Idle surge problem after head and can install.

[93lxSaleenclone]

Finished installing aluminum heads and e303 cam yesterday and now I have the idle surge problem. I went through all the idle resets procedures and now it seems to be better. It now only does it for about the first 30 seconds them seems to idle fine. Before the install it didn't do this. I checked all the vacuum lines and everything checked out good that I can see. I also cleaned out the IAC and tried another one with no change. Also installed a block off plate and removed the emission crap. And ideas what else to check? I have read about 100 post about this and hope I can get it fixed without to much hassle.

 

[90 lx convert]

Provided everything is back the way it should be and you don't have a vacuum leak, change the 02's. Even if they're not that old. Do a computer reset and it should be OK. Make sure you only buy the original Bosch 02's. Mike

 

[93lxSaleenclone]

I'll check them out but what might cause them to go bad all of a sudden? Other than the idle problem its running awesome.

 

[90 lx convert]

I know.......that's what I never could understand. Here's what, 10 yrs ago I did my first HC swap on a 5.0. Up untill then it had always been older mucsle cars that I worked on. So, after this swap the car surged all over the place and shut off everytime you pushed in the clutch. I called Fords tech line and the tech said "change the 02's and it'll be fine" and he hung up. Go figure. So with nothing to loose that's what we did and it worked. Now I've done maybe 10-12 HC swaps and 4 times ran into the surge demon and the 02s fixed it everytime. Like I said as long as you have it back together right and don't have a vacuum leak my next step would be 02's. Maybe they get polluted by silicone from sealants? It worked. Post back and let me know. Mike

 

[93lxSaleenclone]

I'll give it a shot as long as I don't find anything else oviously wrong when I look at it later. Thanks.

 

[4rdnut]

What rpm does the engine idle at? My e303 cam likes 850-900 rpm. I had the surging like yours in the beginning and when i upped the idle, the surge went away and don't expect the eec iv computer to instantly except the changes you make, i drive for a week to allow the computer to learn changes. I have better luck changing the idle speed with the engine off. I just go 1/4 turn at a time with the idle screw and restart. Setting the idle with the engine running, with the iac electrical connector off and expecting to get a decent idle when you reconnect the iac connector is pure fantasy, base idle reset never works with my setup.

 

[93lxSaleenclone]

Its at about 900. The last two times I started it it was doing the surging once and the second time it idled fine. I will see how it goes over the next few days.

 

[93lxSaleenclone]

I have about 125 miles on it since the install and it seems to surge less than the beginning. I'd say it does it about 2 out of 5 starts and still lasts for about 30 seconds then idols. did I haven't changed out the o2's yet because im going to install a new pipes from the headers to mufflers and was planning on changing them at that time. Here is how i set the idol. Is this the correct way?

Reset the computer. Battery was off for a couple hours with lights on.
Unplugged the IAC and hooked up the battery.
Started the car and set the idol with the set screw (900ish)
Turned off car and hooked up the IAC back up.
Started the car and let it idol for a couple minutes then shut off.
Checked TPS voltage and it was .94
DId the same with all accessories on.

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems.

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the fixes & updates. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[93lxSaleenclone]

Im about to start going through the checklist and have a question. How will not having the emissions stuff on the car affect the computer when I go to pull the check engine codes? Should I just dump whatever codes are there and go onto checking the rest and setting the idle?

 

[jrichker]

Im about to start going through the checklist and have a question. How will not having the emissions stuff on the car affect the computer when I go to pull the check engine codes? Should I just dump whatever codes are there and go onto checking the rest and setting the idle?

Removing the emissions gear is a bad idea, but it usually won't cause idle problems. Post the codes you get and I will post the 5.0 Mustang specific definitions and fixes.