'92 7MGTE- high and unstable idle

liona · 07-11-2006, 04:09 AM

GreetingS to all!
Need help pls with HIGH and UNSTABLE idle. Idling RPM fluctuates up and down between 1400 to 1800. I sprayed the vacuum hoses connections with carb cleaner, and don't appear to have any vacuum leaks. Timing set at 12 deg BTDC.
I did notice a crack (which I temporarily tape wrapped) near the hose clamp on the big hose/tube connecting the turbo to the air cleaner . Could this be causing the erratic idle? If not, pls advise whatelse could be causing it.
THANKS MUCH IN ADVANCE FOR YOUR HELP!

mattfurlani · 01-29-2007, 11:28 PM

Quote:

Originally Posted by liona

GreetingS to all!
Need help pls with HIGH and UNSTABLE idle. Idling RPM fluctuates up and down between 1400 to 1800. I sprayed the vacuum hoses connections with carb cleaner, and don't appear to have any vacuum leaks. Timing set at 12 deg BTDC.
I did notice a crack (which I temporarily tape wrapped) near the hose clamp on the big hose/tube connecting the turbo to the air cleaner . Could this be causing the erratic idle? If not, pls advise whatelse could be causing it.
THANKS MUCH IN ADVANCE FOR YOUR HELP!

any vacuum leak can be causing erradic idle.

any cracked hose is bad news. replace it regardless

mrnickleye · 01-31-2007, 05:07 AM

Don't use carb cleaner to check for leaks. It is too strong a chemical, and can cause problems with rubber hoses, electrical connections, and more, etc.

Use WD40, or the prefered,....brake cleaner spray.

Staceman · 01-31-2007, 02:17 PM

I had the same issue as you described. Turns out, the accordian hose to the turbo was split open. Very brittle. PO tried to silicone it, but no go. Only found out after removing it that it was split at the bottom. Couldn't see it otherwise. New hose at the dealer for $47, and she runs like a champ, and idle is great.

mattfurlani · 01-31-2007, 04:14 PM

Any air coming in past that MAF sensor. The box right behind your air cleaner which has a black connector coming out of it is going to make your car idle funny. I have the same problem and i can't find it.

Propane is the best leak detector because it will make your car stop idling funny instantly. But its expensive and dangerous to use. its best to brake cleaner or something else

rnoswal · 01-31-2007, 11:56 PM

Why would something that is expensive and dangerous be the best at detecting anything?!?!?!?! Like saying a stick of dynamite is the best way to put out a campfire, oh, it will do it, but what a mess.

Russ

mrnickleye · 02-01-2007, 06:03 AM

Quote:

Originally Posted by rnoswal

Why would something that is expensive and dangerous be the best at detecting anything?!?!?!?! Like saying a stick of dynamite is the best way to put out a campfire, oh, it will do it, but what a mess.

Russ

Actually, propane is the 'official' approved (EPA, & B.A.R.)gas to use for finding vacuum leaks. At the shop, we have a special adaptor (get from one of the tool trucks)on a bottle of 'camping' propane, with a hose to spray the gas(in short, small bursts) along intake manifold gaskets, and fittings, etc.

A leak will show up quickly.

I don't recommend this for home use or beginners.

mattfurlani · 02-04-2007, 03:18 AM

yeha i mean that propane tanks can explode if your not careful about it. we use it in the shop to detect the leaks. its usually really good.

07-11-2006, 04:09 AM	#1
liona Stock Join Date: Apr 2006 Location: Indianapolis Posts: 6	'92 7MGTE- high and unstable idle GreetingS to all! Need help pls with HIGH and UNSTABLE idle. Idling RPM fluctuates up and down between 1400 to 1800. I sprayed the vacuum hoses connections with carb cleaner, and don't appear to have any vacuum leaks. Timing set at 12 deg BTDC. I did notice a crack (which I temporarily tape wrapped) near the hose clamp on the big hose/tube connecting the turbo to the air cleaner . Could this be causing the erratic idle? If not, pls advise whatelse could be causing it. THANKS MUCH IN ADVANCE FOR YOUR HELP!

01-31-2007, 05:07 AM	#3
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	Cleaning and testing tip Don't use carb cleaner to check for leaks. It is too strong a chemical, and can cause problems with rubber hoses, electrical connections, and more, etc. Use WD40, or the prefered,....brake cleaner spray. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08.

01-31-2007, 04:14 PM	#5
mattfurlani 3" Exhaust Join Date: Aug 2006 Location: Rhode Island Posts: 63	Any air coming in past that MAF sensor. The box right behind your air cleaner which has a black connector coming out of it is going to make your car idle funny. I have the same problem and i can't find it. Propane is the best leak detector because it will make your car stop idling funny instantly. But its expensive and dangerous to use. its best to brake cleaner or something else __________________ Its broke, it could be anything, and cost of repairs will greatly exceed the value of the car

01-31-2007, 11:56 PM	#6
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Propane is Pro Way Why would something that is expensive and dangerous be the best at detecting anything?!?!?!?! Like saying a stick of dynamite is the best way to put out a campfire, oh, it will do it, but what a mess. Russ Last edited by mrnickleye; 02-01-2007 at 06:03 AM.

02-04-2007, 03:18 AM	#8
mattfurlani 3" Exhaust Join Date: Aug 2006 Location: Rhode Island Posts: 63	yeha i mean that propane tanks can explode if your not careful about it. we use it in the shop to detect the leaks. its usually really good. __________________ Its broke, it could be anything, and cost of repairs will greatly exceed the value of the car

01-31-2007, 02:17 PM	#4
Staceman Intake Join Date: Nov 2006 Location: Phoenix, Az. Posts: 48	I had the same issue as you described. Turns out, the accordian hose to the turbo was split open. Very brittle. PO tried to silicone it, but no go. Only found out after removing it that it was split at the bottom. Couldn't see it otherwise. New hose at the dealer for $47, and she runs like a champ, and idle is great.

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