Poor Performance

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Feb 21, 2001 | 01:32 PM

Hanky

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Poor Performance

My 1989 F150 4x4 4.9 just has no power. With 265ft/lbs at 1800rpm this thing should leap off the line. The only way I can pull a hill is the tranmission downshifts to 3rd. I Ran the codes and found a bad EGR valve and replaced it but it didn't help very much. I disconnected the vacuum line to the fuel pressure regulator and ran it about 40 miles and it made abosolutely no difference connected or not. I cleared the computer codes and ran it again then check codes . The computer thinks every think is just fine. It gave me a 1 1 1 1 1 which says everything passed. Is there something that the computer doen't check which could be causing poor performance.

Feb 21, 2001 | 05:49 PM

brown 4x4

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From: Nebraska

Poor Performance

A plugged catalytic converter can rob these engines of alot of power. Had it happen to both my '86 and my dad's '96.

1986 F-150 4x4 300 I6 NP435

Feb 21, 2001 | 06:04 PM

jw300

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Poor Performance

When I purchased my 96' f150 4.9l I had a similar experience, no power. After reading several posts I went to work on it. I installed 9mm MSG plug wires (double crimped and don't come apart), heavy-duty cap/rotor and then set the timing to 10 degrees. I tried several different plugs, but ended up with the best results using the stock Motorcraft plugs. I installed a gibson cat-back system and a heavy-duty radiator (for towing). I also purchased the K & N high flow filter that has been mentioned in this post, (about $150.00). I actually lost power with the K and N so I took the advice from a Ford mechanic and removed it. I now can say that I absolutely love this truck and have lots of power and good gas mileage. I attribute the lack of power to poor plugs, wires, and timing.

Feb 21, 2001 | 11:53 PM

PAUL_2

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Joined: Jul 1999

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Poor Performance

I dont think you will ever get a 300 to leap off any line , or anything for that matter . Its not a high speed , performance engine . Its designed as a work horse . Differential gearing changes would make the biggest difference as far as how the truck accelerates . If you have 2.73 or 3.08 rear end gears you arent going to see any startling take offs .

Feb 22, 2001 | 09:46 AM

paulg

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Poor Performance

The best you will get out the I6 is lots of miles, some where in the vicinity of 200,000 to 300,000 miles and lots of torque. If you modify it correctly it will love you for it. For the problem at hand I would look into replaceing the catalytic converter. These engines love being able to breath.

Feb 26, 2001 | 04:04 PM

Eddie

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Joined: Nov 1999

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Poor Performance

Here's a simple, cheap one: Clean out the idle air bypass valve body and valve, then pull off the air cleaner tubing, rev the wee out of the thing by hand on the throttle body, and spray a can of sensor safe carb cleaner down past the butterflies.

These dry-flow EFI systems are really susceptable to poor driveability and power output because of gunked up intake passages.

Eddie

Mar 2, 2001 | 01:47 PM

woodbutcher

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Joined: Mar 2001

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From: Temperance USA

Poor Performance

check to see if it has the same problem when it is still cold after startup, if it has better power cold it is probably a sensor problem, because the computer runs on presets and basically ignores most of the sensors. If not, then you need to look at basic tuneup work and plugged or dirty sensors(they see a signal that that looks good to the computer but isn't accurate) I've seen more problems with plugs, wires, and air filters than with the electronics.