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

[BodybyFisher]

Thanks for trying..  I was just trying to confirm what bbobynski had told us about the lope being tamed.  

[Olle]

Ok, I have gotten the spare ECM´s in my possession now, a total of 4! pcs (93-94 variety), and a spare E-Prom (BCRN) to go with it also.

I will try that next, then some other AC Delco original sparkplugs I found.

I will make sure to transfer the stock Prom from car´s ECM to the other spare ECM I intend to try.

We will see what the results are,...? most likely no change...but worth a try.

I will report back during the week. I needed a break from wrenching...The movie was good: "Sully", T Hanks movie. we liked it.

cheers, /Olle

 

 

 

[BodybyFisher]

Thanks for the update Ollie and for the feedback on Sully! 

Can't wait to see your results.  

[Olle]

Ok, So, I think I´m on the right track now, things are happening here!

In order of latest mods:

I removed the "newer" Motorcraft plugs, (had it on the car for about 1 year, they were a cheaper version

but a correct fit according to parts-store, always ran well on them since new, no probs since early 2015)

So, I removed the Motorcrafts yesterday and reinstalled the original platinum AC Delcos,  and, low and behold, the wild "swings" of the engine/idle got better, less pronounced, but still not perfect, but it did calm it down a little, so something changed for the better there with going back to AC Delcos! go figure,

Now, NEXT, I installed a different ECM, one from dads old 93 Eldorado, swapped the STS´s Prom over to it, and, WOW!

now we´re talking ! car idles much much better, sounds better and does not smell of raw unburnt fuel fuel anymore!?

So, now, just a few Codes to deal with that popped up with the new computer! ( these codes were Not present with the old original ECM!)

One code says TPS relearn (80) must be performed, ok I get that...but one code says communication problem (47) with instrument cluster or somewhat?

IPC something I think..so, I have to check the connectors to the ECM etc and see whats going on? hope nothing major here, also new ECM tells me to change the "Transmission Oil".. I have now idea why?..These codes only came up with the new ECM, never seen before, but heck! the car idles MUCH better, like it supposes to I guess..

I have to take it out on the road and see if it runs on the road , shifting and all that..I do have other ECM-computers to try out.

So, everything points towards original STS ECM going bad after 22 years of service, why that would happen is a mystery to me but we´ll see how this progresses.

I´ll keep you posted during the week.

/Olle

[BodybyFisher]

Have you checked the fuel pressure regulator?

[Logan]

Export cars were configured with a set of export codes. So codes like 80 and 47 are export codes and mean nothing to US owners. 

In the past...there have been attempts to find a list of exactly what the export codes are and what do they mean to no avail. The Helm factory service manuals do not contain the export codes.

There are 2 possible solutions to get the vehicle out of export mode. If the car was configured as a US vehicle...any future codes or problems would make much more sense to us with our US service manuals.

 

*****This has not been tested*****

There may be a export prom vs a US Fed prom. The prom tables used to be available on the old GM Techline terminals.....that stuff is long gone.....but I may have a old GM Techline CD in storage somewhere.  If a US prom could be located....it may be as easy as swapping the prom.

The IPC should be configured in export mode. It may be as easy as changing a setting in the IPC to 'US market'. There are multiple export settings in the IPC for things like French and Saudi markets.

 

It would be interesting to know what mode the IPC is in right now. Once we know that we can consider what the next step should be....or if it's even something you want to do.

[Olle]

Thanks for all the replies, no, I have not checked the Fuel Press Regulator, but I believe we changed to another one about 3 years ago.

But, Im a bit frustrated, Im going in circles at the moment..spent another 5 hours on it today in the garage.

The confusing results are like this, running other ECM´s from a 93 and 94 Eldo with my STS "stock" (export?) prom gives the same

weird IPC code 47 and 80, it also warns to "change transmission fluid" both ECM´s...ok?..it idles smooth thou, and runs/drives ok..

Pluggin back in my original STS ECM with my prom, no such codes show up!? And...now it idles somewhat smoother all of a sudden, still a little

rich, but acceptable, so, I honestly don´t know what the hell is going on at the moment.

And, Listen to this, while taking it for at test drive on the Eldo ECM, (car felt ok, no major hiccups) then-

All of a Sudden: The Charge Light comes on!, code 7, and now the Generator/Alternator Dies, or has a cable gone bust? This Alternator is only a year old! and has been fine for 1 year since I replaced it (myself)..Checked everything, nope, no loose connections or whatnot, maybe the Zeners are fried inside for some unexplainable reason,,,either it just happened today, because its been about to give up anyway, or its related to my ECM changes, I have no idea..? hopeless.

I´ll keep working on it when I get my energy back...need a break at the moment..Gotta figure out the charging problem..( battery is good, battery fuses in engine compartment are intact ).

/Ollie

 

[Olle]

I do have a bunch of different proms, but dad always told me to make sure to run the prom the car came with.

I don´t know what could go wrong/changes with a different prom in the car?

I can write down the id-codes on the extra E-proms I have laying around some point. they are marked (scibbled/marked by dad) as what car they adhere to,

like 270hp bla bla, Seville this, Eldo that.

[Olle]

Ok, so, the POWER SELECT / WPS 8127N alternator/generator is out now,.. gonna have it tested, try to

find out what is going on, has it gone bust, or why no charge all of a sudden? Ill report back when I find out.

/Ollie

[BodybyFisher]

Thanks Olle, I need to pull my manual out and see if its any help.  

I have a friend who lives in Canada, I am going to see if he has any info on the export model codes that he can share with me

Its odd that your alternator would croak like that, so suddenly, that is an unusual failure, especially after a year.   I am interesting in the results of the test. 

[Olle]

hi, got the test back on the generator, it is indeed Dead...hopefully warrany will cover it (less than a year in service on the car).

will see what happens, I have allotta info in my Service Manual on codes, and code 47 is in threre, among other export codes

and such, also descibs how to set ECM to work around some of these codes and compatability problems..

I can take a scan of it at some point so Youll be able to see also..I dont have time to dig that deeply into all of this, but it appears

like it is all in there in my 2 phonebook Service Manuals.. 

Many thanx,

 

[BodybyFisher]

Thank you.  I hope that alternator is replaced under warranty.

How is your battery?  Have it load tested and check connection at the grounds

[Logan]

Sounds like it may be displaying the codes in the US format.

Some exports cars....would display odd codes on the IPC message center. That's what I thought you meant by codes.

Anyway....here is the US PCM codes...1994 STS.

The failing alternator may have had a bad diode or something....may have been causing the problems along.

 

[Olle]

Hi, Yes, it´s quite possible it´s been erratic/bad power that´s been the culprit all along, who knows?

The guy who did the quick test said he did not think it was a diode, but more leaning against a bad "stator"

or rotor, a bad diode should have shown (at least) a little power, but there was absolute nothing from it 

so, I dunno, it was totally dead he said.

Have to wait a good 2-3 weeks to hear back from parts store warranty department, that stinks..But

considering it cost me usd 300 I would rather they replace/fix it for me, I do not wanna spend that kinda money if I don´t have to.

/Ollie

[Olle]

Dear Caddy friends, I just thought I´d inform you that Im picking up a new alternator on Monday.

It was indeed covered under warranty, so, no money spent, just my precious time...

Anyway, I´ll get back to you with the results later in the week.

Cheers, and have a nice weekend,

Ollie

 

[BodybyFisher]

Thanks for the update, Ollie!  Look forward to the results

[Olle]

Hello all, I now have installed the new generator/alternator, and low and behold, now it idles smooth, so, it definately

was the a bad (or about to go south) alternator causing all these troubles all along starting a month ago.

 

But unfortunately, sorry to say, I have now detected a bad missing issue, like a misfire on one (or more) of the cylinders? but,

it could be a bad injector or something related...I alredy swapped out the coil pack, sparkplugs, some spark wires last night, and

checked fireing order.. no avail. still runs rough, engine shakes when I run it at ca 2.5k´s..etc.. I will try the Power Balance test

next. checking the injectors. flow/voltage Chart 6C-3 and 6C-4  in the Service Manual.

I do have code 46, (but No service engine soon) but this code Ive had for years, still ran acceptable, not perfect but good enough.

But now it´s currently not acceptable, so, I will dig deeper tonight, see if I get somewhere.

thank you all.

/Ollie

 

[Olle]

I thought I might ad what I have swapped out since this new trouble started, (meaning engine misses) maybe one of these changes/ new parts

has started acting up?

EGR Valve

Fuel Filter (brand new)

Injectors

MAP

( all these parts have been on the car/or another of the familys Caddys before and ran well then, so, I guess - somewhat "verified" to have been ok

some years ago when they were taken off and put in storage/"save for later" type thing...hehe...

Cheers!

/Ollie

 

 

[BodybyFisher]

First I would just check plugs, ignition wires and the coil terminals for looseness and corrosion.  Check each ignition wire with an ohm meter, jot down the ohms and divide it by their length in inches or cm and a bad wire will stick out.  Look into each wire connector for burned contacts..

The fact that the injectors you swapped in sat for a while is a concern, they may have sat with fuel in them that jelled up or turned to varnish.  The power balance test will show the bad cylinder, change that injector.  

Make sure they are seated and their o-rings is good.

Next time you fill up try a bottle of Techron

[Olle]

Thanks, will do, I hope not having to open up the intake once again but I guess I will have to.

I was pretty darn meticulous when I reinstalled bolted the thing back together, but I guess something might have gone wrong anyway.

like, an injector gone bad, we'll see..

[Olle]

Hello,

Update:I did remove the top intake cover, swapped out the injectors again, and Maf, cleaned the

surfaces and gaskets etc, bolted it back on again. torqued to specs, also torqued the 4 main intake

bolts a bit harder yet.

also, checked spark and spark wires. used a "spark tester" on the engine´s front plugs (quick check) and they all fire with the same intensity.

Unfortunately, no major change with any of these changes / fixes.

Here is the current situation, took the car out for a test drive.

At light throttle it has a bit of a "steam train" thing to it, "chugg chugg"... but it runs, albeit not smootly.. It is almost like it would run on "bad/faul gasoline" type thing.?

No codes, (besides that 46, mentioned before, that pops up now and then)

The car def has a miss at idle and up round 2k, then further up in revvs it seems better..

BUT, once I press the accelerator and give it more gas, or accelerate hard, even under load -

such as up a hill, kick down, it smooths out and runs quite strong! miss is not as prevalent or noticable.. car actually

takes off without too much trouble...it appears good like that? funny...?

So, heres a situation where car runs better when you give it gas (plenty) but not under light load and at idle, then it misses.

 

Question: Concerning the battery in the car.

I did test the battery under load (we call it "the grill") ("stress test"), it is borderline acceptable according to instrument/tester,

Fully charged, it goes from 12.2 to 11.0 under "stress", and according to instrument/tester that voltage value is just threshold within acceptable.. borderline..

Not perfect, but does pass the test according to guy/mechanic I spoke to..what do I know...?

Actual Question: Can a bad/old battery itself (despite a good Alternator/generator) cause the car to run rough at idle and up to 2.5 ks ?

Im thinking that the battery acts like a "buffer"/"pool of power", and if that is too "shallow" the alternator can´t keep up on itself handling all the power consumption of the electronics? if you follow what Im trying to say..? hehe! sorry..Im a tech oriented guy with a bit of experience (mostly Ford 5.0´s), but not a car mechanic by school or trade, so pardon my ignorance with correct terminology..

Cheers guys, Ollie

 

 

 

 

[BodybyFisher]

It sounds like you are missed at idle and the miss goes away up the rpm range correct?

Overtightening the intake bolts is not better.  How did the intake seals look, any damage?  Did you tighten the 12 bolts around the perimeter of the intake also?  Has the throttle body been off?, have the throttle body's bolts been snugged up?  Note that the throttle body has an oring seal that MUST be replaced if removed, so do not remove the throttle body without a replacement o-ring, the old one expands upon removal and wont fit. 

Have you checked the fuel pressure?

Have you checked for vacuum leaks?

Do you smell fuel at the exhaust at idle?

Are you using synthetic oil?, and what viscosity?

Have you checked the coils?, coil towers for corrosion?

I think your battery is ok at 11 underload but just bearly, but it passed a load test correct?

 

[Olle]

It sounds like you are missed at idle and the miss goes away up the rpm range correct? CORRECT

 

Overtightening the intake bolts is not better.  How did the intake seals look, any damage? Nope, and wiped them clean.

 Did you tighten the 12 bolts around the perimeter of the intake also? TORQUED TO SPEC 13 Nm,

 Has the throttle body been off?, No, never.

have the throttle body's bolts been snugged up? Yep, I would say so.

Have you checked the fuel pressure? No, have not.

Have you checked for vacuum leaks? yes, can not detect anything, but that doesnt mmean I do not have a vaccum leak...more serching needed, perhaps..

Do you smell fuel at the exhaust at idle? not to much, but some, car has smelled of unburnt gas, (when cold) for years, but still ran well.

Are you using synthetic oil?,yes, semi synthetic, for years.

and what viscosity? 10/40

Have you checked the coils?, coil towers for corrosion?, looks good. to my eyes.

I think your battery is ok at 11 underload but just bearly, but it passed a load test correct? yes, according to instrument 11 is still ok, below 11 not totally acceptable..according to its scale..

 

Thanks!

[BodybyFisher]

Ok, have you checked the fuel pressure regulator when the intake cover has been off for raw fuel?  Does there see to be a lot of wet fuel around?

Do you have a known good coil that you can swap into each position?  

In our how to section JimD did an article on testing coils, find that article and test each coil.

Can you get a.fuel pressure.gage and.check fuel pressure?

Has the fuel filter been changed?

Can you change the oil to 10w40 standard oil, dino oil?, as a test?

[Olle]

Hello,

I just tried a different and better battery, load checked ok, more power from it, BUT, no change in how engine runs..

So, problem is not battery-condition related...

No, not a lot of fuel around inside intake manifold when I lifted and removed the cover, looked ok.
 I thought about it and inspected for raw fuel before I removed the rails and injectors..looked dry/ok to me?..

I have a completely diffrent new coil pack on it ( verified to work not long ago I swapped with) no change..

A fuel pressure.gage and later check fuel pressure might be possible to obtain, but not right now, it will have to wait..

I changed the fuel filter for a new one 3 weeks ago.

motor bucks and jerks on the highway pretty bad, ( I was just out today) but when you give it gas, it smooths out ..weird..

The SES light came on breifly, like for 1 minute, the went away while driving...

only code running display diagnostics after I stopped today is HISTORY something"83" ( crank triggers, am I right?)

I did not get code 46 for 10 minutes while driving, but it bucked and jerked just as usual anyway..

I stopped and gave it some fresh gas, no change..

 

I´m leaning against fuel related right now, but need a break from trouble shooting..

Believe me, Ive searched high and low for vacuum leaks, havent located any, yet..

/Ollie