2002 Express 3500 5.7L engine bogs down / low power
October 7th, 2017, 3:21 PM
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2002 Express 3500 5.7L engine bogs down / low power
2002 Express 3500 5.7L
Under light throttle, you can rev the engine. under heavy throttle, it bogs down. Behaves like a clogged catalyst. The problem came on suddenly about a week ago. My friend was driving home from church and almost like a switch was flipped, she can't exceed 45MPH.
However, I've removed the exhaust completely and run open header, and it still does it. Even in Park and Neutral with no load. When driving it, the load makes the issue much more pronounced.
Fuel pressure measures about 55psi running, and spikes to close to 60 on throttle snap. After engine shutdown, the fuel pressure decays slowly over about 10-15 minutes, so I don't think its an FPR issue.
Cleaned MAF.
I took off the distributor cap, and it looks a bit old but should be enough to run. Haven't checked plugs yet, but I doubt they would cause this issue.
When the engine is cold, its very hard to start, or even requires ether in the intake to get it to start. Once running and warmed up, it seems to start ok but with a little difficulty.
I'm leaning toward a fuel pressure issue, but I don't want to just fire the parts cannon at the problem.
What other diagnostic steps should I take? I've already wasted a couple hours getting the exhaust off this thing, only to find that the cats are fine and it still misbehaves.
Under light throttle, you can rev the engine. under heavy throttle, it bogs down. Behaves like a clogged catalyst. The problem came on suddenly about a week ago. My friend was driving home from church and almost like a switch was flipped, she can't exceed 45MPH.
However, I've removed the exhaust completely and run open header, and it still does it. Even in Park and Neutral with no load. When driving it, the load makes the issue much more pronounced.
Fuel pressure measures about 55psi running, and spikes to close to 60 on throttle snap. After engine shutdown, the fuel pressure decays slowly over about 10-15 minutes, so I don't think its an FPR issue.
Cleaned MAF.
I took off the distributor cap, and it looks a bit old but should be enough to run. Haven't checked plugs yet, but I doubt they would cause this issue.
When the engine is cold, its very hard to start, or even requires ether in the intake to get it to start. Once running and warmed up, it seems to start ok but with a little difficulty.
I'm leaning toward a fuel pressure issue, but I don't want to just fire the parts cannon at the problem.
What other diagnostic steps should I take? I've already wasted a couple hours getting the exhaust off this thing, only to find that the cats are fine and it still misbehaves.
