97 aspire idle

[shadetree]

I just swapped the engine due to bad rings, it was doing this before but i figured with the newer engine it would take care of this issue .. It's idling up then dropping down then up then down then it will idle normal and sounds like its missing . It has new plugs and wires and runs perfect while driving no issue at all till you stop and let idle .. check engine light comes on and will clear with disconnecting the battery .
Any ideas

[Pu241]

Did you swap the entire engine intake and exhaust?
Does it do this when started cold?
Just a guess, unless you swapped the O2 sensor I'd say you'd want to start there!

[htchbck]

I'll put in vote #2 for O2 sensor. And since its a '97 (OBDII) doesn't it have two? Though I think the second one after the cat is strictly for emissions and doesn't feedback into the engine controls, but I could be wrong about that.

[shadetree]

I swapped the complete engine ,but the new manifold had broken studs so I switched it for the old one leaving the old o2 in it. So again thanks guys ,I will try that and see were it leads .. and report back !

[htchbck]

Make sure you order the Denso 234-1000 and not the 234-1020. The 1000 is about $20, and the 1020 is in the $50 range. Exact same sensor, but the $50 one comes with the plug already attached, and the $20 makes you crimp the plug but saves you $30. Oh, and don't get the Bosch, get the Denso.

[georgeb]

Scan it.

[shadetree]

Yea scan it I got that .. my scanner is at work. 1.5 hrs away ...

[ericsmith32]

Check and clean your egr valve. Also may sure you clean your IAC . Both are on opposite sides of the manifold. You could also have a short in your internal ignition coil but I doubt it.

[shadetree]

Okay. Replaced o2 and still same thing ! I'm going to get my scanner tomorrow morning so ill try that . It does it when its cold started ,then when it warms up it just drops to a steady ,really low idle and does that (potato potato potato ! ) idle ,like it has a big cam . Actually sounds cool, but if it lopes to hard it will shut off . I'm thinking cat is clogged

[FestYboy]

no, the base idle is too low. also look for holes in the intake tube (just like the festys) and also verify your timing.

[shadetree]

Anybody handy with how to take the computer out of the loop to set base timing ? Or the proper way to set base idle as for the wire that's needs grounded ?

[shadetree]

no, the base idle is too low. also look for holes in the intake tube (just like the festys) and also verify your timing.


Wouldn't it be strange thou both engines doing the exact same thing . The new engine ran fine in the wrecked car I pulled it out of with no issue ...

[FestYboy]

Anybody handy with how to take the computer out of the loop to set base timing ? Or the proper way to set base idle as for the wire that's needs grounded ?

IIRC it's the same with the 94-5 aspires to set base timing. base idle should be the same at the festys.

[nitrofarm]

no, the base idle is too low. also look for holes in the intake tube (just like the festys) and also verify your timing.


Wouldn't it be strange thou both engines doing the exact same thing . The new engine ran fine in the wrecked car I pulled it out of with no issue ...

Yes, so check really good for leaks @ tubes like he also said. The VAF is VERY sensitive.

[FestYboy]

^MAF for the aspire.