Ford Mustang Forums banner
Cancel
Create thread New Garage Forums

Idle Surge Problem

Jump to Latest
1.5K views 23 replies 8 participants last post by  kaminski347  
K
#1 · (Edited)
I have a 306 with afr 185, b 41, trick flow track heat intake that i dropped in my car. Stock injectors and stock maf for right now. Im just trying to get the car to run strong.

I had a problem with the egr that I fixed but its still running like crap. I can get the idle to level off just feathering the peddle. I thought it was a vacuum leak, but I ran a vac test and its showing -10 to -13.

So its showing vacuum and im pretty sure i have everything sealed. I still have no power brakes.

Could it be a valve timing problem? The car starts and runs ok so i dont think the timings off. Anyone have suggestions?
 
#4 ·
Timing advances with spout in. Sounds like the balancer may be off and 10 may be more than 10 timing. So when the spout is put in, its advancing way to much. Set it at 0 if you can, then try and put the spout in, and see what Happens.....

You also need to verify that TDC is TDC on the balancer.
 
A
#5 · (Edited)
A couple things I noticed..

-19# injectors on a H/C/I 306 may not be enough. 24# with matching mass air sensor would help

-"the car starts and runs ok" Im guessing the problems only show up after it warms up? 1 - 2 mins of driving/ running

-"Its weird tho because everytime I put the spout connector back in it dies."
While the spout is out the timing is locked ( no ecu control) . So what ever bad sensor value that is messing up your fuel and spark timing normally, has no effect with the spout out..

-Please pull your engine codes, it will make this easier! Even if you CEL light is not on. Pull you codes! KOEO and KOER if you can!!

-Did you set your base idle? what is your fuel pressure?

-Check your wiring!! check all grounds, confirm there are no shorts from sensor plugs to wire harness in the engine and toward the ECU ...
 
Save
Reply Quote Like Like
#6 ·
If you haven't installed an idle air adjuster plate, do it. Even then, my car with Comp 270HR cam, 24lb injectors and 24-lb calibrated ProM MAF wouldn't warm idle for #### until I got it tuned, and in the several years since, I've never once had an idle problem. Fires right up and idles like stock, no matter what the weather, no matter whether the engine is warm or cold.
 
Save
Reply Quote Like Like
K
#7 · (Edited)
Ok im going to run the codes tomorrow. Im going to just go up and buy the meter. And I'll test the timing with the spout in. Im pretty sure the spout only advances a couple degrees. Its been a while since my car was running but i think it only advances it by 2 degs or so.

I was reading something about the Vacuum reservoir. I dont think i have that connected. I could be wrong but is that on the passenger side at the top of the firewall where two lines run into and one runs out? Could this be a problem with my vacuum?
 
K
#9 ·
What I meant was the spout advances it on top of how much you advanced it. So I put it a 10 deg, the spout advances it a little more so it equals 12 degs total. I could be wrong though. The car has been sitting for three years while i finished college.

Im going to look and see if the vac reservoir is connected anywhere. Where should that line run too if it is connected?
 
A
#12 ·
How much experience do you have with mustang EFI?
Do you have a shop manual for this car?

Pulling the spout plug allows you to set the timing statically with out the computer advancing it, it essentially disconnects the TFI from the ECU,

The factory timing is 10deg with the spout OUT!! If you have premium gas you may go up to 12-14 degs or more.. with the plug in,the ecu can advance the timing to as much as 32 degrees at full throttle. plug the SPOUT connector back in before driving. There is no point in "testing your timing with the spout in"!!!

You said it runs fine with the spout out. Unless you have a bad TFI or ECU problem. Something else is throwing the ECU off with a bad signal/value. Just pull the codes, thru the MIL light is the easiest and it only requires a paper clip. paper and pencil.. KOEO or KOER

please go back to my first post and check the rest of the suggested items.

Let us know what you find.
 
Save
Reply Quote Like Like
F
#13 ·
Maybe someone already cover this... but did you set your tps? I had an idle surge problem and was able to cure it by trying different combos of idle adjustment / tps voltage settings. I am running a PMS, which will probably make more of a difference for me. Have you tried unplugging the tps all together and setting the idle up?
 
K
#15 ·
I do have experience with efi. I have two shop manuals for the car. Im pulling the codes tonight. I havent done a base idle reset. I just read up on it yesterday. Those are the two things im goin to do tonight.

I just wanted to make sure I had all the vac lines right since Im not longer running smog pump and ac.
 
K
#16 ·
I pulled the codes on my mustang. I bought a digital reader and it came up with a code 23, 10, 11. So I looked up the codes. 23 is tps out of range. Im assuming that this is because I dont have the base idle set. Let me know if this is correct.

I have no clue what code 10 is. And code 11 is nothing to worry about. Let me know what you guys think.
Edit/Delete Message
 
K
#18 ·
I attempted to reset my base idle and the volts I was reading was 1.23. I couldnt get it any lower. I know theres a way to lower it more but I need to modify it a little. Im going to research it a little but is there anyone else that had the same problem? Can you give me some tips on how to lower it?
Thanks guys
 
#22 ·
The TB blade is too open, there is no reason to slot the sensor, they don't come slotted so you don't screw it up.

You must have been playing with the throttle stop, thinking it was an idle set screw.
 
Save
Reply Quote Like Like
I
#23 ·
I just went through this. Your tps voltage is obviously too high so your throttle blade is way open at idle. Also very bad. The ECM is made to think the car is off idle. You need to pull the plug off the IAC and set the idle as LOW as you possibly can without having the car stall. In other words, get that throttle blade as close to closed as possible. That is the first and VERY important step of the idle reset. After that, you can go through the rest of it. If you want the car to idle right, the ECM needs to know the car is at idle. My guess is after you turn that throttle screw down, your tps numbers will come down as well. The entire idle reset procedure has to be followed correctly. Do not skip any steps. It is even possible that doing it once will not yield the best results. I had to repeat the process until I got the idle just the way I wanted it. Follow the directions and make sure to adjust the tps after every time where you turned the throttle stop screw. What I do is set my idle with the screw while the IAC is dissconnected and unplug the batt for a bit after. Then start the car (IAC disconnected) and see if it runs the same. If it does turn the car off, check tps, and if all looks ok plug the IAC back in and continue with the reset steps. TPS has to be correct before doing the idle reset. If you fix it later, you will have to do the idle reset again. I screwed with this a good 10 times and doing the above is how I got the best results.
 
Ford Mustang Forums
posts
9.8M
members
208K
Since
2001
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, production numbers, VIN decoders, modifications, troubleshooting, power adders, DIY tutorials, and more!
Full Forum Listing
Explore Our Forums
5.0/5.8 Engine Tech General Mustang Tech Windsor Engine Parts GT & SOHC Engine Tech 94/95-Specific Windsor Engine Tech