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stumble under heavy acceleration? Plus is my ECU pulling my timing?

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blueninteytwo

15+ Year Contributor
99
0
Feb 6, 2007
beacon falls, Connecticut
first things first, these cars aren't civics :( in the first year i've owned it, i've replaced both wheel bearings, right hand inner tie rod end, drivers side drive axle, among other things :(

but we have a different problem now....


problem 1 is that when the car first starts it spews gas... kinda bad... and i get really crap gas mileage, like 13mpg.

once i get going and the temp gauge almost hits where it's supposed to, and i get on the gas to pass someone in traffic, i get nothing. where i'm supposed to get a hit of torque and the spool of the turbo, it feels like the ECU is pulling the timing. the turbo spins fruitlessly (higher than it seems that it should, like it's working harder than it has to) i get some power but not what i should be getting, and i get this vacant feeling of the something wrong. i've noticed that the harder i press on the gas, the more the engine fights (or the more the timing pulls), and when i let off the gas, my torque comes back...as the engine spools down, it seems like the ignition advances again and goes back to normal.

oh yah, and sometimes i'll get my CEL on and it will always read Code 11, which is Oxygen Sensor. my plugs don't read excessively rich, or excessively lean. so it's confusing.


my problem #2 is that if i get on the gas too hard(aka under heavy load), the car will stumble.... it doesn't always, just most of the time, but it feels like you're not getting combustion in one cylinder, it'll just stop accelarating for a split second, then continue revving. sometimes it only does it once, sometimes it'll do it every 2 seconds or so until i get off the gas... also, it smokes out the tailpipe kinda bad, if i'm in front of someone at night, and I get on the gas hard enough, i can see the smoke in the guy behind me's headlights...

becuase it's under heavy load that this is happening, it seems like something's coming up short... like one of the injectors can't keep up, or a plug doesn't fire.... short of problem #1, car runs fine.

the car is a 91 talon TSi auto, hallman Pro MBC set to 13lbs...

things i've tried to fix the problem: new NGK wires, Brand new BR7ES plugs, brand new Walker 02 sensor.... Fuel Pump rewire, brand new fuel filter,

theories i've got:

Problem 1:

Faulty coolant temp sensor (would throw a code if it's broken though, right?)
Faulty transistor
Faulty faulty coil pack
Faulty CAS

Problem #2

intermittantly faulty injector (or clogged)
Faulty coil pack or transistor
lack of fuel pressure


maybe you guys could be of help to me.....
 
first thing check the ecu caps ### it causes prob. like the
ones your having.then check your coil pack for cracks and make sure
base timming is set to 5deg.
 
Check for boost leaks, and you might be getting too much gas aka running rich. Just a few other things for you to check.
 
Have you checked your plugs? Mine stumbled real hard and when I got on it and my plug gaps were real far off fixed them and problem was fixed.
 
my car would start to stumble under WOT, so i swapped out some new plugs (BPR7ES) and threw in a new set of wires, that fixed that problem.


Also your other problem sounds like a boost leak.. do a test and let us know what happens
 
with regards to the plugs, the original plugs were BR7ES's set to .030, but a buddy suggested to me that maybe the combination of a colder heat range plug and larger gap was simply too aggressive for the modest mod list.

so now last night i popped in BR6ES's set to .028, and it still bucks on me when i get on the gas... i'm gonna right now go check on the "timing pull" situation, because it seems like it's always a problem when the car's ALMOST warm, within the first 2-10 miles of driving....
 
nope, stock plugs on stock gap has no discernable effect....

one thing I was able to notice was when the bucking happened... it was only when the car was almost warm, and i would be cruising along at like 2.5Krpm, then gun the gas, good acceleration, but when the car would hit 3.5K or slightly under, the car would miss, then the tach would be back down at 3K or 3.1K.....if you stayed on the gas, it would go back up to 3.5K again and miss on me again, and drop RPM....

so i decided to try it again in each gear.... so i drove about 15 miles or so, really exercising the engine and went to an abandoned road, put it in 1st, and took off... went smoothly, no problems. 2nd, 3rd and 4th all did the same, accelerated smoothly


i've noticed this trend that all the problems appear to come up when the car is almost warm, it actually runs beautifully when the car is cold (save for billowing smoke)..... so i think i'm gonna toss in a new Engine Coolant Temp Sensor...

the ECTS is temperature-dependant, and controls the Fuel Injection system.... seeing as most of the other stuff is brand new (plugs, wires, 02 sensor) it can't hurt.

PS. i don't want to discourage anyone from posting possibly helpful answers, but i'm here because doing the basic stuff isn't solving the problem.. i'm fairly certain that all the basic stuff is taken care of...
 
my mechanic noted that it runs really rich still....

got my CEL back on, but it went off after the car started missing when i got on the gas, i'm fairly sure it's a code 11, aka 02 sensor picking up bad readings.... but unfortunately nothing useful because i already know i'm wayyy out of stoch. on the rich side......

well i'll probably start working on the air side of things, checking on the IAT, MAP, MAF, etc.

hopefully someone that knows a little more than "change the plugs" can chime in....
 
when i got my car back tonite after swapping the coolant temp, and i noticed the following:

1. it seems to spew less gas overall.

2. it misses occasionally at idle now... i've never noticed that before....

all of this stuff is definately making the car run better... but they're not getting at the root problem....
 
Sounds like a less serious form of what's happening to me. Check your mas. Seeing as your 1g it may have nothing to do with it. But it may be "seeing" more air than there is, and overcompensation. If you had a faulty CAS, it shouldn't fire at all. It may be the coil pack like you said. Definitely log it if you have the resources, it's a lot easier to troubleshoot something like this. Take my advice with a grain of salt though, I'm mixing my knowledge of 1g 3S (same CAS) and my 2g GSX
 
Im haveing your probelm number 2 on my 2g gst it sputters and wants to boost but wont and shakes and has no accel when the day b4 ran like a top . i didnt even get on it the day it worked. just up 2 60 a couple times. IVe tried the plugs and wires didnt help. i think mayb its my fuel injectors or maybe something with my manifold mayb im unsure ive only owned the car 4 2 days and its all ready a real PITA
 
my gst did same as your unplug o2 sensor try that plus i put a maft on mine an that helped alot lot if u ever had a ic pip come off or blow a boot say bye bye to your o2 might want a wideband if u dont already.
 
^^What? I've blown IC pipes for almost a decade now and never experienced such a thing. Stock MAFs are great too. You're going to replace your o2 with a wideband? What?


I resolved my issue, which was similar to the OP's. I fixed a couple things at once.

-Plugs and wires were subpar
-1 of the fuel injectors had a different tip
-1 of the fuel injectors had a broken tip
-Missing lower honeycombs on the MAF

My resolution was new wires/plugs, a new coolant temp sensor, a new knock sensor, a virgin 2g MAF, and some Evo 8/9 560cc injectors. I checked the caps in my ECU and made sure I had zero boost leaks. I'm not sure if it was a combination of a couple things or just one thing, but the car is far better now than it was a week ago.
 
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