P-man07

My 96 150 is running kind of rough when I start it after sitting overnight. Once it warms up and I drive it a bit the problems go away, what could be the cause? I'm just hoping it's not the fuel pump. Ideas?

fltdriver

I can rule out the fuel pump for you as the problem wouldn't disappear when it warms up.

Step 1: pull your codes, if you don't have a reader go to auto parts store and they should pull them for free. Make sure they do both KOEO and KOER tests.

Step 2: post your codes. until you complete these we will just be throwing guesses at you.


It sounds to me as though your throttle body and idle air control valve could use a good cleaning.

Depending on how cold it's getting in your neck of the woods oil weight could be an issue.

P-man07

My check engine light was already on for the p0401 code (insufficient egr flow) it's been on for a few months but i haven't noticed any problems happening so I hadn't done anything about it, so I don't know if it's throwing other codes. It's also weird cuz it happened after the weather shot up literally 40 degrees, from 10 to 50. I had cleaned the throttle body in February when I got the truck, but I'll check that out and see if it needs cleaning again. Thanks for the response!

fltdriver

It's more of an IAC thing, just doesn't hurt to clean the TB as long as you are taking stuff off of it. Vacuum lines can also cause rough idles and other running issues, I suggest getting a vac gauge (I got a mighty vac off amazon for $40, use it often, brakes, vac testing, changing other fluids when I don't want to make a mess-crazy handy) and testing them out if not straight out replacing them. Silicone Intakes has super nice thick walled silicone vac/booster lines that will outlast your truck, engine dress up kit + 10-12ft of 4mm will do everything under the hood, 22ft 4mm will do all of you small vac lines that are currently plastic.

P-man07

Just got back from checking my check engine light, and you're right I'm almost positive I have a vacuum leak. 4 codes came up, 2 for cylinder misfires (p0301 and p0307), 1 for Dpfe circuit low voltage (p1400) and 1 for a fault in the secondary air injection system (p0411). All of these problems seem to be likely caused by a vacuum leak, not only this but I've had bad fuel mileage and power in my truck, so I'm thinking it's a vacuum leak.

mattbarron94

Replace your IAC, I did and it did wonders. I also clean my throttle body every oil change, it's easy and helps a lot especially if you live in a dry dusty area like me.

fltdriver

I would mist your wires at night with water and see if you get any sparks, sounds as if your wires are arcing on the dist cap where #1 and #7 pass each other, if you see sparks you can try coating them with dielectric grease or just replace them.

1400:
Vac leak
corrosion on connector

411:
Damaged or missing check valve
AIR pump intake port plugged/damaged
AIR pump clutch malfunction
Holes or damage to exhaust components

P-man07

So you don't think it's a vacuum leak? I've looked around and basically all of these codes seem to be able to stem from a vacuum leak. I don't really wanna start throwing parts at each code if all of the codes are from the same problem, especially since the only thing I notice from all of this is that rough idle.

Chris_1

iTrader: (1)

Test your vacuum with a gauge. Or disconnect things at the tee on the upper intake,plug it off and see if it makes a difference to the rough idle.

fltdriver

I'm not saying throw parts at it, plug wires - test with misted water for crossfire, for the p1400 vac test and look at connectors and wiring (including body grounds) for corrosion or damage, p0411 you will have to check the AIR hoses and check valve for leaks/functioning.

You have to eliminate working parts from the suspect list in order to track down a lot of issues in these trucks. Includes cleaning connectors/grounds, checking for proper voltage, vac testing hoses/components. If you had a vac gauge even vac testing the engine while running can tell you if like 7-8 things are functioning properly. Some times people see a code for something and immediately replace the part the code points to, this sometimes works, but often the part wasn't the issue, it was functioning properly but wasn't getting proper voltage/vacuum/ground/etc...