Hi guys, ive been using this forum a bit as i started to build this car. though this is my first post, i want to thank everyone here for all the help.
the car
95 trans am with a 350 bored 40 over it has the stock heads and a comp 276 cam. something like 224/232. cam springs that are good for like 550 lift everything else is fairly stock, but new assembled by me so it should be correct :P . just installed the engine last week.
The problem
at "cruising " throttle , about 20-35% tps, or 0-35 % tps really. i have a huge bog, like im pulling a trailor. like your exhaust is clogged or intake is clogged.the a/f gauge reads lean at this point. as i push the accelerator it hangs in this "bogged state" until you push the pedal down somewhere past 35% tps at which point the a/f gauge jumps to rich and the car accelerates decently. The air fuel meter is a narrowband and attatched to the drivers bank factory 02 sensor which seems to be working properly. next the engine lacks power and does not want to pull at all above 4000 rpm.the a/f reads rich at this point. Now lastly. the scary part i realized tonight, that helps me diagnose the problem, but also lets me know to take action imediatly. I drove and tested for hours today. got to teh gas station only to realize my gas tank filler neck was actually hot to the touch. and exxtreme pressure buildup. although i dont have any sort of evap hooked up yet. this was clearly excessive. so this made me test something i had forgot. the exxhaust temps. the passenger bank was at 700 pretty even on all cylinders. the drivers bank was at 350 on all cylinders. of course the rest of the engine doesnt seem to be quit that hot by the coolant temps and external laser temperature readings. now for the last interesting part. and probably the problem. the passenger bank 02 is stuck at about 500 or so. although i have an understanding that i gathered somehow that if i unplug the maf the car wouldnt use the 02s to adjust fuel trim and would basically run off of the ve tables.ive been chasing this problem for days now and have removed the optispark to check, checked the plugs burning white on the right bank of course but clean on both none the less), checked the fuel pressure (its 35-40 depending on acceleration) , used a pressure gauge in the 02 hole to check exhaust pressure ( highest was about 3 psi at 4000 rpm, scared to rev much higher because of the way it bogs at that point.), i checked the resistance on the injectors ( all about 13) also tried tuning it myself ( to the tune of one fried pcm the first attempt) second attempt was a mail order tune from garrettuning on ebay. not real impressed with it, but im learnign tuning myself , have succesfully uploaded about 10 different tunes today and have a good understanding of how a car works and timing and whats too much etc. and im confident my problem is not the tune.. im sure ive tested other things but i cant remember. all the time of course not replacing the 02 i know is bad. anyway i have the 02 in my hand, waiting for my car to cool down and some of the evaporating gas fumes to float away and we will see what happens. although i have seen obd1 02 sensors do wild things, i find it hard to imagine its doing all this.
so to anyone who made it throguh that, thank you, advise or criticism is appreciated. also i will give any more info that is needed. im using tuner pro rt to log and can figure out how to upload a log if i need to. thanks in advance.
ps: im sure there are errors, im sorry, ive proof read it like four times, its late. thanks for the help!! i appreciate it so much haha
Reply With Quote
Bookmarks