MAFT Idling trouble

[FASTSPOOLINGST]

First, here's my set up.

680cc injectors (supposidly, I bought from Darksideracing)
255 pump
2.5" pipes w/ FMIC w/ a 3" GM MAF
Fuel pressure is set at 38 w/ line disconnected

I went out tuning last night, to set the base knob. I got my O2 trim to cycle around a hundred at the 620cc knob setting (4 clicks to the right on the base, aux on 1) The high trim was 99.5% after driving for about 5-10 miles.

The problem:
Every time I get to a stop sign or a stop light, the car dies on me.
My A/F gauge pegs off the chart lean and my low trim starts to go up above a hundred, but the car dies before it can finish rising on my logger to what it actually is. I adjusted the idle knob and it is on like 6 clicks to the right (rich) to richen it up, but this did nothing for the problem.

Someone please help me out.

 

[eclipsegsx9797]

are you tunning with just the maft or maft and afc

 

[kpt4321]

Pressure test for boost leaks after the MAF.

 

[sweet97]

I had to set my idle knob at 8 and set the base at 1 or 2 clicks smaller than your actual injector size.

 

[eclipsegsx9797]

i found out with my car that if you just leave everything at 0, and dont even set your base knobs to your size injectors the idle and the car runs perfect.

 

[FASTSPOOLINGST]

1. I am using the MAFT only to tune

2. I am thinking boost leak also, when i hit 20 psi, I can barely hear my wastegate and it's external dump. It's like i'm leaking the boost and the wastegate isn't even opening due to the leak. Besides, I just re-installed my UICP and elbow to the TB after I changed my transmission, it's probably leaking from that, plus I didn't re-tighten them after the couplers got heated up and stretched. I also am running a blow through set up, so there isn't really many places after the sensor that it couuld be leaking from, so that's why i'm thinking it's at the TB/Elbow connection.

3. My idle knob is set I think now at 6 rich, this still did not solve the problem, i'm leaning towards the boost leak. I went today and bought the things from Lowes to make a leak tester. I am gonna check it tomorrow and will post the results.

4. I disagree with you on setting everything to zero. The car may idle, but my fuel trims will be way too rich. When I did set it at 0 which is for 580cc injectors, I had a 85% trim and the car felt really sluggish due to being so rich. I have my trims set properly, just I think the boost leak is getting in the way of unleashing the real power of this damn car i've been working on for way too long.

 

[FASTSPOOLINGST]

well, i made a boost leak tester, did a check. I found the coupler from my front mount to the UICP had a clamp that I didn't even tighten at all. It is hidden by the radiator and i forgot to push the radiator out of the way to tighten towards the motor and tighten it up.

When i first tested it, it wouldn't even get above 5 psi, I found that leak, tightened the clamp, then I took it up to 20psi quickly, I heard a tiny leak from the throttle body, which i was assuming was the problem with my idle. I took off the throttle body and used some gasket maker silicone to seal it up.

Will the silicone be able to hold with boost, or with the pressure cause it to leak again?
I have to go and do another leak test on it today because this f'ng car still is dying at idle.

: It's still showing the same symptoms too.

Those couplers were swelling up big as hell when i had the 20psi in the pipes, I have the camel hump connectors on my GM MAF and they started to swell like balloons

 

[Mike Licht]

Because of different offset or dead times different brans of injectors will require different base setting even though they are the same size. Remember 680cc injectors are rated that wide open, two different 680's can have 50% different fuel delivery at idle requiring different settings. Drive the car at 50-60 ans adjust the base so the HIGH trim is close to 100. That will give you the correct base for YOUR setup. Tune from that point your life will be easy, you don't need an AFC. It does sound like you may have a boost leak
Mike

 

[FASTSPOOLINGST]

Mike,

I have my base set. I drove my car for about 40 miles the other day on the highway at cruising speed of 65mph and am getting a 99.5% high trim.

Car still doesn't idle. I didn't get to go and check the boost leak today. Today is my friday at work, so i am going to do it tomorrow morning.

I'll post what i find then.

Thanks for the input and any more ideas....keep em' coming

 

[Mike Licht]

OK good now oyu have the base adjusted correctly, The idle control will fix the idle let the car worm up to temp and adjust the idle until the low trim come back close to 100. Then use the mid control if you have tip in problem, you can them use the WOT control to get the fulll throttle A/F right
Mike

 

[FASTSPOOLINGST]

that's the thing though Mike, the car will not idle long enough for me to even get out of the car and get the hood up. That is how quick it dies on me. That is after I fixed the boost leak and the TB leak. It won't even idle long enough for the low trim to gradually settle to whatever it is.

 

[BobTurbo]

how is your PCV valve setup? Is it stock? The air flowing thru the pcv system leans out the idle on blow thru applications.

High dead-time injectors will be lean at idle and take a little more time to tune.

What BOV is on the car?


Bob

 

[FASTSPOOLINGST]

yes, i still have the stock pcv valve set up. I am soon going to be doing the mod on it, but i wanted to get the car running right first.

I have a Tial BOV.

Do you think putting the MAFT mode switch to the 3.5" MAF will help? I read that somewhere that it will richen it up across the board and some people have done that with this new version of the transmitter.


Could you further explain the dead time on the injectors.

My injectors are brand new. They are PTE 680cc injectors.

Is there any way to monitor what it is and if it is good or bad by using my logger and watching it at idle? If so, what number should I be looking for on the logger?

 

[BobTurbo]

you should check if the BOV is open at idle, it can generate turbulence and mess with the idle.

The air flowing thru the PCV system is like a boost leak at idle.

Other boost/vaccuum leaks will make it worse as well.

I need to check the deadtime of the 680's if its higher than the stockers by a lot this will add to the condition.

Watch the maf hz, o2 trim, hi/mid/low trims, on the logger.

Setting the MAFT to 3.5 will richen it everywhere, which it seems is not what you need. The fact that idle is so different from cruise indicates a problem like I've listed above.

Get some logs and let us know.

Bob

 

[eclipsegsx9797]

ya your pcv you want to loop back in som how, maybe a t fitting of your brake booster line or something. i have to do this also because of my magnus has no ports for the pcv. as for the v/c hose you dont need to loop that back because you have the gm mas blow thru so it no longer reads that.

 

[kpt4321]

Loop the PCV back into the brake booster line? I don't see how that will accomplish anything....

 

[eclipsegsx9797]

well if you need to loop the pcv pack in you need some way of doing it dont you, and that is just about the only line i know that is about the same size. this is something im not sure of im pretty much asking if some peps have done this.

 

[FASTSPOOLINGST]

Well, I did a motor swap recently and when i changed the engine for the galant motor, I switched to my usdm intake, but i used the jdm throttle body. So i figured maybe something was wrong with the throttle body that was on the jdm motor, so I put back on my other throttle body from my usdm 6 bolt. Now the car is idling, but it is at like 1400 rpms and fluctuating eratically. This throttle body seems better, at least it will idle even though badly. I tightened the biss in all the way and nothing, I changed the o-ring on the biss and still tightened it all the way in, still nothing.

I'm thinking the tb was my problem all along. Anyone got an idea of what the eratic idling is caused by so i can do a search on it and research and fix this frigin pain in the ass car.
F$%@ I'm tired of fixing this damn thing.

 

[94EclipseGST]

Check out your ISC and see if that is functioning. You might also have timing issues. When my timing is off, the car is either idling high and erradic, or too low and the car wants to die.

 

[kpt4321]

well if you need to loop the pcv pack in you need some way of doing it dont you, and that is just about the only line i know that is about the same size. this is something im not sure of im pretty much asking if some peps have done this.

Again, you didn't say which end of the PCV you're talking about looping back in.

If you want to connect the valve cover side, it would make a lot of sense to just hok it up to the factory port...

 

[eclipsegsx9797]

with a magnus intake manifold you dont have the option of hooking it back up to the original port. yes im talking about the vc pcv