Car stutters when the throttle gets mashed

[shook55]

Ok I got my car over the summer and I just been working on it alittle here and there. But it started acting up latly it first started off when I hit the throttle fast it stutters and then clears out around 3000rpms. Another thing that it does is it dosnt always push full boost 1 gear and 2 gear it will push full boost 25lbs and around 3rd it will only push to about 15 or 16 . Can anyone help?

 

[stephen_gst]

have you tried a Boost Leak Test yet? also check your plugs, plugs was my issue with studdering, it turned out for me that my cylinder 1 plug wasnt fully intact and then i pushed it all the way in and it ran beautifully

 

[Nightlife Customs]

Have you done any transmission or clutch work?

I am currently having a shutter what's called "chatter" in my clutch and I will tell you the difference between clutch and trans

Clutch chatter (what I have and will be fixing this weekend) is when your moving in first or reverse then the chatter goes away trough top end 1st gear and your good 2nd through 5th

To fix the clutch chatter - your gonna have to pull the pressure plate off and re TORQUE the screws to torque spec - reinstall and your good to go

Make sure you have a key to center the ring in the middle of your clutch or your going to encounter more issues

If your experiencing the chatter in all 5 gears - it's your transmission issue

To fix this - your syncros are going to have to be replaced which means labor work of dismantling the transmission to the gear box and what not

At this point I would consider putting upgraded gears in there since you already have it apart

If neither of these are your issues

Check your motor mounts and brackets - make sure the bolts that hold your brackets down are down good.. Otherwise the torque of the motor will act like a hammer to your brackets and will strip the bolts and you will be needing to heli coil the holes..

You can tell if the mounts themselves are bad - is signs of cracking or if you can move the motor and see the play within the mount itself

 

[lons99gsx]

Start with the basics, check spark plugs, wires, coils, injectors, compression, and for boost leaks. All of these things can cause as least some of the symptoms you mentioned. Good luck! We can help more with more info on what the condition of the tune up parts, etc. are.

 

[shook55]

ok i ran a boost leak test yesterday there was a couple leaks on my intercooler piping so i tightened the clamp down. Then hit the gas and did the same thing the plugs are new they have 4 miles on them and 4 miles on the fuel filter. But i took it for test ride and through first it did good then i hit second it built boost and then it stutter bad it almost felt like the waste gate was opening and closing fast, and the intercooler, turbo, piping, and radiator are all brand new.

 

[lons99gsx]

What is the boost set at. Anything over 17lbs on the stock ecu may hit fuel cut without tuning.

 

[shook55]

boost is set at 25lbs and i know it runs right because when i first got it it ran good in every gear is there any way i can tell what cc injectors i have i know they are larger than stock but i dont know how big?

 

[Kirkamus]

Yeah wondering what you are using to tune at 25lbs boost as well.

 

[cyhm]

If you have a dvom, you can resistance test the coil packs, plug wires, and power transistor. I'd check leaks again personally. If you fixed a few IC pipe leaks, you may not have heard something. I thought I fixed all my obvious leaks, but was still leaking very badly through my TB shaft seals.

More info about your setup would help us as well. Do you have a wideband? Is it professionally tuned? Internal or external wastegate? Try to find out what brand the injectors are. Not all brands have a distinguishable size marked on them. If they're fic's take one out and you will easily find out what size they are.

 

[shook55]

yes i do have a wideband, not tuned professionally tuned internal wastegate, not sure what brand injectors they have a small RP on the side of them

 

[stephen_gst]

all my plug wires are fairly new too... i had to take a few looks at the cylinder head to find out the my plug on cylinder one kept jumping off the plug and then id have to mash it down for it to sit correctly and as soon as it made full contact with the plug it worked great

 

[haddixjl]

On my older talon I had the same issues your talking about it turned in to be the plug wires got soaked by oil and under heavy load they were failing

 

[stephen_gst]

did you figure out what it was?

 

[koafallenangel]

I had this same problem it was a coupler multiple times and Im only tuned for 16lbs. Make sure you use good clamps T clamps will hold well. Spark plugs will also cause this problem.

 

[shook55]

never did find out the problem but im currently putting a waterpump in and i took the timing belt cover off anf the balnce shaft belt was broke could that have caused any problems??

 

[Bchiles]

I had the same problem with my 92 6bolt. I did all tests mentioned by previous posts and still could not figure it out. I finally figured out the Throttle Position Sensor was bad. I had to have an extra set of hands, but you remove the TPS sensor from the throttle body. I am a little foggy on the exact procedure but it can be found in the shop manual along with all the factory specs. You take a multi meter and hold it on to the terminals where the wiring harness connects to the TPS. On the back side of the sensor there is a small piece that rotates as the throttle opens. Slowly turn the piece and watch the multi meter it should steadily raise and then steadily fall as you move the piece. If you see the multi meter jump up and down or not move as soon as you move that piece chances are the TPS is bad. They aren't the cheapest thing to replace I want to say $150 so I suggest testing it before just replacing it. On the other hand if it is the problem its an easy fix and that $150 is beyond worth it.

I am pretty certain that the balance shaft would not cause this problem since it seemed to clear out at 3000 rpm and that is what mine did to at that RPM. At least you can test the TPS while your working on the balance shaft.

 

[delta448]

TPS is a good place to start.

Acceleration enrichment depends primarily on TPS rate of change and will cause exactly the symptoms you describe.

Vibration will be the main symptom from the balance shaft belt being broken. Since the rear shaft is throwing weight back and forth without being offset by the front shaft throwing it's weight in the opposite direction. Might want to make sure the rear shaft isn't a stubby though before putting a BS belt back on it.

 

[95DsManiac]

You need something more than just a wideband to run 25psi. What is your fuel set up? Fuel pump, injectors, afpr, etc etc. If you only have just a wideband then that's your problem, running 25psi and not being able to tune it. Your boost might be set lower say 16-18psia and just surges to 25 psi and you hit fue cut and or run into problems with not having a car not tuned. Good luck on your journey bro, but if you want to do it right you got to take care of every single supporting mod to be running 25psi. 25psi ain't really nothing either, but it's more than the ecu can handle without link or atleast a flash able black box ecu. You need to get some numbers off your injectors so we can start there and see what your fuel set up is.

Anthony B.

 

[delta448]

You need something more than just a wideband to run 25psi.

DSM Forums - View Profile: shook55

Profile says SAFC and MAFT. Two piggybacks aren't ideal, but lots of guys have made good power using one along with 650cc or smaller injectors on premium pump. As long as the settings haven't been erased or messed with, it's safe to say that the problem lies elsewhere.

 

[95DsManiac]

Good catch. I was on my phone and for some reason it doesn't let me open profiles. I was just going off what I read and the fact it foes say he has 650cc and in his post above he mentions he doesn't know what injectors he has, makes me wonder if it's all up to date and or accurate. Hopefully he posts back and let's us know more.

Anthony B.

 

[Bchiles]

I admit that I do play it safe before I try to get wild. Looking at what is on your profile I would hesitate to run 25 PSI boost. I dont know how the car is built so I dont want so say that it is to much.

That being said I would have a couple of concerns. Before I tried to run that much boost I would double check the entire engine. Check the seals turbo system sensors cooling system and fuel system.

If the balance shafts where going bad I would go over the entire timing system. You can find all of the spec on the shop manuals so you can ensure they are all moving at the rate they should be. When I rebuilt my engine I had a lot of trouble with the auto adjuster. Some people have the right touch to make it work the first time but I did not. just a heads up of some potential pain in the ass parts. Check the CC on the fuel injectors because if you aren't sure chances are the computer may not know.

That being said I dont know what type of gauges you have but I would suggest running all new gauges. 25 PSI is a lot of boost I would want to know exactly how my engine was running at that much boost so I could best prepare the air fuel ratio.
Sorry if I am beating a dead horse but good luck on the ride.