Surging at idle and driving and stalling

[ggt4]

I have a couple problems that must all be related. At idle my marauder the rpm's will surge from 1000 rpm to 1500 about every minute or so regardless of the operating temperature.

When the car is driving I can feel this same surge. It feels like my cruise is on temporarily when its not.

More recently when I back into a parking spot the car stalls when I come to a stop. That has happened about 5 times. Today in traffic the car stalled on the beltway after coming to a stop, and later on that same trip the car stalled when pulling into my garage front first(before it only did this when backing in)

Is this all programming related or is this a bigger problem.

[RCSignals]

Since your car is no longer stock it may be tuning/programming related

[RR|Suki]

I have a couple problems that must all be related. At idle my marauder the rpm's will surge from 1000 rpm to 1500 about every minute or so regardless of the operating temperature.

When the car is driving I can feel this same surge. It feels like my cruise is on temporarily when its not.

More recently when I back into a parking spot the car stalls when I come to a stop. That has happened about 5 times. Today in traffic the car stalled on the beltway after coming to a stop, and later on that same trip the car stalled when pulling into my garage front first(before it only did this when backing in)

Is this all programming related or is this a bigger problem.

Change in the program fix this kind of thing on my car... changed the function for the Idle Air Controller... however this could be the IAC going bad on you too.

[Marauderjack]

Talk to Dave, get Scott Beer's email address and send your tune to him......He fixed mine when it was doing the same!!!:beer:

Funny thing about mine was that it would only stall in Neutral or Park.....Never in drive!!:cool:

Good Luck!!

Marauderjack:D

[HwyCruiser]

The IAC "fix" should be in the tune already, but it may need to be tweaked on some more. Has this just recently started happening or ever since the s/c went on?

Since you have a high idle (should be about 750 rpm in drive), I'd also go over the vacuum lines really good. Any vacuum leaks will really mess with the idle control. The vacuum system on our car is pretty basic - look at the white sticker under the hood. Remember that it's been modified to hook up a vacuum line to the s/c bypass valve.

I'd also check the IAC valve itself ($70, Motorcraft pn: CX1781) since these have been known to go bad.

[MarauderMark]

I have the same problem with the idle ever since i got er running.Called Dennis and he said it's all in the tune.Going to see him 1st week of May for the fix.Thank God for Dennis:up:

[ggt4]

The IAC "fix" should be in the tune already, but it may need to be tweaked on some more. Has this just recently started happening or ever since the s/c went on?

Since you have a high idle (should be about 750 rpm in drive), I'd also go over the vacuum lines really good. Any vacuum leaks will really mess with the idle control. The vacuum system on our car is pretty basic - look at the white sticker under the hood. Remember that it's been modified to hook up a vacuum line to the s/c bypass valve.

I'd also check the IAC valve itself ($70, Motorcraft pn: CX1781) since these have been known to go bad.


The surging has been happening the whole time, but the stalling is new.

[HwyCruiser]

The surging has been happening the whole time, but the stalling is new.

The surging idle could be caused by the s/c bypass valve not opening. The s/c bypass valve opens under engine vacuum and closes when vacuum is removed (0 psi and up). It's main job is to relieve pressure back around the blower right after you get off the pedal, but if it isn't working right it can cause weird idle problems too.

Watch the linkage on the s/c bypass valve actuator (round top where the vacuum line plug in) and have someone start the car. You'll see the actuator pull the linkage towards itself to open the butterfly inside the valve. If it's opening then at least you can check that possibility off.

[RR|Suki]

The surging idle could be caused by the s/c bypass valve not opening. The s/c bypass valve opens under engine vacuum and closes when vacuum is removed (0 psi and up). It's main job is to relieve pressure back around the blower right after you get off the pedal, but if it isn't working right it can cause weird idle problems too.

Watch the linkage on the s/c bypass valve actuator (round top where the vacuum line plug in) and have someone start the car. You'll see the actuator pull the linkage towards itself to open the butterfly inside the valve. If it's opening then at least you can check that possibility off.

what bypass valve do you guys use??

[HwyCruiser]

what bypass valve do you guys use??

The Procharger "ProFlow" inline 1-1/2" butterfly valve. It's the one to the left in the pic linked below, but mine is anodized black.

http://www.procharger.com/images/artwork/bypass_valves.jpg

[RR|Suki]

ahhh ok I've seen those

[Jerry]

Let me change the direction of this thread a bit....

Many if not all of the centrifigual blowers have issues like this. When the dust settles I have NEVER seen a bypass big enough to satisfy my multiple engineering degree mind. If you put a pressure sensor in the tube between the bypass and the throttle body you will never be able to make all the pressure go away when the bypass is open. Please don't argue and say I'm wrong, I can assure you that I have more data proving this than you do. Does this mean it will cause problems? It depends how you define problems. What the fuel trims on a WOT coast down from 6000 RPM, they will not be in control, period. Just because there is no pressure in the tube at idle doesn't mean all is well.

What can you do about it? Unless you want to put several race bypass' the best solution is to put a 2005 Mustang GT MAF a few inches before the throttle body and install a Diablo MAFia on that MAF. Once tuned correctly with this setup your centrifigual blower car will have NEVER ran, idled, or respond like this before.

If you really want to solve all of these problems for good,a nd have a car that responds better than it ever has, think about this.....it doesn't matter what kind of blower it is, Dennis', ProCharger, etc..

j

[thePunisher]

so your saying to switch to a blow-thru setup??? what if one were to switch to a blow-thru maf without using the mafia etc????

[RR|Suki]

Let me change the direction of this thread a bit....

Many if not all of the centrifigual blowers have issues like this. When the dust settles I have NEVER seen a bypass big enough to satisfy my multiple engineering degree mind. If you put a pressure sensor in the tube between the bypass and the throttle body you will never be able to make all the pressure go away when the bypass is open. Please don't argue and say I'm wrong, I can assure you that I have more data proving this than you do. Does this mean it will cause problems? It depends how you define problems. What the fuel trims on a WOT coast down from 6000 RPM, they will not be in control, period. Just because there is no pressure in the tube at idle doesn't mean all is well.

What can you do about it? Unless you want to put several race bypass' the best solution is to put a 2005 Mustang GT MAF a few inches before the throttle body and install a Diablo MAFia on that MAF. Once tuned correctly with this setup your centrifigual blower car will have NEVER ran, idled, or respond like this before.

If you really want to solve all of these problems for good,a nd have a car that responds better than it ever has, think about this.....it doesn't matter what kind of blower it is, Dennis', ProCharger, etc..

j

That seems like a rather involved conversion, when it's a simple fix. If the IAC knows what to do half the headache should be gone.
I used to stall constantly when I had my diablo chip, and I thought it was a dirty IAC... when I took the chip out I switched to sniper tuning software, and a PMAS Infinity calibration MAF, a little tweek here a little there, all is well. As long as the software lets you change IAC stuff and such this should not be hard to fix :confused:

[Jerry]

so your saying to switch to a blow-thru setup??? what if one were to switch to a blow-thru maf without using the mafia etc????

Depending on some things you may or may not need a MAFia, it depends on the amount of air flowing through the engine and the diameter of the tube where the 05 Mustang MAF is put in. But you HAVE to use a 2005 Mustang MAF to do this.

j

[Jerry]

That seems like a rather involved conversion, when it's a simple fix. If the IAC knows what to do half the headache should be gone.
I used to stall constantly when I had my diablo chip, and I thought it was a dirty IAC... when I took the chip out I switched to sniper tuning software, and a PMAS Infinity calibration MAF, a little tweek here a little there, all is well. As long as the software lets you change IAC stuff and such this should not be hard to fix :confused:


Go put a pressure gauge about 6" from the throttle body and tell me how much pressure is in the tube when you are curising down the road. Now the flow through the IAC valve has changed because you have pressure in the tube on one side of the throttle body and vacuum on the other. The flow across something is a function of the pressure drop acrossed it. The pressure drop has increased so the flow through the IAC valve has changed.

I bet your car with pressure in the tube won't work well at altitude. Now there are different pressures at the inlet and in the intake and the flow chagnes. While there is a IAC transfer function in the software there is no compensation for pressure in the inlet tube.

Also go look at a GM car, where is the MAF? A few inches from the throttle body. Take even the most lame of GM engines and do a quick stab on and off of the throttle and see what happens? I bet it revs pretty fast. Try that on your Marauder and see what happens? The engine will raise in RPM a small amount AFTER your foot has come off the pedal. Why? They don't have 2-5 feet between the air meter and engine. They don't have to have all the vodoo in the software to make up for the lag and response issues of having the MAF so far away....

There is A LOT more to this than what you think, it's just not as simple as you say.

j

[Breadfan]

Jerry, I don't want to further over-simplify this, but question regarding N/A cars and cars with Roots blowers, based on your description above, would a simple relocation of the MAF closer to the TB give these cars quicker throttle response?

Would additional tuning be necessary by moving the MAF further from the air filter and closer to the throttle body?

Just curious if such a change would be as simple as relocation of the MAF for roots and N/A cars with a normal intake tube.

[TooManyFords]

Also go look at a GM car, where is the MAF? A few inches from the throttle body. Take even the most lame of GM engines and do a quick stab on and off of the throttle and see what happens? I bet it revs pretty fast. Try that on your Marauder and see what happens? The engine will raise in RPM a small amount AFTER your foot has come off the pedal. Why? They don't have 2-5 feet between the air meter and engine. They don't have to have all the vodoo in the software to make up for the lag and response issues of having the MAF so far away....

Jerry,

Not to hijack this thread, but I too am interested in what would need to change in a tune if the MAF was placed directly above the throttle body plates. I happen to have that EXACT setup on my car, right down to using GM LS2 MAF's (a pair) that sit right on top of the throttle bodies.

BTW, I emailed Tana about a "hobbyist" type of subscription to EFITO. Let me know if there is going to be such a thing.

Cheers!

john

[RR|Suki]

Go put a pressure gauge about 6" from the throttle body and tell me how much pressure is in the tube when you are curising down the road. Now the flow through the IAC valve has changed because you have pressure in the tube on one side of the throttle body and vacuum on the other. The flow across something is a function of the pressure drop acrossed it. The pressure drop has increased so the flow through the IAC valve has changed.

I bet your car with pressure in the tube won't work well at altitude. Now there are different pressures at the inlet and in the intake and the flow chagnes. While there is a IAC transfer function in the software there is no compensation for pressure in the inlet tube.

Also go look at a GM car, where is the MAF? A few inches from the throttle body. Take even the most lame of GM engines and do a quick stab on and off of the throttle and see what happens? I bet it revs pretty fast. Try that on your Marauder and see what happens? The engine will raise in RPM a small amount AFTER your foot has come off the pedal. Why? They don't have 2-5 feet between the air meter and engine. They don't have to have all the vodoo in the software to make up for the lag and response issues of having the MAF so far away....

There is A LOT more to this than what you think, it's just not as simple as you say.

j

no disrespect but you are very wrong with regards to my own car, let me say again my issues have been solved, and whatever voodoo that sniper has done works, and works quite well. I'm not saying there isn't a difference in pressure the blower is making pressure well away from the throttle body. All I'm saying is it's not a problem for me, and that tells me that other can get the fix too without re making their whole induction system. And my MAF is probably well over 5 feet from my throttle body. I don't have this phantom rev, my revs actually stop shaply once I let go of the throttle, much like my sport bike. I actually might like the throtle to stay open for a sec or two so the bypass wouldn't have to work so much... that's another matter entirely.
All I'm saying is that my car doesn't have these problems, and it had them with other software, perhaps it's a matter of the back ground scales being terrible... beats me. However I'm just pointing out that voodoo or not, I have solved this issue without having to re invent my intake (again).

[Zack]

no disrespect but you are very wrong with regards to my own car, let me say again my issues have been solved, and whatever voodoo that sniper has done works, and works quite well. I'm not saying there isn't a difference in pressure the blower is making pressure well away from the throttle body. All I'm saying is it's not a problem for me, and that tells me that other can get the fix too without re making their whole induction system. And my MAF is probably well over 5 feet from my throttle body. I don't have this phantom rev, my revs actually stop shaply once I let go of the throttle, much like my sport bike. I actually might like the throtle to stay open for a sec or two so the bypass wouldn't have to work so much... that's another matter entirely.
All I'm saying is that my car doesn't have these problems, and it had them with other software, perhaps it's a matter of the back ground scales being terrible... beats me. However I'm just pointing out that voodoo or not, I have solved this issue without having to re invent my intake (again).


All Jerry said, in a nutshell is:
Another few years have gone by, and with that comes new research.
The 05GT MAF with a MAFia is the newest and best way to overcome all these issues.

And most likely, Jerry is the guy who wrote your base file.

[RR|Suki]

All Jerry said, in a nutshell is:
Another few years have gone by, and with that comes new research.
The 05GT MAF with a MAFia is the newest and best way to overcome all these issues.

And most likely, Jerry is the guy who wrote your base file.

Indeed and all I said was that I like my Infinity calibrated MAF, and sniper software, and since I changed my previous troubles have gone away, and as such makes it seem like changing the whole intake path is a more complex and expensive thing. And I no longer have that diablo tune at all, I pulled the chip and nailed it to my wall that tune was going to blow my motor... again :censor:

[Jerry]

Jerry,

Not to hijack this thread, but I too am interested in what would need to change in a tune if the MAF was placed directly above the throttle body plates. I happen to have that EXACT setup on my car, right down to using GM LS2 MAF's (a pair) that sit right on top of the throttle bodies.

BTW, I emailed Tana about a "hobbyist" type of subscription to EFITO. Let me know if there is going to be such a thing.

Cheers!

john

I don't expect their to ever be a hobbiest level. The idea of EFITO is to keep the rif-raf (like SCT) out and have an information exchange on a mature level, and so far it works very well. Everyone has a great respect for each other and I think eveyone is benefiting.

You have LS2 MAF's on your Marauder?

j

[thePunisher]

05 gt??? the mustang or race car??? isnt the mustang gt maf part of the air box lid???

[Jerry]

Jerry, I don't want to further over-simplify this, but question regarding N/A cars and cars with Roots blowers, based on your description above, would a simple relocation of the MAF closer to the TB give these cars quicker throttle response?

Would additional tuning be necessary by moving the MAF further from the air filter and closer to the throttle body?

Just curious if such a change would be as simple as relocation of the MAF for roots and N/A cars with a normal intake tube.

There is nothing simple about relocating the MAF, but in a nut shell yes. Ford has some very complicated software to compensate for how far the MAF is from the engine and things like that. GM also uses a MAP sensor for transient control of fuel as well. The Marauder has a MAP sensor, but I'm not sure if it's used for trasnient fuel control or not, but I can look into it.

It just makes sense to move the MAF close to the throttle body, and yes most cars would benefit from it. You do get much better throttle response if done correctly.

j

[Jerry]

05 gt??? the mustang or race car??? isnt the mustang gt maf part of the air box lid???

The Mustang (GT or V6) use the same MAF. It's called a 'slotted" MAF by the way it slides in. It's not in a housing like the older MAF's so it's not that hard to relocate.

j

[Jerry]

no disrespect but you are very wrong with regards to my own car, let me say again my issues have been solved, and whatever voodoo that sniper has done works, and works quite well. I'm not saying there isn't a difference in pressure the blower is making pressure well away from the throttle body. All I'm saying is it's not a problem for me, and that tells me that other can get the fix too without re making their whole induction system. And my MAF is probably well over 5 feet from my throttle body. I don't have this phantom rev, my revs actually stop shaply once I let go of the throttle, much like my sport bike. I actually might like the throtle to stay open for a sec or two so the bypass wouldn't have to work so much... that's another matter entirely.
All I'm saying is that my car doesn't have these problems, and it had them with other software, perhaps it's a matter of the back ground scales being terrible... beats me. However I'm just pointing out that voodoo or not, I have solved this issue without having to re invent my intake (again).


If your issue has been solved can you tell me what the ISC KAM's are at sea level and at altitude? Can you tell me that actual and desired RPM track right on top of each other during a startup across the temperature range? You did not fix your problem, someone changed something in the software and most likely masked your symptoms. You have no data to verify that your problem is solved and not just bandaided.

Also it doesn't matter whose software you have, SCT, Sniper or Diablo it has nothing to do with the software, it has to do with the person programming and their understanding, or lack there of, of the control system...

So, no disrespect to you, but there are some people in this thread that are trying to learn, so unless you have something to contribute that's worthwhile and can be backed up with data, you don't need to add anymore. We all know your problem is "solved".

j

[Zack]

:popcorn: 56789

[RCSignals]

If i were to use a 2005 Mustang GT MAF with the Trilogy kit having the relocated IAT, would i need adjustement to the tune?

[RR|Suki]

lol worthwile contribution I suppose is measured by how much extra it's gonna cost... it actually has alot to do with the software, becasue it is quite clear to me alot of people who are writing these scales don't even know what their software is doing. This was very clear to me when un named person at diablo told me I have a mechanical issue, the software is fine... guess what it's really not fine... It was the base tune that was off and causeing all the comotion.
I actually do have data, $900 of dyno time worth actually, but really why do I care to get into it? You have already decided that my problem isn't fixed, because clearly you are familliar with my Infinity MAF and clearly you know what my scales look like :rolleyes: ,
and besides if you are the one that wrote the base tune on the chip my marauder came with, quite frankly what you think about if my car is "fixed" means about as much as the chip that is nailed to my wall.
Bottom line is what you are saying may work fine, however it's neither a simple nor cheap matter... on the other hand if you just get the car tuned right it will be a non issue, bandaided or not a moot issue is a moot issue :rolleyes:

as an add on when that tune had my car at 15a/f I was told it's my fuel pump, it's my filter, it's the 90*bend... whatelse... ohh all kinds of stuff, all this other stuff that would "fix" it "more" but I still have a 90* bend and a stock filter and I am at something pig rich like 10.8a/f... so all I'm saying is that if you can get results with what you have do that before going out and buying all this new stuff you don't need...

[Zack]

If i were to use a 2005 Mustang GT MAF with the Trilogy kit having the relocated IAT, would i need adjustement to the tune?

Yes yes and yes.

[RCSignals]

Yes yes and yes.

a lot of yeses

the IAT is already relocated, and tune adjusted for that.

Would the tune need to be adjusted (more) if using a 2005 Mustang GT MAF, possibly with a MAFia?

[Breadfan]

There is nothing simple about relocating the MAF, but in a nut shell yes. Ford has some very complicated software to compensate for how far the MAF is from the engine and things like that. GM also uses a MAP sensor for transient control of fuel as well. The Marauder has a MAP sensor, but I'm not sure if it's used for trasnient fuel control or not, but I can look into it.

It just makes sense to move the MAF close to the throttle body, and yes most cars would benefit from it. You do get much better throttle response if done correctly.

j

Thanks I appreciate your thoughts. I helped a friend with a Mangassun (Eaton) blower install on an LS1 and have also worked on some other GM cars and noticed what you mentioned in regards to the positioning. In addition, I always felt they had better response to the pedal when revving, I did not piece the two together but it makes good sense, thanks.

[TooManyFords]

You have LS2 MAF's on your Marauder?

Yes. There is a box under the hood that converts the signals from GM and combined the two into the factory Ford outputs. I'm just not sure I am taking full advantage of them sitting right on top of the throttle bodies though. You mentioned voodoo before, so what sorts of changes should I be making to increase my throttle response because of this?

Thanks in advance!

Maf's hiding:
http://www.cvmusclecars.com/images/mafs-1.jpg

Maf's exposed:
http://www.cvmusclecars.com/images/mafs-2.jpg

Cheers

john

[Local Boy]

Just a thought - motor running lean, super chargers no matter what type, require adequate fuel presure and flow