Car dies between shifts.. Possible alternator problem

[crazyquik22023]

I am having a problem where my car wants to die between shifts. If i shift and let off the gas for more than a second the car will die. The car idles perfect, ISC is good and no leaks anywhere. I just replaced the alternator a few days ago and the belt could possibly be a little bit loose but would this cause the car to die between shifts? The alternator also isn't charging the battery past 12.5 volts. I am hoping its because the belt is loose. I haven't been driving the car and I'm going to tighten the belt tomorrow, I'm just wondering if you think that a loose belt or bad charging alternator would cause the car to die between shifts. I think its a good chance that's the problem what do you guys think? Thanks

 

[crazyquik22023]

Did this happen after your 4" intake?

Nope, I've been running the 4" intake for a while now, the car ran fine with my current setup for about 5000 miles, then I blew a headgasket so I decided to go all out and get a new Buschur stage 3 block and head. I am still using all of the same stuff I was using before I got the new Buschur engine. I'm going to clean the MAF, tighten the alternator and check back. Thanks

So I just tighten the alternator belt, it was extremely loose, but that wasn't the problem. The car charges good now idles great but dies when I rev and let off the gas whether under a load or not. I cannot get my airflow per revs to be stable. I adjust the MAF sliders in dsmlink and it doesn't change anything. I'm thinking I have a bad MAF. If anyone has any other ideas let me know.

 

[crazyquik22023]

I had a topic posted with this issue... kind of... so anyway my car wants to die when i rev it past 2500 or when i let off of the gas between shifts. No boost leaks, ISC is good, throttle body cables are adjusted correctly, TPS adjusted correctly, compression is good. I'm thinking it's a bad MAF. MAF reads 35-45hz on dsmlink at idle. I was going to clean it with this MAF cleaner I have but it says do not use on Karman based MAF sensor i.e. Supra's, Mitsubishi's, & most Lexus's. So I really don't wanna use it. Let me know what you guys think.

 

[mikus]

A gazillion enthusiasts have sprayed it on Karman sensors before, risk of having issues is there but low. This isn't a hotwire MAF though, so, the benefit is questionable.

 

[rlacasse1]

Is your BOV recirculated?

 

[razrman8]

What ^ said

 

[gofer]

I had a topic posted with this issue... kind of...

No, its actually the exact same problem you posted earlier and we were trying to help you fix it. You just made one step forward, then two steps back because you posted another thread about the same issue so I'm merging the two.

The car dies in between shifts or when revved up because the massive amounts of airflow the MAF is metering. You mentioned installing a Buschur 3 head on it, does that include any port work on the intake runners or bigger valves?

Whatever the case may be, the car is dieing because the throttle plate is closed yet the MAF is still seeing air coming in so it continues to pulse the injectors which in turn floods the engine. You can easily correct for this in ECMLink using the Idle Clamp feature, just read this Wiki article to set it up. ---> ECMLink Wiki: Idle Clamp

 

[crazyquik22023]

Thanks for merging the threads gofer. The only reason I made a new one was b/c I was trying to avoid the responses of "check the alternator wires, and so on." But anyway thanks for the response I will set up the idle air clamp function. Hopefully that will solve my problem.

So i tried doing the idle air clamp function. Gofer, you were correct that is my problem that my airflowperrevs are rising when I let off the throttle. I logged the AvgAirVolPerRevY and but the values in the Idle Clamp table. My car is still dying though when I rev and let off the gas and the airflowperrevs are still rising. Here is a log showing what happens. Look at about 26secs is when i rev it to 3000rpms and it dies.

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[ExpresS]

My exact problem also. Driving the car cold it won't happen but reving or shifting when the car gets warmer it will just die. Instant lost of power. Hey crazyquick how's your Idle speed switch? Good connection?

 

[crazyquik22023]

My exact problem also. Driving the car cold it won't happen but reving or shifting when the car gets warmer it will just die. Instant lost of power. Hey crazyquick how's your Idle speed switch? Good connection?

Yes the idle speed switch has a good connection. My ISC position is much higher than it should be but I can get it lower to around 35 where it should be without my car idling at like 400 rpms.

 

[gofer]

Gofer, you were correct that is my problem that my airflowperrevs are rising when I let off the throttle.

Change your Idle Clamp settings to reflect the table below, then the next log you do make sure the cars FULLY warmed up (180*+ coolant temps). Also, you'll want to make sure you're capturing AvgAirVolPerRevW and MAFIdle values in your log, that way I can see where the changes need to be made if the table below doesn't fix it. Another log of you revving the car like that is perfect, just make sure its completely warmed up this time is all and you've got those values I mentioned above being captured.

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[crazyquik22023]

Ok gofer, will do. My car will not get to 180+ temps b/c I have a 160deg. thermostat in but I have the coolant offset adjusted accordingly so when I'm at 160 it should be fine. How did you come up with those values if you don't mind me asking? If those are the values that are in the table originally, then those don't work. I adjusted the table to try and match my Raw values. I'll try it again with those values and Ill capture AvgAirVolPerRevW and MafIdle.

 

[gofer]

Ok gofer, will do. My car will not get to 180+ temps b/c I have a 160deg. thermostat in but I have the coolant offset adjusted accordingly so when I'm at 160 it should be fine. How did you come up with those values if you don't mind me asking? If those are the values that are in the table originally, then those don't work. I adjusted the table to try and match my Raw values. I'll try it again with those values and Ill capture AvgAirVolPerRevW and MafIdle.

Thats good you've got a 160* t-stat in there, I didn't even bother to look and see if you had the coolant offset since I don't see anyone ever using it. To be honest with you I pulled those values straight out of my ass shhh since I couldn't see your AvgAirVolPerRevW or MAFIdle (both will show the same thing though)... I lowered the values a bit, specifically where the car idles (1500 to 500rpm) to "clamp" a low airflow reading so the ECU doesn't actually see what the MAF is metering.

Some changes may need to be made but odds are those values will fix the issue, then we'll just tweak and peak them a bit after reviewing the next log.

 

[crazyquik22023]

Ok sounds good, I'll get those values logged and ill try the table you suggested. I'm not really sure how to adjust these idle clamp values. Thankfully that's why you are here. I'll post back in a bit.

 

[STLskater92]

If your running a vented bov and don't have a MAFT then you may have just solved your own problem. Possible short in the fuses may cause the problem. How long can you sit there and let the car idol? Like will it die after 30min or can you leave it on for hours?

 

[phunny]

If your running a vented bov and don't have a MAFT then you may have just solved your own problem. Possible short in the fuses may cause the problem. How long can you sit there and let the car idol? Like will it die after 30min or can you leave it on for hours?

Gofer got it

 

[ExpresS]

Ok sounds good, I'll get those values logged and ill try the table you suggested. I'm not really sure how to adjust these idle clamp values. Thankfully that's why you are here. I'll post back in a bit.

Verdict?

 

[crazyquik22023]

So i tried entering gofers values in the Idle Clamp table and the car still dies when revving and letting off gas. It helped a little bit, maybe, but I tried taking it for a drive and as soon as I got into any boost (1-2psi) it started bogging really bad. Could this be a bad maf? That's what I am leaning towards. Also here are the values you wanted me to log gofer. This was a log of me driving up my driveway and then the car died.

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[crazyquik22023]

Anybody care to chime in before I buy a new MAF?

 

[STLskater92]

Get a MAF translator if your gonna get a new MAF. It will allow you to override your stock MAF sensor and allow your ECU to compensate for the extra air flowing into the motor. I have a MAF off of a 1999 camaro and a MAFT. it will more than likely fix your problem once you get the proper settings.

 

[crazyquik22023]

If I do get one it will probably be a GM maf and ya I would get a translator, but I want to know if my MAF is actually bad which from what I can tell it's not or if my MAF just needs to be tuned better.

 

[Ghost_GSX]

The only way I know how to test (correct me if I am wrong to tell him this) is to unplug it at Idle to see if there is a change.
Are your injectors known to be good?
Timing set?

 

[crazyquik22023]

Yes injectors are good, timing is good, no boost leaks, engine has less than 500 miles on it. All of the major problem areas have been checked. Just trying to figure out how to properly adjust the maf clamp in dsmlink and to determine if my MAF is indeed bad or not. I wouldn't think it is based on the fact: it reads the proper frequency, there is no CEL on, the car ran fine with the same MAF about a month ago and boosted fine, now it bogs when I get into boost, but I can't really do any good test drives because my car keeps dying when I let off the throttle. And BTW that is not the correct way to test a MAF. It is possible the car will idle better with the MAF unplugged, but its not really the way to test it.

 

[Ghost_GSX]

Can you get a AFR at Idle?

 

[TSI_AWD_FTW]

Mine does the same thing if i dont have my BOV recirculated

 

[STLskater92]

@ TSI AWD FTW
As I've said before, if you vent your BOV you MUST MUST MUST have a MAFT.

@crazyquik
Who cares if its bad!!! Upgrades are never frowned upon