How to test VTCS?

[crackerjakx]

I checked out the shop manual and it says VTCS should operate under 3k RPM and when the coolant temps are under 149 F. I watched the actuator during these conditions and rev'd up and down a few times. The actuator didn't move at all. Is there a problem or am I just testing wrong? Still trying to figure out why I'm having issues with misfires when the car is under operating temp and around 2.5-3k rpm range.

 

[crashkelly]

did you check your plugs?

 

[orng1]

Yeah I'd check the plugs, what's the code? It could be from a lean code that it's misfiring, maybe the gas, just about anything. The actuator should be closed and open at higher RPM's.

 

[crackerjakx]

Already changed plugs. Here's pics of my previous plugs (which are apparently fine). Did a compression test which ran 180 across all 4 cylinders. Retightened all hose clamps. Ran seamfoam in the gas tank and pcv hose.

The symptoms seem to happen when the car is warming up (coolant temperature under 185F). When I'm around 2500-3000 rpm in 3rd - 5th under light accelleration/cruising load.

I borrowed an actron scantool and recorded some params when it started. The main thing I noticed is the ignition timing retarding each time it happens. My boost gauge also jumps down 2-4 vac and then goes right back up 1 second later (which is what originally prompted me to start looking for something). Which is why I think it's a misfire. It doesn't seem to happen after the car is warmed up.

I can post some excel graphs I made later if anyone thinks they really have some insight into what it could be. I haven't been able to find anyone with smilar issues except 1 other person on here. And they were stumped too.

EDIT: There is no CEL/MIL.

 

[Prodigy]

My car was doing that before I put Denso Iridiums(IK22) in the car, now the car idles perfectly and doesn't detonate in light boost.

 

[crackerjakx]

My car was doing that before I put Denso Iridiums(IK22) in the car, now the car idles perfectly and doesn't detonate in light boost.

What do you mean by light boost? I'm at 8-16 vac when this happens.

I just feel like this isn't a plug problem.

Just further info, my idle sits at 697-701 RPM and my vac is 21-22 @ idle.

 

[crashkelly]

What do you mean by light boost? I'm at 8-16 vac when this happens.

I just feel like this isn't a plug problem.

Just further info, my idle sits at 697-701 RPM and my vac is 21-22 @ idle.

what are your mods? it could be a plug problem you might need to run a step colder plugs if you have a lot of mods.

 

[crackerjakx]

Stock. (drive2)

 

[orng1]

You should try some sea foam in the intake. These cars build up carbon like crazy from running so rich. It might work, it's cheap and at the very least the car will run better.

 

[dirtysouth_msp]

You should try some sea foam in the intake. These cars build up carbon like crazy from running so rich. It might work, it's cheap and at the very least the car will run better.

Read post #4...(headshake

 

[orng1]

Guess I didn't read it carefully enough, I'm just trying to be helpfull.

 

[dirtysouth_msp]

Guess I didn't read it carefully enough, I'm just trying to be helpfull.

Man, I'm just messin with you. Guess that was the wrong smiley. Here ya go, lol. (poke)

Seriously though crackerjaks, check you plug wires and coil packs. My msp did that and it turned out to be a bad plug wire. Don't run colder plugs if you are stock, it will most likely make it worse.

 

[crackerjakx]

Seriously though crackerjaks, check you plug wires and coil packs. My msp did that and it turned out to be a bad plug wire. Don't run colder plugs if you are stock, it will most likely make it worse.

I checked the wires and the packs with a multimeter. Everything was within spec. I guess its possible they're still bad. But that's an awful lot of money to waste on a maybe.

Could you be more specific when you say your car did it too? What were the symptoms you experienced and what triggered them? In your words.

 

[Prodigy]

What do you mean by light boost? I'm at 8-16 vac when this happens.

I just feel like this isn't a plug problem.

Just further info, my idle sits at 697-701 RPM and my vac is 21-22 @ idle.

Every time I gave the car a little bit more that partial throttle(40%), it would predetonate.
Anywhere from 15vac to 7psi...

Everything was fine if I drove like a granny except for the rough idle.

 

[dirtysouth_msp]

I checked the wires and the packs with a multimeter. Everything was within spec. I guess its possible they're still bad. But that's an awful lot of money to waste on a maybe.

Could you be more specific when you say your car did it too? What were the symptoms you experienced and what triggered them? In your words.

Well, around 3k rpms under light load while driving in vac the car would feel like it was stuttering and the rpms would dip along with vac during the stutters. Mine was a pretty obvious misfire and it even tripped a code at one point. Mostly though, I would only see the misfire in pending codes which do not trip the CEL. Have you checked your pending codes?

Another thing you may want to check for is pre-turbo exhaust leaks. I've seen them cause similar symptoms to what you are describing. Feels like a misfire, but never trips a code. Usually worse when the vehicle is not all the way to operating temp, beause once the engine is at operating temp, the metal expands and somewhat seals the leak. Just a thought...

 

[Prodigy]

Another thing you may want to check for is pre-turbo exhaust leaks. I've seen them cause similar symptoms to what you are describing. Feels like a misfire, but never trips a code.

bingo...
I also have an exhaust leak on the right side of the exhaust mani, thanks to a stripped bolt.
I never thought of that.

 

[dirtysouth_msp]

bingo...
I also have an exhaust leak on the right side of the exhaust mani, thanks to a stripped bolt.
I never thought of that.

Damn son you post quick! Just edited my last post with some more rationalization, lol.

 

[crackerjakx]

Well, around 3k rpms under light load while driving in vac the car would feel like it was stuttering and the rpms would dip along with vac during the stutters. Mine was a pretty obvious misfire and it even tripped a code at one point. Mostly though, I would only see the misfire in pending codes which do not trip the CEL. Have you checked your pending codes?

Another thing you may want to check for is pre-turbo exhaust leaks. I've seen them cause similar symptoms to what you are describing. Feels like a misfire, but never trips a code. Usually worse when the vehicle is not all the way to operating temp, beause once the engine is at operating temp, the metal expands and somewhat seals the leak. Just a thought...

Don't have the dipping RPM symptom... Just a slight stutter and quick vac drop

I checked for pending codes and there was nothing. I'm gonna try getting some better clamps today and maybe some stretch n' seal tape. I'll give it a shot, again, at being a leak.

 

[crackerjakx]

Found my TPS @ idle is registering 11.3% open (I guess to allow air in at idle) but when i have the pedal to the floor it only shows 86.6%... is this normal?