Question for a friend, Cutlass Supreme bad idle

[5speedz34]

Ok, so my friend has got a '93 Cutlass Supreme with 160k on it. After about 15 min of driving when the car warms up it just starts running rough. And it drops down in RPM's and idles at like 300-500 rpm, and sometimes eventually dies, but he can start it back up. We cleaned the IAC today and as much of the TB. I noticed when his car was running rough, his cat started to vibrate violently so I'm thinking clogged cat am I right?

[Robby1870]

Na......if the motor is running that rough and at that low rpm the whole exhaust will shake. I would check coils and wires

[5speedz34]

It just does it out of now were, usually once the car is warmed up, and the cat has always shook.

[hazmatic]

my regla did the same thing for awhile so i got some fuel injector cleaner and that solved my problem

[GnatGoSplat]

Sounds like a coil. When the car is driving bad:

 

- Is there ever a funny smell after driving, like burnt matchsticks?

- Does tranny downshift rough?

 

If the answer to both those questions is Yes then I'm 99.9% sure it's a coil.

[maybe2fast]

Reseting the Idle Always Helps

[5speedz34]

It doesn't do it all the time and doesn't smell like matchsticks, and the trans doesn't do a rough downshift.

[rudefyet]

EGR maybe...any SES light?

 

Just throwing out some ideas

[4spdz34]

i know what it is.................its a kanuter valve also check your blinker fluid and your muffler bearings

[5speedz34]

i know what it is.................its a kanuter valve also check your blinker fluid and your muffler bearings

 

 

Ur a ass josh, its getting a code but only when it starts to run rough, and its the MAP sensor code (high voltage, low vacuum). The reason though I think is cuz of low idle, cuz the service manual says it will come up with a low or rough idle.

[89oldscutlass]

The TPS could be going bad if the idle is getting low enough to die. Is it showing any codes on the ecm yet?

[5speedz34]

Like I said the Map sensor but I think thats because of the low idle that is making that code come up. Ne other ideas, like I said it just does it ocassionaly.

[Slade901]

Tell you what... check your friends coolant reservoir. That symptoms is identical to my cutlass supreme previous problem.

 

If the coolant reservoir is in the middle of the radiator and it's full of coolant, as the engine warms up excess coolant goes back to the coolant reservoir and the top cover of the coolant reservoir is not really tight fit and so part of the excess coolant squirts down below where the Ignition Module, Ignition Coil, Spark plug wires are located.

 

By the time you open the hood and check the coolant reservoir level, it may have gone low a bit so you won't noticed it over flowed.

 

It happened took me more than 6 times and when the engine finally died and won't start back up immediately and I have to wait about 5 minutes then the engine would start again.

 

I removed the excess coolant fluid from the coolant reservoir and it's now 1/4 level. It used to be 3/4 level when I was having that problem. Once I have lowered the coolant reservoir level to 1/4 then I did not experience that problem anymore.

 

Again, this might not solve your problem but just give it a shot and verify the coolant reservoir level.

[sdwhite]

You know, I'm having a similar problem. Cold, the engine runs perfect but as it warms up problems begin. When I come to a stop, the engine surges until I hit 3mph, then the idle will drop so low it shakes the car violently. I'm getting code 33 and code 35. I also have the Engine Manual for my '93 3.1 but it's nearly worthless unless you have the scantool. Have you found any other ideas?

[musthavemuzk]

have had my 93 GP LE 3.1 for a week now.

i got codes 23 and 43.

idled a little rough and ran like crap.

was ok cold but got worse as it warmed up.

friday night i dug into it and had to replace the knock sensor. which was code 43. doing this cleared both codes as well as helped the car run a little better. still not right though.

so sunday supremestyle21 (justin) was in town and he took a peak. unplugged the TPS and it ran worse than it was. so we did an idle relearn. that helped a little bit.

tonight i did plugs and wires and a relearn.

better than it was but still not right.

i am comparing this to my 90 cutlass 3.1.

 

not sure what i am going to look at next, but for now it runs alot better than it did when i drove it home.

 

Monty

[5speedz34]

Ok well we cleared the codes and did a relearn, and now it doesn't do it as often, and when it does do it just idles rough. So I'm thinking Vacuum lines?

[musthavemuzk]

sounds like me

picking at it til i get it.

 

my next step i believe is vacuum lines.

specifically anything that has to do with the tranny.

as i believe there is a modulator or something for the tranny.

since at idle in neutral it is fine. even when pressing the gas. once car is in gear it gets worse.

so mayb something to do with tranny in my case.

 

Monty

[jamcneely]

If the coolant reservoir is in the middle of the radiator and it's full of coolant, as the engine warms up excess coolant goes back to the coolant reservoir and the top cover of the coolant reservoir is not really tight fit and so part of the excess coolant squirts down below where the Ignition Module, Ignition Coil, Spark plug wires are located.

 

Not to familiar with that type of car, but I know a lot of GM vehicles had Ignition Module problems that sound just like what your explaining. The Ignition Modual controls the timing advance, but it can't do this untill the engine comes up to temperture, and goes into closed loop (when the 02 is warm enough to start sending a signal). So what happens is the engine is running in limp-in mode, until the engine warms and once that happens it starts going all wacky ass because of a fucked up Ignition Module. This might just be a two part problem. Where your coolant is spilling out onto your Ignition Module causeing it not to be able to control Ignition Timing. I could very well be wrong on this though, because I haven't diagnosed an Ignition problem on an OBD I vehicle in a long time, plus I not sure if it was the distributorless Ignition Modules that had this problem. Just throwing out some Ideas.

[Slade901]

Where your coolant is spilling out onto your Ignition Module causeing it not to be able to control Ignition Timing.

 

The 3 ignition coils sits on top of the ICM (Ignition Control Module) and they are located directly behind the radiator. The CPS (Crankshaft Position Sensor) wire goes directly to the ICM.

 

The coolant reservoir is on top, right behind the radiator and which is centered directly with my ICM, Ignition coils, spark plug wires.

 

I've used a Dexcool coolant and noticed that the spark plug wires, ICM, CPS wires has a dried up orange color which tells me that the coolant reservoir overflow hose is not doing its job instead the coolant overflows to the top of the coolant reversoir cap.

 

I know this for a fact because when my car idled bad or sometimes just died in the middle of street, I noticed that there are wet orange spots on the spark plug wires, ICM, CPS wires, etc. The CPS wire itself has its two bare wires about 1/2" bare wire that leads to the ICM. I would guess the previous owner or technician strip that part of the CPS near wire near the ICM so they can test it. I have since wrapped it with rubber tape.

 

Now, I've drained the coolant on the coolant reservoir so it is level with cold level indicator on the coolant reservoir. I did not have any problem since.