My car now is starting to do this thing where once i’m in third gear, going about 4000rpms it hits a wall and stops revving and pulling. like i have a rev limiter in it and its not getting fuel?
Sometimes it does it sometimes it doesnt but lately the car seems to run funny and doesnt feel as strong.
I ordered a fuel pump anyway just cuz i need one for a cam swap next spring so if thats my problem i’lll find out soon. I hope to get it in before saturday as i want to go to MIR sunday!!!
What you guys think? Not enough fuel getting to the motor? it only happens in third so if it was ignition wouldnt it happen in first and second?
Thing is tho, the pump supplies ample fuel pressure at the rails and holds nicely. it doesnt drop off once the car is shut off which is one tell tell sign of a bad pump so i read. I dont think i have bad injectors or regulator. Any input appreciated
you put a pressure gauge on the schreader valve, and drive around to see how pressure is under load? I got a gauge you can borrow if needed. Just tape it to your windshield.
i have a permanent gauge mounted to my holley fuel rails. never did see what it was doing under load. it very well could be a regulator as those things are notorious for going bad. I already orderd a fuel pump so when that gets in i’ll try it.
update
after doing more datalogging i’m now seeing what looks like a bad 02 sensor…the milivolt readings are not flucuating like they should…i’m not getting the right cross counts and they sometimes dip reallly low or get really high. so i think that may have something to do with my topend but i’m not sure. i dont see how they could affect WOT at third gear
yeah they have to switch but O2s should only be used by the PCM for closed loop. wot open loop is all programmed MAF or MAP.
try it, your gas mileage should atleast get better.
i estimate my sensor is near 15K miles or possibly near 20. somewhere in there. I may try a o2 sensor replacement since its only 30 bucks or so. but i will also add the fuel pump and HOPE it goes away. else it could be something with the injectors perhaps? maybe MAF…
what are you datalogging with? if you have access to equipment that can see O2s switching you should be able to look at your MAF voltage.
Really it sounds like a fuel problem tho, probably not injectors becuase it doesn’t sound like it’s missing.
btw is it a precat or postcat O2? either way just replace it, can’t hurt anything. post cat is just emissions shit tho nothing to do with fueling
i only have one o2 sensor and its on the header, drivers side.
i’m datalogging/scanning with TunerPro RT with my lap top and ALDL cable. i cant see any MAF voltages with it but i can see MAF grams/second so i can make adjustments to fueling.
I really need a wideband o2 sensor tho to properly tune
narrowbands lie especially if it’s only reading one bank. wideband that shit!
watching grams/sec would be the same as voltage since that’s how it’s read. it should increase as throttle increases
yep so far so good…everything has been reading ok except for the o2 sensor. i’m gonna replace that tommorrow and see how it goes
new o2 sensor is in but havent really done too much testing. idle and part throttle millivolts looks better than before. only 21 bucks so might as well replace it.
Fuel pump wont be in till friday i think so i’m gonna be hard pressed to get that in and test it before i go to MIR on sunday or whenever we leave. I want to go but its lookin like i wont beable to
well shit, i did a pull to about 100-105 or so and rpms were near 4800-5000 from what i could see…car seemed to be FINE.
no bogs, no rpm stops/drops, o2 milivolts read 91x-92x so its abit on the rich side but not too bad, MAF was pulling in air, blm’s looked good, etc etc
i hit it again to 85-90 i think and shut down with the car running the same way, just fine so far. i doubt just an o2 would make the difference as the o2 isnt suppose to be used in WOT from what i understood.
So maybe i dont need a fuel pump…not sure if i should replace it on friday cuz it may take me awhile if i run into problems…then again i dont wanna go to MIR and have it fuck up down there and be pissed. Better insurance to put it in.
maybe i’ll take it to hybrid afterall just to do quick 3 runs to see if it happens again and that way i can watch my fuel pressure closely and monitor the motor better. I just called them today telling them my pump may have gone out and i wont be in this week…if i have time this week hell, i may go for it.
interesting that the O2 mVs would be damn near the same for my car. 960 is considered safe for boost. while 880-900 is ideal for NA.
i was near 950-980 at times but i leaned it out some. i was about 12.5 to 1 AFR at the dyno earlier this year but that was before timing adjustments and such… i hope to get it near 13.0 to 1.
so its not the fuel pump i guess…car still runs kinda shitty… its weird…exhaust note even sounds different now… i wonder if i should change out the spark plugs and check my cap/rotor
getting a new cap and rotor and new hotter ignition coil. although its a good investment, i think the car would be running bad in all gears if it was a ignition related problem…i strongly think its a fuel problem with either the injectors or fuel regulator. i will try igntion first