Wussie 302
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Senior User
Joined: Apr 2003
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From: DeKalb, IL
Wussie 302
On my 88 F150 the 302 seems a little lagging in the power department. The engine runs real well just does not seem to want to go anywhere real quick. The only problem that I have with it is that it does not idle that well very often. There are times when it lopes and when it idles rough. No continous codes from the computer too. I have not had the time to do a KOEO test yet but I was thinking that the MAP sensor could be bad. Whenever I give the truck a little gas she accelerates just fine. When I hammer down on the gas she does not really respond all that well, as in you can tell there is a load on the engine but it does not pull like it should. It is almost like it should accelerate better. My brother has the same truck just two years newer and his pulls a lot better than mine at higher rpm's. Both motors are stock. Any suggestions?
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Joined: Jul 2003
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From: Cincinnati
1. Have you adjusted the TPS to the correct voltage? The throttle position sensor tells the engine how much the throttle is open.
2. I'd also check the timing. Stock timing is set to 10 deg BTDC with SPOUT connector removed.
3. What spark plug gap are you running?
4. It could be your brother's truck is geared differently than yours.
2. I'd also check the timing. Stock timing is set to 10 deg BTDC with SPOUT connector removed.
3. What spark plug gap are you running?
4. It could be your brother's truck is geared differently than yours.
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From: DeKalb, IL
Well as for the gearing difference they both have a 3.55 rear end ratio. He actually has taller tires than I do too. On my truck the TPS seems to be fixed. Is there really an adjustment to it? I did replace it a while back when it went out but it seemed as though it stayed in a fixed postion. I may check that out too. The timing is actually set a little high. I have it at about 12 BTDC right now. It will not run with anything unless I have it advanced a little. The spark plug gap is the stock gap, not sure what that is off the top of my head right now. This is why I started thinking that it could be the MAP sensor. I am still going to check that out but I thought that I would see what you all in here had to say. Anything else that you can think of?
More Turbo
Joined: Jun 2004
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From: Sweden
My '87 302 was seriously lagging in the power department, turned out to be the timing chain.
Also the vac system had some leaks- those plastic straws they used were all cracked up from the heat where they passed over the exhaust manifold.
Also the vac system had some leaks- those plastic straws they used were all cracked up from the heat where they passed over the exhaust manifold.
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From: DeKalb, IL
You know, I did have a crack somewhere in the line that feeds vacuum to the EGR valve. I may check the others too. I will say that I have removed the air pump and blocked off the heads while keeping the solenoids there and plugged in. I have also capped off the ends where there would have been check valves. But speaking of the timing chain thing, I decided to check that, well sort of. I did the check in the Haynes manual that says to check it by when the rotor starts to move after rotating the crank counterclockwise from TDC. I believe that I found it to be at about 7 degrees or so. According to the manual it says that anything over 5 degrees is probably stretched and should be replaced. Does anyone else think that this is a decent way to check for slack in the chain without removing the cover? I do notice a rough idle sometimes as well as a wandering idle as well. No computer codes either. What do you all think?
P.S. -- The TPS voltage when closed is a little low too, about .95 volts or so. I am going to change it to 1 volt as soon as it warms up a little here.
P.S. -- The TPS voltage when closed is a little low too, about .95 volts or so. I am going to change it to 1 volt as soon as it warms up a little here.
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Joined: Oct 2002
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From: Grande Prairie, AB
Hey that truck might have a fuel pump problem running out on you. See the truck will run on low psi ratings, but when it really acts up thats where you get the surge and fumbling idle. Check the psi at idle should be 35-45, somewhere in that range. If its a two tank system try the other tank
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From: DeKalb, IL
It does it at random, somewhat. The fuel pressure is good. I checked it a about a month ago. I have installed a new inline high pressure pump a couple of months ago and it does not matter what tank that I have selected. The tank selector valve has also been replaced. I am beginning to think that it may be a computer problem as well as the timing chain being a little on the loose side. I think that I read a TSB on it somewhere. I may try to find that again and post it. What do you think about what I had mentioned in my previous post? Any other ideas?
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From: DeKalb, IL
Well I got around to adjusting the TPS and that did seem to help a little. But there is still some lacking in power. Anyone got any ideas?
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Senior User
Joined: Apr 2003
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From: DeKalb, IL
You know what? I have not checked that yet. I tend to change that way more often than I should though. It is an older truck so I think that I may just change it to be safe. I guess that there could always be a build up of crud and such coming out of those tanks. Thanks for that! Not sure that I would have even thought about that one, an easy one at that. Is there anything else that you could think of? The truck has about 105K on it. It has just been broke in. lol Anything else come to mind? Maybe some mods that would help out? Thanks everyone who has replied to this.
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Joined: Nov 2004
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From: Mount Tremper, New York
sorry...cant think of anything else of the top of my head. i just knew about the filter cause its happened on every ford i every rode in or drove...86 f150, 88f150, 89 f250, 90 f150, and my 91 bronco
More Turbo
Joined: Jun 2004
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From: Sweden
The steel "coffee can" vac reservoir, should be behind the battery, will be rusted out by now which of course kills your vac too.
I don't see a lot of ambiguity here based on my experience with my '87 302. The loose chain not only messes with the ignition timing but the valve timing too, and since it's "loose", at lower rpm it will shake back and forth rather than be a fixed lag and it has a rough, lopping idle. There will be no error codes.
Now there is a 2:1 ration between the crank and the cam. When you say "about 7 deg", is that saying you can rock the crank +/-3.5 deg without turning the rotor, or more like the rotor has 7 deg of slack in its rotations?
I know it's a rough job, but it'll run like new. A slipping timing chain when you're away from home sucks big time- trust me on this one. You wanna go ahead a replace the water pump, thermostat, and coolant hoses at the same time if needed.
I don't see a lot of ambiguity here based on my experience with my '87 302. The loose chain not only messes with the ignition timing but the valve timing too, and since it's "loose", at lower rpm it will shake back and forth rather than be a fixed lag and it has a rough, lopping idle. There will be no error codes.
Now there is a 2:1 ration between the crank and the cam. When you say "about 7 deg", is that saying you can rock the crank +/-3.5 deg without turning the rotor, or more like the rotor has 7 deg of slack in its rotations?
I know it's a rough job, but it'll run like new. A slipping timing chain when you're away from home sucks big time- trust me on this one. You wanna go ahead a replace the water pump, thermostat, and coolant hoses at the same time if needed.