: High idle???

12-25-06, 05:04 PM
I just replaced the water pump on my 1995 FWB for the second time in a month :mad2: (first one was a rebuilt and leaked from the weep hole right away) and then changed the plugs and wires while I was at it. Figured it was a little easier since the water pump was off. Never doing it before, this took me about 6 hours. :) Those spark plug wires are a b@#%$ !! Anyway, after I was done, my car idles really high, well not REALLY high, but it idles at 1100 rpm's or so. Isn't that a little high? Thought it was a vaccum leak or something, but the only vaccum line I touched is the line the one going in the top of the intake tube. I just moved it out of the way and that is it. Any ideas???

12-26-06, 04:34 PM
You might still have a vacuum line unplugged somewhere. 1100 rpms doesn't sound high to me for the cold-weather idle right after you start it, but 1100 is too high for the engine after it's warmed up.

12-26-06, 04:54 PM
You might still have a vacuum line unplugged somewhere. 1100 rpms doesn't sound high to me for the cold-weather idle right after you start it, but 1100 is too high for the engine after it's warmed up.

I think that might be it. I was just leaving NAPA Auto parts and got in my car (left it idling when inside) and just before I stepped on the brake to put her into gear, the RPM jumped from 800 to 1100. The car is reading 180 for temp. I was just sitting in my car dumbfounded. I bought some carb cleaner and I am going to spray some arounfd all the vaccum lines to see if it makes a difference.

I cleaned my throttle body this past weekend, when I was changing plugs and wires and my waterpump. The throttle body was pretty dirty. Maybe that has something to do with it?? All the gunk inside was holding the vaccum in and now since it is clean all the vaccum leaks past the throttle shaft?? I am just throwing some ideas out there...


12-26-06, 09:54 PM
When you stepped on the brake to put it in gear, the RPM's went up? Hmm, that's new to me.

12-27-06, 01:49 PM
No...before I stepped on the brake, the RPM's mysteriously went up. I sprayed all around the intake manifold, throttle body, all vacuum lines I could see, EGR, MAP, Air Density, MAF, and no change in RPM. So, as far as I know, no vacuum leak or intake leak. My car is strange...any other ideas?


12-27-06, 02:05 PM
There are two vacuum lines in the bottom of the opti. One leads up the air intake elbow. The second line runs alongside the driver's side of the intake manifold and into the side (there is a cylindrical shaped blue filter here).
I would guess that one of these was knocked off the bottom of the opti?

Otherwise the PCV valve rubber line connects on a tube underneath the TB.

12-27-06, 03:55 PM
Can you reach the ones on the bottom of the opti with everything on, or do I have to take stuff off again? I will look tonight after work. The PCV one is fine. Checked.


12-27-06, 04:38 PM
I'v been working on my caddy, it has a 307. The ILC vacuum line was hooked into the anti-dieseling solenoid and the carb vacuum line for the EGR was hooked into the ILC; EGR didn't function and the car was dieseling on occasion :X. Additionally, it would idle high and continue to idle high until I pressed on the gas from a cold start; now it no longer does that it seems.

It's something that could be reversed if you're dealing with a water pump as those lines can get reversed easily and are near the pump intake lines.

Also, did you replace the thermostat and temp sensor? Those items should always be replaced when you do a water pump job since if they fail, they will cause high idle; the ECM has no clue as to when to stop idling high since there's no temperature reading so it continue's high idling until you press down on the pedal. There's a timer in there that it keeps the high idle going irregardless of throttle usage; I believe 30 seconds until you can force it into low idle. Additionally, make sure you dumped, bled and refilled the coolant in the system, cleaned the radiator and didn't reverse any wires. Failed waterpumps can leave behind a lot of crap and clog ventricules and lines.

Then again, if it's a 95, then you're probably dealing with a FWD fuel injected beast, which is very different than the 307; I'v got a maze of vacuum lines, you've got a haywire computer. Also, when I replaced my water pump it high idled for a few minutes then outright dieseled for a good 2 minutes before I pulled the battery leads; the amount of load taken off of the engine sometimes requires the engine to adjust some to less load there since the ECM will handle idle characteristics based upon load.

12-27-06, 05:07 PM
It's a 95 RWD with the LT1 corvette/firebird/camaro/caprice/roadmaster motor. Anyways, that makes me think a little. I think my temp sensor wouldn't be a bad thing to replace anyway. I think it is going out since when I was in diagnostic mode on my car the temp sensor was going "haywire" at one point (it read -101 degrees fahrenheit) and then I unplugged it and then plugged it back in and it was fine (it read 180 degrees fahrenheit). I think I am going to pick up a new one tonight and replace that and my thermostat. Hopefully that solves the high idle problem...:bomb:

12-27-06, 08:34 PM

Lemme give you a tip. Whenever you're going to do some major work on your caddy, always service it *completly*. That basically means research the practice you're doing. There are some parts you should just "let go" until they fail; the engine and trans are two such examples since they are expensive and time consming to service. You could hone out the cylinders every 60,000 miles, but is it worth it? You might as well buy a second trans and engine and rotate them when necissary. If you're going to replace an air pump, for example, then it's likely time to replace the hosing connecting it to the rest of the car, the belt, and potentially the pulley.

For a water pump, you should replace

*Gasket. RTV sealer gets you extra points for longevity as the gasket will never be the failurepoint. Make sure to use threadlock on the bolts and clean the bolts with the brake cleaner.

*Temp sensor, inspect wiring. Temp sensors break down right around the time the water pump does. The wiring needs to be inspected for becoming brittle. If it's brittle, run new wiring, although usually wiring fails all at the same time throughout the entire engine compartment and car and is something you replace with engine swaps.

*Thermostat and thermostat housing and gasket. Again, replace it with the water pump since it's ready to go when the water pump goes.

*Check your rubber hosing for dryrot and replace as is necissary. (shouldn't have to say this)

*A cooling system cleaning and coolant flush (same for radiator replacement). Failed waterpumps can leave behind metal filings, lubricant, and the heat from the friction in the waterpump can cause the chemical properties within the coolant to change. Most importantly, a water pump doesn't fail overnight; it fails over the course of several years and during that time gunk builds up, especially if you don't flush it every year like you're supposed to. Pick up some of the radiator cleaner solution and fallow the instructions. DO NOT under ANY circumstances add sealant into the mix once you're putting it back together; it's made of fine grain sand and will clog pinhole leaks, gasket leaks, bearings, lubricant, and venticules trading a short-term gain for a long-term failures.

As far as a coolant mix goes, it depends on the time of the year. I usually will drain and bleed the system in the spring and put a 15/85 mix in of coolant to water and as any coolant boils off, add water to it; the coolant mix there is purely for protection purposes As fall comes on, I'll drain the resivour and add in pure coolant to up the mix to right around 35/65 (remember, coolant circulates from the tank into the radiator due to pressure; as you drive the vehicle, the solutions will mix). Some people do the same but use 50/50 and the mix comes to right around 25/75. Come the next fall, I'll drain, flush and clean, then do any other fluid maintainance (wheel bearing packing, trans fluid change, differential fluid change, oil change, ect). Costs about $30 a year to do and is well worth it since it increases the longevity of all the parts of the entire system to about 30 or 40 years. You can spend $1200 for 30 years of operation, or replace radiators, waterpumps and engines as they go so overall it's cheaper.

12-28-06, 12:57 AM
Thanks for the great advice. :highfive: I am sure to follow it, since it makes complete sense. :) I was doing a little checking tonight, replaced the upper radiator hose, thrermostat and gasket and added new coolant. I am going to flush it this spring (since this is the second time I changed my water pump in the last month and when I changed it the first time I flushed the system, everything is pretty much clean now). Anyway, back to what I was talking about, I did some checking tonight and looked at my IAC valve, it was really dirty. I cleaned it and now my car idles fine. I think I will replace it soon. But thank you, really, for the advice, because I will follow it.

12-28-06, 01:29 AM
No problemo man :).