Too much boost on a STOCK turbo?!

[babiebluboi]

My car is misfiring and a lot of people already told me to change the spark plugs. I haven't got the time, but I am planning to do it this weekend (hopefully). But would bad spark plugs cause the turbo to overboost? Stock boost is like at 13-14 PSI, right? When I boost it, it'll boost to like 21 PSI, then misfires. Is this also caused by bad spark plugs? Some dude told me that it could be just a bad turbo (which I am hoping, so I can swap). What's going on?!

 

[dsmgrimreaper]

nope wastegate isnt opening check the vaccum. if your going to change your plugs it would be a good time to change the plug wires to.

 

[dalatinromeo]

My car is misfiring and a lot of people already told me to change the spark plugs. I haven't got the time, but I am planning to do it this weekend (hopefully). But would bad spark plugs cause the turbo to overboost? Stock boost is like at 13-14 PSI, right? When I boost it, it'll boost to like 21 PSI, then misfires. Is this also caused by bad spark plugs? Some dude told me that it could be just a bad turbo (which I am hoping, so I can swap). What's going on?!

Well the misfiring can be caused by bad spark plugs/wires. I would swap them this morning. I still don't believe that your spiking is caused by the plugs. Stock boost is suppose to be 10 psi. Do you have a mbc?? Because then you can either have the setting two high or the boost controller can be going.

 

[Dream On]

Yeah you should check that your bcs is working, and your wastegate.

 

[phillabaum03]

Stock boost is 12. Atlest on my car and all my friends.. You got something wrong.

 

[babiebluboi]

I bought new spark plug wires only a few months ago, along with my NGK spark plugs. If the spark plugs/wires are that new, could it still be messed up?

I had a boost controller, but I took it out. So I'm running on stock boost right now. How much would a good aftermarket wastegate go for? And are you guys talking about external or internal wastegate?

 

[kronus]

My car is misfiring and a lot of people already told me to change the spark plugs. I haven't got the time, but I am planning to do it this weekend (hopefully). But would bad spark plugs cause the turbo to overboost? Stock boost is like at 13-14 PSI, right? When I boost it, it'll boost to like 21 PSI, then misfires. Is this also caused by bad spark plugs? Some dude told me that it could be just a bad turbo (which I am hoping, so I can swap). What's going on?!

To "like" 21 PSI? Do you happen to have a Boost Guage hooked up so you can actually see the how much boost you are achieving? Also I wouldn't "hope for a bad turbo" because those are expensive pieces of equipment to replace.

BTW here's a good thread I found that will give you and idea where to start to look for fixes...

http://www.dsmtuners.com/forums/showthread.php?t=184101&highlight=Boost+Spikes

-Kevin-

 

[larsenracing]

You have a sharp looking car. Do you still have the T-28 if so im pretty sure that turbo will not hit 21PSI as for spark plugs and wires the plugs may be ok but they are cheap to replace so id do it any way but for wires what wires did you use, the elcheapo wires are junk they will not last very long if thats the case replace with OEM, NGK, or better wires. Good luck on the fix and if you have anyother information please let us know and we will try our hardest to help ya.

 

[babiebluboi]

Yea I have an aftermarket boost gauge, but I don't really know how to read it. Instead of having 10-20 something PSI on the gauge, the only numbers it has on it is 0.5, 1, 1.5, and 2. How do you read that? Stock boost hits a little under 1, but when I'm having boost spikes, it jumps to 2.

I was told that 0.5=7psi, 1=14psi, etc. I'll check my spark plugs/wires this weekend, and let you guys know what's up.

 

[GVR4592]

It sounds like your gauge reads in bar, so 1 bar=14.5 psi. If it is hitting 2 bar then that is 29 psi. You should stop boosting your car immediately and find the problem or you wont have a car to drive anymore. The "misfire" you feel is probably the ecu pulling timing due to high knock. Do you have any exhaust modifications, or a boost controller?

 

[IHeartTurbo]

It sounds like your gauge reads in bar, so 1 bar=14.5 psi. If it is hitting 2 bar then that is 29 psi. You should stop boosting your car immediately and find the problem or you wont have a car to drive anymore. The "misfire" you feel is probably the ecu pulling timing due to high knock. Do you have any exhaust modifications, or a boost controller?

1 bar = 14.7psi

 

[v8killar]

It sound's like you forgot to re-install the Y hose going back to the wastegate after you took out your MBC.

 

[SiNiST3R]

It sound's like you forgot to re-install the Y hose going back to the wastegate after you took out your MBC.

beat me to it

Check all your hoses make sure they are right.

 

[babiebluboi]

I think I did forget to reconnect the Y hose back to the wastegate...gotta check. I don't think this matters, but to GVR4592, I do have an exhaust modification. I have straight pipe from the downpipe back. The inlet of my exhaust is 3.5 or 4 inches. Maybe it's too big?

 

[GVR4592]

1 bar = 14.7psi

That's what most people think, however it is not correct. Bar is often confused with atmospheric pressure. The two are not the same. 1 atmosphere is 14.696. 1 bar is 14.504. Don't believe me? Look it up.

 

[GVR4592]

I think I did forget to reconnect the Y hose back to the wastegate...gotta check. I don't think this matters, but to GVR4592, I do have an exhaust modification. I have straight pipe from the downpipe back. The inlet of my exhaust is 3.5 or 4 inches. Maybe it's too big?

If you do not have a catalytic converter then you will most likely experience boost creep. This can be solved by porting the turbine housing and wastegate passages of the turbine housing. Porting the O2 housing can help as well, and since you have to take it off to port the turbo you might as well do it. www.vfaq.com for a porting guide.

 

[madman]

My car is misfiring and a lot of people already told me to change the spark plugs.

First off we are assuming you have a stock turbo and stock fuel system. Please update your car profile so we can better help you (doesn't show you have an aftermarket boost gauge). Thanks.

IF you're going over 15~16 PSI, then that's a big problem. You should install your boost controler back in and keep the PSI under 15. An electronic boost controler like Greddy's can help prevent you from going over a specific PSI (good if you have boost creep problems). It you didn't reconnect the lines back properly when you took the controler out, then it could definetley afftect your PSI.

1. Does the "misfire" feel like you hit a brick wall and it seems as if the car shuts off for a split second?

2. Or is your car sputtering when it starts to boost?

If it's no 1. then it sounds like FUEL CUT. It happens when you're running to much boost on a stock car. This could happen if your boost is creeping up like GVR4592 said. I started hitting FUEL CUT around 15 ~ 16 PSI.

Do some research on FUEL CUT. There are some tricks to help prevent it and run a litter higher PSI. But if you still have the stock turbo (T25) then you shouldn't really go much over 14 anyways, especially without the proper modifications. You also might want to look into a bigger fuel pump it you start increasing the PSI, for saftey (for the motor).

If it's no 2. then it sounds like plugs or wires. Double check you gap on the pulgs. Should be at .030". If the plugs look ok then try a new set of wires. My stock wires didn't even last 9 months before I had to get new ones. I went with Magnecor 8.5mm and they are great. I'm not sure about the quality of OBX wires.

 

[GVR4592]

I don't mean to be a dick, but you must not have read his post very well. He said he hits 29 psi. He's obviously over boosting. He said he doesn't have a cat, which most likely means he is experiencing boost creep. A boost controller won't do anything if he has boost creep. The only way to fix it is with porting or an external gate. Porting is by far cheaper and easier for most people.

 

[dsm-onster]

That's what most people think, however it is not correct. Bar is often confused with atmospheric pressure. The two are not the same. 1 atmosphere is 14.696. 1 bar is 14.504. Don't believe me? Look it up.

I did look it up... 1 bar = 14.67 and 1 atmosphere = 14.67. Also stoich = 14.67, fyi

 

[dsm-onster]

If you do not have a catalytic converter then you will most likely experience boost creep. This can be solved by porting the turbine housing and wastegate passages of the turbine housing. Porting the O2 housing can help as well, and since you have to take it off to port the turbo you might as well do it. www.vfaq.com for a porting guide.

Hay, I know. I look like I'm flaming you but I'm not... Really.

But come on. Have you ever had boost creap with a 14B?

I have never heard of boost creap with a 14b and I know guys running straight pipes out to the front of their rear tires with no porting of any kind anywhere.

With a 16g, that is something different... Even then, the creep is only to at the most 25 psi... If this guy is getting 2 bar then his wastegate is jammed or not connected properly.

 

[dsm-onster]

Ok now i am flaming you ...just don't get mad yet. I promise to be civil with your response to this.

I don't mean to be a dick, but you must not have read his post very well. He said he hits 29 psi. He's obviously over boosting. He said he doesn't have a cat, which most likely means he is experiencing boost creep. A boost controller won't do anything if he has boost creep. The only way to fix it is with porting or an external gate. Porting is by far cheaper and easier for most people.

... but just read this. He said:

I think I did forget to reconnect the Y hose back to the wastegate...gotta check. I don't think this matters, but to GVR4592, I do have an exhaust modification. I have straight pipe from the downpipe back. The inlet of my exhaust is 3.5 or 4 inches. Maybe it's too big?

FIY: no creap with no cat or muffler on my old 14b. Major creep from 15 psi to 20 psi with my small 16g. When I turned up my boost to 20 psi, I did not get creep to 25 psi. When I ran a few weeks without a BCV, it sucked and was slow and i had creep from 10 psi to 14 psi. Never tuned below 20psi with my 18g, but got only 2 psi of creep. I had my cams by then, so i'm sure the 18g was struggling to keep my manifold at 20 psi of boost much less creep a whole lot.

You're right he is overboosting. Yes. But, from an unregulated wastegate. Again, boost creep goes away when boosting upwards of 25 psi on a 16g variant because there is creep only to that point. Boost creep is not at all common with a stock dsm turbo.

He for sure has fuel cut. And he could be getting "sputter" from spark 'blow out'. I surely did with stock heat range plugs gapped just a little too wide: on the acceptable high side.

 

[madman]

I don't mean to be a dick, but you must not have read his post very well. He said he hits 29 psi. He's obviously over boosting. He said he doesn't have a cat, which most likely means he is experiencing boost creep. A boost controller won't do anything if he has boost creep. The only way to fix it is with porting or an external gate. Porting is by far cheaper and easier for most people.

Thanks, but I did read his post and I don't have a cat either and I don't creep to 29psi. I might (emphasize might) creep 1 - 2 psi over what I have it set at. I've used a EBC, which I mentioned will keep it going over a select point and I'm currently running with a MBC, not cat, no port work and I can control my PSI.

Cost wise.....

Check you connections and reinstall MBC (optional) ........Free
Disassemble your car and port necessary part........ Not free and time consuming. (may not fix problem)

 

[LTTuner91]

Change the plugs and wires i had the same problem with my car

 

[screwdgie]

Hay, I know. I look like I'm flaming you but I'm not... Really.

But come on. Have you ever had boost creap with a 14B?

I have never heard of boost creap with a 14b and I know guys running straight pipes out to the front of their rear tires with no porting of any kind anywhere.

With a 16g, that is something different... Even then, the creep is only to at the most 25 psi... If this guy is getting 2 bar then his wastegate is jammed or not connected properly.

I am still running the 14b, and I have an evo3 o2 housing, 3" turboback w/ test pipe, and I am getting boost creep.