Missfire when crusing about 45 to 65 mph, runs fine when under heavy acceleration

Surges under load but only while going uphill Page1 - Chevy High ...

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Mar 6, 2011 - 14 posts - ‎8 authors
Trying to help out a friend. ... The truck starts, runs, and drives fine until you get to a hill. When going up hill it begins to surge, almost stalling but not quite. ... rubber fuel lines suck shut under a heavy load and act like that. .... tranny fluid level o.k.? ya got me stumped. runs great when it's on a flat surface?

Ford 460 engine - RV mechanic

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Will not take gas going up a hill but will maintain speed at 55 mph. ... Want to do a diagnostic test on my 1997 F250 with 460 engine. ... only get to about 40 miles an hour if i push it the engine acts like its running out of gas,thank you .... The truck hesitates on acceleration, while driving on flat surface is fine, however climbing ...

rough idle, stalling, loss of power. - CarGurus

Engine is under max load in the situations you describe, so any weakness in spark or low fuel prssure can cause this, even a weak ignition module.

have vehicle scanned most auto stores offer this service for free the code will assist in repairing your problem

This would likely be spark plug wires breading down under the increased cylinder pressure of a heavy load like acceleration or pulling a hill.

escape 2001 runs rough, but after a certain speed ( 50 mph ) runs smooth.

Hello! You have symptoms that point to incorrect fuel pressure.
First have the fuel pressure tested as follows; #1...engine running at idle: 13- 20 psi. #2...key on engine off: 23-30 psi. If pressure is incorrect change the fuel pump.

Does the engine "surge" at idle? If so, check the "fuel injection pressure regulator idle air control valve". Apply a vacuum to it; If fuel flows it is not the problem.


Guru.............saailer




I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Hello,
It sounds like you have an engine missfire. Possibly a plug or wire.
I hope this helps.
Roy

Does this car have its original ECU? I ask this because this and a number of early 1990s Mitsubishi cars/truckas had isses with capaciors leaking. In truth I believe it is a matter of when and not if. As the ECU begins to fail the engine can begin to run poorly ( I speak from experience after changing both ECUs in my Montero and my son's Doge Stealth (3000GT) ) I did have an issue too with my son's Stealth running poorly, by good luck I happened to be looking under the hood with poor lighting and noticed a faint blue spark from the wiring leads by the coil after a good look I fould a wire would ground out when the engine was throttled; this caused the engine to torque slightly causing the wire to rub and finally ground out.
I hope this may have helped,
Tom

Had a similar problem before. Change the feul filter. This often fails due to sand in gas and limits gas being pumped into your turbo. If you change this and the cars runs fine, eventually you will have to change the feul pump. Do the feul filter first. It's cheap and easy.

First You Need To Make Sure You Don't Have A Cracked Distributor Cap Causing A Missfire Remove Plug Wire One At A Time From Cap Until You Find The One That Doesn't Make A Difference. IF The Plug Is Firing, The Engine Should Drop In RPM. If All Checks Out Ok, Starting Checking Other Abvious. Things...Like Fuel Preasure. Those Style Vortech Motors Have Trouble With Intake Gaskets Blowing Out And Leaking Water, Sometimes Into The Crankcase. Just Do A Good Visual Of Everything, And Just Think....What Makes An Engine Run?.......INTAKE-COMPRESSION-POWER-EXHAUST- Good Luck