Throttle Body blues

[DenverQ]

Today I decided to take apart the throttle body and clean it, I got it all apart and cleaned then I rigged a towel and stick to get inside the plenum it looked great for what I could reach. So anywyas I got it back on and fired up the car it started right up and warmed butr then idle stayed about 1250 and in drive it would be a little above 750. From previous posts this is way high but I do not know where ther AIC adjuster screw is =(, but i thought it was somehting else I didnt have a new paper gasket top I used the old on. I assumed this was the problem and it was letting air in and screwing things up, I bought some make your own gasket stuff carefully removed the old one traced a outline and cut out the new one with a exacto knife. I got it all togehter everyhting was tight and such fired up the engine and still the same problem =( Could it be the aic is adjusted wrong or is there somehting else wrong? and now its makes a gurgling sound I can hear it inside the car, I made sure my coolent was good. Does anyone have any ideas?

[longrunQ]

I cleaned mine as well this weekend and I noticed that my idle went up. Its about 900 in park and about 750 in drive. I read somewhere that this was normal with a TB cleaning

[Q45tech]

From the passenger side look at the middle rear of the plenum you will see the IAC and the bypass adjustment screw. Turn the screw all the way in, then out 3-3.5 full turns. This should be the correct point if everything is clean as new!

Best to have a Consult so you can read the duty cycle the ecu is commanding of the IAC to maintain correct idle.......it show be 10% [no loads] after 15 minute warm up.

Never try to adjust the idle till the coolant has warmed up to 176F may take 10-15 minutes and never if your thermostat is bad [after 3 years].

[Q451990]

You might also check to make sure there's a little slack in the throttle cables... if you tighten them too much (especially when the fast idle cam is in the cold position) you can have that problem as well. NEVER try to adjust the fast idle cam - it should be fine for the life of the car - Dennis has mentioned several instances of sub-par techs. causing problems messing with that.

The gurgling sound you mentioned is probably just air that got in to the cooling system. After a few days you might need to top off the cooling system.

Heath

[DenverQ]

Well I found the screw (thanks Dennis!!!) It was way out!! I had to turn it like 10 times before it bottomed out. So anyways I got it back to where it needs to be. The idle is a lil rough now i Hope its not a injector and just cleaning stuff that hasnt evaporated would a vacum leak cause some roughness? Thanks for all your help guys!

[Q45tech]

AGAIN you need the Consult or some way to ACCURATELY read the rpm...............big difference between 635 and 650 or 675 rpm in idle smoothness. Doubt you have gotten the entire intake system as clean as BRAND NEW.Also the IAC interior and PVC system need to be clean.....the tiny vacuum holes under the throttle plate.

Once its perfect then you do a power balance test and clean the injectors till the idle [1200 rpm] balance is perfect [same rpm drop when each injector is shut off......50-75 rpm....but they must be EXACTLY the same number.

[jefftrexler]

Well, today I too had the throttle body cleaned by a friend that owns an auto-shop. He did the whole cleaning in about 1/2 hour and only cost me $20! He even cleaned out the tiny little ports that are inbetween the TB and the plenum. This week I shall also be taking my '91 Q45 back to him to get the plenum and intake runners honed out. Whilst the intake is out, the thermostat and PCV valve shall also be replaced. I tell ya, with just the throttle body clean my car's idle has REALLY smoothed out. Initially the idle was around 1000RPM, but that dropped back down to around 650RPM after about 5 minutes. I guess the ECU kinda freaked out with the TB being clean and all. The TB was absolutly caked with black goop! Upon a brief inspection, the plenum looked to be caked with the same gunk! Wow...this is gonna be interesting!

BTW...is there anything else under there that I should have replaced? All the hoses have already been replaced so there is no worry on those. Oh...and is there any way through the VIN number of my car to find out if the timing chain guides have been replaced? Any help or advide would be greatly appreciated. Thanks!!!

[Q451990]

Any dealership should be able to run the VIN, if it hasn't been purged. It appears that they're only keeping the older VINS if they're still seeing the dealership regularly. If the front cover still has the light blue RTV seal from the factory, it's a good guess that they haven't been replaced.

As far as under-plenum work, as long as the hoses are new, the only thing else you might need to do in there is replace knock sensors or their harness if they're not working.

Heath

[Q45tech]

"The TB was absolutly caked with black goop! Upon a brief inspection, the plenum looked to be caked "

Every make car [4/6/8 cylinders rotories inlines] I've seen from Accura to Volvo [ for the last 10-12 years] has a dirty throttle body ,plenum, and runners. Just a common maintenance item on all car with individual injectors.

It amazes me that owners have to be told. Forced to get things cleaned up.

No wonder 4 out of 5 cars on the road have major technical issues.It is a miracle that they run under these conditions and abuse.

[DenverQ]

WHen I celaned mine i cleaned everyhting thing i could see! I got a old tooth brush and attached it to a stick and scrubbed the inside of that plenum as much as i could it was nice and shiny silver again when i was done I wonder how bad the runners actually are. When I get enough guts, ill pull the plenum, but im still scared since i cant loose the car for more then 2 days

[firstq]

Tory, removing the plenum for the first time was a bear - unfortunately, I had to redo the whole setup within a week (broke one of the intake runner - overtightened it) - the whole job took 3 hours[ 1 hour removing, 2 hours buttoning it up].

You got to do it once to learn it - and you will take time, but once you know where the hoses and clamps are, it will be just like any other job. I was devastated to find out that the runner was broken as my first time with plenum was kind of painful, but to my surprise the second time was a piece of cake - now I can do this in an evening - semitrained hands and recently siliconed hoses go long ways....

[jefftrexler]

Well my '91 Q45's intake plenum and runners are now spotless! I tell ya, its rather scary the difference that cleaning the air path makes. Heh...now I have to be careful with the throttle because the tires spin all too easy now! Wheeee!