Cutlass running rough, no CEL... UPDATE on page 3

[Crazy K]

I think they are talking about it holding a vacuum.

 

what you describe as rpm drops during heavy pumping while idling is normal. now if it makes the car nearly stall, then something might be wrong.

 

If you let your car sit for 24 hours, and pop that booster valve off, it should still make a whoosh. at the yard, I pretty regularly pop off those booster valves and am rewarded with an inhaling whoosh... from a car that has sat for weeks!!!!

 

I'm not sure at all what could have been wrong.

[nebojsa_o]

Well, it sat since yesterday, and today when I pulled that little fucker off, I almost gave myself a heart attack. I wasn't expecting that pop/whoosh sound I got. So I'm guessing it holds a vaccuum... I really have no clue what happened then... But no, if I pump the brake pedal very fast, it doesn't stall, or nearly stall, just drops the rpm needle a touch, maybe 50 rpms, and then smooths out again.

[ns87]

Every car hits a threshold where everything breaks at once. Your car is hitting it now Don't worry,sooner or later it'll go back to normal

[nebojsa_o]

I can't say I'm worried for now, since I bought it almost three years ago, and had no problems with it until tho months ago. It's just letting me know who's the boss, and that I never should have bought the Maxima.

 

It's been fine for a couple days now, but something is still off. It was idling while I was in the garage, and I heard it get kind of rough, about to die, and then went back to normal. And hitting the brake and car changing its tune, is wierd, not the same as before... I'll see if I can figure something out when it starts to get nicer outside. It's pretty good already, but when the temperature is in the positive numbers, I'll feel much better about spending a day outside.

[Brian P]

when the engine is running rough, it usually doesn't produce enough vacuum, hence the brake pedal problem. Either that or the main vacuum line has a problem. Check your PCV, vac line going from the PCV, to the top of the manifold, and from there to the canister purge solenoid under the DIS (this is a 1 piece vacuum line) maybe it cracked or became dislodged while working on the CPS all that time? Also another possibility is a stuck open EGR valve.

[nebojsa_o]

when the engine is running rough, it usually doesn't produce enough vacuum, hence the brake pedal problem. Either that or the main vacuum line has a problem. Check your PCV, vac line going from the PCV, to the top of the manifold, and from there to the canister purge solenoid under the DIS (this is a 1 piece vacuum line) maybe it cracked or became dislodged while working on the CPS all that time? Also another possibility is a stuck open EGR valve.

 

What's the DIS? I checked the PCV, and the hose to the manifold, but I'm not sure where this "canister purge solenoid under the DIS" is?

 

Is there a way to test the EGR valve?

[Brian P]

The DIS = Digital Ignition System (Coil packs) under this, actually mounted on the bracket just below it, you'll see a small black module with a red plug attached to it. There should be two lines on it: The vacuum line, and the hose which carries fuel vapors from the tank.

[nebojsa_o]

Oh I know where it is now. Thanks for clearing that up. I'll probably be fucking around with that this Saturday. I'm not really sure how that's related to me causing a funky idle by hitting the brake pedal though. Either way, I'll check it out this weekend.

 

Can the EGR be tested to see if it's stuck open?

 

The way the car is now though, you can't even tell something is wrong. Only while idling at like 600 rpms, and if I press the brake all the way down with some serious force, or pump it really fast, you can hear the idle change, and then smooth out again. So while driving normally, you never notice that since you don't have to do that to the brake...

[Brian P]

the idle's changing with hitting the brake because of the vacuum assist. Some of that would be considered normal.

 

The EGR may throw a code but other than that it's hard to diagnose. I would say check the easier things first like all vac lines, also the vac line at the MAP sensor.

[89GP_SE]

Neb I think you are going crazy trying to find problems with your car haha. Every car I have had do that when I hit the brakes while idling. I have had cars raise in RPM and lower in RPM when pumping the brakes while idling. I wouldnt worry about it if your saying that it is only 50 RPM. now if it was say 300 then I would worry.

[1990lumina]

When you drive the Cutlass how long and how far do you typically go? Maybe the OBDII tests don't have enough time to run and therefore no engine light (I'm thinking EGR)..it's far fetched though. When your EGR was causing issues last time in Regina did your SES light come on?

[nebojsa_o]

Yeah, it always used to. But it was causing different problems, very obvious, and stalling, and what not. It would do that everytime after higway speeds for over an hour or so. After I cleaned the EGR up all was fine, I've made several 600 km trips since then, and it's been fine, but I suppose it could be acting up...

 

Like I said, I'll look for vaccuum leaks and stuff like that, but I won't sleep under the hood until I find it, since the car seems to be performing just fine. I'll worry about it when/if it occurs again. The plan is to do the gaskets, and valve seals this summer, at which point I'll have all sorts of stuff out of the engine bay, and will check the hoses and such. Maybe I find something.

 

Thanks for ideas, and hep.