tscholz2001

I have a 95 F-150 302 with 105k miles on it. Lately every time I start the truck when its warm, it isn't smooth at all, almost like its not getting enough fuel but once it starts, its all good. When starting cold its still a little rough but starts up much better. The rough idle cant be seen in the needle but can be felt in the truck. When cold, the idle tends to move around a bit, slowly, which I think is normal but I'm not sure. No codes are thrown when I try to pull them (both KOEO and KOER). During the KOER test, there was a lot of spark knocking during the WOT test even though timing was adjusted. No check engine light. Also, between 30-40ish mph, in the gear right before the trans (4R70W) shifts into overdrive, there is an intermittent shudder, only when under load. This is when the shudder is most noticeable, however I think there is a very slight miss when under load at low rpm. I've also had some pinging and adding a higher octane fuel fixes this, but I've adjusted the timing to try and get rid of the ping; truck only pings slightly when accelerating from stop occasionally ( even though timing is retarded to about 8). Gas mileage is fine (14-16mpg). Here is all I've replaced already. I don't want to continue to throw money at the truck, just want to get her running right again with the right parts.

• O2 Sensor
• Distributor, wires, plugs, ignition coil
• Checked timing, all is good
• Sparkplugs were done at 90k, have 105k now, pretty sure copper plugs were used.
• Checked for vacuum leaks with smoke machine, none present
• Checked TPS, working properly.
• MAF is working properly
• Air Intake Temp Sensor is working properly
• Cleaned throttle body
• Ran seafoam through both tanks

I am stumped at this point and can't figure out what is causing the rough startup and slightly rough idle along with the shudder under load. Any help would be appreciated.

Doug Raney

Did you ever get these issues resolved? I have a similar shudder under a slight load.

raski

Verify you have proper fuel pressure.You may be experiencing a lean miss. Have you replaced the fuel filter recently? Also, with the spout disconnected, adjust the timing at whatever is stated on the engine decal. Do not fudge with it. Make sure your EGR valve is functioning properly as this can lean out the mixture and cause shuddering and pinging. Check the plugs and regap if necessary.

mallet135

Have you figured out the problem was? I have a 1994 that’s presenting the same issues you’re describing. They’ve replaced just about everything but the Cam Shaft sensor. If you have it fixed, I’d love to hear what fixed it. Thank you.

mallet135

Have you figured out what the problem was? I have a 1994 F150 with a 5.0 and it’s exhibiting the same issues. I’ve changed just about everything but the CamShaft sensor. If you have it fixed, I’d love to hear what fixed it. Thank you.

Fixitagain

Test your Fuel pressure regulator, mine was bad on my truck causing a lean code and random misfires. Remove the vacuum line and cap it off and your fuel pressure should shoot up. If it doesn’t it’s bad

Fixitagain

Verify your engine coolant temp sensor is working correctly, not the one that shows your gauge in the dash but the one that tells the computer if the engine is hot or cold, your engine may be running in open loop if your ECT isn’t working right which could explain the hard starting when it’s hot. You need a scan tool that will show coolant temp data. Verify the temp it shows when the engine is cold and warmed up