Another clue to rough idle problem (pics) - Toyota Nation Forum : Toyota Car and Truck Forums

damone · 01-06-2005, 04:28 PM

I got my car parked for winter But I decided to start it up and let it run for awhile today to get fresh antifreeze and fuel line antifreeze through the system.. And once again, it started to miss and stumble.. (a problem thats been off and on for about 8 months..)

After checking EVERYTHING.. again.. Just for the hell of it, I pushed on my intake manifold (see first pic), and wouldnt you know it, Idle smoothed Right out.. I didnt have to put a lot of pressure on it..

So I gently pulled back on the manifold, like this.. And the idle got much worse..

I checked some of the manifold mounting bolts.. (the ones I could see) and TB mounting bolts.. and they seemed to be tight.. Im hoping this sheds some light on my intermittant rough idling problem...

Anyone figure This one out???

Edit: 1990 supra turbo a/t about' 17 in/hg vacuum at idle

Jeeves · 01-06-2005, 11:16 PM

The gasket on that manifold isn't infailable, have you pulled it to check its condition?

damone · 01-07-2005, 01:29 AM

Quote:

Originally Posted by Jeeves

The gasket on that manifold isn't infailable, have you pulled it to check its condition?

no.. it was getting dark when I noticed, and pulling the manifold off seemed like a lot of work.. any precautions? tips? I'll replace both manifold gaskets while I have everything apart.. Is there anything else I should replace while im down there? thinkin about replacin all the vacuum lines with silicone ones..

I thought that maybe it was bad wiring somewhere.. a broken wire that was grounding out.. But the rough idle sounds too much like a vacuum leak, and not so much electronic..

By the way, if I did have a bad leak in the intake manifold, Could that cause the car to misfire?

Not so much idle rough, but sometimes even when its idling smooth i'll feal and hear the car misfire.. Im hoping all these problems are related so I can be done with it and have a reliable car again..

Jeeves · 01-08-2005, 02:27 AM

It could, ya never really know. Personally, I'd pull that manifold apart. Scrape both edges as smooth as I can, then slap a new gasket in and make sure it's tightened nicely. Switching to Silicon hoses is a nice endeavor but rarely nets you anything other than a dent in the wallet.

damone · 01-09-2005, 02:59 AM

Im almost scared to pull the intake manifold off..

My brother had the engine rebuilt summer before last (HG) But the guy who did it was a complete f%#&*'n Moron.. last summer my exhaust manifold started to leak, On closer inspection I realized that he used large 11mm house grade bolts to fasten the manifold.. He just stripped them Right in there with 10 washers on each bolt because they were too long.. I had to pull it all out, drill them and heli-coil them, new gaskets, studs and bolts, rebuilt and upgraded turbo.. etc.. etc.. costed a pile of money And ive also had other problems with the car due to his Shady re-assembly..

im not sure i wanna know why the intake is leaking.. but after im done it'l be re-assuring to know it was done properly

Jeeves · 01-09-2005, 03:08 AM

Well, since the HG's holding he did at least ONE thing right. With that in mind however, I'd definately pull that intake manifold apart and start inspecting it.

91gredsupra · 02-13-2005, 10:49 PM

a quick but risky way to detect a intake leak is to apply propane around the intake manifold if the engine speed changes you know you have a LEAK

damone · 02-14-2005, 03:16 AM

thanks for the tip..

But ive already just about got it back together..

BTW, is there any site or anything where I can find info on what size/pitch all the different bolts are under the hood? Im missin quite a few from the a$$hole who did the engine, and theres also a few he stripped..
I want to get everything under the hood back together properly

***bgrieger*** · 02-14-2005, 08:20 AM

Quote:

Originally Posted by 91gredsupra

a quick but risky way to detect a intake leak is to apply propane around the intake manifold if the engine speed changes you know you have a LEAK

If you like the idea of being charcoal, along with your car and garage, go right ahead. I'll be sure to vote for you come darwin awards time. Reminds me of some incidents where people used the oxygen cylinder to blow work benches or welding tables clean from grinding shavings when they were too lazy to get the air hose cause the torch was right beside them...one spark, or still smouldering ember and the next thing they know their on the way to the hospital smelling like a steak with their skin feeling kinda tight.

There are many far less deadly ways to detect leaks that work better than this. Carb cleaner in a spray can is perhaps the easiest and safest. Spray the suspected union. The engine will start to chug as it sucks it in, or die out if it was bad enough.

Jeeves · 02-14-2005, 05:05 PM

Quote:

Originally Posted by bgrieger

If you like the idea of being charcoal, along with your car and garage, go right ahead. I'll be sure to vote for you come darwin awards time. Reminds me of some incidents where people used the oxygen cylinder to blow work benches or welding tables clean from grinding shavings when they were too lazy to get the air hose cause the torch was right beside them...one spark, or still smouldering ember and the next thing they know their on the way to the hospital smelling like a steak with their skin feeling kinda tight.

There are many far less deadly ways to detect leaks that work better than this. Carb cleaner in a spray can is perhaps the easiest and safest. Spray the suspected union. The engine will start to chug as it sucks it in, or die out if it was bad enough.

+1

americanjebus · 02-15-2005, 03:03 PM

check your tps sensor too, could be that dunno just see if its a little loose.

Jeeves · 02-17-2005, 12:08 AM

TPS isn't in use at idle.

***Ne0z31*** · 02-17-2005, 09:55 AM

just dont blow those welds on ur intake manifold...

naw, can you just just remove the bolts and hellicoil new ones in there? might as well, better than having shitty idle

damone · 02-17-2005, 05:47 PM

Got it all put back together last night and it runs great.. No more bogging or missing.. Idles nice and smooth.. Intake vacuum at idle is a healthy 19-20 in/hg's
Just extremly loud because thats all I have is a 3" downpipe..

thanks for the tips..

nasty87supra · 02-21-2005, 01:52 AM

anybody in here built a 1jz and put it in a 87 body? and what are some good top and bottom block preps to do while the block is on a stand? anybody here have some good 1/4 mile/daily driver recipes