Desperate, tempted to sell!

krahkin

krahkin

Member
May 7, 2004
183
0
16
Acworth GA
#1
I have tried everything under the sun to get the idle on my car correct. I have tried setting base idle based on numerous threads within stangnet, corral.net and muscularmustangs to no avail. Here's the situation. I recently installed Trick Flow Stage 1 cam, AFR heads, Cobra intake, BBK 70mm TB, C&L 76mm MAS. After the install, however, my car refuses to idle steadily at anything under 1500. If I try to set the base idle any lower than 1500, it will begin to fluctuate more and more until it finally stalls out. The fluctuation only occurs after the car has been running for about 1 minute. The first minute of crank time is fine. I traced all of the vacuum lines and they appear to be correct, and I have yet to hear to find any leaks. The idle valve is in working order, I even swapped with another working unit to double check. The TPS has been set to .98v with a digital multimeter. Any help would be appreciated. I know the 94-95 can run cams with LSA under 115, Ive seen it and know folks that have. I want to get the idle fixed before moving on with my upgrades.
 
#2
i drilled 1/8" hole in my throttle body butterfly and mine idles fine at 950rpm, i had same problem with E303 cam, our computers are not very adaptive with major modifications. i think you should try the same.

- Kons
 
#4
when you installed new heads an cam do you have to set the tps voltage? i dont get what that does or how it even works, can someone explain because im thinking about getting the trickflow H/C/I kit from summit.
 
#6
I thought about drilling a hole in the butterfly, but I thought the screw next to the idle valve did the same thing? Maybe someone can chime in on that one.

I guess I could get a tweecer, but I dont have a laptop....

Donjohn, Ive already tried the muscularmustangs.com method.

Keep the ideas coming though! I hate to drill into a new TB, but if it works...
 
#7
do you have access to a vacuum gage??? would be cool to see what it pulling for vacuum...whats the LSA on your cam?? I hear you on others beeing cool with low LSAs...seems these EECs are all different....mines never given me a lick of trouble....thats why i didn't go TwEECer....I bought the freakin laptop though.... :bang:

anything under 1500 is no dice...thats crazy right there...
 
#9
I might just be temped to do the hole trick...you can always fill it back up with JB weld if it doesn't work....


cb18201 said:
when you installed new heads an cam do you have to set the tps voltage? i dont get what that does or how it even works, can someone explain because im thinking about getting the trickflow H/C/I kit from summit.
Click to expand...

The TPS should be re-checked any time you undo the throttle linkage and remove the TB....things move around..
H/C/I are gonna change airflow and such for sure....the TPS and idle should be verified and re-set....
All the TPS does is tell the EEC where the throttle position is....the computer reads its position and sends fuel/spark/timing to accomadate the throttles position....when the time comes we can run you thru it...its not really all that voodoo... :D
Hope that helps some...
 
#10
A vacuum gauge might be of assistance. But with a nasty cam, it will probably fluctuate (sp?) & not help much at all.

How long have you ran the car without disconnecting the battery? From what I have read, it seems the computer needs time to learn the new cam. Some people say up to a week or two.

I say set the idle at 900, and let it stay there as long as possible. If it's going to stall, give it some gas. Let it idle like that for at least 10-15 minutes. Hopefully the computer will adapt.

Drilling a hold in the butterfly valve will only increase the air to the engine, without changing the TPS voltage. It might be just enough to prevent the motor from stalling.
Scott
 
#11
Scott...Thats what im curious about....i'd like to see the vaccum and get a reading....
i run the steeda 19, a mild cam, and get 15-18 steady idling....with his idle wanting 1500, it wonder if its a low vac thats making that happen??? I can go down to like 650 if i want...sure its lumpier, but it would go there....im at 800 now...

A vac gage is cheap money....i have an Accu-tron, same as the guys who makes the code readers...i think it was like 15.00...
for nothing more than finding a vac leak that you thought you didn't have, to just seeing if that cams the cause, she will be jumpy and low if so....raising the RPMs some should level it right out....or something else is wack????

he mentioned he did the reset stuff (muscularmustangs)...i used the same link and got mint results...its pretty ABC in the write-up....sounds like he's been there done that...many times... :D
 
#12
I don't want to sound too paternal here, but you didn't mention it so I have say it. The first thing I would do is check for computer trouble codes.

I've owned a number of different Ford's over the years, and they've all had a wandering idle to one extent or another when I bought them. I've always just cleaned the heck out of the IAB valve, throttle body, and MAF sensor, (along with a general tuneup) disconnected the battery to erase PCM memory and that's it. Problem solved. The car would idle like new.

I have also had a couple of car's where the IAT and the ECT sensor's were starting to head south, and they were the cause of the random wandering idle. I replaced both sensor's (they're quite cheap!!) disconnected the battery to erase the PCM memory and the idle was like brand new.

I've done the above procedure's on half a dozen different Ford's and it has fixed the random idle every time.

One more thing, setting the TPS on a 94/95 to <1 volt does nothing. The computer takes a baseline reading from the TPS when the key is turned on and calls that voltage reading "throttle closed" (doesn't matter if the voltage is .9 or 1.2). In fact there's some debate that setting the TPS to a specific voltage on a 94/95 does more harm than good. Do a search on setting TPS for the 94/95 on both StangNet and The Corral and you'll find many posts on this topic.

Hope that helps
 
#13
mo_dingo - I cant set the idle at 900, thats my problem. If I try to go under 1500, it starts to fluctuate until its finally doing 500 to 1500 thus stalling out on the lower side. Ive reset the computer too many times to count in the past 2 weeks :D

rio - i'll run to the part store tomorrow and pick up a guage and let ya know what its pulling at various rpms

silver - my check engine light does not come on, will i still have codes to pull? ive read that setting the tps on sn95 doesnt do any good (i visit corral too), but ive read one or two that had positive results with it, so i figured what the heck?

thanks for all the responses. maybe i can get this figured out, its been frustrating the heck out of me.
 
#14
You will probably need to get a chip burned. This costs about $380 I think. My buddy had to do this for his 95 5.0 after he put GT40p heads on it, an E303 cam, a Cobra Intake, exhaust, and some other minor stuff. After he got the chip, the car ran great. Before that, it wasn't getting enough fuel.
 
#16
krahkin said:
Like I said earlier, I want to check as much as I can before getting the chip/dyno tune. After all, I still have a blower to mount on :rolleyes:
Click to expand...

:rlaugh:

When you disconnect the battery, it forgets everything it's learned thus it starts from scratch.

What I mean is turn the idle down below 1500, and let it try to stall out. When it does, give it some throttle & get it back. Repeat the process for at least 15 minutes. Hopefully after that, the computer will learn what to do. It may take some time, but if it works it will be worth it.

Good luck.
Scott
 
#17
As you put more and more mods on your car for max power you will see a decline in the drivability of your car and a steady idle is one of the major frustrations of all of them.

Go over to one of the tuner sites and you will see that most of the talk is about trying to get back some drivability and a good idle is the focus of most of those threads.

Even with all mechanical adjustments correct and having access to fine tune the values in the pcm it can be a time consuming task to achieve a good steady idle.

After I put on heads & cam my drivability was really bad and at that time I was using the stock maf which you know has the correct transfer curve.

I did not make very much headway with slaying the drivability gremlins until I made some adjustments to the pcm's values to compensate for the all of the hot rod parts.

I do feel your frustration but it seems that each combo is different cause some have more probs than others and the fix is different for some than others :shrug:

Later
Grady
 
#19
my check engine light does not come on, will i still have codes to pull?
Click to expand...

I would check for codes if you haven't already done it. You could have some trouble codes stored without the CEL coming on. Besides, it only takes 5 minutes to do and then you've eliminated that possible cause of your idle problems.

One more thing, as I mentioned in my earlier post, how old are you're IAT/ECT sensor's (O2 sensor's too for that matter)? They have been known to cause problems when they get old. They're output goes all wonky, but not enough to hit the preprogammed limit that would cause the PCM to notice and trip a CEL. The car starts to run less then ideal and the PCM tries to compensate by adjusting a/f ratio (injector pulse) among other things. Now the car has the wrong a/f ratio for the conditions which will cause a number of other problems as I'm sure you are aware. One of those being, your idle is going to be off a bit. The PCM tries to adjust the idle speed with the IAB valve, but its making those adjustments based on the assumption that the input from the other sensor's are accurate, when in fact they're not.

Because the information from some of the sensor's is inaccurate (IAT/ECT in this case), the PCM adjusts IAB valve incorrectly and doesn't see the idle speed it was expecting, it again adjusts the IAB valve to try and get the idle where it's supposed to be, again using the data from the inaccurate sensor's.......you can see where this is going right? Wandering/fluctuating idle. Throw some performance parts into the mix with inaccurate sensor's, and well, good luck getting a steady idle. :bang:

Long story short, replace your IAT/ECT sensor's if they are old!! (well under $100 for the pair) :) (O2 sensor's too!! They're only good for about 80,000 miles under optimum running conditions) :banana:
 
#20
I bought a vacuum guage and tested today. At 1500 RPM, it holds steady at 18 hg. If I drop the idle, the vac varies with the fluctuation from 14-18 hg.

I may run back down to the parts store and pick up some sensors. At least that will help narrow it down if it doesnt fix. The only thing is, I never had idle problem before I made the mods, so it makes me think the sensors would be ok.
 
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