bad maf, bad ecu? wtf? (bogging under boost)NOT SOLVED

[stephen p]

ok, so my car runs like ass. it was running ok, but just slow. now, whatever the problem is, has gotten way worse. i did the boost leak test. and all is good. so here's the deal now it's gotten to where when you give it gas, and it goes to boost, it it's like it hits a wall, it will boost to 15 lbs, but it goes no where at all... the only way the car is drivable is to drive out of boost, and feather the gas. i put in a walbro 255 last night, and the filter is new. any ideas, before i go throwing parts at it? it's throwing a fuel trim code

 

[1gentalonfan]

well apparently everyone decided to skip over what this problem probably is. When was the last time you replaced your o2 sensor? It won't necassarily throw a code, but if it's out or going out it will make your car feel boggy, it will randomly cut and feel like its running on 3 cylinders or 2, and in boost will just be hell. I've had almost every car I've owned in the last 3 years exhibit these problems and all of them had slow or dead o2 sensors.(my z's ecu has a self diagnostic where i can monitor how many times the left and right o2 sensors cycle.) People like to neglect changing those and it's entirely necessary.

 

[Chris12398]

You should be using a AFPR (pressure regulator) with a 255! Thats my first observation. A stuck or clogged injector/fuel filter would do that too. Depends rich/lean, but overall Id say you need a regulator as the stock regulator wont be able to handle that much return fuel....

 

[Chris12398]

I was actually having this same problem, I was trying to figure it out like you. My Spark Plug Wires were shorted somewhere and in high RPM or boost it would cut out a cylinder almost. Change those....

In my case I changed my fuel lines, fuel filter, spark plugs, relocated the coil, re-wired fuel pump, and a new MAF. Now my car runs beautiful, all that it was turned out spark plug wires.

 

[nik95gs-t]

You ever consider knock pulling timing? or any other factors like Spark knock, detonation. My car felt like it hit a wall at WOT turned out my Knock went bad and pulled out all the timing.

 

[2gGst98]

did u put new plugs in. when i got my car some one thought it would be good to get platnum plugs but the were wrong i bogged under boost. when i would rev it up slow it wouldnt bog. try plugs, something small and easy can cause alot of heart ach

 

[DSMGary]

Hi, Have you ever considered that your injectors might be leaking. This would cause you see the "bogging down" effect you mention.

By reading the entire post, it seems to me that the problems is getting slowly worse. If your injector(s) are leaking and only getting worse, this could explain your problem.

Just my 2 cents, goodluck

 

[cumpersgsx]

check/replace all your vac lines. If they are hard and brittle you may not notice that they are cracked.

 

[AlaskanDsm]

This thread is a year and a half old and was solved by replacing the MAS and the TPS...