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´95 Eldo engine oscilation ?


FSchuett

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Frank have you hooked up a vacuum gage to it?

Hello,

no, I don´t have a vacuum gauge.

And I´ve checking all rubbers and lines, all are OK...

Now, what is a rubber collar and where is it ?

Frank

Frank did you physically inspect the rubber seats?

The one at the back (without the yellow dot) can be easily pulled off and you can check if it has any cracks etc.

Hello Cyr,

I´ve pulled off and check the two rubber at the back... it´s optical OK...

Here is a photo...

post-1843-1185708397_thumb.jpg

With two lines and a plug in the middle...

Frank

Frank, then i think you are in for a vacuum gauge as BodybyFisher already suggested (don't think they are very expensive)

If you are in complete control..... you are not going fast enough....

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Mike, do you mean these rubber collars?

Cyr, there is a rubber collar between the rear of the throttle body and the intake manifold on the older years (95 and older, I think), they can develop cracks and suck air, that could definately cause a problem.

Logan recently had this problem as did someone else, I will try to find out who else it was recent Mike

Here is it, darn I am good, I have to ask Logan for a raise :lol: see the recent link here

http://caddyinfo.ipbhost.com/index.php?sho...46&hl=logan

I will put in a good word with Logan for your raise.. you never know it might help.

Anyway, see above picture, the upper vacuum collar was cracked in my case and i just simply put a tape around it, reconnected the vacuum hoses and all was fine again.

Mine was so cracked though (my own fault!) that i had an idle of 4-5000 rpm's.

That makes it all a little more easy to troubleshoot.

I think it´s not these rubber collar, because the engine runs very fine under load and in idling

and over 2500 RPM... and my Eldo has no error codes.

Frank

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it doesn't have to be those specific rubber collars, it can be anywhere in your vacuum system but without a vacuum gauge there is no way to tell (other then replacing the whole vacuum system of course)

i believe such a Vacuummeter costs somewhere around 15 euro. (i will be corrected by others on the board if i'm wrong)

If you are in complete control..... you are not going fast enough....

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Hi Frank. :hatsoff:

I don't think it's a vacuum leak. With a vacuum leak you would typically have some looping idle, even with an ISC motor trying to control it. I don't think it would react fast enough to hold the idle steady like your idle is.

Another thing, if you had a vacuum leak I think that your idle would be at the same rpm not sometimes at 800 rpm and sometimes at 1500 rpm.

This sure seems like an ISC problem. If the contact in the ISC works fine I would check if the motor itself is functioning as it should, perhaps it is heavy loaded from old grease or something like that. Correct me if I'm wrong but if a stepper motor gets 10 impulses from the PCM and for instance the grease is making it going heavy, perhaps it only moves 5 steps instead of 10. I don't think that there is some signal back to the PCM telling it that it has moved the 10 steps like a servo motor has. I dissembled my ISC motor on my -93 STS and degreased it carefully. After that I regreased it with small amounts of ordinary bearing grease for roller bearings. You can get a tube of that in any gas-station I think.

I had some similar problems, high idle sometimes, rpms wouldn't come to rest while driving slow, high idle at coasting sometimes, sometimes a code would set, but that was probably the contacts setting it (they were dirty). I cleaned the contacts but had the same problem anyway, after regreasing it was gone!

I have a 3-gear bicycle and it once felt like it was equally heavy to propel regardless of gear, only speed varied...Degreased and regreased it and it still works like it should, must have been 15 years ago :)

I don’t think it’s an EGR problem either since it would feel like a spongy, surging feeling on light loads at for instance 50 mph or at takeoff. Like in the old days with carburettors, start the car, apply some choke, apply to little and you get a too lean mixture and it feels like it surges when accelerating.

With vehicle in idle and neutral, apply gas slowly and note the feel. Is the engine increasing rpms smooth and accordingly to the accelerator pedal or does it feel like you can push the pedal more and more and suddenly get a rise to 1500-2000 rpms from idle?

Just a little check if it’s “ok”. Could be contacts not reacting or plunger sticking in the ISC fooling the PCM to think that the engine is still at idle.

My experience is that we sometimes overlook the obvious faults believing it’s ok like I did on my -93, changed plugs, wires etc, cleaned and adjusted and so on when I had a cylinder with no compression. That was due to carbon build ups from a previous owner never hitting the gas followed by someone really hitting it making the build-ups on the valves to glow and causing the burned valve.

Please don’t worry, the valve thing is absolutely not common according to our guru and if since you are living in Germany I guess that your car never will be seen puttering along at 40 mph ;)

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Mike, do you mean these rubber collars?

Cyr, there is a rubber collar between the rear of the throttle body and the intake manifold on the older years (95 and older, I think), they can develop cracks and suck air, that could definately cause a problem.

Logan recently had this problem as did someone else, I will try to find out who else it was recent Mike

Here is it, darn I am good, I have to ask Logan for a raise :lol: see the recent link here

http://caddyinfo.ipbhost.com/index.php?sho...46&hl=logan

I will put in a good word with Logan for your raise.. you never know it might help.

Anyway, see above picture, the upper vacuum collar was cracked in my case and i just simply put a tape around it, reconnected the vacuum hoses and all was fine again.

Mine was so cracked though (my own fault!) that i had an idle of 4-5000 rpm's.

That makes it all a little more easy to troubleshoot.

I think it´s not these rubber collar, because the engine runs very fine under load and in idling

and over 2500 RPM... and my Eldo has no error codes.

Frank

Frank, I have been trying to find a photo of the part I thought it might be but I can't find it. It is not one of the photos above. It is the size of the thottle body opening, its big like three inches across, it connects the rear of the throttle body to the intake. BUT, I dont think that your year has it for some reason, and also, I think your problems would be worse. So NO I don't think that its a LARGE vacuum leak anymore because you would be getting a lean condition and you would have a bad idle.

I for the life of me can't fathom what would create the problem you are having in that RPM range and not in the entire range... I am going to point other members to this thread, we need ideas. Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thinking about it, and please do tell me my technical mind is rubbish if i'm talking crap :fighting0025: , but could it be coming from the transmission?

So that the problem is not with the engine but the engine is reacting on feedback of the Trans?

When under load all components are under pressure/traction/torque etc. because the engine is excercising power to the trans

when going off hill without giving gas the weels are giving feedback to the trans and automatically the trans is feeding this back to the engine.

When in a stand still the engine is running fine because there is no power transferred to the trans nor coming power from the trans back to the engine.

If the trans has a problem it could want to up and down shift / can't decide which gear to select?

Obviously a actual gear shift would be felt by Frank but i was thinking of maybe a minor thing?

Just spitting out ideas so please don't shoot me if i'm way off and above is not even technically possible etc.

Marc.

If you are in complete control..... you are not going fast enough....

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No Cyr, that is a very good thought and this crossed my mind also....

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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No Cyr, that is a very good thought and this crossed my mind also....

Ah... a little compliment coming from you Mike makes my day.

If you are in complete control..... you are not going fast enough....

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No Cyr, that is a very good thought and this crossed my mind also....

Ah... a little compliment coming from you Mike makes my day.

This is what is called brainstorming. Frank has been having this problem for a long time and its time to think outside the box. But thanks. I wonder if its possible also that this could be an engine mount or tranny mount or dog bone vibrating?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thinking about it, and please do tell me my technical mind is rubbish if i'm talking crap :fighting0025: , but could it be coming from the transmission?

So that the problem is not with the engine but the engine is reacting on feedback of the Trans?

When under load all components are under pressure/traction/torque etc. because the engine is excercising power to the trans

when going off hill without giving gas the weels are giving feedback to the trans and automatically the trans is feeding this back to the engine.

When in a stand still the engine is running fine because there is no power transferred to the trans nor coming power from the trans back to the engine.

If the trans has a problem it could want to up and down shift / can't decide which gear to select?

Obviously a actual gear shift would be felt by Frank but i was thinking of maybe a minor thing?

Just spitting out ideas so please don't shoot me if i'm way off and above is not even technically possible etc.

Marc.

Hi Marc,

yesterday I´ve the same idea - the transmission - why not ?

Because the engine runs very fine under load and in idling.

Frank

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obvious question which then follows (and apologies if this sounds as a stupid question)

Did you check the oil level of the Transmission box? (when warm and running engine etc.)

If you are in complete control..... you are not going fast enough....

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Hello Marc,

I´ve change the tranmission oil last month because I´ve installed new "a+b solenoids".

Tomorrow I want to clean "throttle body" once more,

because at the last cleaning "party" I do not uninstall the TP.

Now, I want to uninstall the throttle body and clean very well ;-)

post-1843-1185819576_thumb.jpg

How can I uninstall the TB ?

Is it difficult, because at the right side is the throttle cable and many more...

Did anyone photos from the uninstall ?

Frank

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Frank, I have a 96, and am not sure how different the R&R is. However it was easy, there were two cables on the right, on for the accelerator and one for the cruise control I think. I have some photos in this thread:

There is an EGR spacer on the 96, between the TB and the intake. You should have all gaskets and o-rings on hand before you pull it, see my photos here:

http://caddyinfo.ipbhost.com/index.php?sho...mp;hl=crossover

and here

http://caddyinfo.ipbhost.com/index.php?sho...sover&st=90

I hope someone with a 95 will post some photos, something tells me you dont have an EGR spacer

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Jeezz Mike.....

Just been looking at that threat.........

I already feel tough when replacing my starter....

My wife and sons feel i'm the best mechanic around because i can do all that stuff myself.....

I'm now awaiting my strut mounts and that will be the most difficult job i've did on my car so far (i think it will be)

But you..... you must be out of your mind...... :hatsoff:

Marc,

p.s. did dis/assemble an engine from the boat a long time ago though

If you are in complete control..... you are not going fast enough....

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