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car runs poorly, tach doesn't work. SOLVED: bad ECU

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blueninteytwo

15+ Year Contributor
99
0
Feb 6, 2007
beacon falls, Connecticut
1. you guys are the best. so here are some questions.



2. my car (91 Talon TSi A/T) idles at like 400RPM when i'm in any forward or reverse gear. it rattles the whole car. is this normal? in park or neutral it works fine, idles great, so i'm worried about messing with the BISS screw.

3. my tach doesn't work. sort of. it moves, but when you start driving, it basically stays at 1.5 /2 grand. it'll drop when you shift gears, but it'll drop from like 2K down to 1.5K, depsite the fact that i'm clearly pushing like 5 or 6 on the motor. even revving it in neutral it moves up to like 3 grand when the motor's pushing like 6...

4. my car runs like crap. it moves, but even with the turbo boosting all the way, it has to downshift a gear to get up hills and stuff....

in neutral, it's slow to rev up... i'm going to try and remove all the slack out of the cable, but it's much worse than that...

-when taking off, it's like the car starts in 3rd gear... it takes off REALLY slow and is even slower to pick up speed..it stutters a little bit when you first get on the gas... it gets a little bit of pickup when the turbo starts boosting, but it shouldnt feel like that..

-when driving, it runs the motor pretty damn hard just to stay at like 40mph.... if you're driving along and you come to an incline, it'll just lose RPM like you're in 5th gear (in a stick) and try and drive up a hill you should be in 3rd gear to go up... it's like there's no torque at all...

no CEL on, (depsite the fact it runs like total CRAP) and i can't pull codes because i don't have an analog multimeter to watch the needle.

I think the worst part is that it could be ANYTHING... clogged intercooler, Cam position sensor, crank position sensor, coil pack, retarted timing, messed up ECU, bad injectors, anything really. i'm kinda clueless where to start.



i guess proceeding from here means someone telling me about how the tach gets its signal (cars i've messed around with before either use the Crank Position sensor or the distributor) and maybe the answer to why the car runs like crap is somewhere in there...

thanks in advance.
 
my 90 awd stick is acting the same way,
yesterday it started to smoke(unburnt gas) and run like crap, seemed like it was hitting fuel cut.
But I built a boost leak tester today and theres a huge leak somewhere.
tomorrow is the day of rekoning for half that crap under the hood hahah!

I would suggest doing a boost leak test, thats what is wrong with my car now,
my wideband is almost pegged out under WOT for being rich.

oh yeah, my tach is doing the exact same thing too, after around 4k it gets a signal loss, ill figure that out in the morning for sure.
 
well today i'm going to relocate the boost gauge, when i bought the car it was hooked up all the way by the wastegate... i'm gonna relocate it to the blow off valve line and see what that does.... clogged intercooler?
 
ok, my ECU doesn't apparently work either.... i used to directions on pulling ECU codes, and i can't get anything. no answer at all. i've been trying with a test light hooked up to alligator clips, (with the key in acc.) and i get nothing at all. please help me.
 
Sounds like leaky caps in the ECU. Contact Steve from the site. He is the ECU master and can probably help you out more with that. Bad caps will cause all sorts of havoc with a DSM.
 
thank both of you guys for your help. i actually solved the problem today (it's my easter miracle)...


for some ungodly reason I was only getting 7.6volts to basically all of the car...so I swapped out the ECU with the ECU from a buddy's car and VIOLA... it worked great.

so for bonus points.... is one of the infamous capacitors at fault for this? i can easily replace the capacitors, and since the ECU isn't really mine, i can give him back an ECU... my capacitors haven't blown up and made a mess, but still broken? i dunno.
 
not to bring up an old thread but my car is doing the same thing and my fans aren't coming on and and its smoking from a fuel problem did yours have any of these problems too
 
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