The 5K stutter cutout misfire stumble breakup Thread [Merged 7-8]

[Newlogics]

My project 92 Talon just wouldn't be nice to me.

I figured that my smoking problem was due to my turbo leaking oil, since upper IC pipe had whole bunch of oil in it.

Now more porblems arize....

1st: It wouldn't idle normally, instead it revs up to 2K and drops back to 1K every like 2 sec. if idle is adjusted to be lower then 1100 rpm

2nd: When rmp reach 5K under WOT, it hesitates violently. As soon as rpms drop a bit, it's fine again.

(The good thing I fix the unlock buttons, 'cause it had shaved handles and you couldn't get inside by any means except a trunk....)

 

[Jhoe]

Serious? AFC-II or the other? I don't have a II, if mine does I don't know how, how do you go about doing that after this I wouldn't mind it.

 

[spyderturbo007]

Serious? AFC-II or the other? I don't have a II, if mine does I don't know how, how do you go about doing that after this I wouldn't mind it.

I just assumed that you had the SAFC-II. I have never owned the original SAFC, so I can't comment. Sorry.

 

[gstspyder53172]

what is wrong with my car? when I punch the gas it spools up fine but once I reach around 5k RPM the RPM stays at 5k and it slowly goes up(very slowly) and the car doesnt seem accerlerate anymore and I know thats not normal can someone PLEASE tell me whats wrong with my car! and how can I fix it?

 

[eclipsegsx1736]

Please fill out your vehicle profile so we can help you better. You most likely are experiencing fuel cut, but it would help if we knew your mods. What turbo? How much boost? Fuel pump? Injectors? Tuning? Do you have a datalogger?

 

[gstspyder53172]

Sorry. my profile is upgraded now.

 

[andymoraitis]

Based on your profile, you still have the stock T25 and this won't spool and pull like an animal above 5K RPM. However, I feel that your issue is more akin to a boost leak. These are common and will cause horsepower loss under heavier engine load. You'll need to make a boost leak tester and make sure the system holds 20psi for 30 second before bleeding down. To build one, reference http://www.vfaq.com and look under the Intake section.

Once you complete the boost leak test and fix any leaks, you should find that spool will continue past 5000 RPM, but I wouldn't shift much past that on a stock T25 anyway (around 6000 RPM is more than enough).

Hope that helps,

Andy

 

[gstspyder53172]

Yeah i have already done a boost leak test and it was leaking from my BOV . But i already fixed that. and it didn't seem to leak from anywhere else. But the one things that confuses me is that when i did the leak test it would only reach about 14-15 PSI and not 20 PSI as the Vfaq reads it should. Does that mean it has to be leaking from somewhere? THANKS for any responses

 

[nc90awd]

Its possible your catalytic converter may be clogged.

 

[andymoraitis]

A VERY good point. I think I've been hanging around Bruce too long and forget to go past the boost leak test.

Andy

 

[gstspyder53172]

Sorry i'am a noob. But how could a clogged catalytic converter affect my RPM's

 

[IHeartTurbo]

Sorry i'am a noob. But how could a clogged catalytic converter affect my RPM's

It would cause excessive backpressure in the exhaust. This would make it so the exhaust gasses wouldn't be able to get out of the cylinder, so that would mean fresh air/fuel wouldn't be able to get it. Therefore no more making power. And it would be more evident at higher RPMs like you are experiencing.

 

[gstspyder53172]

could it also be my Spark plugs, Wires?

 

[majik2k5]

Chances are you'd notice at idle if it were plugs. Everytime my plugs have been fouled, my idle goes straight to hell.

 

[acidflux]

Hey, just bought a 91 TSi AWD. My only gripe other than the actual problem it has is, its an automatic. With that being said, it shifts fine and the transmission is in good shape.

Down to the nitty gritty. Under about 75% to WOT, the engine bucks HARD around 4800-5200rpm. Whoever had the car before me already hacked the MAF. I inspected it myself and it was done neatly. silencer is gone, etc etc. I can hear a slight clicking in the center console also and the check engine light comes on as well. The light does NOT stay on, it goes off soon after the engine smooths out. Im suspicious its fuel cut, big puff of black smoke out the rear im thinking of doing a 2g MAF swap, or a 3" MAF translator install. ive done both on my buddys 1g with no problems. could this be a TPS problem, car idles high, from about 1000-2000 rpms, it usually sticks at about 1200 till it gets hot, then it runs higher. throttle cable is adjusted properly. CAS?? dunno much about those but i do have a used spare one that was last known to be "good". just throwing out some ideas. need some help. THANKS

 

[femmeDSM]

Well, I would hesitate to say it's the CAS, first of all.
Usually, when those go, they *go* (meaning, the car won't start or run because the engine will never be in time).

As far as the bucking....Check the obvious things like boost leaks and plug wires. If the MAF was "hacked" correctly, it shouldn't be giving you any of these problems.

As for the CEL, you will need to hook up some sort of logging device and see what the ECU has to say about that. If it's the TPS as you suspect, it should throw a Code 14 IIRC.

 

[acidflux]

hmmm, sounds good. thanks for the advice. im no noob to DSM's but this is my personal first. ive worked on all of my friends cars and im pretty knowledgeable when it comes to them. however, never ran into this before. odds are its a boost leak. all the hoses are still from 1991. i bet its one of those flex hoses by the IC. guess ill find out tomorrow. thanks.

 

[ddavisaf]

Here is the correct way to run a Boost Leak Test.
Make sure you're holding 20 psi without it bleeding down for at least 30 seconds.

What kind of spark plugs are in the car?

 

[acidflux]

yeah, i bought the parts for the pressure test. gonna try it tomorrow, had too much on my plate today. plugs are NGK ones. dunno the exact model, didnt write it down. they are the stock replacements from autozone. also, theres a clicking behind the center console, every time i step on the gas i can hear something clicking. check engine light comes on randomly also, only under acceleration. roomate swears its not a boost leak, hes all into swap-tronics. he says i should swap out a few parts and see what happens but, im not blowing money on stuff i dont need. he says its something with the "MPI relay"

for the hell of it, i had a spare that i tossed in but, car runs the same. leak check and take it from there is the plan, we'll see what comes up.

 

[acidflux]

WOOHOOOOOO

i got bored at about 11pm and said, ahh what the hell, ill give it one more try. maybe its something stupid. i read another post on there that said something about hooking up the turbo directly to the wastegate and bypassing everything. well, before i even got that far when i was taking off the vacuum lines, i noticed a cut in one. BINGO!!! re-plumbed the vacuum lines back the way they were, minus the cut piece and it runs like a dream, pulls hard all the way to redline. only one bi*** now.....

apparently, wastegate wasnt receiving a signal. i was boosting hard. now, that im running stock boost again, the car feels like a TURD. hahahaha, oh well. now i got a taste of what the stock turbo is capable of.

thanks for the help/input guys. any suggestions of what to do next. im thinking of installing a SAFC, MAFT, MBC, upgrading IC piping and installing an FMIC. also wanna throw on 3" exhaust turbo-back. sound good?

 

[Spoolio]

yea exactly what the title says, i take off in any gear once it gets to like 5-5500 rpms it just sputters and takes forever to hit 6k, anyone got any suggestions?

 

[Spoolio]

and by the way im only pushing 10-11 psi

 

[95TalonOwner]

Boost leak test.

 

[Spoolio]

been there done that, not my problem, anyone else with a logical suggestion?

 

[compression]

do you get a cel? or do you have one?

 

[compression]

it sounds like a boost leak to me too, but ive had a problem like this to where my mafs wigged out and was reading 2800-2900 hertz and i had no boost leak.