4A-GE MK1 Engine 85' Idle Problems, Need help!

hotwheels · 04-05-2007, 12:27 AM

Heres my problem.
I own an 85', stock everything scept the K&N crap airfilter that directly replaces the stock paper filter, and I wanna restore it.
I've replaced a lot of parts, and recently I serviced it, replacing the oil, oilpan gasket, tranny fluid, and fixed a slave cylinder leak i had.
I more main prob.
When I start the car, winter or summer, if the engine is cold, it idles at 2000+ rpms untill it warms up and then it drops to 1000 rpm.
I know for a fact that the flex pipe is broken, so an exhaust leak may have something to do with it. I havent checked for any vacuum leaks yet, but is there any thing else I can do to troubleshoot?
any experts out there?

85 hardtops · 04-06-2007, 03:52 AM

A couple of things to check,... there is an idle control / ac compressor idle speed thing-a-ma-bob adjuster, driver's side engine bay, that can cause that if not adjusted correctly, also, almost all Mk1 exhaust manifolds are cracked, or at least every one that I've had. Don't know if that helps, but it's all I know to throw out there...

blazer9903 · 04-06-2007, 08:57 PM

I believe this is normal. My '88 NA idles in exactly the same fashion, and every other NA I've owned has done the same. Even the '86 that my dad had bought in '87 with 5k miles on it idled exactly as you're describing. the 4age loves to run high revs, just don't keep it at 6k for more than 5 or 10 minutes.

I'm no expert, but I think you're chasing a ghost on that one.

CpuZapper · 04-06-2007, 11:24 PM

That's normal. Usually when something is wrong they don't end up idling down and will just stay at 2k since the waxstat in the throttle body goes bad. You might just need to screw in the idle speed screw (it faces up on the throttle body) a little bit till warm idle is down to about 800 rpm.

hotwheels · 04-07-2007, 01:05 AM

thanks.
So is it normal that 4age's idle so high when cold?
What kind of MPG is normal for these engines stock?

hotwheels · 04-07-2007, 01:07 AM

hmm, a lot of people are telling me that, too so you're prob right.
Its still annoying though...

blazer9903 · 04-07-2007, 10:02 AM

my '88 is stock and with 127k mi. its averaging about 26mpg - mostly around town driving.

CpuZapper · 04-17-2007, 02:05 AM

I get about 24-28 around town, and if I keep it under 70 mph, I can get 32+ mpg highway. I once managed to get about 40 with very careful driving, regular gas, and slightly tweaked timing and air flow meter doing 65 down I-5.

AustinTxMR2 · 04-25-2007, 07:02 PM

Quote:

Originally Posted by hotwheels

Its still annoying though...

I like a engine to idle slow when cold to assure plenty of oil is circulating. It still bugs me how high it revs when started but I have come to grips with it.

32 MPG on the highway is easily attainable with discipline and if you car is in good tune.
John

04-05-2007, 12:27 AM	#1 (permalink)
hotwheels elvis Join Date: Mar 2007 Posts: 33 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	85' Idle Problems, Need help! Heres my problem. I own an 85', stock everything scept the K&N crap airfilter that directly replaces the stock paper filter, and I wanna restore it. I've replaced a lot of parts, and recently I serviced it, replacing the oil, oilpan gasket, tranny fluid, and fixed a slave cylinder leak i had. I more main prob. When I start the car, winter or summer, if the engine is cold, it idles at 2000+ rpms untill it warms up and then it drops to 1000 rpm. I know for a fact that the flex pipe is broken, so an exhaust leak may have something to do with it. I havent checked for any vacuum leaks yet, but is there any thing else I can do to troubleshoot? any experts out there?

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04-06-2007, 03:52 AM	#2 (permalink)
85 hardtops No Skills Join Date: Apr 2007 Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	A couple of things to check,... there is an idle control / ac compressor idle speed thing-a-ma-bob adjuster, driver's side engine bay, that can cause that if not adjusted correctly, also, almost all Mk1 exhaust manifolds are cracked, or at least every one that I've had. Don't know if that helps, but it's all I know to throw out there...

04-06-2007, 08:57 PM	#3 (permalink)
blazer9903 No Skills Join Date: Apr 2007 Location: St. Louis, MO Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts My Google Map iTrader Rating: (0/0% )	I believe this is normal. My '88 NA idles in exactly the same fashion, and every other NA I've owned has done the same. Even the '86 that my dad had bought in '87 with 5k miles on it idled exactly as you're describing. the 4age loves to run high revs, just don't keep it at 6k for more than 5 or 10 minutes. I'm no expert, but I think you're chasing a ghost on that one.

04-06-2007, 11:24 PM	#4 (permalink)
CpuZapper RallyRacer Join Date: Mar 2005 Location: Portland, OR Posts: 482 Thanks: 7 Thanked 25 Times in 22 Posts My Google Map iTrader Rating: (1/100% )	That's normal. Usually when something is wrong they don't end up idling down and will just stay at 2k since the waxstat in the throttle body goes bad. You might just need to screw in the idle speed screw (it faces up on the throttle body) a little bit till warm idle is down to about 800 rpm.

04-07-2007, 01:05 AM	#5 (permalink)
hotwheels elvis Join Date: Mar 2007 Posts: 33 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	thanks. So is it normal that 4age's idle so high when cold? What kind of MPG is normal for these engines stock?

04-07-2007, 01:07 AM	#6 (permalink)
hotwheels elvis Join Date: Mar 2007 Posts: 33 Thanks: 3 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	hmm, a lot of people are telling me that, too so you're prob right. Its still annoying though...

04-07-2007, 10:02 AM	#7 (permalink)
blazer9903 No Skills Join Date: Apr 2007 Location: St. Louis, MO Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts My Google Map iTrader Rating: (0/0% )	my '88 is stock and with 127k mi. its averaging about 26mpg - mostly around town driving.

04-17-2007, 02:05 AM	#8 (permalink)
CpuZapper RallyRacer Join Date: Mar 2005 Location: Portland, OR Posts: 482 Thanks: 7 Thanked 25 Times in 22 Posts My Google Map iTrader Rating: (1/100% )	I get about 24-28 around town, and if I keep it under 70 mph, I can get 32+ mpg highway. I once managed to get about 40 with very careful driving, regular gas, and slightly tweaked timing and air flow meter doing 65 down I-5.