The Oldsmobile Connection

myfathersoldsmobile · Joined: 15 Sep 2007 Posts: 41

I own a 1995 Olds 88 Royale and I have been having a sporatic hesitation while starting out and the engine bucks and hesitates when the transmission reaches it's highest gear. Sometimes it accelerates unevenly, will falter and recover immediately. Other times it behaves fine. I have owned the car for five years. It has 170K. I did a valve job and head gasket last year, fuel pump two years ago, fuel filter, air filter and plugs recently.
Any help would be appreciated. Thanks!

andrewk · Joined: 18 May 2005 Posts: 1245 Location: Ames, IA

Hello myfathersoldsmobile, all,

Welcome to TOC, hope you enjoy your stay!

When did problem this first start happening? Was it right after the major work you had done? Does it only do it after it has shifted to the highest gear? Are there any other noises or symptoms that you think might be relevant?

My gut reaction is that you have a problem with the lock up switch for the torque converter, but we will need a little more information first.

Regards,
Andrew

91parkave · Joined: 29 May 2007 Posts: 518

Throttle position sensor can have the same effect.

myfathersoldsmobile · Joined: 15 Sep 2007 Posts: 41

Andrew, Thanks for the reply. The car ran fine after the head gasket/ valve job several months ago. This problem started several weeks ago.
It hesitates in all gears, but seems to be worst when the rpm's go down for the highest gear.
The only other noise worth mentioning is a slight knock heard at idle.

Thanks,
Jon

myfathersoldsmobile · Joined: 15 Sep 2007 Posts: 41

91parkave wrote: Throttle position sensor can have the same effect.

Thanks for the info. I did buy the 2-Book factory manual, but it's not big on troubleshoooting specific symptoms.

91parkave · Joined: 29 May 2007 Posts: 518

curious, does this happen when you first start driving or does it do it when everything is up to operating temps? Ive seen The TPS sensor start acting sporatic at operating temps,

another scenario i want to ask:
Can you accelarte more than 50% throttle? if so when you do, does it start bucking then? can you go more than 70mph? without it bucking? does your gas mileage really suck? if so then those are tell tale signs of a bad MAF sensor basicly is "safe mode" where the car runs pig rich. and retards timing at a certain throttle position.
edit: I have to add that if it is indeed runnig like i just mentioned, the rich condition will also increase exayst temps considerably which in turn could destroy your catalytic converter.

myfathersoldsmobile · Joined: 15 Sep 2007 Posts: 41

I drove the car today and tried to pay attention to the symptoms. There didn't seem to be hesitation starting off cold. When I got on the highway, it faltered around 70 but still recovered. When I set the cruise control it does fine at 70-75 until hitting a hill, when it coughs and sputters. I don't think the fuel consumption is excessive.
Maybe it's more likely a TPS problem.

88 Coupe

myfathersoldsmobile wrote: ........ When I set the cruise control it does fine at 70-75 until hitting a hill, when it coughs and sputters ........
Check here. Coil test, with a VOM, is an easy one.

Quote: ........ Maybe it's more likely a TPS problem ........
Faulty TPS would cause idle, possibly off idle, problems. Not the symptoms you describe.

TPS test, using a VOM, is an easy one. Your FSM should show how it's done.

Norm

andrewk · Joined: 18 May 2005 Posts: 1245 Location: Ames, IA

91parkave wrote: if so then those are tell tale signs of a bad MAF sensor basicly is "safe mode" where the car runs pig rich. and retards timing at a certain throttle position.

The MAF sensor is a peripheral, not a controller. It is the computer that processes the data, not the MAF, so only the computer could go into
"safe-mode" if it were so equipped. If the computer went into "safe-mode" (Which I don't think these cars even had, but I don't know) then the car would act the same way all the time because its readings would not change, as they would still be out of tolerance. His symptoms do not match up to a MAF malfunction.

I am more inclined to think you have an intermittent connection somewhere, but Norm's link would be the best place to start, as you should ensure that you have the essentials right (IE spark, fuel, etc), before we worry about what depends on those essentials.

Does the car ever display the "check engine soon" light?

Andrew

91parkave · Joined: 29 May 2007 Posts: 518

andrewk wrote:
The MAF sensor is a peripheral, not a controller. It is the computer that processes the data, not the MAF, so only the computer could go into
"safe-mode" if it were so equipped. If the computer went into "safe-mode" (Which I don't think these cars even had, but I don't know) then the car would act the same way all the time because its readings would not change, as they would still be out of tolerance. His symptoms do not match up to a MAF malfunction.

Yea every 3800 equipped vehilce since the series one is equiped with a safe mode. If a sensor happens to go bad that is essential to its function it goes into safe mode period. If a MAf, or oxygen sensor goes bad then the car dosent have a way to meausre incoming air, outgoing air then it goes into safe mode.

Marshall

91parkave · Joined: 29 May 2007 Posts: 518

myfathersoldsmobile wrote: I drove the car today and tried to pay attention to the symptoms. There didn't seem to be hesitation starting off cold. When I got on the highway, it faltered around 70 but still recovered. When I set the cruise control it does fine at 70-75 until hitting a hill, when it coughs and sputters. I don't think the fuel consumption is excessive.
Maybe it's more likely a TPS problem.

Exactly meaning when a increased load is placed on the engine it wont respond with a normal manner you have to ease it to go faster at those speeds right? sounds like the safe mode i was describing and either way using a volt meter cant predict a bad TPS/MAF sensor per say, Theres been times where they will work fine and times when they will stop working, they can do some very starange things butat leas you have a starting point let us know what happens

andrewk · Joined: 18 May 2005 Posts: 1245 Location: Ames, IA

91parkave wrote: If a sensor happens to go bad that is essential to its function it goes into safe mode period. If a MAf, or oxygen sensor goes bad then the car dosent have a way to meausre incoming air, outgoing air then it goes into safe mode.

There is a default value stored in the computer, but I wouldn't call it safe-mode, at least in the sense of technology today, where cars control all aspects of the vehicle to make it home so it can be repaired.

Quote: Exactly meaning when a increased load is placed on the engine it wont respond with a normal manner you have to ease it to go faster at those speeds right? sounds like the safe mode i was describing

Or any other problem that could cause the engine to miss or lose power.

Quote: and either way using a volt meter cant predict a bad TPS/MAF sensor per say

You're right, they don't make predictions, they don't have the "ESP-o-meter" to give you data like that. What it will do is tell you if voltages are within spec, and how close they are to spec. Bottom line is, a VOM is what is used to measure how these components work. Trying to go off of previous history or statistics is not only ignorant, but it can be expensive. The key is empirical diagnosis.

Save the "you didn't catch the per say" reply-

91parkave · Joined: 29 May 2007 Posts: 518

andrewk wrote:
There is a default value stored in the computer uh..SAFE MODE
andrewk wrote:
but I wouldn't call it safe-mode, at least in the sense of technology today, where cars control all aspects of the vehicle to make it home so it can be repaired.
Does it matter what name? limp mode safe mode its all i the same, you know the function so....

andrewk wrote:

You're right, they don't make predictions, they don't have the "ESP-o-meter" to give you data like that. What it will do is tell you if voltages are within spec, and how close they are to spec. Bottom line is, a VOM is what is used to measure how these components work. Trying to go off of previous history or statistics is not only ignorant, but it can be expensive. The key is empirical diagnosis.

Save the "you didn't catch the per say" reply-

so after that nice little paragraph youre back to the same thing, spare me of the remarks you make as none were thrown at you. I didnt say it happened to me this is your problem because it happened to me. No no i didnt. I listed scenarios for the OP, to help diagnose whats wrong, or at least get an idea of where to start. none of your post benefit the op in anyway nor discrediting my earlier post did youor the op any good.

Brando · Joined: 06 Jun 2003 Posts: 3067 Location: Michigan, USA

It's called OPEN LOOP...

Safe Mode is when you can't boot Microsoft Windows normally. :doh:

TOC Admin
Brando

andrewk · Joined: 18 May 2005 Posts: 1245 Location: Ames, IA

91parkave wrote: uh..SAFE MODE

uh.... STILL WRONG.

Quote: Does it matter what name?

Yes.

Quote: limp mode safe mode its all i the same, you know the function so....

The function is completely different. Limp-home or safe-modes shut the car down to basics, and the computer takes more control of the car instead of less, like when it goes into open loop.

Knowing the function is fine, but once you start throwing jargon around things become confusing for those that don't fully understand the function. That leads to more misinformation, which we try to avoid.

Quote: so after that nice little paragraph youre back to the same thing

Yes, telling you that you are wrong, a VOM will tell you how the TPS is working-

Quote: , spare me of the remarks you make as none were thrown at you.

They didn't need to be. This thread doesn't need another "oops" reply followed by you defending it and beating the thread to death.

Quote:
I didnt say it happened to me this is your problem because it happened to me. No no i didnt.

Did I ever imply that you did? You can stop with the diversions anytime.

91parkave wrote:
I listed scenarios for the OP, to help diagnose whats wrong, or at least get an idea of where to start.

And shooting in the dark with no experience is not the way to do it.

Quote: none of your post benefit the op in anyway nor discrediting my earlier post did youor the op any good.

:boohoo:

You told him that testing with a VOM was not the way to do it, that "it can't predict (I can only assume you mean it cant tell you) when its bad" which is wrong. The FSM wouldn't tell you to use it if it wasn't going to work. You told him that his MAF goes into safe-mode, which it does not. I am correcting your piss poor information, nothing more, nothing less. You can stop the diversions anytime.