm not sure but it seems as though with the relay in use I should see more psi when revved? or am I wrong? Possibly the stock resistor is going bad? I even swapped the relays around and tried a second relay and same results. Only when it's jumped do I see higher then 50psi. If anyone can chime in with anything I should or give any guidance I would defiantly appreciate it. Thanks guys.
WOT sputtering, fuel help!!
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Start out with the cheapest things first. These trucks are so tempermental. I have had almost all of these problems occur over the last 10 years
1. Check plugs, no cost
2. Wire the dropping resistor in parallel, no cost
3. Make sure your coil packs don't have any water in the plug holes (Usually on Weapon-X coils, no cost
4. Check for vacume leaks, no cost
5. Check fuel pumps and "y" fitting for problems, no cost
6. Check battery volts and alternator, low voltage could drop the flow on pumps and could effect coil pack fire, no cost
7. Datalog your WOT and see what the MAF is doing, no cost
8. Change fuel filter, about $18
9. Clean and flow injectors, about $150
10. If running leaded race fuel, change O2 sensors, about $160
What is the A/F gauge doing when it stumbles ? At what point was it running ok and did you make any changes inbetween it running good and now ? Hope this helps, let us know :smt023
1. Check plugs, no cost
2. Wire the dropping resistor in parallel, no cost
3. Make sure your coil packs don't have any water in the plug holes (Usually on Weapon-X coils, no cost
4. Check for vacume leaks, no cost
5. Check fuel pumps and "y" fitting for problems, no cost
6. Check battery volts and alternator, low voltage could drop the flow on pumps and could effect coil pack fire, no cost
7. Datalog your WOT and see what the MAF is doing, no cost
8. Change fuel filter, about $18
9. Clean and flow injectors, about $150
10. If running leaded race fuel, change O2 sensors, about $160
What is the A/F gauge doing when it stumbles ? At what point was it running ok and did you make any changes inbetween it running good and now ? Hope this helps, let us know :smt023
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Excellent list of trouble shooting
Alright I def appreciate the reply. I have new plugs and are putting the gap at .032 and Im ordering a set of new coils just for the hell of it. All vacuum hoses are good, checked them already. Y fitting has been eliminated due to some aftermarket braided lines being used as well as a 2 in 1 out Mallory fuel filter assembly. As far as data logging, I have an Xcal2 and sadly it isnt up to par with that feature. And my A/F gauge is on the fritz. It doesn't read the ration. It's almost as if it follows a pattern repeatedly. Repeats the same thing over and over no matter what the engine is doing. It's like its in some dealer display or demo mode. I bought the truck only about 3 weeks ago and it has done that since. The previous owner said it was basically just thrown in the pod hole, so was never really installed fully. I have the truck scheduled to be tuned in a week, so my plan is to change plugs, COPS, fuel filter, and see how its looking on the dyno. I just want to make sure everything is checked before get to the shop.
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3,701 Posts
Without a doubt, get that A/F gauge fixed. The sensor could also be loaded with lead from race fuel. Buying a used modded truck sometimes takes time so be patient it will come together. And don't do anything crazy until you find out the problems. A very cheap part can cost you a entire motor, especially if it is the tune or effects the A/F ratio.
The regulator is 1:1. If you have 39 psi at idle with vacuum, you should have about 51-52psi at WOT if you have 10lbs of boost, about 56-57 if you have 15psi boost. It seems odd that the truck is at 75psi WOT with the resistor jumped. The reason it goes to 60 at idle with the pumps "full on" is because the pressure regulator is over-run. On my truck, the pressure dropped back down to normal levels with boost.
dude lightning has a good list, except I don't understand his #2. Definitely change the fuel filter.
dude lightning has a good list, except I don't understand his #2. Definitely change the fuel filter.
Thank you dude lightning and ruppster for the inputs. Def appreciated. I def WILL NOT go WOT until I get the plugs, coils and fuel filter changed. Coils are on order and should be here Tuesday. I'm about to go investigate the A/F gauge and see if I can get it working correctly. Seems my pressures on fuel seem alright then, but like you said with the relay jumped at idle im sitting about 70ish no higher then 74ish...possibly my pump resistor is on the fritz? any way to test that? And dude lightning could you explain what you mean on some of your inspection procedures? I def appreciate it from all!
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the xcal 2 can do data logging...
Also here is a current update. Fuel filter was replaced. Fuel pressure still checks good. I fixed the wideband gauge too. The sensor was bad. Good news is I'm not running lean! Actually the exact opposite. When at WOT it pegs my a/f gauge all the way down to 10.2 so I'm thinking its just flooding my engine with fuel. I cam to realize that when the truck was originally tuned, it was on 14psi. Currently its only seeing 10psi. I called kenne bell to verify what pulley combs produce what boost and with the current setup im spot on to only see 10 psi. So, with that said if the pulley has been changed from a previous owner and was not retuned that means its running less boost now on a tune that was for 14psi. Could explain why its dumping so much fuel. I have the smaller pulley that should push me back to 14psi. You guys think I should install it and see where I'm at then? I'm scheduled for a tune tomorrow anyways.....? Would def rather use the smaller pulley....I mean why not have more power lol. I appreciate it guys. Thanks.
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2,620 Posts
Sounds like spark plug blow out!!! I have similar mods and gap plugs at 29
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10.2 AFR @ WOT is definitely way too rich. This could cause the hesitation and power loss you are feeling. You need to have the truck tuned on the dyno ASAP. Don't go WOT until you have it tuned. A good conservative AFR @ WOT should be around 11.2-11.70 . Over 12.0 on a stock block with boost is asking for trouble. Also keep the timing conservative, as detonation will kill the rods VERY quickly. I'm not sure if your block is built yet, but you should keep the HP around 400-450 WHP if the engine is stock. Some stock engines will handle closer to 500whp, but you are rolling the dice. Good luck.
Totally understand. I'm aiming for 11.5 give or take a little. My engine is fully built too. Manley components, JLP stage 3 heads, cams, kenne bell 2.3 currently on 10psi. But as I said, it was tunned on 14 psi and I'm pretty sure the pulley was change to lower boost but still on the 14psi tune. Hence the flooding at WOT and low a/f ratio. Plugs are going to get installed today soon as i get off work! Gasped at .032 this time and new coils as well. Dyno day is tomorrow!
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What ended up being the issue?
Bro that was 12 years ago....
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Welcome to 2011.
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I'm asking for myself not asking to help him fix the issue he had 12 yrs ago. Mf its 2001 when im driving this sum bitch around.
The thread is 12 years old. The likelihood of him being around to answer is 0.
Just start a new thread.
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