engine idling problem

87 GT MUSTANG · 03-25-2002, 01:55 PM

i was wondering if someone could help me out here, i have a problem with my engine idling up to 1500-2000 rpm's when i am at a stop light or just sitting in neutral or have the cluthch pressed in, My car is a 1987 ford mustang with a k&n filter and nothing else, i run 91 octane, she is bone stock, it is mostly when my car is warm that it wants to rev high, it has been an on going problem since i first bought the car last year and i recently did a tune up including plugs (bosch platinum), wires (accell street custom fit), cap & rotor (platinum gold) and an oil change with valvoline higher mileage engine oil and it seemed to not want to idle as much as it used to but it is still there, i have been told to replace my oxygen sensors and i have been underneath the car and they look like they have never been done since it first came out of the factory, so i am wondering if anybody else has had this problem and if they have fixed it with the solution i just said (oxygen sensors) i know it would be a good idea to replace the sensors as it is but with $60.00 a piece canadian and with two of them needed, money is kinda tight, so that is why i need to know if this is the problem, thanx.

GreenPony · 03-25-2002, 04:52 PM

I have the same problem, But when the weather is cool outside it won't idle high and stick, but if its humid and even if i just start the car and drive off it will still do it,. But if i turn my car off then back on real quick it will be back to normal..I dunno maybe we both can get an answer here.....
Berry

fast88 · 03-25-2002, 10:22 PM

replace the idle air bypass valve on the side of the throttle body,some people tell you to try to clean it but trust me just replace it as they never seem to run worth a flip after you take it apart and try to clean it.

exgmguy · 03-25-2002, 10:52 PM

You can check the idle air bypass by unplugging it while it it idleing high. If it drops like a stone the IAC motor is out of whack. Hard idle may have to be reset, or the motor cleaned or replaced.

kevknotch88 · 03-25-2002, 11:24 PM

jus my thots

1. idle air bypass is the likely culprit

2. throttle position sensor could also be out of adjustment.

3. check carefully for vacuum leaks

have experienced similar problems and mine was a combo of 2&3.

kevin

Import Slayer · 03-26-2002, 05:31 AM

i had a different problem, my car was idling really erratically, and just today i bought some throttle body cleaner, took off the intake hose, sprayed it up and down and all around and up into the idler bypass and low and behold now it runs great!

only things i reccomend are putting a blanket or rag around the throttle body so spray doesnt get everywhere and when it leaks out, and i didnt see a need to remove the idler bypass thingamajigi just sprayed her right in. one more thing it may take a couple cranks to get ur car going again, but once itturns over i runs beautifuly.

i hope this can help someone

Chevyguy · 03-26-2002, 09:13 AM

I clean out behind the throttle plate every few thousand also. The EGR belches exhaust gas behind the TB and carbon and other crap builds up back there. Also when I removed my upper manifold for the valve cover change, I removed the idle bypass valve and totally cleaned out the passage and valve tip.

Like others mentioned, if the Idle motor itself is malfunctioning, cleaning it won't help. Also good tip, remove the passage housing and valve together from the TB, then carefully unscrew the motor from the pasasage. You can strip out those little screw heads easy.

I would expect to find a vac leak also to account for that high idle

abesmith69 · 03-26-2002, 12:27 PM

when I have had this problem I disconnect the idle air bypass for about 5 min and reconnect it and my Idle is back to normal.

-Abe

RMARIANI · 03-26-2002, 01:03 PM

Try this!! My problem was identical to what you guys are describing. Right behind the intake there are two (or three as in my case) 10-pin connectors. They are white and black. Right now sitting at my desk I'm not sure if I had one white and two black or the other way around. In any case, pull these connectors apart. Do one at a time!! You'll probably find a lot of green sludge. Clean this out with electrical terminal cleaner (from Radio Shack or other electronics store) and re-apply some sort of conductive gel/grease (also from Radio Shack). I hope this works for you. After struggling with the TPS, throttle body, etc., someone on this board recommended cleaning the ten-pin connectors and it worked for my car. Good luck and let me know how it turns out.

GreenPony · 03-26-2002, 02:19 PM

I will have to try that when i get home..I will post a reply on if it helped any.
Thanks

Chevyguy · 03-26-2002, 05:59 PM

I saw a thread on the Corral.net board that also mentioned poor contact in the 10 pin connectors. My car had the upgrade done (factory mod sticker on the rad shroud) this puts a jumper wire that gives more slack to the 10 pin harness, supposedly excess tension caused intermittent check engine light etc.

HMM I remember having that flashing check engine in my brand new 91!! The dealer said nothing was wrong at the time BASTARDS!

87 GT MUSTANG · 03-27-2002, 12:02 PM

i was looking in my hynes manual and i came across a diagram showing my exactly where the air bypass valve is located, now i have owned another mustang but it was a 2.3 and has a similar if not the same air bypass valve, my question here is would a throttle air bypass valve from a 2.3 fit a 5.0, i am guessing right now the answer is no because of the different air ratio's from a 2.3 to a 5.0, well anyways let me now if anyone has attemted this.

wgp2002 · 04-27-2002, 01:05 PM

I have a problem too. It idles at 1400 rpm and i have replaced the tps, egr valve cleaned the little black and white clips on the intake. It still idles there and stays there all the time. I ran a diagnostic test and it said the egr valve was bad so I replaced that, but nothing happened. I unplugged the harness from my tps and nothin happened is that a problem too.

abesmith69 · 04-29-2002, 07:28 AM

disconnect the idle air bypass for 5min and plug it back in.

Comatose · 04-29-2002, 11:01 AM

For reference:

Disconnect the IAB when the car is running or shut off?

Thanks,
Jeremiah

abesmith69 · 05-01-2002, 07:04 AM

when the car is shutoff

mike5p01 · 05-01-2002, 03:10 PM

I too had that same problem... tried all those things mentioned. I was so aggravated by it. One day when I had the hood up I heard a whistle... turns out it was just the vacuum line that ran right behind the distributor.

Mike5p0
_________
'93 Lx 3.73, O/R H-Pipe, 2 1/2 cat back

03-25-2002, 01:55 PM	#1
87 GT MUSTANG Registered Member Join Date: Mar 2002 Location: Oshawa,Ontario Posts: 46	engine idling problem i was wondering if someone could help me out here, i have a problem with my engine idling up to 1500-2000 rpm's when i am at a stop light or just sitting in neutral or have the cluthch pressed in, My car is a 1987 ford mustang with a k&n filter and nothing else, i run 91 octane, she is bone stock, it is mostly when my car is warm that it wants to rev high, it has been an on going problem since i first bought the car last year and i recently did a tune up including plugs (bosch platinum), wires (accell street custom fit), cap & rotor (platinum gold) and an oil change with valvoline higher mileage engine oil and it seemed to not want to idle as much as it used to but it is still there, i have been told to replace my oxygen sensors and i have been underneath the car and they look like they have never been done since it first came out of the factory, so i am wondering if anybody else has had this problem and if they have fixed it with the solution i just said (oxygen sensors) i know it would be a good idea to replace the sensors as it is but with $60.00 a piece canadian and with two of them needed, money is kinda tight, so that is why i need to know if this is the problem, thanx. __________________ Adam pennington

03-25-2002, 04:52 PM	#2
GreenPony Registered Member Join Date: Feb 2002 Location: Louisiana Posts: 43	Idleing High I have the same problem, But when the weather is cool outside it won't idle high and stick, but if its humid and even if i just start the car and drive off it will still do it,. But if i turn my car off then back on real quick it will be back to normal..I dunno maybe we both can get an answer here..... Berry __________________ 92 GT Hurst Short Throw, BBK Equal Lengths, BBK OFF Road H PIPE,@ Chamber Flows, FLex Fan, K&N.Dying For More!!May not be the fastest but sure sound Good!

03-25-2002, 11:24 PM	#5
kevknotch88 Registered Member Join Date: Jun 2001 Location: Athens, WV Posts: 29	jus my thots 1. idle air bypass is the likely culprit 2. throttle position sensor could also be out of adjustment. 3. check carefully for vacuum leaks have experienced similar problems and mine was a combo of 2&3. kevin __________________ kevknotch88 1988 Coupe 135k BBK uneq, X-Pipe, mac 2.5, pullies, southsides, alum d/s, 3:08's, Tremec, TFS Stage 1 cam, 65 TB, Mass Air, Gt-40 U&L = 13.645 @ 104.61

03-26-2002, 05:31 AM	#6
Import Slayer Registered Member Join Date: Mar 2002 Location: bc canada Posts: 48	i had a different problem, my car was idling really erratically, and just today i bought some throttle body cleaner, took off the intake hose, sprayed it up and down and all around and up into the idler bypass and low and behold now it runs great! only things i reccomend are putting a blanket or rag around the throttle body so spray doesnt get everywhere and when it leaks out, and i didnt see a need to remove the idler bypass thingamajigi just sprayed her right in. one more thing it may take a couple cranks to get ur car going again, but once itturns over i runs beautifuly. i hope this can help someone __________________ now daddy ran whiskey in a big block dodge 89 5 speed LX 5.0 - off road h pipe, B&M short throw, 13* timing, blue bottle glasspacks, removed air silencer, accel super stock 8mm, bosch platinum 4's, no times

03-26-2002, 09:13 AM	#7
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	I clean out behind the throttle plate every few thousand also. The EGR belches exhaust gas behind the TB and carbon and other crap builds up back there. Also when I removed my upper manifold for the valve cover change, I removed the idle bypass valve and totally cleaned out the passage and valve tip. Like others mentioned, if the Idle motor itself is malfunctioning, cleaning it won't help. Also good tip, remove the passage housing and valve together from the TB, then carefully unscrew the motor from the pasasage. You can strip out those little screw heads easy. I would expect to find a vac leak also to account for that high idle __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

03-25-2002, 10:22 PM	#3
fast88 Registered Member Join Date: Mar 2002 Location: Rockingham,N.C. Posts: 80	replace the idle air bypass valve on the side of the throttle body,some people tell you to try to clean it but trust me just replace it as they never seem to run worth a flip after you take it apart and try to clean it.

03-25-2002, 10:52 PM	#4
exgmguy Registered Member Join Date: Feb 1999 Location: Utica, Michigan Posts: 2,631	You can check the idle air bypass by unplugging it while it it idleing high. If it drops like a stone the IAC motor is out of whack. Hard idle may have to be reset, or the motor cleaned or replaced.

03-26-2002, 12:27 PM	#8
abesmith69 Registered Member Join Date: Nov 2001 Location: Ocala, FL, USA Posts: 62	when I have had this problem I disconnect the idle air bypass for about 5 min and reconnect it and my Idle is back to normal. -Abe __________________ *Officially not stock anymore!! 1990 Mustang GT Convertible, Blue with Grey ground effects and white top. Black Leather interior pw,pl,ps,pm, premium sound system and flowmaster mufflers.

03-26-2002, 01:03 PM	#9
RMARIANI Registered Member Join Date: Apr 2000 Location: New Jersey Posts: 167	Try this!! My problem was identical to what you guys are describing. Right behind the intake there are two (or three as in my case) 10-pin connectors. They are white and black. Right now sitting at my desk I'm not sure if I had one white and two black or the other way around. In any case, pull these connectors apart. Do one at a time!! You'll probably find a lot of green sludge. Clean this out with electrical terminal cleaner (from Radio Shack or other electronics store) and re-apply some sort of conductive gel/grease (also from Radio Shack). I hope this works for you. After struggling with the TPS, throttle body, etc., someone on this board recommended cleaning the ten-pin connectors and it worked for my car. Good luck and let me know how it turns out.

03-26-2002, 02:19 PM	#10
GreenPony Registered Member Join Date: Feb 2002 Location: Louisiana Posts: 43	Ten Pin connectors I will have to try that when i get home..I will post a reply on if it helped any. Thanks __________________ 92 GT Hurst Short Throw, BBK Equal Lengths, BBK OFF Road H PIPE,@ Chamber Flows, FLex Fan, K&N.Dying For More!!May not be the fastest but sure sound Good!

03-26-2002, 05:59 PM	#11
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	I saw a thread on the Corral.net board that also mentioned poor contact in the 10 pin connectors. My car had the upgrade done (factory mod sticker on the rad shroud) this puts a jumper wire that gives more slack to the 10 pin harness, supposedly excess tension caused intermittent check engine light etc. HMM I remember having that flashing check engine in my brand new 91!! The dealer said nothing was wrong at the time BASTARDS! __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

03-27-2002, 12:02 PM	#12
87 GT MUSTANG Registered Member Join Date: Mar 2002 Location: Oshawa,Ontario Posts: 46	throttle air bypass valve i was looking in my hynes manual and i came across a diagram showing my exactly where the air bypass valve is located, now i have owned another mustang but it was a 2.3 and has a similar if not the same air bypass valve, my question here is would a throttle air bypass valve from a 2.3 fit a 5.0, i am guessing right now the answer is no because of the different air ratio's from a 2.3 to a 5.0, well anyways let me now if anyone has attemted this. __________________ Adam pennington

04-27-2002, 01:05 PM	#13
wgp2002 Registered Member Join Date: Apr 2002 Posts: 18	Re: Idleing High I have a problem too. It idles at 1400 rpm and i have replaced the tps, egr valve cleaned the little black and white clips on the intake. It still idles there and stays there all the time. I ran a diagnostic test and it said the egr valve was bad so I replaced that, but nothing happened. I unplugged the harness from my tps and nothin happened is that a problem too.

04-29-2002, 07:28 AM	#14
abesmith69 Registered Member Join Date: Nov 2001 Location: Ocala, FL, USA Posts: 62	disconnect the idle air bypass for 5min and plug it back in. __________________ *Officially not stock anymore!! 1990 Mustang GT Convertible, Blue with Grey ground effects and white top. Black Leather interior pw,pl,ps,pm, premium sound system and flowmaster mufflers.

04-29-2002, 11:01 AM	#15
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	For reference: Disconnect the IAB when the car is running or shut off? Thanks, Jeremiah __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

05-01-2002, 07:04 AM	#16
abesmith69 Registered Member Join Date: Nov 2001 Location: Ocala, FL, USA Posts: 62	when the car is shutoff __________________ *Officially not stock anymore!! 1990 Mustang GT Convertible, Blue with Grey ground effects and white top. Black Leather interior pw,pl,ps,pm, premium sound system and flowmaster mufflers.

05-01-2002, 03:10 PM	#17
mike5p01 Registered Member Join Date: Apr 2001 Location: Bloomington, IL Posts: 25	I too had that same problem... tried all those things mentioned. I was so aggravated by it. One day when I had the hood up I heard a whistle... turns out it was just the vacuum line that ran right behind the distributor. Mike5p0 _________ '93 Lx 3.73, O/R H-Pipe, 2 1/2 cat back __________________ 93' - MAC 2.5" off-road h-pipe w/ 2-chamber Mac's, 3.73s, Eiback sport springs, adjustables, screwy interior

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