t24todd

iTrader: (7)

So coming home today I made a quick but harder pull onto a on ramp after about 15 easy minutes of driving. Car felt off for some reason after the pull vacuum seemed normal on the boost gauge. Throttle felt very touchy at slower speeds, came to a stop and idle surges from 1k to 2k fast bounces up/down/up/down. Got home checked for any vacuum leaks with the starting fluid nodda, unplugged tps/pressure sensor/o2 / and bac valve never changed the pulsing rpm still from 1k-2k hard bouncing (pulling 7-15vacuum) and smelled very rich with hesitations slower accelerating speeds around the block. Checked tps reading and it was at 9.8x at throttle closed and warmed up. tried adjusting a bit but cant get it out of 9.7x-9.8x ohms...when it suppost to be @ 1k check it every other oil change

car has been good for awhile and nothing changed to it last week or so no problems driving to and from work as the daily.

Thinking something wrong with the rtek ecu or signal going out???

S4 T2
aggressive streetport/emissions all gone solonoids and everything/fmic/ lots of bolt ons

RotaryRocket88

iTrader: (7)

The ECU has no affect on the TPS; it's the other way around. If your TPS is reading way too high, there's a problem with it.

t24todd

iTrader: (7)

So are you saying the tps is more likly the culprit? It goes bad that damn quick like night and day?

jjcobm

iTrader: (18)

You have a vacuum leak. That bouncing idle is your car telling you so.

The TPS should be adjusted through voltage. 1V to be exact. The resistance method is not accurate since you are not getting the right voltage getting sent to the ECU, only the internal resistance of the TPS.

There are a few threads on the voltage method floating around.

RotaryRocket88

iTrader: (7)

Nothing can cause the TPS resistance values to change other than the TPS itself.

t24todd

iTrader: (7)

theres not a vacuum leak i checked out everything and i only have about 15 silicone hoses to check. Good friend down here makes a tps mod getting rid of the rx7 tps and putting on a later gm unit. hopefully we will move the project up to now for my car.

HAILERS

If you have a RTEK2.1 then you can set the TPS using the PALM device. Just FULLY WARM the engine up. Then look at the Palm and the TPS reading. It should read 20% (that's the equiv of 1vdc being as how 1v is 20% of the possible highest reading of 5v.

In other words turn the TPS screw till the TPS reading on the Palm is 20%. There is no logic in ohming out a TPS. None at all unless one suspected a dead spot in the pot. You can do the same by looking at the Palm TPS reading and slowly stepping on the pedal and watching the reading to make sure there are no openings in the reading from the lowest reading to the fullest reading (usually about 4.8 vdc give or take.

Even if its a RTEK chip instead of the full blown RTEK 2.1, you can probe the pin 2G at the ECU and it should read approx 1vdc with a fully hot engine. Key ON

t24todd

iTrader: (7)

yea its rtek 1.7 have the megasquirt sitting next to me already to throw in just waiting for the turbo to get done so I only have to pay for tuning once...

t24todd

iTrader: (7)

So obviously its getting worse and i have to wait a couple days for my buddy to get back so we can fab up the mount, but Im trying to make sure it is what it is till then.
warmed up checked for vac leaks again just to make sure no change... nothing
car starts and goes up to 3k for like 8 seconds(like how it used to do with stock ecu)
bouncing starts, light gas it will still bouce what ever rpm you try to hold(pulse)
checked the tps once warm now it dosnt show anything 0.00 acrocc sometimes jiggling around with the probes i can pick up .4-.8 jumping around then vanishes just as fast as it came when i havent moved a thing, used to be able to probe em, holds the reading consistantly while i adjust and wala. also if I unplug the tps connecter it jumps up to a steady 3k and holds till i plug it back up then back to the bouncing.
4.41v out of the ecu wireing on the other side of the tps connecter.
TPS is shot.... the list on the (to replace) is getting very short these days

t24todd

iTrader: (7)

So got another tps set it @ 1dcv. might be a vacuum leak but went through 3 cans of starting fluid and ripped off the uim several times also. Going to go get it smoked the next day or so. Why is it that every time I start the car hot or cold it jumps up to 2800k slowly rises to 3100k then drops within 20seconds then goes back to the surging idle from 1500k-1850k constantly. pulls about 10-5 vacuum instead of about 16.

SoloII///M

iTrader: (13)

Have you checked compression?

t24todd

iTrader: (7)

compression?Have you read my whole thread? I dont know how that has anything to do with my question just asked but im sure compression is fine 18k on rebuild starts everytime immediatly, drives fine(slow speed it almost drives itself)boosts fine, theres no sign of bad compression so back to the question if anybody knows why it does this start up high rpm now or?

K-Tune

iTrader: (26)

check compression, possible chipped apex seal.

t24todd

iTrader: (7)

so thats what you guys are thinking. Finally got a day off tomaro so it will be first on the list. Warm it up check compression then run over to shop and smoke it for leaks. Thanks for the responses, car really frustrates me at times. I need to get another daily and leave this for the weekends. Will report back with #'s.

K-Tune

iTrader: (26)

with just the corner piece chipped off it will have a very rhythmic idle and a pulsing vacuum needle. car will still drive and boost great like this, but compression test will show if it's the case.

t24todd

iTrader: (7)

compression test done solid 90+ bumps on each face. . . no vacuum leaks either. MAF???

soldave

iTrader: (1)

You get any further with this as I'm having a very similar issue? I've checked the MAF on mine with a known working one and with no luck.

t24todd

iTrader: (7)

thermowax unit bottom of throttle body... got a new one modified it blocked off coolant set fast idle screw fixed. really starting to get tired of this car.

soundquest

where are you now with this. Keep going. Replaced the thermosensor yet? Cleanted the BAC of carbon? SeaFoam your engine yet through the brake booster line to clean your entire intake out?

t24todd

iTrader: (7)

?
I replaced the whole throttle body(modified it down to bare necessities) rerouted coolant line back to bac valve and reset the fast idle screw and tps thats it.
bac valve has nothing but Coolant going threw it NO CARBON
i never said anything about a thermosensor guess you are referring to the temp swith?
My engine is completly fine all emmisions removed and blocked replaced lines with silicone (theres only about 15)
Dont seafoam a rotary

LunchboxCritter

iTrader: (9)

Does pushing the clutch to the floor change or stop the bouncing idle? If so check your neutral switch (the switch on the transmission, by the shifter).

t24todd

iTrader: (7)

dosnt change the rythmetic pulsing.... I pulled up a old thread from njgreenbud awhile back his car did the exact same thing videos and like 12 pages long. No luck for me. Driving is still the same if your over 1600 rpm under like parking lots it gets very frustrating i dont even touch the gas just work the clutch.

FelixIsGod29X

iTrader: (50)

Im glad you made this thread because my basically stock S4 n/a has the same exactly idle issue that yours has been having besides what i have quote from you above.

Ive done the same changes like changed stock TB, adjust fast idle cam screw,tps adjustment plus 3 spare TPS's, new gaskets, ect ect solid 90+ bumps on all faces, just bumps not total compression. Either way the motor starts asap no smoke ect ect.

I hope you can figure out the problem. - Nick

LunchboxCritter

iTrader: (9)

Have you tried setting your tps using test lights (2-12v lights, and a few spade connectors from Radio Shack are about $5.00)? Supposedly it's more accurate because it shows you what the ecu is seeing. I tried both methods and found that the multimeter method got me close, but the test lights got me together.

lastphaseofthis

iTrader: (8)

never had a bouncing idle caused by anything but a TPS( 10% of the time), or a vacuum leak(90% of the time). sounds like boost blew a line or a nipple off.
do you have paper or metal intake gaskets?( or maybe just silicon?)
Paper or silicon, i would check there also. or do a intake pressure test, as these dont seem to expensive to get the parts to do. just some homedepot fittings, guage, and some soap and water.