Sudden loss of power – 96 B2500 RAM Van

[Meridivs]

After borrowing the Van to a friend for a short trip we begun to notice a significant loss of power and performance. Previous performance was satisfactory given the van’s weight/aerodynamics.

Now the van cannot go over 75mph, pedal to the floor. The higher the speed, the less response you can get from acceleration.

Any idea where I should look first to tackle this problem?

Engine is a 3.9L V6 Magnum. It had some problems starting when cold – I had to give it gas to keep it from dying – that were solved after I cleaned-up the IAC and idle air passages. There are no error codes stored in the PCM.

Update: This van has a second LPG fuel system installed along the factory system and the problem is the same on both – we can rule out the fuel pump on this one.

I’ve noticed a batch of misfires when the van starts to stumble and on idle after that. On high-RPS’s it smooths-out so I wonder if the cat is the problem… I never had a cat failure until now but I imagine that high-rpm’s should be a problem with a clogged cat.

I suspect if we don’t have a failure in the ignition system (coil, rotor, cap, or wires). Van shows no error codes yet but something is obviously wrong.

Topic

[college man]

Start with a tune up. Plugs,cap,rotor, wires If it has a fuel filter change it.

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

[Bill]

Since LPG burns much hotter than gasoline I suspect that the catalytic converter is partially plugged. I wouldn’t expect too much more speed outta a 3.9 in a B2500 Van.

[Meridivs]

Solved the problem – we found a scuffed spark plug wire and decided it’s time for a tune-up.

Changed the spark plug wires, plugs, dist. cap and rotor and now the usual performance is back.

We also have a MSD coil on the way since the old coil is the only thing left to change for a complete tune-up. Will let you know if there’s any change after that.

[EricTheCarGuy]

Great news! Thanks for the update. Yes, anytime you have performance issues with no CEL, start with the basics like tune up items. As you can see, you get results.

Thanks for using the ETCG forum.

[Meridivs]

After we changed the dist. cap. rotor, spark plugs & wires with a quality set and thrown in a MSD coil for good measure performance comes and goes, one day it pulls great when you press on the gas pedal, the other it’s sluggish and slow in taking off from a stop.

New development after the tune-up – at first start if you try to take off right away the engine misfires and has no acceleration. After a few minutes it behaves more or less normal.

Airflow and exhaust are good, no fouled plugs, clean tailpipe but performance is like we’re burning hot air instead of gasoline… Any idea on what to try next?

I’m thinking about TPS or Oxygen Sensors but I don’t know if those could cause this kind of issues.
:S

[Author]

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