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Discussion Starter #1 (Edited)
I just did a gasket(oil pan up, minus timing chain) overhaul on my 351 but now it ''surges'' at idle and or in gear. By surging I mean. goes from 8-1000rpm to 4-500rmp,up and down numerous times.

No CEL but I pulled codes and got a 334,(but by searching I dont see how there related. Where do I start testing???

Doing the overhaul I installed rebuilt heads, a new fuel pressure reg,freshen up the injectors, new plugs and wires,new vac resivoir(coffee can),thermostat,water pump, torque converter and did the 3g swap. If any of this matters. ;)
 

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Satyr of the Midwest
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If you cleaned the IAC, that's probably why you have the rolling idle.

The 334 could easily be related. Are you SURE you have the vacuum lines properly connected, especially to the EVR and EGR valve?
 

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Discussion Starter #3
If you cleaned the IAC, that's probably why you have the rolling idle.
I didnt mess with the IAC besides unplugging it. When it is unhooked,the motor stalls

The 334 could easily be related. Are you SURE you have the vacuum lines properly connected, especially to the EVR and EGR valve?
Yes,its a green vac line.
 

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Crusher Mike
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I just had the same problem it turned out to be the FPR but it looks like you changed that out on your truck. try cleaning the IAC I used carb cleaner on mine until it ran clear.
 

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BKO's: there is kinda a joke when asked: does the back window work and does it idle? We all are in the same boat. I can only tell you what I did to solve my surging idle. I got my Volt-Ohm meter ($2.99) and started to read all voltages and ohm ratings of sensors; I stripped insulation off wires and re-taped. Some guys use a needle or pin to stick in the wire, I didn't have luck with that. Turns out I had a bad Oxygen sensor. Got another one from K....n, turns out it was bad out of the box. I was going nuts; ever had that feeling of being a a world of S**T? Checked warm and cool for the ohm reading. Took it back and They gave me a new one. Now, the engine starts, idles, doesn't surge or give me the rich condition I had. It can be anything or a combination of bad things. Good luck.
 

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Discussion Starter #8
Yes I took off the IAC and it wasnt dirty on the inside,but I still tried to clean it and the truck still runs the same.
 

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Discussion Starter #9
BKO's: there is kinda a joke when asked: does the back window work and does it idle? We all are in the same boat. I can only tell you what I did to solve my surging idle. I got my Volt-Ohm meter ($2.99) and started to read all voltages and ohm ratings of sensors; I stripped insulation off wires and re-taped. Some guys use a needle or pin to stick in the wire, I didn't have luck with that. Turns out I had a bad Oxygen sensor. Got another one from K....n, turns out it was bad out of the box. I was going nuts; ever had that feeling of being a a world of S**T? Checked warm and cool for the ohm reading. Took it back and They gave me a new one. Now, the engine starts, idles, doesn't surge or give me the rich condition I had. It can be anything or a combination of bad things. Good luck.
Thanks for the tip,I seem to be running rich also.
 

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Throttle position sensor?
 

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Was it running ok last time you tested it?
 

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Discussion Starter #13
No,I tested it before because I had a high idle problem.

Some more problems I noticed about the truck is it seems to have a abnormal amount of liquid coming out the tailpipe, It does not want to start up right away, and it surges while driving also.
 

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Satyr of the Midwest
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Sounds like it's got PMS or something.... :rofl:

Check your fuel pressure? Make certain there's good vacuum at the regulator's vacuum port?
 

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Discussion Starter #15
Ok after some driving today the CEL came on,pulled codes and the only new one is 173 along with the 334.

Bad o2 sensor?
 

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Satyr of the Midwest
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They usually don't fail putting out a high signal, which is what that would indicate (lack of switching, stuck high, etc.). You're probably running rich.
 

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Discussion Starter #17
What would make me run rich,fuel press regulator,fuel pump?

I have a new FPR on(i hope its good) so the last thing to check is the fuel pump?
 

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you need to check your fuel pressure. ECT sensor could make it run rich, bad FPR, ACT, stuck injectors, bad oxygen sensor could also do it. You're getting a code pointing you to the oxygen sensor. I'd replace that.
 

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Discussion Starter #19
Yea,that's what im prolly what im gonna do seeing that its a maintenance part anyway. If I still have the problem, I have to start testing those parts.
 
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