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2G Poor idle/car start

Karrade

Probationary Member
10
0
Apr 18, 2021
Clyde, North_Carolina
A few months ago I took out the injectors to have them cleaned because one was misfiring, one was identified to just be bad and needed replaced so I got a new set, should be same size as old set, and installed them.

Now the car has a hard time starting, I have to jump it because the battery died but once cranking it has to sit there and crank for a solid 10-15sec, turning over faster and faster as time goes on, and once it gets to a certain speed turning over it will probably catch.
It normally sputters and won't idle worth a damn unless I hold the throttle open a few times bouncing on the 2 step at 5k rpm then it'll idle, slightly rough but overall pretty normal and gets better the longer it idles. If I turn it off and back on again I have to repeat the process.

AFR at WOT is 14.7 and 12.2 according to ECMLink, so I'm assuming the new injectors are doing well.
Injectors are new, PTU/Coilpacks/wires/plugs were replaced early this year. Not to say any of that couldn't be the problem anyway.

Any ideas why it has such a hard time starting? I have logs of starting the car but I can't attach them for some reason.
 

1990TSIAWDTALON

Moderator
9,712
5,549
Nov 14, 2013
Independence, Kansas
The log is saying that you are too lean. The computer wants to add 16% more fuel.

What size injectors?

I would get rid of that 655 deadtime figure. I've never seen deadtime so high (but I am not a tuner, I'm an engine builder, it just sticks out). I would change the global fuel to -26%, which will richen up the mix some.

Watch your STFT's and LTFT's. Try to adjust global and deadtime to get them to within + or - 5% of zero. I can reach in my car, turn the key, and she does everything to warm up. I never have to touch my gas pedal.

I can also see you have "disable airflow when using SD" in MAFCOMP. Are you on speed density? If you are NOT then you should UNCHECK that box and smooth that table, it looks like an EKG.

I'm not hacking on you, just pointing out things I see that don't look "right". I don't use "enable hot start enrichment" because if the tune is right, you don't need it.

Some others will probably look and find some other stuff but you might try richening up the mix some and lower the deadtime.
 

Karrade

Probationary Member
10
0
Apr 18, 2021
Clyde, North_Carolina
Have you had the battery tested? Does it still crank slow with the car being jump started?
The battery is bad, it cranks slow when starting and spins faster and faster until it gets to a point where it finally catches.
The log is saying that you are too lean. The computer wants to add 16% more fuel.

What size injectors?

I would get rid of that 655 deadtime figure. I've never seen deadtime so high (but I am not a tuner, I'm an engine builder, it just sticks out). I would change the global fuel to -26%, which will richen up the mix some.

Watch your STFT's and LTFT's. Try to adjust global and deadtime to get them to within + or - 5% of zero. I can reach in my car, turn the key, and she does everything to warm up. I never have to touch my gas pedal.

I can also see you have "disable airflow when using SD" in MAFCOMP. Are you on speed density? If you are NOT then you should UNCHECK that box and smooth that table, it looks like an EKG.

I'm not hacking on you, just pointing out things I see that don't look "right". I don't use "enable hot start enrichment" because if the tune is right, you don't need it.

Some others will probably look and find some other stuff but you might try richening up the mix some and lower the deadtime.
The injectors are 575cc, should be the same size as what was replaced minus all the crap that was in the old injectors. I knew it was running lean but not that lean. I've never seen an SD sensor on the car only a MAF so I'll need to turn off the speed density setting.

I'm wondering if there's not something going on with the plugs or having to build up enough charge in the battery to fire the plugs and start it causing starts to take forever because I checked an old log and it also ran lean there too, slightly less than now but only by as percent or so which old clogged injectors could cause I would imagine.

Thanks for all the input!! I've always loved DSMs but I'm still fairly new to the platform.
 

1990TSIAWDTALON

Moderator
9,712
5,549
Nov 14, 2013
Independence, Kansas
As probably needed, check and if needed, replace the battery.
It could be a bad starter. It could be a mechanical issue. Hard to tell so far.
My cars spin over and fire right up. Maybe a tune issue involved?
 

Karrade

Probationary Member
10
0
Apr 18, 2021
Clyde, North_Carolina
As probably needed, check and if needed, replace the battery.
It could be a bad starter. It could be a mechanical issue. Hard to tell so far.
My cars spin over and fire right up. Maybe a tune issue involved?
I went ahead and replaced the battery, it wouldn't hold a charge at all, and also got new plugs as well. The old ones were black.

It will catch nearly instantly now but also instantly dies. I have to smash the gas peddle to get it going, once it's running if I rev it up sometimes it's instant and climbs to 5k quickly and smoothly. Other times it stumbles, is slow to climb, and then finally starts to rev normally. It can hold a 2 step at 5k fine so I don't think it's the fuel pump but I could be wrong.

Any ideas about the stumbling in start or some revs?

I'm thinking it's starting to feel like a tune issue, I'm tempted to throw the old injectors back on and see if the problem persists. I did remove the SD setting and richen the mix some so far.
 

Karrade

Probationary Member
10
0
Apr 18, 2021
Clyde, North_Carolina
Taking my deadlime down and trying is what I'm planning on trying today.

You sure the new injectors are identical? Same resistance?

Sounds like how my car ran when it had a shit tune and 750cc injectors, the injectors would flood the car at startup and would take a while to clear out all the fuel and idle correctly
I'm fairly sure based on the information the company that cleaned the old ones gave me, however the model number doesn't come with anything so I'm not fully sure unfortunately and it's seeming like a tune+injector problem. It's why I had the idea to throw the old ones back in and see what happens.
 
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