240SX no power at WOT above 4000 RP
filed in 1995 Ford F150
Question: Are you saying that the car won’t rev above 4000 RPM now, or it still revs to 6000 RPM but with no additional power?
At first glance, the former scenario seems to be a fuel delivery problem (eg fuel filter, fuel pump, pressure regulator), while the later could be the loss of the kickdown gear in an automatic transmission.
Can you provide some additional details?
Answer: Would anybody know why I no longer get any power from about 4000 RPM at Wide Open Throttle? I would say this started sometime after 60,000 miles. I used to get great performance at WOT all the way up to the red line! I’ve checked quite a few things and am starting to wonder if something other than the Electronic controls might be to blame; e.g.: timing belt guide, which is supposedly prone to abnormal wearIs the engine stuttering, or does it just seem sluggish?
If it is sluggish, then you may have an intake/exhaust restriction. Check your exhaust system for pinches, crimps, etc. If it shows no problems, disconnect your cat (temporarily!) and see if that makes a difference.
If it stutters at WOT, you may have an ignition problem. Check your plugs, replace and/or gap as necessary. Also check your ignition leads (plug wires).
I would check the exhaust system, specifically the cat’s. I had the same problem with my mustang. Turns out the cat’s had blown out and clogged both themselves and the mufflers. Dealer looked at it, found a recall had been issued, and replaced the cat assembly.
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