I need some help on this car I'm working on. I'm thrown for a loop on this and just can't figure out what's going on. I have some speculations but I want a little bit more ideas before I proceed.
The car is a 95 Lumina with a 3.1 SFI motor.
The problem is that on cold starts it has a very hard idle and stumbles a lot, but symptoms go away when you step on the accelerator pedal.
But if you go WOT and start the car, it will start and run fine.
It has had an EGR code in its history, and after testing I deemed the EGR operative and just resulted to cleaning the passages, which seemed to have fixed it a little bit.
But after awhile, it continued to happen again, this time once you reach 20 mph, there will be a dead miss and it seemed like it was running on 4 cylinders rather then 6. That ended up being a coil that was going bad, and changing that coil seemed to have fixed the starting problem for awhile too.

But yet again, it is back...and I'm getting angry. I've checked all the coil resistance and they're all within spec. I've checked injector resistance it its within spec. I've hooked up a spark tester on the ends of all the plug wires and each of them has got a nice, strong spark during these symptoms.
Short term fuel trim for it is fluctuates around 115-135..which its cycling from rich to lean I assume.
I've checked O2 sensor voltage shortly after and yep, I'm seeing a rich to lean readings. But the smell from the tail pipe suggests that its constantly running rich. I've tested ECT too and that seems to be working, along with fuel pressure regulator.
Again I'm at a complete lost now...I can't think of what more to test.

The car as about 180,000 miles on it...I am leaning towards a leaking injector...but since its a pricey little unit, I don't want to exactly jump head first into it.
I also hear that cam sensors tend to go bad on those things, which could result in these symptoms...if so, whats a good way to test those?

An o2 cycling like that means it is working. Have you checked to coolant temp sensor? If that goes bad the car usually stay in open loop, ecu thinks the car is in a cold environment and stays in fuel enrichment.


"The problem is that on cold starts it has a very hard idle and stumbles a lot, but symptoms go away when you step on the accelerator pedal.
But if you go WOT and start the car, it will start and run fine."

I dont quite understand what your trying to say here. If you have the throttle wot and start the car if runs fine but cranking without the throttlebody open results in your stumbling also? Have you checked tps voltages? And im pretty sure cleaned the TB passages and IAC out too right?

I haven't yet cleaned out the TB passages and IAC but will sure do that.
What I meant by that was that if the throttle is wide open, then the car with start up just fine, but if the throttle is closed then it will start up still, but it will stumble and idle really rough. Which I find weird as it is because at WOT the injectors should go into clear flood mode, shouldn't it? So then why would it still even start without an injector pulse at that point.

And as for the O2 cycling, yeah I stated that to verify that the O2 sensor is working, but even with it cycling between rich and lean, I can still constantly smell fuel at the tail pipe.

As for the coolant temp sensor, yes I did test it. I disconnected it and ran the car, as I tested it for resistance value. I also had a temperature gun aimed at it. And it's resistance values at different temperatures fall within spec.

my mom told me if i get a 1900+ on my SAT, im gonna get a celica, but if i get a 2100+ ima get an evo. I just checked my scores today and i got a 1930. Should i get the celica, or study a little harder and get the evo?

evo by far. thats kinda of a no brainer

kinda want a car asap tho and its not gauranteed im gonna get a 2100, thats kinda hard to do >.<

try for the evo but it u miss the 2100 then take the celica.

btw what kind of celica is it, anyways, evo eats celica, unless you have a 400hp 3s-gte under the hood of the celica, but thats not the case, try to get an evo.
study hard it really pays off anyways

probably the 7th generation one, either that or an rx7 fc

hmm, if your do get a fc, try 2 find a turbo 2, you can make it as fast as an evo wit some money, plus u can use it for drifting around.
id get an fc over a celica anyday, the motors r awesome, rotary power!

honda jazz 85000ks or so

sometimes when i stop at a traffic light the car vibrates (holding down the brakes enough that it wont move) but if i hold down the brakes harder it stops

ps: the cars wheel alignment is a bit off, as i let go of the wheel straight, a while later it goes left

do i need a wheel alignment or new brakes to stop the vibrating?

check your breaks and make sure they arent down to their last leg and make sure your rotors arent warped, but if it shake your steering is probably out of alignment and something might be wrong with your front left driveshaft axel.

ide check your brakes but it sounds like one or more of your rotors may be warped.

lol rotary Fails compared to piston engines,

and before people flame me if rotarys are so super awsome why isint there more of them? because they suk.

less efficent less power / torque per liter and just generaly a pain in the ass to repair.

well a simple reason is that they are unique to their design, but they suck up alot of gas and actually their power to liter raitio is quite high, especally compared to honda and their vtec, a 1988-91 13b non turbo produce 160hp, and it was only a 1.3 liter motor, thats 123 hp per liter, which is quite high to todays standards, but even so it is a lower power output, but it can easily eat a delsol vtec and 2000 civic si
for breakfast. there isnt more of them due to the fact of production cost, piston motors are easier to produce and less complicated than a rotary. their only a pain in the ass to repair to those who havent worked on them, not to me, i would know because i have worked on rotaries, taken them apart and put them back together, otherwise people who are not concerned with the performance point of view would think of it as a pain in the ass. a 13b rew twin turbo out of a 3rd gen rx7 (FD) 93-97 w/e, could produce as much horsepower as a supra twin turbo, big difference there in displacement, 1.3 to a whopping 3.0, yet some how the rotary can make as big as numbers as a 6 cylinder twin turbo can.
that is why rotaries are great, besides the fact that they have the crappiest gas mileage right next to big american v-8 motors.
just giving my opinion.