need advice, engine has lopey idle and slight vibration

[jimtash]

It's a rebuilt engine that I purchased a while back and it has this strange lopey idle in it like it's cammed and also a slight vibration that goes away once the rpm's rise. I also get a slight misfire when first starting it in the morning that goes away after the car runs for a while. One other thing is the engine doesn't feel as strong as the original one so that leaves me to ask could the timing be off somewhere or something be wrong with the valvetrain?

 

[93rev2sev]

Could be a lot of things. I bet pulling the codes and posting them here will help you.

 

[SASHO91]

vacuum leak....

 

[thecrew2999]

vacuum leak i second that. simular problem in the past.

also codes dont get throw for vacuum leaks.

 

[SASHO91]

yes it will...

HEGO- Lean
either both banks, or just one.

 

[Sho Amo]

i got that code also. mines runnin lean cuz of the cl73 maf. i also got a code that said ego not switching.

 

[jimtash]

I've pulled the codes before and nothing came up but I'll do it again as soon as I get the car back from the trim shop. Any other suggestions?

 

[jimtash]

OK, I got a code for the TPS and I replaced it but it didn't cure the idle so I decided to look at the maf because of the above post and also because of some other posts that I read concerning the a/f ratio. So just for kicks I decided to go back to my stock 55mm unit from the 70mm unit I bought a few years back and it seems to have solved the problem. In fact, it's made a big difference not only at idle but throughout the entire power band.

 

[DHMag]

I decided to go back to my stock 55mm unit from the 70mm unit I bought a few years back

you failed to mention that in the beginning.