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hesitation and bog under throttle

Brunoboy

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Apr 25, 2008
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Ok so 5 Ecu's later, link, and other stuff I just added. FIAV/ISC Blockoff, TB Shaft seals, new BOV, well, I got the car running again today, I always had this problem where it would hesitate at 4k for a bit, then loss of power, boost leak? I have no idea, I use the fog machine to check leaks, and it was only at the TB. Well After I replaced the shaft seals and FIAV/ISC Block off, my vacuum is normal 18 in hg, But now under WOT It seems to bog at 4k hesistate and all the bs. Is this a boost leak? I have no idea, I also have to replace the injector wires tomorrow because the wires are kind of rigged. So, does anyone else have an idea besides BLT?
-Shane
 

mitsuturbo

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When i bought 555 it ran like this. Turned out a couple valves were slightly bent.

Check compression. If it's not great, do a leakdown. If everything checks out, make sure your timing is good, your plugs/wires are good, and you're getting proper fuel pressure.
 

The injector wires might just be the problem. A friends talon recently suffered a similar ailment due to an injector clip that was broken. The car would run as expected until he'd get into the boost. Sometimes at 2 psi, sometimes at 10 or 16, the car would stutter (or bog), lose power, and generally run like crap. He'd back out of it and it'd be back to normal until he'd boost it again. He figured it out by luck, but once we changed that clip it runs awesome.
 

Brunoboy

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Quoting mitsuturbo:
When i bought 555 it ran like this. Turned out a couple valves were slightly bent.

Check compression. If it's not great, do a leakdown. If everything checks out, make sure your timing is good, your plugs/wires are good, and you're getting proper fuel pressure.


cant be, I took it to a local dsm shop, he also has a BG vr4. He redid my timing belt and all that, about 1000k miles ago, new plugs new wires, BPR7ES and compression is 150 across the board.
 

Brunoboy

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im gunna replace it anyways, if you saw how i tried to fix it last time, well lets say Im surprised it runs lol.
 

Could be a bad maf sensor. Once you roll into boost it starts acting up on you could be the maf not reading all of the air the turbo is pulling in correctly.
 

Brunoboy

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Yea, i did drop the maf hard before installing it hmm
 

The_Big_Weave

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Feb 26, 2009
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Rapid City, SD
I had this same problem when I first got 554. One of my lifters broke and shoved a rocker up and away from the valve. So on of the exhaust valves was not open. Take your valve cover off and look and your rockers.
 

This may sound pretty basic, but check your timing. I was having the 4k hesitation issue and my timing was the cause.
 

Brunoboy

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I dont think it would be anything inside the head, it was all fresh when put together, I am going to do a BLT and Re check timing, but wont be able to check timing til next tuesday. I also changed the injector clips but still same problem, and I will be trying new injectors and dial them in on link and post a log of normal driving, I also replaced the maf and still the same problem, I am thinking the TPS has something to do with it also, and the way i installed the TB shaft seals. Its kind of stiff when I touch the gas pedal.
-Shane
 

For the stiff pedal check the throttle cable near where it wraps around the small pulley. If you have a logger just check your tps% I bet it wont be a 100% you can do this with the car not running just turn the key forward and fully depress the pedal. If you are not at 100% when the pedal is all the way in then your throttle cable needs adjusting
 

stevep

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St. Charles, IL USA
Quote:
If you are not at 100% when the pedal is all the way in then your throttle cable needs adjusting


The ECU doesn't really care if the TPS doesn't read 100% at WOT, it cares about the changes in position and what it reads when the throttle is closed along with the IPS input.

As long at the TPS reads correctly then the throttle is closed and the throttle cable actually opens the butterfly 100% your all good and what the TPS reads is what it reads. (Within reason, discounting a bad TPS)

The throttle cable needs a bit of slack when the throttle is closed to avoid pulling the throttle open when things heat up.
 
Last edited:

Brunoboy

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On link lite it says 80% on the tps when my foots at WOT. I have a log.

log on tuners
 

Brunoboy

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hey, can my bog be because I have a low temp thermostat installed? 160*F, Maybe its running super rich because it doesnt warm up?
 

mitsuturbo

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Quoting brunoboy:
hey, can my bog be because I have a low temp thermostat installed? 160*F, Maybe its running super rich because it doesnt warm up?



No.
These cars run fine dead cold, in my experience.

I assume since you said compression is 150 all the way across... you DID check it, right?
Just because it was fine last time you checked it, doesn't mean it's fine the next day.
 

Brunoboy

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shopped checked it, and Ive been getting response on tuners that my log shows I fluctuate from 160-190*F and anything between 126-170 degrees is going to be adding fuel. Also whenever I drive around, the car temp gauge drops all the way back to cold.
-Shane
 

Tre3zy

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South San Francisco, CA
your thermostat might be shot if if drops like that....
 

Brunoboy

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Apr 25, 2008
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San Bruno,CA Home of SFO
I will replace it tmrw with a 180*F one, and I maybe getting Phantom Knock. If I gas the car, it rise all light bars of knock without boost......
 
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