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Cannot figure it out

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cliffkemp

10+ Year Contributor
391
11
Apr 19, 2010
carrollton, Georgia
Over the last year and a half, my talon has been getting worse and worse with partial turbo spool at around 3500 rpms. I am not sure what is going on with it. It is doing 2 things now and, I just replaced the coilpack thinking it was just going bad.

1. It is sputtering as the turbo is almost spooled up at around 3500 like it is not getting spark or fuel and this is at about 30 to 40 percent throttle but, if I give it around 50% throttle, it acts normal and spools up and pulls with no issue

2. If I get into boost for a full gear, any gear and go to around 7000 or so rpms, it pulls normal. After shifting to the next gear, it sputters and does like it does in the situation above at any throttle position for about 2 to 4 seconds or so. If I just let off the gas completely and then hit the gas after about 4 seconds or more, it starts to run fine.

My a/f is around 10.5 to 11.2 at full throttle and slightly leaner at less than full throttle but, never goes leaner than 11.5 in any gear under any load based on my meter but, it is not being logged. I have an upgraded FP green on the car. It did not do this when I took it to the track at couple years ago and pulled great in 1st and 2nd and started knocking in third and 4th and let off and did not run again. It was running good enough to run a 2 at the 60 foot (my second run ever) and ran a 13.6 letting off in 3rd and 4th @ 92 mph. I tuned the knock to where it was just about nothing and then this started. I thought it was a boost leak but, it is not. I am running about 16 to 18 psi as my boost gauge quit working. I will try to get a log off of link in the near future.

Any ideas what would cause this? It still has the same BOV, boost controller at the same postition, and same exhaust setup with tial wg. Nothing has been changed at all other than turning out the knock over a year and a half ago.
 
Is your bov recirculated?
no, It has never been. Not for the last 7 years. I bought it like it is now. It pulls great for one gear, has the hiccup for a few seconds or so, then it is fine for another pull in the next gear. It did not used to do this.
 
Yeah that’s probably your problem. Because I know when people have the same issue you describingits because of the bov not being recirculated. The metered air is all of the sudden not going into the intake when the bov vents. It’s weird that it didn’t do it befor, but you should only vent the bov when on speed density or a gm maf.
 
Yeah that’s probably your problem. Because I know when people have the same issue you describingits because of the bov not being recirculated. The metered air is all of the sudden not going into the intake when the bov vents. It’s weird that it didn’t do it befor, but you should only vent the bov when on speed density or a gm maf.

Do you think it could be the BOV is going bad? it is pretty old. I am thinking of getting another one anyway. It never did this for the first 5 years of owning it. It is so strange.
 
Every car that has a maf like ours need to have the bov recirculated for the same problems your having. I understand it’s ran fine befor like this but it’s not the right way.

This car and my race car both have GM sensors. It is not the stock sensors. My auto talon has a recirculated bov and has a 2g sensor with a bad temp sensor and does not do this. My eclipse (race car) does not do this and has the exact same setup but, it is a 2.3L with a hybrid sc61 turbo.

I am not saying you are wrong at all. I am just saying that my race car does not do this even now. Only this talon does it. I am going to replace the bov and see about a recirculated bov anyway. Good for christmas gift to myself. :) If you can think of anything else, let me know.

Also, both are GM blow through about 8 inches or so from the TB. the talon is a 2L with 9.0 compression just like the eclipse but stock crank and not the 4g64 like the eclipse. Not sure if this info will help or not.

Thanks
 
It could also be the fuel pump getting weak or fuel filter clogged.

Start with the basics, plugs wires fuel filter as a first step

pump is a 255 and fairly new, the filter is very new, too. Wires are 6 months old. New coilpack on yesterday. Pressure set to 37 psi, and 950cc injectors. Duty cycle was around 75% last I remember. Been a while since I did anything on link with it after tuning out the knock but, that was under wot.
 
It could be but when you let off the gas and is messed up that’s because metered air is going missing when the bov opens instead of going back into the intake.

Just letting off the gas does not do anything to it. It is ok and just idles down. It is when hitting the gas again shortly after the shift. Just trying to be as precise as possible. I just do not want to go replacing things at will but, I have done all the maintenance on it as far as the ignition goes even to put a new pack on it. Fuel is good and set to stock. Filter is new for the miles and so is the plug wires and plugs. I have done all that. As far as the ignition and fuel, should be good. I cannot really think of anything else. I will say that the engine has a fair amount of blowby under boost. I have cleaned out the intake system including dropping the intercooler and cleaning it. MAF sensor is not all that old and is working decent based on the last time I had link on it.

I even have my plugs to around .020 or so to make sure it has spark. I have tried many different gaps on differnt plugs over the last several months, too. The plugs are new and, I have several sets set to different gaps and, they are 7s and 8s for the heat range since the green is putting down around 300+ hp and tq.
 
Then yes your bov is leaking or not closing fast enough. Try adjusting it.

Will do. Thanks. I will in the coming days and update. I have to work the next 5 days and will not get to it. Thank you for the help. I had just about narrowed it down to that or something went bad in the tune, for some reason. I was going to see if anyone had encounted this before and it be a tuning issue with a larger turbo as, the spoolup is different based on stock timing and fuel and, I was missing something.

I will let you all know and thank you for the help. I wanted to have some more opinions on this to see if I was headed down the right path.
 
You say it’s not a boost leak or you don’t have any leaks but a leaking bov would be just that. I’m talking about leaking inside and not the gasket that’s used for installation. My 1g bov did that badly at like 2-3 lbs of air. Did you ever get another working boost gauge?
 
You have link. Log it.

I have link v3 and will do a pull on it in the near future. I do not have much time off of work but, I will when I get a chance to do so. I put a stock BOV on it and, it is still doing the same thing and nothing changed. I am going to get a better BOV as, the stock one may have an issue holding that kind of pressure without crushing it and, I do not really want to do that.

I hope to be working on the car this coming weekend if weather permits.
 
You say it’s not a boost leak or you don’t have any leaks but a leaking bov would be just that. I’m talking about leaking inside and not the gasket that’s used for installation. My 1g bov did that badly at like 2-3 lbs of air. Did you ever get another working boost gauge?

I have not gotten another gauge as, I cannot seem to find a Faze gauge anywhere now. I have looked on Ebay and Amazon for the gauge that I have and, I have not seen one but, I will look again shortly. I am thinking of getting a Tial gauge like I have on my other talon and see if that will help but, I have no seen a Tial that will work with a 2 bolt setup. My other talon is a vband. My eclipse is a vband with an HKS valve so, I cannot interchange this one but, can the other 2.

The only other thing that I think it could be is the GM sensor could be going bad too. I have about 5 working ones and may just replace it and see if that helps. It has been used quite a bit and may need cleaning or replacement. If the weather will be decent this weekend, I will work on it then and do a few pulls and log them to see if Link can give a picture as to what might be wrong if the other fixes do not work.

Thanks,

Cliff
 
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