old man neri

Try carb cleaner on the ICV, not brake clean.

jpyles

I only had brake cleaner available to me. Last carb'ed vehicle was a 1990 grand wagoneer. Does brake cleaner have negative side-effects? I saw some other posting where it was used.

theiceman

brake cleaner should be fine .. it is actually very aggresive but it should certainly clean it up. Can you see the internals moving at all ? it is just a gate on a motor that opens and closes to let more or less air in.

old man neri

Nothing wrong with brake clean, I just found that carb cleaner or throttle body cleaner to be more effective at eating through carbon build up. That's all.

jpyles

Thanks for the reply. i don't have a Bentley manual. Could you describe the ICV check in more detail? With engine off, remove ICV, plug it in, and "turn it" toward me?

I still suspect the ICV over vacuum leaks, but I'm going to delve back in this weekend and see what I can find out.

I also might take a look at grounds. I'll have to do some googling to find out where the locations are. I suspect this because my gas gauge has started acting up at the same time as the idle.

theiceman

before doing anything else spend 75.00 and buy the Bentley...

rusnak

I don't think there is any common ground or common power between the GG and the DME.

The DME grounds are on the left side intake manifold, near the rear fuse panel or fuel filter IIRC, and there should be another one near the front fuse panel. Going off of memory here which is not advised. Grounds don't make the idle bounce though. It's always a good idea to clean your battery contacts, clean your grounds, and clean the fuse contacts in the front fuse box, as already covered here.

You can safely check the ICV after the engine is warm by first removing it (disconnect the hoses and clamps) and then plugging back in the harness that goes to the ICV. Look in there to see that the idle is "regulating" the intake air. Also once it is out, which you had to do to clean it anyway, make sure that it can move around and is not all gummed up. The Bentley describes a series of ground and resistance checks. I agree, that is one essential tool that you must buy before doing any serious work on your car. I could not do without mine.

DRACO A5OG

I recently had similar issues, Driving around town, I suddnely felt my idle drop to below 800 at a stop sign.

Check for vacumm leaks but could not find any. Unplugged the O2 Sensor and ICV. Started her the RPMs stayed steady at 880-900. (Sw Chip 964 Programming) RPM's did not drop.

Plugged everything back together and started her. The idle would start at 880 then drop to 800.

I checked the ICV, unplugged and no change in idle. it is supposed to drop so I suspect a defective ICV (but it is only less than 2 years old). I will check with a buddy's DVM to see if both the ICV and CHTS are in proper readings.

dshepp806

Couldn't a flakey idle control switch be contributory?

Best,

Doyle

DRACO A5OG

will check that too wiit. thanks for the heads up.

whalebird

dshepp are you a rush fan?
I hate to sound contrary here, but that describes exactly how a aftermarket chip and MAF works. That is the trade off with them. Ihave never had much luck with these mods-especially in cold weather. I have removed several chips because of this problem. Autothority are the best going in my opinion but there is a trade off.

dshepp806

I would consider myself a "disciple" moreso than a "mere" fan......had the opp to work with this group on a few tours (FOH sound) ,....unbelievable...


When you say "several" chips,...who's? And what problems did you encounter relating to the seasonal changes? The noted problems? Or others?

My best,

Doyle

whalebird

I too am a huge RUSH follower - the band has really touched me beyond entertainment. I knew a girl years ago who was a personal assistant to the band. I asked her about them and she pulled out a box of photos. She said the same as you-just a great group of people she considered friend.
To answer your question, I have taken out several chips of various manufacture of which I cannot recall. I know three times I have installed and then removed autothority chips. One of which I sent back to them and they reflashed it differently to help with the problem. When it was all over we took the chip out and replaced it with stock. Customer said the gain was not worth the hassel - stock was fine(92 911 3.6). I have found this in other situations where similar cold start problems as described above was prevalant. Again I did not commit the details to memory. As a factory technician, I was told that chipping a car was not worth the money. I believed them because they said that problems just like this thread describes would result when there is very little gain-just different. I duplicated this in the field and to this day I still doubt chips offer much performance gains. We did however use an autothority chip in our supercar series 930. It helped on the track under certain conditions. We worked with autothority to get what we needed.

DRACO A5OG

For me I will never go back to stock chip with the infamous Carrera Lag but only to swap out for Ca Smog. I do realize our babies must be in top condition to upgrade to a mod chip. From my experience, Hi-Pro Mod Chips will enhance everything even the faults. My 2 Cents.

Update:

Spent 5 hours tracking down the low idle issue at stops.

Component Check:
OHMs on the ICV = 20 (+3) Center 40 (+2) Outer Two, Good
OHMs on the CHTS = 298 Hot, Good
Voltage on Idle Position Switch = 0.5, Good

Vacumm Test:
The A/F ratio was purposely Leaned to find a hint of a leak
Disconnected O2 Sensor and ICV
Started and Brought up to Normal Running Temperature
Sprayed Starter Fluid (Ether) on Following Points
ButterFly Clamps
ICV Clamps
Manifold Clamps
Behind Butterfly Hose
Behind Manifold Connections
Right and Left Fuel Pressure Regulators
Manifold Gaskets
Fuel Injection Ports
Result = No Sudden Raise in RPMs = NO VACUMM LEAKS

We were listening to the idle then suspected a Mis-Fire at one of Cylinders, to verify we disconnected Fuel Injectors one at a time.
Using an AFR meter to measure when an injector was disconnected, we got the following readings:

#1 = 17.4
#2 = 16.6
#3 = 17.6
#4 = 18.2
#5 = 18.4
#6 = 18.3

Driver Side seems to have issues with proper flow. We suspect it being the cause of the richness of the A/F ratio on the AFM.

Patrick B, a Track Buddy of mine with an '85 had issues getting the proper AFR, when he replaced his injectors the issue was corrected and never returned. I am thinking I may have the same issue. But my friend did say that others have changed out injectors with no change, hmmm.

Corrected the A/F Ratio to 14.7 and Idle to 880-900RPMs. On my drive home, she drove great trhough out all the gears and throttle response was perfect but she started to drop to 810RPMs at stops. It's got to be those injectors!!! 180K+ on the clock

Any thoughts or input?

Lorenfb

"I hate to sound contrary here, but that describes exactly how a aftermarket chip and MAF works."

That's it! But had to take two pages of posts to arrival at that?