Rough Idle After Engine Replaced? No CEL

[mitecl96]

I will sum up this story.

My rebuilt engine blew lest than 5,000, All 4 rod bearing failed from Oil starvation.

Well pulled a junk yard motor with 127,000 miles and new timing belt.

Only thing I used from Junk yard motor was the block and Head. I used my old Valve cover and every sensor besides the oil and knock sensor. I used my old intake, throttle body, and header.

My old motor ran fine, idled perfect. The junk yard motor is idling rough, almost like it has a cam but I know it doesn't car was completely stock. Looked like a stock cam when I pulled the valve cover. I don't have a CEL either. My old motor had a CEL for the rear O2 sensor but it has gone away with the new motor.

I have checked the vacuum line many times and I know it isn't a vacuum leak. I am completely stumped on this idle problem.

Also when I am driving it almost feels like it misses when I am driving every once in a while. Brand new spark plugs by the way. NGK gapped at .035 like my old motor.

 

[1davho]

Is there a chance that your timing belt is one tooth off?

 

[mitecl96]

No I checked the timing before I put the motor in and it was right.

 

[1davho]

Could be an injector issue. Did you put your injectors in or run the used ones? Try swapping them and see what happens

 

[mitecl96]

The hole intake part is my old one. I didn't even take it apart.

I know I have a leak on my header, can that cause it without throwing a code?

Really need help guys this has stumped me and I have tried everything, read many forums.

 

[mitecl96]

Well I decided to shot a video of the idle.

https://www.youtube.com/watch?v=luE4WcAk8zQ&feature=youtube_gdata_player

I also noticed that when I cruise at a low RPM , more noticeable in lower gears, it will jerk like it's missing almost.

 

[1davho]

If you have a leak on your exhaust manifold it could definitely cause a problem. Your o2 sensor would see that as a lean condition and could be adding too much fuel.

 

[mitecl96]

I read about the leak at the manifold, it will hurt fuel mileage but it wouldn't cause a bad idle. I've tried fixing the leak 3 times with different kind of gaskets but no luck. Whats the best gasket to use?

Tomorrow I am taking the throttle apart and cleaning, last thing to do, hopefully works or timing is next.

I have checked for vacuum leaks, using throttle body cleaner, no luck. Spark plugs are new and gapped correctly, Wires are fine, coil checked out. I replaced the PCV no luck either. Changed the EGR valve and cleaned the tube out, nothing. IAC is new along with the TPS. I still have no codes. Coolent Temperature Sensor works and is making a connection. Fuel injectors check out also and fuel filter is replaced.

I have literately checked everything. This is driving me crazy and I am not getting much help. I have searched and read about every idle problem on this site that deals with the 420a motor.

I'll let everyone know how the throttle body goes tomorrow, if not I need ideas and help.

The car only idles bad feeling like a miss but isn't. Car runs fine and perfect after 2,000 RPMS.

 

[jayson427]

Sounds like timing to me if you have checked all the other stuff you said.

 

[thomcasey]

Spray some brake clean or carb cleaner around your injectors. Maybe an injector seat is leaking. Heck, just spray if around anything suspect and listen for an idle change.

 

[mitecl96]

I have tried the throttle cleaner, nothing.

I have cleaned the throttle body and EGR tube and EGR valve still nothing

Guess its timing doing that tomorrow unless anyone can think of something else.

 

[mitecl96]

FFFFFFFFFFIIIIIIINNNNNNNNAAAAAALLLLLLLLYYYYYYYYY!!!!!!!!!!!!!!!!

I got to look at the timing again and the intake cam was advance a tooth, put a new belt on and put it in time. She idles perfect again. Finally, just weird that it was in time when I had it hanging on the engine hoist, wonder what happen?

 

[Slo2gen]

Did you rotate the engine after setting the timing and remove all the "slack" from the tensioner?

 

[mitecl96]

Yeah I did when I changed the belt. Before I installed the motor I just checked timing I never took the belt off and it was in time then. I just wonder what happen.