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Discussion Starter #1
I have two issues

This weekend I fired up the rebuilt 351W in my 89, the engine didnt have a timing marker so I took one of the 1987 302. The 302 marker should be the same as the 351?
It likes to run better at 20-25 degrees rather then 10, at 10 it idles worse.

At 30 BDTC it idles even better by ear, with the Spout removed, however it pings at this setting under load.

At 20 and 10 degrees in drive, stopped the engine will idle at around 900 then drop to around 700. It will idle for about 20 seconds relatively smooth, and the the rpms will fluctuate by about 300 RPMs. Recently it has this has led to the engine shutting off, to reduce the fluctuations putting it in nuetral will cause the flucuations to be smaller at about 100 RPMs.

2.

When the truck is lightly accelerating, the RPM reaches 1300 and it will begin to stumble/lag. Minor advances in throttle do not increase engine RPM at all until enough throttle is applied that it overcomes whatever is causing it to stumble, at which point the RPM jumps up about 500 RPM and it accellerates smoothly, it just recently started doing this around 2000 RPMs as well.

With the help of Will, K4amu, (hes been helping alot) we pulled the codes and just got a 33, something to do with the EGR.

The EGR where it meets the upper intake is cracked by the one bolt that secures the EGR to the upper. Shouldn't be a huge factor at this point?

At first we thoguht it was timing, but ruled this out since syptoms occur at 10 and 20.

We also thought it was old gas since it has been sitting in the tank since the summer. I just ran out that tank and put some fresh gas in with the same symptoms occuring.
Everything should be plumped correctly as before the engine was pulled (stock), a little backround, the reason for the rebuild was 2 bent rods from sinking it in a water crossing. Also the rebuild was to stock .30 over.
Suggestions?? Thanks
 

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To tune the timing on my '86 351 I used a vacume guage. Make sure vacume advance is hooked up correctly and then hook the vacume guage up to the manifold vacume and turn distibutor untill the guage reads between 19 to 21 in. of vacume. If it pings, drop it back a little at a time untill it stops, and that is it. I have found this to be a much better way then any timing light. It also makes a great way to check idle mixtures with a carb set up.
 

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<<<<When the truck is lightly accelerating, the RPM reaches 1300 and it will begin to stumble/lag. Minor advances in throttle do not increase engine RPM at all until enough throttle is applied that it overcomes whatever is causing it to stumble, at which point the RPM jumps up about 500 RPM and it accellerates smoothly, it just recently started doing this around 2000 RPMs as well.>>>>


I have been fighting a problem very similiar to this with my truck. Would run fine up to about 2000 then start stumbling and missing. Everyone told me several things to try, the most prevalent being a vacuum leak. However I had none of those issues. Mine was the distributer. Did you replace the distributer? If not you might want to check the sensor inside the base of it. Mine was burnt. I cleaned it up with emery paper and the truck runs like a top now!!

Just a thought...
 

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[QUOTE='86junker]To tune the timing on my '86 351 I used a vacume guage. Make sure vacume advance is hooked up correctly and then hook the vacume guage up to the manifold vacume and turn distibutor untill the guage reads between 19 to 21 in. of vacume. If it pings, drop it back a little at a time untill it stops, and that is it. I have found this to be a much better way then any timing light. It also makes a great way to check idle mixtures with a carb set up.[/QUOTE]

Its a 1989 motor, fuel injected. MAP sensor sends vacuum readings to the EEC which then makes calculations with it. You're 86 is carbed.

Edit: I'm not too sure bad gas can be ruled out. 5 gallons of bad gas with 25 gallons of good gas is still bad. I want to check fuel pressure but I doubt thats the problem since it does it in a no load situation at idle.

Why is the timing so f'd up!?

-Will
 

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when you set timing did you have the spout connector removed?
 

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Discussion Starter #8
Gacknar said:
Is this a 302 to 351w swap?
nope its the same engine, just rebuilt by the builder back to a long block


and spout connector was removed when timing was set

it has started to backfire occasional accel from a start, since I set the timing back to 10, Im going to bring it back to 20 tonight
 

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Discussion Starter #11
gack i went to the shop and picked up the engine as a longblock i dont know whats on the other side of the timing cover, or internally

and there is a crack in the egr tube from the exh mani to the upper, didnt think would cause these problems?
 

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That EGR crack is not a complete crack yet, keep in mind, I doubt it would affect it this much.

The engine was primed as much as Kris could until his drill smoked/melted, was destroyed.
I told him to buy the biggest drill Home Depot had but NOOOOOO...

Anyway, oil pressure was good from the get-go, I dont think there would be any problems with the cam lobes.

I'm almost at a loss for things to check. Codes return KOEO 11, 33 in CM.

TPS is fine per Kris, he said he'll clean the IAC tomorrow.

He said it feels like 4 cylinders randomly shutting off. I doubt the truck would run as well as it does when encountering this problem if it only had 4 cylinders.

-Will
89 XLT 460
 

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firing order correct? CCW and 351 order...did it get a cam put in it???what FO is the cam... Call the engine builder...ask about the timing marks on the gears..did you break the cam in w/ a 30 min 2500rpm run time?


dc
 

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The Anti Yam!
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You guys test the TPS yet?

FordFuelInjection.com said:
Throttle Position Sensor (TPS) Self explanatory, it measures how far you push the skinny pedal. This tells the computer how aggressively we want to drive, the computer is programmed to enrich fuel mixtures the further the throttle is opened. Just like an accelerator pump in a carburetor. Programming also alters the timing more aggressively to match. This sensor is very important in clueing the computer to future events, as it responds quicker to driver changes than any other sensor.
http://fordfuelinjection.com/index.php?p=30
 

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When it's stumbling at idle, try spraying some carb cleaner at that EGR crack. If the revs go up or smooth out, that's a vacuum leak, and should be fixed.

My ranger used to stumble at idle, it was an intake manifold leak at the back of the block.
 

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Discussion Starter #16
DcSkater602 said:
firing order correct? CCW and 351 order...did it get a cam put in it???what FO is the cam... Call the engine builder...ask about the timing marks on the gears..did you break the cam in w/ a 30 min 2500rpm run time?


dc
firing order should be correct I double checked per the haynes twice, stock cam. broke in the engine 15 min at 2500 rPM, changed oil

TPS i checked last night, checked good, im thinking about picking one up so i can definalty elimnate that as a possibility
(while driving it last night I remember the idle variations before I sunk the engine it just wasnt as bad or as often so IAC or TPS I'm thinking)

ill give the carb cleaner a whirl
 

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Discussion Starter #18
I replaced the TPS sensor even though the old one checked out ok... just to be sure
Also I used the IAC off the 302 I have sitting around because it looked cleaner, the 351 IAC is soaking right now....
Results were.......drum roll please.....

nothing, well it idles alittle nicer, but the same syptoms occur

I also set my timing to 12.

Im thinking vacuum leak, last night when i was at a stop light, it was doing the rpm flucuations and during the very large changes I heard what sounded like a vacuum guage so I guess ill try to get a guage
 

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The Anti Yam!
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kaudbron said:
Results were.......drum roll please.....nothing
I hate it when that happens. :cry

kaudbron said:
Im thinking vacuum leak,
Verry likely
 
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