What's your MAP values at idle with XFI?

[turbojimmy]

I'm trying to chase down a problem I've having after moving my MAP sensor over to the RH fender and wiring it to the stock plug. I have a digital dash car and used Casper's adapter to use the factory wiring. Because I have a digital dash, that plug on the RH fender was previously unused.

After I moved the MAP the car started running stupid rich and can't control the idle. In a strange twist of events, both the CTS and the IAC valve failed at the same time. I replaced them both and now have coolant temp values but still can't get idle below 1,100 after closing the throttle blade all the way.

It's acting like it has a ginormous vacuum leak, which is entirely possible, but I haven't been able to find it yet. There is a suspicious whistle at part throttle (no, it's not the turbo - sounds like air).

I want to eliminate the MAP as a possiblity. kPa at idle (1100 RPM) is in the high 30s. What's yours?

Thanks,
Jim

 

[turbojimmy]

Well, I figured it out.

In another strange twist of events, my EGR had come loose. The whistle was it sucking air through the EGR. What's even more strange is that this condition caused a 2nd IAC to fail. Once I corrected the EGR leak, I got a 128 error from FAST indicating an IAC fault. The IAC is dead, again. Now both were used and presumably stock and thus 20+ years old, but still....

So I sealed up the vacuum leak but the idle hasn't returned to normal because of the IAC problem. I'm going to pick up a new one tomorrow and see what happens.

Jim

 

[Otto J]

DO NOT plug and unplug the IAC with the key on.
This will burn up the IAC driver in the XFI box.

 

[turbojimmy]

DO NOT plug and unplug the IAC with the key on.
This will burn up the IAC driver in the XFI box.

Uh oh.

Did that a couple of times to see if it was working. Though the first IAC valve proved bad when plugged into my brother's car. But, last night was the first time I got the SES light and the 128 code. Probably baked the driver in the box. That's just f*cking peachy.

Jim

 

[Blazer406]

DO NOT plug and unplug the IAC with the key on.
This will burn up the IAC driver in the XFI box.

+1

Been there.... done that!

 

[turbojimmy]

+1

Been there.... done that!

I assume the result is the 128 error I'm seeing? The description of the error is a short to ground or short to 12V+. Seems to confirm that the driver is baked. It doesn't seem smart enough to throw a code if the IAC isn't reacting the way it thinks it should be.

Jim

 

[turbojimmy]

I spoke with FAST today and also tried a brand new IAC. The folks at FAST figured the driver was baked - they were right. The XFI module is toast. Need to send it back.

If I had kept my MAF I could pop my ECM back in. But I didn't. So I can't. Dead in the water....again.

Jim

 

[Boost231]

well this is a good leason learned.

 

[turbojimmy]

well this is a good leason learned.

Certainly is. Glad to help

It should be stated somewhere in big bold letters, or perhaps on some sort of sticker that THOU SHALT NOT UNPLUG THE MAF WITH THE KEY ON.

Jim

 

[Boost231]

Certainly is. Glad to help

It should be stated somewhere in big bold letters, or perhaps on some sort of sticker that THOU SHALT NOT UNPLUG THE MAF WITH THE KEY ON.

Jim

you ment IAC but i got you.

 

[turbojimmy]

you ment IAC but i got you.

Oops, yes. Of course I meant the IAC. The perils of multi-tasking.

Jim

 

[Blazer406]

I found my old post....

IAC Driver Post


Anyway.... it was fixed after we sent it back to FAST. It sux you can burn up your $1800 box by unplugging and plugging in a sensor...... I bet the GM ECM won't burn up when you do that......

Hopefully they learn from their mistakes.

 

[TurboBuRick]

What a crock of chat but good info, sorry it was at your expense Jimmy. :redface:

 

[turbojimmy]

What a crock of chat but good info, sorry it was at your expense Jimmy. :redface:

Well now I know.

It's weird, though. In reading that thread, it seems the ignition module went bad, too. I had my CTS and IAC fail on the same day not too long after the FAST install. Dunno if it's coinkydink or not.

The FAST box is in a box in my car. Need to drop it off at UPS on my way home from work. Weather's going to be crappy this weekend anyway.

Jim

 

[turbojimmy]

Got my XFI unit back today. Popped it in along with a brand new IAC valve and....it does the same frrrrrrrrreeeeeeeeeaaaaaakkkkin' thing. Pig rich, smokey idle. Eyes burn....CO monitors go off in the house.

It all went to hell in a handbasket when I moved my MAP sensor. I'm going to try putting it back where it was.

The EGR was definitely leaking, too. Maybe it still is, who knows. I have all weekend to goof around with it.

On the Dashboard the idle value is in yellow as is the IAC target. What does this mean?

On the idle properties I can see where it wants the idle to be, but the bubble is well above it.

Jim

 

[lazaris]

Sounds like the Map sensor is bad.

 

[Boost231]

sounds like you need to push the car off a cliff LOL

 

[turbojimmy]

sounds like you need to push the car off a cliff LOL

We don't have any high enough in NJ. It needs set on fire.

Turns out the EGR is still leaking pretty bad. When I first put the engine back in, I used an EGR block-off plate. I couldn't get that to seal so I put the EGR back in. But I had lost the stud and nut for the EGR clamp so I used the bolt that came with the block off plate. That bolt is tough to get at and does not work very well at all.

So last night I goobered up both sides of a brand new EGR gasket with copper silicone sealer and installed it along with that EGR block off plate again. Hopefully that will seal it up. I resisted the urge to run it last night and let it dry overnight.

I don't have high hopes that this is my problem, though. If it's the MAp I'd be a little concerned since that would be the 3rd sensor to bake since I installed FAST (the CTS and the IAC both quit).

The other thing I did last night was move the MAP into the car and plug it directly into the Casper's harness. At idle, it's reading 24 which is low. I don't know what the right values are. If I unhook the vacuum to it, the MAP goes up to 98 (and the value turns green on the dashboard) which is probably correct (close to 1 bar). I'm confused, though, as to how to translate kPa to vacuum. The more vacuum there his, the higher the kPa is? If so, then why does the kPa go UP when I remove the vacuum?

Anyway, it's acting like it's getting air from somewhere. It's not the FAST unit, it's something I did recently. It was all working very well before.

Jim

 

[norbs]

1 psi= 6.894733 kpa

24 kpa / 6.894733 kpa = 3.48 psi

1 pound per square inch = 2.03625437 inches of mercury

3.48 x 2.03625437 = -7.08" of vacuum.

You have a major vacuum leak no wonder it barely runs!

I get about -7.5 psi at idle with a 224 cam unless yours is bigger its not possible to get your numbers

 

[Chuck Leeper]

Didn't I see somewhere that someone had found that the harness had a wire out of place??
At my age, CRS is a constant problem... Maybe I didn't see that...But, I did see this:
Fisher Scientific UK - Pressure/Vacuum conversion table
A handy conversion chart!!