Well this started all of a sudden about a week ago. When I start the car, the idle will go up to 2K and stay there. I blip the throttle a few times to try and get it to come down but it refuses. It is now idling at 1K in drive and its set in the PROM to idle at 750 RPM when at operating temp. Now I have checked the usual things including vac leaks and found none. I have done extensive searching here as well to try and find out how to kill this very aggravating problem but cant seem to find the answer. As stated, the car was fine up until about a week ago, then this started all of a sudden. I replaced the EGR solenoid due to an issue with it. Sometimes the car will act normal but most of the time it does what I described above. It's really pissing me off. Almost forgot, its a 2.8 engine why I posted here.

 

did you break a vacuum tube connected to the solenoid?

 

no all vacuum connections were checked, then checked again.

 

I had that problem my TPS was loose put it back in its place tightened it down and I was good to go.

 

already went over that. Its tight and reading .55 volts

 

Clean the IAC. It may be gummed up with exhaust carbon (from the EGR) and need cleaning. The screw threads need to be cleaned as well as the part on the end that seats against the throttle body. Also, check the gaskets for the throttle body, top and rear and the IAC gasket, and the sealing of the PCV valve and the breather grommet in the valve covers. Could also try setting the TPS to .45V.

 

Already checked most of that Mav. The TB gaskets are new as well as IAC gasket. The IAC and passages are clean. I did that second after looking for vac leaks. Could this be a VSS problem even though I have ZERO codes?

 

A long shot would be to test the TPS signal with the engine RUNNING... I've seen the base voltage change for whatever reason with the engine running. Also, if you have a DMM that is capable of frequency measurement, test the freqency signal coming out of the MAF.

Also, I know I'm beating a dead horse, but what's the condition of the idle air pipe at the union where all of the pipes and hoses come together? Check to make sure the glue or whatever that's holding the large tube in the union hasn't let go.

 

Its hard to see all the way around that thing since its jammed in the back of the intake. The car has taken to stalling now. It will start, rev up to 2K, start to idle down then just crap out. Other times, it will start, idle, and drive just fine, but this is becoming rare anymore. As I said, I made all the usual checks that might cause this and I have come up empty handed and scratching my head. The frustration is more than I have ever experienced with this car. How something like this could start all of a sudden and not go away is beyond me. Where on that big plastic pipe does it usually go bad at? Checked ECM for codes again today, and nothing, It flashed the code 12-all clear at me.

 

That black tube will break anywhere, unfortunately, but especially on the evap canister line and the union where everything comes together (glue joints breaking). Also, check the rubber ends on the union and the big line at the TB to make sure they aren't cracked and deteriorated. And check to make sure the PCV hose is fully seated on the union. It sounds like you have a serious vac leak going on now. Also, check the check valve sealing against the brake booster by pushing it one way or another as the engine is idling (if you can get it to). Another thing to try is to disconnect the vacuum hoses one by one and plug them to see if the attached component is leaking (such as the HVAC control valve in the control panel by the radio).

Don't just spray starting fluid or whatever on the hoses, but spray it on things like the EGR valve (at the hose end, not the side facing the pass wheel as that has an open filter on it, which is supposed to be that way), the canister purge valve (mine leaked BAD and later fell apart), the check valve at the brake booster, the check valve at the back of the engine that the HVAC is supposed to be connected to inline with the cruise control, the cruise modulator, and finally, the orb of power under the battery (vacuum tank ball), which is known to crack due to where it's located and the fact that it's right under the battery.

Finally, if all else fails, it could be that there is a cracked intake plenum or manifold gasket or a cut o-ring on a fuel injector or more.

:edit: What was the last repair/modification that was done on the car? That could be a clue as to what's messed up.

 

The last repair was the EGR solenoid. I replaced it because it was leaking vacuum badly. On a side note, my cruise control has been inop since I got the car. I am not sure where to start on that one. The switch was replaced due to it being broken. The canister purge valve? Is it that round looking thing in the fat line coming off the canister? I have suspected the canister could be a problem but have no real proof. There is no fuel smell or codes in the ECM to point that way. The cruise control transducer could be a source of a leak. I just dont have access to a vacuum pump right now. All vac lines were replaced due to black crap rubbing off on my fingers. the only ones I did not mess with are the ones in the dash controlling all the HVAC crap.

 

The car actually has 2 canister purge valves. The one in between the can and the tank line is vacuum controlled and can be replaced. The one that plugs into the engine harness, on the can itself (with the 2-pin red connector) can't be replaced separately, so it would have to either be bypassed as if the car were an older car or the can replaced or deleted altogether (I have my purge valve bypassed due to not having a connector). The electronic one is the one that broke on my factory can.

As for the cruise control, there should be a T in the line near it, correct, with one line running out of the fender down to the vacuum tank ball and the other running to the engine? Remove the hose from the engine side of the T, plug it with a spare bolt or even a screwdriver if you have to, and try to run the engine.

The HVAC system may not have been touched under the dash, but the system inlet comes out of the wiring harness near the A/C heater box and runs to a check valve at the back of the upper plenum, in line with the cruise control hose. If this line is melted or broken, or the elbow on the end of it is bad and you didn't replace it with a piece of hose, this will cause a constant manifold vac leak. Same for the plastic line running into the heater control valve by the alternator (if you have A/C, non-A/C cars shouldn't have one).