H3 Just finished motor swap... rough idle

[tgomes78]

So we just finished with the engine swap in my H3... the truck idols rough though. I spoke with somebody who is an expert with vehicle electronics. He told me that the computer should relearn itself after driving it for 50 to 100 miles. There is no smoke and when driving it runs fantastic. Is there a way to manually adjust the throttle body? If I can figure out this issue the swap will be a complete success.


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[adhtx]

Clean TB and Map Sensor

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[tgomes78]

The throttle body was cleaned and map was replaced.


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[mjferencak]

Whats in it now?

 

[tgomes78]

I replaced it with another OEM 3.5


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[mjferencak]

Could be a relearn, a bad plug(s), a bad coil pack(s), still some dirt in the throttle body. Start with the cheapest fix and go up the list.

 

[atvspeed4]

I had a similar problem with my alpha idling and they had to do a idle relearn. Not sure if that applies to the 3.5 as well

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[tgomes78]

I was just talking to a friend who is a mechanic... he's actually putting tires in it for me this week and he said he can do an idle relearn or diagnose any other issues


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[Happy Hummer]

Glad to hear the swap was successful and that you did it so swiftly.
What kinda plugs you running?
Did you make sure the breather hose under the air resonator is attached and in good shape?
How are the injectors?

 

[tgomes78]

Honestly don't know what my friend put in for plugs... we were working on it together but he's a professional auto mechanic and I'm an Hvac Mechanic... so I know enough to be dangerous lol. However I believe the injectors and that hose are in good shape. It runs great if I keep it above 1000 rpms.


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[mjferencak]

Check the hose that Happy Hummer mentioned. I replaced mine awhile back. I could hear a vacuum leak when I stood near the back of the engine. Took the cover off and found that the hose had disintegrated from all the oil that was being passed through. Helped my surging idle.

 

[tgomes78]

I will take a look at it as soon as I get home from work thank you guys


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[tgomes78]

So that will be a breather hose near the intake and throttle body? By the air box?


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[deserth3]

It goes from the bottom rear of the resonator (the box just before air goes into the throttle body) to the vent tube on the top rear of the engine.

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[tgomes78]

Ok great thank you


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[Happy Hummer]

Reason I ask about plugs, is that the I5 does not seemed to like odd ball sparkys. And the only way to know if the injectors are behaving is to test them... Were they the ones that came with the replacement engine? Also, make sure your intake manifold bolts are tight...

 

[tgomes78]

Yes they are the ones that came with the engine


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[tgomes78]

And I will get oem plugs for it... these motors are so picky. I've never owned such a picky truck. I'm used to the old 5.7 and 5.3 vortec... much easier to diagnose. I'm gunna replace the battery terminals... I read that these sensors are extremely picky and the if there is any kind of poor connection at the power source then the sensors won't read properly.


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[tgomes78]

What spark plugs should be in the truck


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[Happy Hummer]

If you are in need of spark plugs I'd recommend the O.E.M units. Gap is typically set to .42-.43

06-07 Spark Plugs: AC Del 41-103

 

[JPaul]

It's not that it's picky, it's just that it really prefers OEM everything, there's no need to go "high end" or gimmicky on anything, and lower quality parts do not last long at all if you use the vehicle like it was meant to be used. I've had lots of other cars that you could get away with using the cheap parts from Autozone and whatnot and be fine, but not this one. For some reason the aftermarket parts are pretty shoddy but they still want a lot for them.

 

[Happy Hummer]

I kinda agree with the above sentiment, albeit with one caveat. There are cheaply made parts and cheaper prices parts. Second being desirable the first not so much. There is a market for both and both do serve a purpose. But, overall I agree....." long after the cheap wears off, you are stuck with a dissatisfying taste in your mouth!"

 

[tgomes78]

The thing is I spent $4000... I definitely didn't cheap out. There's just something wrong or something is defective... there were 18 engine codes


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[tgomes78]

I have a list of all of them... cleated them out and drove it for a day to see what comes back. I'll have my friend run the computer on it again on Monday


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[Happy Hummer]

Wow, that's allot of codes. Not a small dollar amount either.