Hesitation While Accelerating
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From: Hutto, Tx
Hesitation While Accelerating
I have a 1994 F350 dually with a 351W. It is hesitating, chugging, or missing inbetween surges....... not a smoothness while going through the gears.
Going up hill and barely accelerating it feels like a mis fire.
When the truck is in park it will rev up like normal. I am seeing small puffs of dark smoke out of the exhaust.
I have replaced the following parts:
IAC, TFI, Coil, and TPS
I read the codes and it is passing the code checker tests
I am going to place a spark checker on the coil and the dizzy now.
Going up hill and barely accelerating it feels like a mis fire.
When the truck is in park it will rev up like normal. I am seeing small puffs of dark smoke out of the exhaust.
I have replaced the following parts:
IAC, TFI, Coil, and TPS
I read the codes and it is passing the code checker tests
I am going to place a spark checker on the coil and the dizzy now.
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From: Ottawa, Ontario
Test the plug wires they should all have about 5000ohms resistance per foot. Considering the mods you have done I wouldn't be surprised if it's running extremely lean, may be a good idea to get a wideband O2 for it to see if it is, and if so you may be able to get a more favorable mixture under load with an adjustable fuel pressure regulator.
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From: Hutto, Tx
I put the inline spark checker on each plug wire. I put them on at the plug itself. Every wire is lighting very bright. I checked the wires for cracks and or burns. None found. These are the Belden wires and they are pretty new maybe 10,000 miles on them and the plugs.
After all the mods were done the truck did not have this problem. Why would it start having lean problems now? Would a questionable fuel mixed with my mods cause this issue?
I still have not converted over to MAF (even though I have a MAF system to pull off of a 94 f150). I now I need to do it, but replacing the entire wiring harness sounds very time consuming.
After all the mods were done the truck did not have this problem. Why would it start having lean problems now? Would a questionable fuel mixed with my mods cause this issue?
I still have not converted over to MAF (even though I have a MAF system to pull off of a 94 f150). I now I need to do it, but replacing the entire wiring harness sounds very time consuming.
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From: Hutto, Tx
Changed out the fuel filter. Seemed better for a short run but the chuggin came back. It doesnt seem as bad. Actually WOT it was kinda gone (seemed like it). Half throttle or .75 throttle it was still present. Like I said it feels a little better, but the problem is still there.
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From: Hutto, Tx
I swapped out the fuel regulator with my 94 f150 (302). Cleaned the battery terminals (because the battery light is now on!).
The thermatic air system is not that setup anymore. I have the smog pump hooked up, but it only runs air into 1 side of the engine. It is screwed into the back of the engine (drivers side head). I actually seperated the hose and plugged it for now. Think it would run better if I put it back together?
Oh yeah the fuel regulator didnt really make a difference. It does seem better on the 1/4, 1/2, and 3/4 throttle positions. Now the idle is bad again. Back and Forth.
The thermatic air system is not that setup anymore. I have the smog pump hooked up, but it only runs air into 1 side of the engine. It is screwed into the back of the engine (drivers side head). I actually seperated the hose and plugged it for now. Think it would run better if I put it back together?
Oh yeah the fuel regulator didnt really make a difference. It does seem better on the 1/4, 1/2, and 3/4 throttle positions. Now the idle is bad again. Back and Forth.
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From: Ottawa, Ontario
You don't have the air pump connected directly to the back of the head do you?
That system needs to be 100% original and fully functional or 100% removed because it is connected to the exhaust system upstream of the O2 sensor and any fresh air getting in there when it's not supposed to(which is most of the time) will mess up the A/F ratios. If you don't have a cat anymore take it all off and plug the holes in the heads(5/8 x 1" coarse bolts), the pump can remain as an idler.
That system needs to be 100% original and fully functional or 100% removed because it is connected to the exhaust system upstream of the O2 sensor and any fresh air getting in there when it's not supposed to(which is most of the time) will mess up the A/F ratios. If you don't have a cat anymore take it all off and plug the holes in the heads(5/8 x 1" coarse bolts), the pump can remain as an idler.
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From: Hutto, Tx
I have it going through the stock air regulator system that is next to the coil. Then it goes into the head. I just re-connected the air system. We will see what happens tomorrow. I disconnected it because it was making the exhaust sound terrible.........almost a backfire sometimes. That ended up being a leaking header gasket, but I never reconnected the air system.
I have cats, but they are brand new. I know the thermatic air system makes the cats last longer, so that is why I tried my own system. I had make my own because I put long tube headers on it (no butts to install the exhaust to exhaust air connectors). F350 air systems are exhaust manifold to exhaust manifold instead of head to head.
I have cats, but they are brand new. I know the thermatic air system makes the cats last longer, so that is why I tried my own system. I had make my own because I put long tube headers on it (no butts to install the exhaust to exhaust air connectors). F350 air systems are exhaust manifold to exhaust manifold instead of head to head.
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From: SoCal
If you're dumping air into one of the heads, you could be fooling the EGO sensor and causing that side to run rich. And dumping air in with a rich exhaust can cause back fires, or burn up the catalytic converter.
I once messed up my fuel injectors trying to use a cheap cleaning setup. That led to stumbling and very poor performance. I fixed them by removing and then back-spraying them with fuel injector cleaner. I used a small battery and some jumper leads to activate them so I can shoot the cleaner into the pintles. In my case, it worked, but my original problem remains. Some times it will back fire through the intake when transitioning quickly from on-off-on throttle, like when shifting through gears. But I can live with it for now.
I once messed up my fuel injectors trying to use a cheap cleaning setup. That led to stumbling and very poor performance. I fixed them by removing and then back-spraying them with fuel injector cleaner. I used a small battery and some jumper leads to activate them so I can shoot the cleaner into the pintles. In my case, it worked, but my original problem remains. Some times it will back fire through the intake when transitioning quickly from on-off-on throttle, like when shifting through gears. But I can live with it for now.
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From: Hutto, Tx
The 02 sensor is only on 1 pipe (the h pipe), so I am not sure how it would know which side is leaner.
I reconnected the air system and only had 1 hesitation that was barely noticeable. Seems to be running good again. I will drive it over 100miles today, so we will see how the truck is doing by the end of day.
Mine only was backfiring when I had the air system hooked up and I had a blown out header gasket. Samething when you pop the gas and let off real fast it would back fire. I just never reconnected the air system after I corrected the blown header gasket.
If the mods I have are making it run to lean and the air system makes it think I am running too lean, then perhaps the air system is helping (tricking) the pcm make adjustments to run richer?
I reconnected the air system and only had 1 hesitation that was barely noticeable. Seems to be running good again. I will drive it over 100miles today, so we will see how the truck is doing by the end of day.
Mine only was backfiring when I had the air system hooked up and I had a blown out header gasket. Samething when you pop the gas and let off real fast it would back fire. I just never reconnected the air system after I corrected the blown header gasket.
If the mods I have are making it run to lean and the air system makes it think I am running too lean, then perhaps the air system is helping (tricking) the pcm make adjustments to run richer?
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From: Ottawa, Ontario
When the engine is operating in closed loop.. which is all the time once it reaches operating temp except when accelerating hard, it uses feedback form the O2 sensor to adjust fuel trims and since it has been running well that proves the system has enough adjustment range to adapt to your engine mods. Any fresh air getting into the exhaust upstream of the O2 when the system is in closed loop will make the computer think the engine is running lean and it will add more fuel, and that may result in backfiring on deceleration. This is why it's important that this system be completely sealed to the outside when attached or completely removed and the holes in the exhaust plugged.
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From: Hutto, Tx
On the way home I had 3 full tanks in the bed which contained about 30 gallons diesel. I was also pulling a trailer with a huge bbq pit on it. Underload the symptoms are back. So the problem is still here. So the only fix is to do the MAF conversion? Why does it have a problem now, but it has not had it for the last 1.5 years?
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From: Ottawa, Ontario
How are the plug wires routed? You want to keep those for #5 and $6 seperated as much as possible to prevent induction or arcing because those cylinders follow each other in the firing order.