97 N* Shaky idle - Page 4

N*Caddy · #46 (**permalink**) 11-01-09, 09:25 PM

Since is a day after Halloween I thought is the perfect time to bring this dead thread from down under…
So the other day I went to met a fellow Cadillac owner (’96 STS and ’97 ETC) and he was looking to my car just out of curiosity (you know the same way dogs sniffing their behind). And when I popped the hod up he had two remarks: “Wow I have never seen such a clean engine” and “man this engine is so quite almost like idling low”.
Well I didn’t pay much attention (we were discussing about the recent exhaust job I did) so I missed the “idle low” remark. Until today when driving home all of a sudden it cam to me…HEY! My car always had a slight shake when idling (I mean nothing that anybody but me will notice) that I could never figure out in 4 years. This usually happens after 3-5 seconds after stopping at a traffic light and now I realize is only whit the engine at normal temperature. Could it be that the idle is too low?
So I was just stopped at the traffic light and I watched the tach…in the first 3-4 seconds it was still going slowly down from 700 RPM or so. When it finally cam to a “resting” position I noticed the slight shake starting (again don’t imagine a rough idle or such just a very, very slight shake here and there). And what do you know the engine does idle little low than the normal 650 RPM. Is more like a 625 RPMs.
Between 0 and 1000 RPM there are 4 segments (250 RPM each). My idle stays DEAD on half way between 500 and 750 RPM lines (i.e. 625 RPM). I just slightly touched the gas pedal (just a tiny bit) and the needle climbed to 640-650 (is just an impression over where it was) and what do you know…is smooth like ... a Cadillac. Absolutely perfectly dead smooth, really you can not tell the engine is on (even if you are in a silent garage) that is the butter zone.
So it took me 4 years to finally realize the obvious…it idles just a tad to low. In these 4 years I change the fuel line, the FPR, the EGR the PCV, spark plugs, cleaned throttle body, inspected every singe vacuum junction… I was just about to buy a new set of injectors; the price was pretty good for a brand new set of AC Delco injectors but still unnecessary. Well an IAC is little under $50 and I was planing to change mine any way since the surface is not shiny any more (just esthetics reasons), I should be able to adjust the one I have but now I got another reason to get a new one.

**Ranger** · #47 (**permalink**) 11-01-09, 11:02 PM

When was the last time you cleaned the TB? I think the recommendation is every 30K, but I do mine every spring.

N*Caddy · #48 (**permalink**) 11-02-09, 09:29 PM

Last year (so about 20K-25K ago) no difference then (I do-it every year in fall).

creeker · #49 (**permalink**) 11-02-09, 11:48 PM

Quote:

Originally Posted by Ranger

OH Canada! I think we went through this before and it was only a U.S. recall. I forgot about the fix. Yeah, if that was in place, I am pretty sure it is stil OEM.

When I bought my 97 sts about 2 years ago
I got in touch with G.M. canada, and it was like it was news to them,
when I asked about s.s. fuel rail replacement, yadda, yadda, they have no record of any problem with fuel rails.