Backfire/Sputter/Loss of power (not a boost leak)

[CorrupTTalon]

i just need help determining whether this is coil, VAF, or something else. i dont have much money to spend on parts and want to buy the right part the first time

i did a resistance test on the coil and VAF and the readings from the coil were weird and the vaf was low i guess - im not sure because i didnt use a hair dryer, instead my finger to warm the sensor

what happens is from start up (it usually takes two turn overs to get it goin) the idle is rough. if i let it warm up and take it for a spin it will go in and out of sputtering and loss of power. meaning i could have it WOT and it will have zero power then all of the sudden it kicks in and rights itself and takes off!

after a warm-up-spin and another few mins of idle, it will finally right itself and be fine for the rest of the duration of driving - meaning the idle will be rough (a low "blup blup blup") and after a while the idle will rise quickly like i just started it and then fall to 900k at a smooth idle - until i shut it off next, then its the same thing all over again.

ALSO if im driving and the car is doing this, if i push the clutch in and turn the car off and then turn it back on while driving, the problem goes away for at least 20 seconds. could this be an ECU issue?

any ideas or suggestions, i am all ears - thanks

 

[bluegs03]

Do you have any way of adjusting ignition timing? I know on a 90 there is a Crank angle sensor that adjusts timing and i had it adjusted right in the middle which was way to lean and caused the exact symptions you are describing. It was hard as hell to start, like 30 seconds cranking and when power came on you could hear the turbo spool but nothing. Although for me an easy way to tell if this is your problem is a RED HOT manifold after a 2 min drive, i mean smoke pouring out of the top hot manifold.

 

[CorrupTTalon]

no i just have a fixed metal plate and a crank sensor. timing should be set tip top - ive done it a million times and just recently (before this) reset it because i had to adjust the tensioner. i should peak at it, but the fact that the car corrects itself after a significant warm up period means its not timing, as timing would be a consistent problem

 

[quiksilver20004]

For warm up the ECU changes the timing

 

[CorrupTTalon]

awesome. i forgot to mention, that if im driving and the car is doing this, if i push the clutch in and turn the car off and then start it while driving, the problem goes away for at least 20 seconds. could this be an ECU issue?

any ideas? could this be ECU? i figured these symptoms would narrow it down and someone would pick up on it

 

[sighless]

i have this exact same problem..

i tried to change my plugs, to champions.. ( cant get the NGKs Here) and it ran worse.. so i put the NGKS back in... jim not quite sure where to start the car hold boost fine according to the gauge.. BOV is vented back to the intake as it should be.. havent done much else as i just got the car like this.

 

[CorrupTTalon]

ah great to see a reply.

i have found someone locally who is willing to swap out parts for me. everything from the vaf, ecu to the coils. im going to swap them out until i find the problem. i will keep you updated through here as i hope you do the same!

 

[awd_tsi91]

i posted a problem like this earlier..same thing kind with my car! maybe its a dsm flu or something? ...suck when you throw parts at it and the bill stacks up...i cant figure mine out either

 

[sighless]

i will keep this updated as much as i can but my car is a three hour drive from me.. tucked away in my dads garage for the winter.. i try to work on it whenever i can..

if i find something i will for sure let you guys know.

 

[CorrupTTalon]

hey just an update. i tried massive things today. but no results.

i picked up a coil, and MAF from a salvage yard today and swapped them out one by one, nothing. then i swapped in new plugs and it road amazing for a little bit, then started it back up.

my old plugs were as white as snow. so i am running lean, it has to be fuel cut. im not sure where to start. i guess i can start with the resistance of the pump and change the fuel filter.. etc. any idea?

 

[greyspyder117]

restricted exhaust???? check your pressure using a gauge in the 02 slot

 

[CorrupTTalon]

anyone figure this out?

i unplugged my FPR and the problem was basically fixed. what could this mean? pic attached

 

[brandon1239]

uh this is a shot in the dark, but if you unplugged the FPR and it was fixed it might not be holding pressure in your fuel rail. might just basically let the fuel flow freely through the rail and back into the tank. like i said a shot in the dark ahah. I had this problem but I was running rich, turns out it was making me have too much pressure for whatever reason and would make my car studder and stumble all over itself. I just replaced the FPR and it helped.

 

[CorrupTTalon]

i didnt know you could have too much pressure? would too much matter? considering the injectors give the cylinders the correct amount each time?

 

[EagleTSIawd]

Yep, Too much or too little will change the performance. I see that you have the fpr vacuum line tapped, I keep the bov line and fpr lines clear.

 

[CorrupTTalon]

what do you mean when you say "clear"

 

[boostedawd42]

By clear I assume he means do not "T" into the lines to your BOV or FPR.

 

[jbl_5star]

this sounds close to my problem. I found this out slowly it started going bad. Now i cant even spool up, at around 3500 rpms it give just a power loss, in every gear. i just got a wideband, what could cause this?? Burning rich im sure of it, but does burning mega rich cause funny problems?? like the fuel just cuts off and stalls. I have to let go of the gas petal and re press it to go again, and my turbo wont even kick in.???
what could be the problem?

 

[EagleTSIawd]

Yes, Thats what I meant

 

[jbl_5star]

even put in new plug and wires..

 

[CorrupTTalon]

do you pull any codes? i havent pulled a code, however i have an odb2 reader i was thinking about plugging in just to see if my dummy dash light wasnt working OR it could be the ECU not properly working which could be the actual cause of this.

i can actually spool. i just got back from subway and it ran poorly on the way home, my turbo spooled right up, you could here it, everytime, however the power was not there. something was holding it back. every now and then it would kick in.

stumped on this one. i really do not want to go through and replace a million things, i wish there was a way to diagnose this specifically

 

[jbl_5star]

thats how my problem started out, just wasnt boosting like it should. now it cuts off before the turbo has a chance to spool.

 

[skatershawn]

did you fix you lean problem??
You figured out you FPR was jacked, im assuming you replaced it!?!
Cause with or with out a turbo, running lean, your car will fill slow and not power!
Just because there is a turbo slapped on there, it wouldnt make it pull any much more if its still running lean!
If you havent fixed that FPR, do so and come back and let us know whats up!
If you HAVE, you should mention that and let us know what all it is doing now!

 

[CorrupTTalon]

@skater thanks for the info

@5start me too. i dont think its our ignition system, specifically plugs/wires, i believe it has to do with our fuel or electrical.

this actually didnt start happening until i touched my alternator main lead to the frame of my car - blowing my alt fuse. everything went to shit after that. have you done anything like that? or experienced anything before these symptoms occurred?

and thanks, there will be no T'ing.

i do have codes. even though ive never thrown a CEL. pretty lame.

P0141 oxygen sensor heater circuit bank one sensor two
P1500 means this alternator output signal is not working properly or a bad ECU
P1105 Fuel Pressure Solenoid.
P1104 Turbocharger Wastegate Solenoid.
P0135 oxygen sensor heater circuit bank one sensor one

Mitsubishi OBD-II Trouble Codes

im just going to run through them and fix what i can.

anyone know how to check fi an ECU is "good"? i want to check mine and one from a salvage yard

 

[jbl_5star]

where is the obd port on a 93 gsx? cant find it under the steering wheel