Wierd Timing Problem

[jonheslop]

I know from the factory service manual that when you set your timing you are supposed to ground the timing terminal on the firewall. Then it should read something like 5BTDC. Then when you unground the terminal it should read 8BTDC. However when I set mine to 5 it ends up being 20BTDC after I unground that plug. I have to set my timing to about 20ATDC to make it come back down to 8BTDC. Does anyone know why this is happening? My timing belt is set perfectly fine so I know that's not the problem. Please Help

 

[sbiggi]

The ecu controls the timing when its ungrounded.

What is your car idling at? 20 degrees of timing would be correct if your idle is between 1000-1250rpm, since that is what the stock map is.

If your idle is 750-1000 the timing should be somewhere between 10-16 degrees on a 1g when it not grounded

 

[pneumo]

You might want to set the BISS first. If it's misadjusted the ECU will add timing to keep the idle speed up. Hopefully your ISC is good, if it's bad it could explain your high timing.

You can use your logger to get the base timing set near 5 degrees. Simply adjust the CAS until the timing on the logger matches the timing you see with the timing strobe. The timing will fluctuate by a few degrees as the engine idles, so you'll have to check the logger and the strobe a few times until they match.

 

[sbiggi]

You might want to set the BISS first. If it's misadjusted the ECU will add timing to keep the idle speed up. Hopefully your ISC is good, if it's bad it could explain your high timing.

You can use your logger to get the base timing set near 5 degrees. Simply adjust the CAS until the timing on the logger matches the timing you see with the timing strobe. The timing will fluctuate by a few degrees as the engine idles, so you'll have to check the logger and the strobe a few times until they match.

Logger does nothing other then report what the ecu thinks is happening. The function in mmcd and pocket logger for basetiming is only used to set the correct offset for the timing it reports to you, it has no effect on the car at all.

With the timing grounded and the logger not hooked up, the timing will stay rock solid at what ever the cas is set for regardless of rpm.

If you have the logger hooked up and the timing grounded, you are telling the ecu you want to set idle speed. At which point the timing will be controlled by the ecu and the isc will be set neutral for you to adjust the biss.

 

[jonheslop]

I am not using a logger so I don't have that problem. I know all about how hooking up the logger will actually set the ECU for setting the BISS. That's not my problem. My car does idle pretty high. I'm assuming from all the mods I've done. I can't get it below 1500 rpm. So at around 1500 rpm the timing is at 20 degrees advanced when the plug is grounded. Does that sound right? Where can I find a chart or something telling me what the timing should read at what rpm point? Thanks for the help.

 

[GVR4592]

How did you try adjusting the idle?

 

[jonheslop]

I grounded the timing plug. Then I checked it with a timing light and adjusted the CAS according. It took a little bit of experimentation before I found that 20 advanced would get me a setting of 8BTDC when I tightened everything back down.

 

[GVR4592]

How did you try adjusting the idle?

Ok read it again.

 

[sbiggi]

"Mods" wont cause the car to idle high.

Unmetered air will. Sounds like you have a boost/vacumm leak after the maf.
Or the switch on the throttlebody that tells the ecu the throttle is shut isnt working.

My car idles almost perfect with 950cc injectors and fp2 cams. Its a little lopy when its cold but other wise rock solid at 850 rpm.

 

[jonheslop]

Well, I have been having idle surge problems lately too so maybe that's why my idle is so high (unmetered air is getting through) I have been working on this idle surge forever and have tried everything imaginable except for changing the ECU. So I know it's not a vacuum leak. I think I will figure it out eventually but as you all know tuning these dsm's takes a lot of work.

 

[GVR4592]

How are you adjusting the idle?

 

[jonheslop]

I have blocked off the FIAV completely. Blocked the EGR system. There are no vacuum lines coming from the throttle body. They are all blocked. The BISS has a new o-ring. The ISC has been tested and works fine. I have my GM Maf right next to the throttle body on a blow through setup. I have tried setting the BISS and messing with the MAF translator as well as my SAFC II. I have tried setting the timing the best I can without the idle staying steady enough to read it. Other than that I don't think there is any else to do. The only thing I can think of is that air is leaking through past the throttle plate because it has some very minor dings on the edges where sunlight shows through. Nothing major, but enough to let air through.

 

[pneumo]

You should focus on the idle speed first. Forget about the timing until you get the idle stabilized. If the timing is off a little it won't raise the idle speed that much.

Your high idle problem is caused by extra air getting into the engine somehow. Why don't you try smoothing out the butterfly so the throttle plate closes completely. Check the throttle cable to make sure there it has a little slack, and check the closed throttle position switch to make sure it isn't holding the throttle plate open a little too far. The closed throttle position switch is on the top/back of the TB above where the cable hooks up, it has one wire coming out of it. You can adjust it by loosening the nut and turning it by hand.

 

[jonheslop]

The idle switch is set perfectly and the throttle cable is loose enough. I will try smoothing out the throttle plate though.

 

[HighPSI TSi Guy]

Ground the idle pin, and UNPLUG THE LOGGER FROM THE DIAGNOSTIC PORT. If you have the logger plugged in with the timing set pin grounded, then you will be in idle set mode, not timing set mode. the timing ground pin locks the timing to base, and will not advance it. set the timing to 5* if you want your advance to match the ECU's map. You must also make sure you are using a timing light that does NOT have a dial on it. Adjsutable timing lights are not compatible with waste spark ignition.

 

[jonheslop]

HIGHPSI, you are telling me something I already know and has nothing to do with my problem. And once again, I DON"T HAVE A LOGGER.

 

[GVR4592]

Ok pay attention to what people are telling you, you have to get your idle fixed before you can adjust your timing. If you can't get it below 1500 rpms you aren't doing it right or you have a mechanical problem. So I'll ask again, how are you adjusting your idle?

 

[pneumo]

He can't adjust his idle because he has a mechanical problem. Post # 12 covers it.

 

[jonheslop]

I'm not worried about the timing right now. My idle is the only problem now that I know it's directly related to the timing. My idle is only high because of the bad throttle plate. Every other check has been done except for changing out the ECU which is the last resort. I've explained above how I'm adjusting my idle.

 

[GVR4592]

I read post 12, I've seen damaged throttle plates before and the car idled fine. Im sorry I just don't see where you posted how you are adjusting your idle. The reason I ask is because almost everybody does it wrong and can't get their car to idle. I was just curious how you were doing it.

 

[jonheslop]

Well, for the most part the idle sets itself. The only thing you can adjust is the BISS. To do that I ground the timing plug and ground the plug on the diagnostic plus. Simple. However, the BISS screw does nothing because the idle is surging too bad. Other than that there isn't much you can do because everything is set to the factory specs. The ISC, TPS, idle switch, etc. They are all set and work properly. Somehow too much air is still getting through and the only thing I can think of is the ISC not working properly even though it checks out fine on a multimeter. That is what leads me to believe it could be the ECU. The ISC, BISS and throttle plate are the only openings for air to get through that aren't blocked off yet. Does that explain how I am setting my idle? If not I guess I don't understand what you are asking.