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car has interesting problem at 4000 rpm and above

3670 Views 17 Replies 11 Participants Last post by  mkb
I believe my ecu is goin bad on my car and thats why its getting bad gas mileage and not running right but usually it drives and runs halfway decent but today it made up a new trick.

i was pulling away from a stop sign and the car ran fine and right at 4000 rpm when the boost was comming in the car started to stutter.

but not like a misfire or anything it sounds and acts like it has a 2-step set at 4000 rpm itll run fine then hit 4000 and bap bap bap bap bap bap untill i let off it seems like its not getting any gas but ik its not the boost cut because the was no buzzer sound when it started to miss.

please tell me what the deal is.

oh btw i just plugged up another ecu and the car runs decent now and only missed when it first started up and now runs ok i had it stutter once after i plugged the new ecu up so whats the deal bad ecu? 2 bad ecus?
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ECU probably not.

Have you done a tune up lately? Wires, cap, rotor, plugs, fuel filter, O2 (gas mileage)? Could be a bad ground around the coil etc....

Looks as if you have a few 1st gen sixes under your belt. Troublesooting starts with the basics. And the funny thing is the basics cost the least.

Start there and get back.

For got about timing!! check it too.
i had a problem like that.It was my fuelpump. does it do it when u turn right too?
id guess you need a tune up, or have a boost leak. which is much more likely than a bad ecu
ok i drove the car all day today and it didnt do it to me so idk...

ive been driving around with the new ecu plugged up and it seems to run ok has a rough idle when its put in drive right after starting it up.

will the cap going bad make it get bad gas mileage i mean im gettin like 160-180 miles on a full tank?

also want to ask why does my auto tranny stick in 3rd gear untill the motor is warmed up really good. it just wont shift into 4th till its gotten hott. it will just ride around in 3rd gear then when it wants to it shifts.

my transmission is full of fluid and it look pretty clean so i dont know whats goin on... any ideas on that?
Sounds like there is an issue in your ignition system somewhere. Chances are its your plugs and/or wires. Maybe the inside of the disty got damp somehow.

Are you running stock boost? If not, it could very well be blowing the spark out.

car is running on stock boost. the plugwires are brand new excel 8.5mm wire and the sparkplugs are pretty new there ngk forgot the model but there dual prong ones.

does anyone has any idea about my transmission? and why it will shift 1 to 2 and 2 to 3 but not into fourth gear?

i think i figured out why its getting bad gas mileage.

if the front wheels are pointing in the slightly in the opposite direction i believe its like riding with the brake on.
well if the transmission is vacuum activated & your tranny isn't shifting when it should, this would explain a few things.....why it's not shifting right & why yer gettin crappy mileage. Someone confirm if the trans is vac activated. Might be as simple as a vacuum leak????
it will shift but only when the temp gauge on the dash is just a lil above halfway and then it will shift it seems like the transmission fluid might be gooey or something untill it gets really hot but i dont know.

if it was a vaccum leak wouldnt it stay stuck in 1st gear and not shift at all.

it shifts fine all the way till 3rd and then it stays there when driving it will downshift to 2nd and to 1st but wont shift into 4th so i dont know about the vaccum leak.
same problems

so i have a 91 mx6 gt turbo and at 3000-4000 RPM my engine will sputter then shut off but only when the clutch is in. its not an ecu issue its an individual sensor problem. i talked with a mechanic from a ford dealership who used to own a mx6 and he was 95% sure the problem with mine was the cam position sensor the other 5% he said could be either the throttle position sensor, or the crank position sensor. i'm yet to fix the problem but i'm taking it to a shop to get the engine light checked. i'll let you know what i figure out soon!

my car is a auto and the sputtering noise is gone now well atlea1st for a little while and it really wasnt a sputter sound it sounded more like the rev limiter but at 4000 rpm it cant be that.

anyone know why my auto transmission wont make the last shift till hot?
my bad

sorry. the problem with mine only happens when the clutch is NOT pushed in. when the clutch is pushed in the engine will rev all the way to redline.

japracing: if you have an automatic tranny it is computer controled. and since you have a turboed engine i'd assume you have the gt version. well my point is that you might have replaced the ecu with the same year and make but not one set up for the turbo version of your mx6. not sure though, just a thought.

no it wont shift with either ecu and the one i plugged in is a turbo ecu for a automatic.

its been doing it since ive bought it. it didnt just start when the ecu was changed
no it wont shift with either ecu and the one i plugged in is a turbo ecu for a automatic.

its been doing it since ive bought it. it didnt just start when the ecu was changed
you suppose to let the car warnup/get to operating temp before you drive it. quick way to destroy the auto tranny and cause a huge carbon buildup in the motor
u guys arent payin attention i said the car has to be hot. like over half on the temp gauge. to do that idling in the morning would take about 40 min. thats alot of gas

i let it warm up for about 10 min everyday before school.

the car wont hardly warm up enough to shift sittin in the driveway it needs to be drivin to get that hot.
For the trans it sounds to me like you have a sticking solenoid or an o-ring for an accumulator that doesn't seal fully until it gets hot. I would check for a boost leak on the stuttering. They tend to hide making it difficult to locate. Like the bottom of the TB boot.

Good luck,
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