Rough starts...?

[Skunksmash]

On my '87 5.7L 2wd auto, (TBi) the engine seems to run very rough on startup. It feels as if there is just a very bad misfire. But once it gets warmed up, ir runs great. No misfire feeling of any kind. Feels solid and smooth. The trucks odometer says 45k, but as we all know that could be 145k, or 245k. Point is i realize the motor is likely pretty old and it is going to be like that, as that is just something old engines will do. Heck new engines will do it so some small extent. But i would like to find the root of the problem and try to weed it out if i could. What do yall think could be done? I have heard that installing a self heating oxygen sensor can help, but i have only heard of this once and have no one else's opinion to go on. Thoughts? Ideas? Opinions?

[Irish_Alley]

When you say at start up do you mean just on a cold start up or a warm start up?

[Irish_Alley]

it might be the coolant temp sensor. To test the coolant sensor, unplug the wire connector and test the resistance across the two terminals of the SENSOR with an ohm meter.

The sensor screws into the intake manifold, on the front passenger side, by the thermostat housing.

Coolant sensor approximate resistance specifications:
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.

[Skunksmash]

Yeah sorry i meant cold starts only. If i do a warm start it runs fine. So i guess you could call it cold blooded. Anyway that is a good idea, i will try that. However, There would seem to be 2 of these little sensors on my truck. One is in the intake as you said, but there is another one in the cylinder head. Well, it looks like there are two lol. Im not really sure what that other one is, but i took it out and it looks just like the other one.

[Irish_Alley]

the one in the head is for the dash the one in the intake is for the ecm

[Skunksmash]

Well i went ahead and checked it out and they did seem to be a little off. So i went ahead and replaced them both. Not a big deal they were not that expensive. But it did not really do a whole lot to fix the problem. Any other ideas on how i could get rid of my rough cold starts?

[VileZambonie]

Unplug the vacuum hose from the egr valve to verify it's not being opened. Check for vacuum leaks at the base of the tbi unit. Check your map sensor voltage at idle.

[Skunksmash]

Well, the EGR valve's vacuum hose has to stay off, cause when it is on the truck runs real rough all the time. I am guessing i need to get a new EGR valve? I dont think you can simply clean the old one. They are like a hundred bucks that is why i have been putting it off.

[Irish_Alley]

when you took off the hose you did plug it right. how long b4 the rough idle and you taking the hose off

[VileZambonie]

That means your egr solenoid is stuck open. You need an EGR solenoid not an EGR valve. You may want to take the valve off and clean it.

[Russ130]

I agree with Vile it is not the EGR but the EGR solenoid. As far as the rough start I think you will be looking more towards a fuel issue than EGR. Pump, filter or ECM could be at fault with the pump being most suspected.

[Skunksmash]

Yeah after i posted that i was thinking, if it runs smoother after unplugging the vacuum line to the EGR valve, it cant be the valve it has to be something before it. Cause it is sucking through the valve, and if i plugged it back in, i would be plugging it into something that it could not suck through. I think...

Anyway the fuel filter is new, i did a full and complete tune up when i bought the truck. As for the ECM... do you mean the vehicle's main computer? On my stang it was a separate little chip under the air cleaner. Also maybe installing a fuel pressure regulator might help? Anyway here is a link to the two that Orielly's sells... which one is it? I hope its the cheaper one. It asked if it was a K engine code, but im afraid i dont know how to find that out.

http://www.oreillyauto.com/EW3/DisplayTheParts.do?categoryIndex=0&didSearchFor=Egr%20Solenoid

[Russ130]

Yeah by ECM I do mean main computer (Electronic Control Module) or at least the eprom.  This not like the TPI or MPI where the pressures are much higher. The pressure on this system is somewhere around 9 psi. The first question to ask really is what code if any are you receiving? If I remember correctly the eprom has nothing to do with the fuel system. If it turns out to be the ECM, eprom or cal-pack I have one you can have. I could even send you a fuel pump that ran great as of last week but in reality dropping the tank or removing the bed is enough work that a new pump would be a better bet. The module on the ford is for ignition only.

[Skunksmash]

Yeah i was thinking ICM, or ignition control module. They sold a special tool to get it out. 

[Russ130]

Yep or grind down the sides of a socket Incidently I also have the EGR solenoid that was also working great and if you want it you can have it.