STS 1994 severe idle problems, please have a look, need input

[Olle]

 

And, Ive done a crank triggers swap on the car before, tricky job, but it never ran this bad (or like this) when those were showing up as codes

on the display while driving.

cheers, /Olle

[BodybyFisher]

If you are getting crank sensor codes that could be your trouble.  The crank sensors are located behind the front manifold, check the connectors.  Dont mix up the connectors.  

What I worry about is the wire hitting up against the exh manifold, if the wires are not retained good

 

[Olle]

Ok, I will check later, I know were the triggers are, Ive removed / changed them before..

[OldCadTech]

What is engine vacuum at idle?

[BodybyFisher]

I don't know if there is any spec that I can recall over the years.   Historically, I felt that 20Hg was good.   This article gives a range of 17 to 21Hg and is a good description of engine vacuum and shows what happens with leaks, etc    The vacuum should be steady, a fluctuating needle would be an indication of trouble as would low and high readings, check this out

http://www.gregsengine.com/using-a-vacuum-gauge.html

 

[Olle]

Thanks guys, yesterday I "ohms-measured"  the leads to and also the actual Crank-triggers/sensors.

They are identical, about 1K ohms to both of them loosening the connector at the coil pack, so, my

estimation is nothing wrong there with cabling and most likely nothing wrong with triggers..

I also made sure the wireing at the coil-pack from triggers are clean and seem to contact good ( little pins etc).no codes now when test-driving.

 

Sorry for my language here, but I will try to make sense with my somewhat limited car-vocabulary..

I took the car out for a 15 minute drive:

I get the code "46" on the dash, as per usual ( no other codes, no crank trigger codes or anything) ..trying to find/google what the 46 flashing on the dash implies?

Export code? no one really knows...could be Anti theft system, or...? another way of saying " left/right fuel imbalance"  ?

I do NOT have P046 code stored in ECM/computer as a trouble code...

Did an Oxy sensor measurement/balance test: front bank is 135, rear is 119, is that really bad ?

it starts up fast and idles, but quite rich, (nothing new).. then as it warms up

stops smelling as rich, idle is a little rough but not terrible, but I would´nt say it sound totally "100% healty", listen to the sound clip-

if you follow me?... short clip, one pipe.

It almost sounds like terrible misfire, or, Worse yet, I have a valve problem of sorts ? Why ?

I´m beginning to suspect I have a valve problem!! or something mechanical? why is beyond me? I have not mashed the pedal in years..

But I guess anything is possible, Need to make a compression test on all cylinders, tricky, I can not fit my copression test tool in there, its too tight..

 

Thanks a Lot!

 

 

Caridle.mp2

[OldCadTech]

Still need the vacuum at idle reading.. It will tell you a lot.

Is it steady?

Does the needle bounce?

[Olle]

Finally !!!

Got it running well again!

Yesterday I found out what was wrong with it since installing the new Alternator. (2nd one, covered under warranty)

You are not going to believe this,...but it was a miss from cylinder no 2, due to  a freakin SPARK PLUG!!

darn! Man, do I feel stupid.. ( but I will happily feel stupid if it makes the car run well again...hehe)

 

You see, the ground electrode had probably gotten hit when I installed it again a few weeks ago, (I had to drop it in, due to lack of correct type/size plug socket)

and then get it to catch the treads, maybe it hit aginst the "floor" of the head, and it closed the gap too much, electrodes were almost touching, resulting in a really

feable spark, which would not fire the combustion thorougly, maybe like only 50% of the time?, hence It was missingbadly on cylinder no2.

Took the plug out, re-gapped it, opened up the gap back to normal, put the plug back in, runs like a charm! haha!

Unbelievable...

It currently idles smoother then in has in a long long time, so at least I know I do not have a bad vaccuum leak, or screwed anything else up..

( I seem to remember a test (swap) with another set of older stock plugs about a week ago, but is´s quite possible that old set was not up to par either, resulting in my switching back..I have no idea, it got too confusing with all the parts being interchanged left and right for the past month..)

Driving it some 30 miles after the fix, it feels great, I do have one little fault code that pops up intermittently (083 current, with engine running yesterday) indicating a bad "crank sensor/trigger" so I might try and order 2 of those sensors new from Rock Auto and swap out later.

But, interestingly, it has not had an affect on how it runs,,,yet...

Thans for all your help! and being a 22 year old car, i`m sure I´ll be back soon with more questions..hehe..
Cheers,

/Olle

 

[BodybyFisher]

Hey Terrific Olle!!!!

Yes, I too would replace your crank sensors you may spontaneously stall so be careful.  Well, she is running better because of all the work you did so that is great.  Plus you learned a lot and so did we.  Thanks for looping back and letting us know the cause and that all is good.  

If you find you need parts, I might be able to help, my scrap yard has shelves filled with old parts.   

Mike 

[Olle]

Hello Mike and everyone,

(and thanks for the offer on cheap left-over parts Mike!)

I just thought I´d "loop back" with some finding regardning my Crank Sensor problem..This is an interesteting one!

Ive been having an intermittent fault code (code 083) and SES light blinking lately on and off . you could feel engine bucking as the SES light was flickering..etc

Yesterday I installed new sensors (Delphi) but it made absolutely no change or improvement !  hmmm..

( Im starting to get pretty quick with removing and installing these crank-sensors at this point..mind you, for better or worse)

So, looked in the service manual, and next step could be cabling/ and or Coilpack, checked cables, installed a different Coil pack, no change.

 

So, "Last resort" according to service manual was to change computer, so I did, along with original 94 STS "Prom" swapped over naturally..

And, low and behold, no more code 083 and car idles smooth as silk!? funny...the ecm im using now is from a 93 Eldorado, but prom is correct for my car.

 

My guess is, (just a guess) that the Alternator trouble I had this fall where the faulty alternator wreaked havoc with the whole Engine Management System until

the Alternator finally blew one day, might have "zapped" the original computer (ECM?) and it was never the same after? just a thought..

Anyway, it is intersting to notice the original ECM computer seems to have stopped reading the crank triggers/ignition (on/off) cousing intermitten problems.

Like I said, with new computer engine idles just fine (despite asking for an idle relearn process (P080) and not a hint of Crank Trigger problems or stumbling idle etc.

Im hoping it will stay this way now for the duration of the winter for which Im using the car..

Many thanks guys, Olle

 

 

 

 

[BodybyFisher]

If it comes back, don't overlook the connectors, the female part could have become too loose and could be causing an intermittent.

Glad you fixed it, Olle, It was 17 degrees F here today, we are having a cold streak.

See you soon, Mike

[Olle]

Car still runs great after a trip of about a 100 miles, And, the code for idle relearn process (P080) actually cleared itself 

after being sitting in traffic for half an hour...so, no SES light or stumbling at the moment, runs like a charm..

35 to 43 degrees (F) here this coming week, not too bad, believe me, it can get A LOT worse this time of year.

Merry Christmas, /Olle

 

[bobbygotit]

Had the same problem olle!!!! Pop of your valve cover and there is a part called a "throttle body coupling/coupler" it's rubber and metal and mine was around 6 inches in diameter.mine had a crack in the rubber and was sucking air and causing every problem you have named in this thread.I would bet money that this is what's causing your issues.

[BodybyFisher]

On 3/13/2018 at 8:11 AM, bobbygotit said:

Had the same problem olle!!!! Pop of your valve cover and there is a part called a "throttle body coupling/coupler" it's rubber and metal and mine was around 6 inches in diameter.mine had a crack in the rubber and was sucking air and causing every problem you have named in this thread.I would bet money that this is what's causing your issues.

Olle has a 94 no intake plenum/coupler on it like your 02