First Log with DSMLink, Help me get rid of 5,000 / 5,000 RPM Stutter

[majik2k5]

I'm using the stock MAS. And my copy of DSM Link has been registered by the previous owner of the car, since he is the one that bought it. So until I get ahold of him and retrieve the information I need to access DSM Link forums, I turn to Tuners.

 

[gixrman]

Ok then disreguard my post. But the tunning part will still apply. If you don't have a GM (xx)bar I suggest getting one, very easy to hook up and more accuate than the boost est. Also why can't you post the dat. logs without the outside link? I don't want to download unknown software so I can't look at your log.

 

[majik2k5]

I really haven't found anywhere decent to host the datalog file. The other sites only hold the file for a few hours at most.

 

[gixrman]

I don't understand why you have to have them hosted. I just attach them like any other file. Can you not do this?

 

[majik2k5]

Let's try this.

 

[majik2k5]

I tried pulling some timing on the ride home last night just to see how it ran. The car still started breaking up, but it's almost pinpointed to 5,500RPM's when it starts. I stayed on it just a little bit last night once it started and noticed the car started backfiring pretty severely. Don't know if this is any help to anyone or not.

Just another note, after starting the car and running down the road to get some work, it completlely pulled all the way through third gear without any hesitation whatsoever, while it was still cold. Once the temperature got above 120 degrees or so, it started again.

Could this be the initial fuel curves?

 

[tenn-gsx]

Ok couple things. What plugs are you using? What do you have them gapped to? Is your fuel pump rewired? Next log you do include battery voltage. Your going lean at 5400 rpm. I think your pump is either quitting or your alt is dropping voltage.

 

[SiNiST3R]

Mine did this the other day pulled the number 1 plug and the top part was melted off all other 3 where fine. I then changed all four and went to BPR8ES works find now.

 

[kraka]

I know it won't help since I never solved the issue, but on my old Talon, I couldn't have my logger connected at the same time as my Eprom.

After I put in my chipped Eprom (5k 2-step, etc) the car would run fine. But one day I decided to hook up the logger, and as soon as I connected it, my new rev limit was set to 5k. In every gear, even if I slowly crept up to 5000rpm's, my fuel would just cut out (0% IDC) and the car wouldn't move. As soon as I disconnected the logger, it went back to normal.

Can't explain that, but my 2-step was based off a speed sensor so for some reason it would malfunction when the prongs were connected into the diagnostic cable.

 

[voodoogsx]

Estimated boost shows up as a high of 23.7....a few pounds higher than 20 you mentioned...though you do have 850's so....I would think they could hold it together.


Also the a/f ratio is reading 18 to 1 pretty much the whole time with a few blips in there....that doesn't seem right.

Get some test runs with more data. the dsmlink site has some instructions on tuning the car, they have suggestions on what data to record, start with that.

Good luck!

 

[majik2k5]

I started thinking of plugs and so on. But, if the top of a plug were melted, wouldn't you think the car would cut out at lower RPM's as well?

And the car leaning out seems to be an after-effect of the sputtering. I had a friend with me today when I logged it. The car will buck, then lean out on the logger, then buck, then lean out, and so on and so forth.

Also, I monitored the voltmeter, and the alternator only loses voltage after the car drops, and since the car drops in RPM's so rapidly, so quick, and then bounces back up, it would make sense for the voltage to drop on the alternator.

I'm leaning towards something fuel related. The fuel pump is a 255 with AFPR and 880cc injectors. When the car's cold, it will pull all the way through any gear. Once it warms up, it starts the bucking and hesitating.

 

[tenn-gsx]

Im telling you your leaning out and that is causing the sputter. Log your battery volts and do a pull. If it works fine while the car is cool then id say the alt is getting hot and the voltage regulator is crapping out. when that happens the voltage drops, fuel pump doesnt flow as much, pressure drops, and you go LEAN.

 

[tenn-gsx]

Also is the pump rewired? It only takes .3 volts to make things go lean if your pushing the pump.

 

[majik2k5]

I'm keeping a consistant 14.2 volts from 3k up on my voltmeter, and on my timer, though. I'll log it with DSMLink and see what I get, but I think it's been fairly consistant.

No, the pump is not rewired.

 

[GVR4592]

It's not leaning out according to the datalog. It's odd how it starts at exactly 5500 rpm's. It's almost like a rev limiter. Start looking at the ignition system, cracks in plug wires, broken or damages plugs, etc. Do what you can to get registered on the link forums, those guys will be able to help you out a lot better than we can.

 

[majik2k5]

Those were my thoughts exactly. And if I pull any timing or fuel from it, it will either do the same thing or start just a little bit earlier. I'm running coil on plug, and really haven't had any problems with it to date, but this has me completely stumped.

Plugs are almost brand new, but I'm gonna go ahead and pull them out tomorrow and see what I find. I really haven't the slightest clue on this.

 

[tenn-gsx]

Yes my friend it is leaning out. a/f ratio on link is usless It is only an estimation the ecu uses and it is only accurate if everything is in perfetc order. Since his airflow is off a/f will be inaccurate as well. look at your o2 voltage. It goes from .94 to .8x. that is definately lean. Your o2 volts should stay between .92 and .96 to be in a good safe range. You ARE leaning out dramatically.

 

[GVR4592]

Add a bunch of fuel from 5000 rpms and up just to see if the problem goes away. I dont think it's lean because if it was lean enough to cause a major misfire under full boost, knock would be through the roof. I think it's going lean as a result of the misfire.

 

[Black95TSIawd]

Who tuned your airflow sliders? Set them all to zero and do a pull.

 

[majik2k5]

Should I adjust the MAF settings under airflow, or the VE table? They're both what I loaded off of the ECU when I first logged the car. So I haven't adjusted anything yet until I get the hang of what's going on.

 

[tenn-gsx]

Did you get a new log yet?

 

[majik2k5]

I raised the fuel values from around 3500 clear to 8,000 RPM's, and it honestly seemed to make the hesitation start sooner.

 

[GVR4592]

Post another datalog. Any luck getting registered on the Dsmlink forums? There are a lot of really experienced guys over there that could give much better advice, it would be worth your time.

 

[majik2k5]

Here are my latest two logs. I'll make a few more if need be.

 

[tenn-gsx]

Ok I dont know what you got going with your set up, but you need to zero your fuel and timing back out. Log stft ltftlow and ltftmid. Your voltage is good but you really need to rewire the pump so that your getting good voltage to the pump. Adjust fuel trims till mid and low are as close to 0 as you can get them. + or - 5% is within specs.