I got it on video
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
I got it on video I swapped PCMs yesterday and drove the car today...3,000rpm idle again. I'll process the video later...right now I have to take down Christmas decorations. (coming dear!)
It drove fine on the other PCM. I don't know if I have a bad IAC, O2, I know Jesse will say it's still a vacuum leak, but I've plugged most of the ports and I don't see how it could be a systemic leak on the manifold and have it be so intermittent? Why would it run perfect for a week and perfect on a different tune and PCM?
I'm not blaming the tune or the PCM, I think it may be an input causing the W4Me tune to interact with the IAC...possibly the IAC is bad???
It drove fine on the other PCM. I don't know if I have a bad IAC, O2, I know Jesse will say it's still a vacuum leak, but I've plugged most of the ports and I don't see how it could be a systemic leak on the manifold and have it be so intermittent? Why would it run perfect for a week and perfect on a different tune and PCM?
I'm not blaming the tune or the PCM, I think it may be an input causing the W4Me tune to interact with the IAC...possibly the IAC is bad???
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
Here's two samples, I've got a few more...remember the car ran perfect for a week on this same setup. It also runs well after it does this if I swap the PCM. The problem tends to follow this PCM (different tune) but initially it was likely due to a vacuum leak at the throttle body.
High idle
high idle 2
High idle
high idle 2
When i ported my TB, it did the same thing. I thought it was the MAF, replaced, same thing. It ended up being the tb. The increased surface area or somethign was messing with the IAC. All i did was filled in the void where the IAC goes with epoxy, and the redrilled the hole. Problem solved.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
Here's the one showing the idle changing as I depress or release the clutch while coasting in neutral down the highway.
Clutch in and out changing idle
More clutch affect at 0MPH
Clutch in and out changing idle
More clutch affect at 0MPH
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
And when I put it away...SES and struggle to idle. final
Now if I put the other PCM in, it drives normally except for poor hot restart and it runs rich, but it doesn't have a high idle issue. So I don't know if I have an issue like a vacuum leak that is giving the W4Me tune an input that it is reacting to or if I have a bad PCM or IAC???
I sincerely doubt a vacuum leak as I have tested everything I can think of. If I can run a vacuum gage or find some other way that would indicate a vacuum leak I would perhaps tear the intake off again, but I'm very doubtful this is it.
In a few of the videos you can see the O2 readings, they're all over the place, but it seems like my other motors behaved the same...how much could an off O2 reading affect the idle speed???
Now if I put the other PCM in, it drives normally except for poor hot restart and it runs rich, but it doesn't have a high idle issue. So I don't know if I have an issue like a vacuum leak that is giving the W4Me tune an input that it is reacting to or if I have a bad PCM or IAC???
I sincerely doubt a vacuum leak as I have tested everything I can think of. If I can run a vacuum gage or find some other way that would indicate a vacuum leak I would perhaps tear the intake off again, but I'm very doubtful this is it.
In a few of the videos you can see the O2 readings, they're all over the place, but it seems like my other motors behaved the same...how much could an off O2 reading affect the idle speed???
Trending Topics
How long are you going to put up with bullshit like this before buying your own tuning software? It really isn't that hard to learn the basics, and there is plenty of forum help on the more advanced issues. Since you aren't FI, the likelyhood of damaging your motor from a **** up is very low.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
How long are you going to put up with bullshit like this before buying your own tuning software? It really isn't that hard to learn the basics, and there is plenty of forum help on the more advanced issues. Since you aren't FI, the likelyhood of damaging your motor from a **** up is very low.
"Really dear, we can both use EFI live"
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
OK, with factory PCM and Predator tune
Startup
Drive
More driving
LTFTs
I wonder if I can swap tunes with the predator? This way I can see if it's a hard fault with the PCM? If I save the wait4me tune on my PC and then down load it to my factory PCM and try it out that way...Jesse told me the Predator may not up load all the parameters though and that he uses a different operating system so I may not be able to do this.
I'm telling you, if I had an extra $1,000 I'd buy EFI live and a wideband setup tomorrow!!
I still don't think this is a tuning fault. My stock motor always held its idle at around 2,000rpm if you were at speed and depressed the clutch. My other 02 SS also did this, but maybe at 1,800rpm and only for maybe 20 seconds. With the mods and a more reactive tune perhaps a problem I had all along is much more pronounced now???
I'm really open to all suggestions. Anybody know if one of these things will work as a good scanner logger with my laptop?
Startup
Drive
More driving
LTFTs
I wonder if I can swap tunes with the predator? This way I can see if it's a hard fault with the PCM? If I save the wait4me tune on my PC and then down load it to my factory PCM and try it out that way...Jesse told me the Predator may not up load all the parameters though and that he uses a different operating system so I may not be able to do this.
I'm telling you, if I had an extra $1,000 I'd buy EFI live and a wideband setup tomorrow!!
I still don't think this is a tuning fault. My stock motor always held its idle at around 2,000rpm if you were at speed and depressed the clutch. My other 02 SS also did this, but maybe at 1,800rpm and only for maybe 20 seconds. With the mods and a more reactive tune perhaps a problem I had all along is much more pronounced now???
I'm really open to all suggestions. Anybody know if one of these things will work as a good scanner logger with my laptop?
Last edited by ssheets; Dec 30, 2007 at 12:26 AM.
Do you think the IAC is working? If you pull the IAC connector
does anything change? Some PCMs omit IAC driver components
but there's not any indication of it, that you'd see from the PC.
A core from a drive-by-wire original vehicle might or might not
have the IAC drivers. If it doesn't then the IAC will just sit where
it sits and not be stepping to target.
If the IAC can be commanded by bidirectional controls (i.e. you
change the value, and you see the idle RPM change sensibly)
then it'd be more a matter of "intention" and maybe some "buried
crap" (things the tuning tools don't make accessible, but might
bother the tune somehow).
Since you don't have the tool yourself, maybe try to find a local
who can hook up and probe the IAC angle?
If you have a voltmeter you could look at the four IAC phases
(wires) and see if they show a sensible voltage. A PCM with the
IAC components omitted will show just millivolts of noise but a
functioning IAC will have several volts average on any wire to
ground.
does anything change? Some PCMs omit IAC driver components
but there's not any indication of it, that you'd see from the PC.
A core from a drive-by-wire original vehicle might or might not
have the IAC drivers. If it doesn't then the IAC will just sit where
it sits and not be stepping to target.
If the IAC can be commanded by bidirectional controls (i.e. you
change the value, and you see the idle RPM change sensibly)
then it'd be more a matter of "intention" and maybe some "buried
crap" (things the tuning tools don't make accessible, but might
bother the tune somehow).
Since you don't have the tool yourself, maybe try to find a local
who can hook up and probe the IAC angle?
If you have a voltmeter you could look at the four IAC phases
(wires) and see if they show a sensible voltage. A PCM with the
IAC components omitted will show just millivolts of noise but a
functioning IAC will have several volts average on any wire to
ground.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
Thanks guys. Yes, I inspected and cleaned the pins with electrical cleaner. They look fine. I can check the IAC with my fluke, the mV vs. voltage signal is great info. I've also cleaned the IAC and cycled it out of the TB (careful not to lose peices) and it travels when you turn the key on and off.
I live kind of in the sticks and there's not a lot of resources around. There's one guy about 60 miles from here, but he just wants to sell me a $500 tune.
Do I need to have the IAC connected to load the circuit when I test it? Do I test each of the phases (one of four wires) to ground?
I'll ask Jesse about programming my factory PCM...or send back the one with the problem and try another one? I'm not sure if I want to give up the one that at least runs decent.
I live kind of in the sticks and there's not a lot of resources around. There's one guy about 60 miles from here, but he just wants to sell me a $500 tune.
Do I need to have the IAC connected to load the circuit when I test it? Do I test each of the phases (one of four wires) to ground?
I'll ask Jesse about programming my factory PCM...or send back the one with the problem and try another one? I'm not sure if I want to give up the one that at least runs decent.
Last edited by ssheets; Dec 30, 2007 at 01:06 PM.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
I just went for a quick trip to the store and this is kinda interesting...it does hang a little (I bleive this is normal, but tell me if it's not) while traveling at ~30+mph when I depress the clutch it will hold around 1,800-2,000rpm. Engaging and disengaging the clucth has a few hundred rpm effect on rpm, but it's the opposite direction as the other PCM.
Now if the IAC wasn't working how else would the motor alter rpm so much? A/F ratio might change it a bit, but not a few thousand rpm. From a tuning perspective, what imputs does the PCM use to drive the IAC counts??
If this wasn't so frustrating it would be very interesting. When I do get tuning software I'll have a fundemental understanding of what to do.
Now if the IAC wasn't working how else would the motor alter rpm so much? A/F ratio might change it a bit, but not a few thousand rpm. From a tuning perspective, what imputs does the PCM use to drive the IAC counts??
If this wasn't so frustrating it would be very interesting. When I do get tuning software I'll have a fundemental understanding of what to do.
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
When referenced to ground both PCMs showed either 13vdc or .489vdc at idle. The OEM PCM had the low voltage on the outer pins while the new PCM was the opposite, but I assume this is just the PCM driving the IAC solenoid?
Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
Went for a drive with the W4Me PCM and it runs normal...it will likely run this way for a week or so or until my wife gets near it. I videoed the LTFTs and the O2 readings. I'll post them later.
I videoed the LTFTs and the O2 readings. I'll post them later. Thread Starter
TECH Fanatic
iTrader: (1)
Joined: Nov 2003
Posts: 1,037
Likes: 0
From: Gardnerville, NV.
OK, you wouldn't think it was the same car. This is the exact same setup as the first video at the beginning of this thread. This is the Wait4me PCM and it behaves perfectly. So again I don't see how it could be a tune issue? Perhaps a cold solder joint internally to the PCM??? I inspected the pins again on the header connections and they look perfect. I don't know what else could cause such an intermittent problem?
in shop
from a stop
cruising down the road
O2 readings
in shop
from a stop
cruising down the road
O2 readings