Idle problem

87_stang · Feb 5, 2007

OK, I jusst picked up a 1990 LX verrt the other day. The car has a 306, trickflow stage one cam, trickflow intake, Bassani headers w/ straight pipes all the way back, going to put on flowmasters this week, everything else is stock basically. It is about 15-20 degrees outside so it may be the problem but about 3/4 the time I come to a stop the car will die. My dash lights don't work right now (needs a new switch) so I couldn't tell where it is idling at right now. So I am not sure if it is the cold weather, no mufflers(no back pressure at all) or something else. Any ideas would help guys. Also, when it does sit and idle you can hear the cam and after about every 2-3 lopes the engine will surge up to about 1200 rpm's or so. I held my lighter up there once to try and see where it was idling at and all I saw was when it surged up. Thanks

87_stang · Feb 5, 2007

U2SLO450 · Feb 5, 2007

have you pulled the computer out to see if it was still good. It could be burnt up.

sprayinit · Feb 5, 2007

87_stang said:
OK, I jusst picked up a 1990 LX verrt the other day. The car has a 306, trickflow stage one cam, trickflow intake, Bassani headers w/ straight pipes all the way back, going to put on flowmasters this week, everything else is stock basically. It is about 15-20 degrees outside so it may be the problem but about 3/4 the time I come to a stop the car will die. My dash lights don't work right now (needs a new switch) so I couldn't tell where it is idling at right now. So I am not sure if it is the cold weather, no mufflers(no back pressure at all) or something else. Any ideas would help guys. Also, when it does sit and idle you can hear the cam and after about every 2-3 lopes the engine will surge up to about 1200 rpm's or so. I held my lighter up there once to try and see where it was idling at and all I saw was when it surged up. Thanks

Check the battery / alternator - make sure everythings all charged up and working. If so, next I'd check the IAC.

Also, it may also be just that it's really cold outside and the car hasn't had enough time to warm up or not been used regularly enough. Does it stall after you've been driving it for a while? Or have you not driven it that far yet? You could let the thing idle in the garage for 10 minutes and then drive it around the block ...

HISSIN50 · Feb 5, 2007

A flashlight held by an assistant might be more effective than a lighter.

You could start by cleaning the IAC, especially if the car has cold idle issues (it idles too low). The dashpot function can be inhibited from a dirty IAC. Otherwise, it might take some tweaking due to the HCI to get the idle up a bit (be it from a tune or simply running the throttle stop screw up).

As suggested, yanking codes is a great place to begin.
Good luck.

87_stang · Feb 5, 2007

Thanks for the ideas guys. How do I go about cleaning the IAC? Sorry, that may sound dumb but I have never done it before. I can gut an engine and build a new one but when it comes to the computer and vaccum and all that stuff, I am at a lost most of the times.

HISSIN50 · Feb 5, 2007

87_stang said:
Thanks for the ideas guys. How do I go about cleaning the IAC? Sorry, that may sound dumb but I have never done it before. I can gut an engine and build a new one but when it comes to the computer and vaccum and all that stuff, I am at a lost most of the times.

This write-up might be helpful.

Good luck.

87_stang · Feb 5, 2007

Thanks alot man, that looks easy enough! I'll do it when I get home tomorrow. The symptoms in the link explain everything my car is doing.

Hissin50, I haven't been on the site for a while but aren't you the one who has the 4 eyed cobra?

jrichker · Feb 6, 2007

You guys with idle problems could same a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first post has all the fixes, and steps through the how to find and fix you idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $25 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.

HISSIN50 · Feb 6, 2007

87_stang said:
Hissin50, I haven't been on the site for a while but aren't you the one who has the 4 eyed cobra?

Not me, though it's a common source of confusion (I wasn't aware of his username when I joined).

Neither of my stangs is comparable to the guy you're thinking of ((Hissing Cobra)). As I recall, he's in the fraternity of magazine shoot members.

87_stang · Feb 6, 2007

Oh, ok. Im getting ready to go straighten up the garage a bit and then change the rear brake pads and try cleaning the IAC. Hopefully that helps, if not I'll try others. Thanks again guys!

fox-gt · Feb 6, 2007

http://forums.stangnet.com/showthread.php?t=665835

87_stang · Feb 6, 2007

Start engine and set idle speed to desired RPM with stop screw on throttle body 900 rpm works great with E303 or larger cam)
Turn off engine and reconnect the air bypass solenoid*Optional — set TPS to 0.90 - 0.95 volts (Do not exceed 1.0 volts MAKE SURE!) Use a digital volt meter!

I got this off of the above link. Can someone give me a step by step process on exactly how to do this? Thanks again everyone. BTW, I removed the IAC and cleaned it out w/ carb cleaner and it did help some (about 60% better but still dies and surges everyonce and a while).

HISSIN50 · Feb 7, 2007

87_stang said:
Start engine and set idle speed to desired RPM with stop screw on throttle body 900 rpm works great with E303 or larger cam)
Turn off engine and reconnect the air bypass solenoid*Optional — set TPS to 0.90 - 0.95 volts (Do not exceed 1.0 volts MAKE SURE!) Use a digital volt meter!

I got this off of the above link. Can someone give me a step by step process on exactly how to do this? Thanks again everyone. BTW, I removed the IAC and cleaned it out w/ carb cleaner and it did help some (about 60% better but still dies and surges everyonce and a while).

If you take a cruise through the link I provided above (it's multiple pages long), you should be able to get a pretty good idea. I think pics (like in the link) are easier to ingest than narratives.

Good luck.

f4fntm · Feb 7, 2007

http://www.corral.net/forums/showthread.php?s=&threadid=10805&highlight=connector

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