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Discussion Starter · #1 · (Edited)
Guys, I'm having an intermittent low power mode without any CEL aka limp mode lite.
'08 Redline Automatic. All stock internals with RPM Tune done about 2 years ago.

Here's what happens most days:
Starts up, sometimes it will run ok during full key cycle.
Most times though it will start up in limp mode lite, boost maxing at 2-4psi, throttle limited to 45%.
Sometimes it eventually 'wakes up' mid- drive and then I have full boost and power until key cycle again.
I have not yet experienced it reverting to limp mode lite during that key cycle, even with extended (30+ min) on time.
Sometimes happens 2-3 min in, sometimes 20 mins in.

Research online has pointed to several potential causes: wiring, air leak, solenoids, wastegate, MAF
I've seen a lot of threads where the car will start fine then go in/out of limp, but not where it behaves as mine where it wakes up then is good for the rest of the drive.

I've checked all my intake and IC hoses and tightened them all up. Intercooler looks intact from visual inspection (no ballooning).
I bought a VCX Nano (Chinese Tech2) to see if I can pull a code from that but I am still not seeing anything.
Not sure if I'm just not looking in the right place though as I'm still learning it, and I don't know what baseline should be on some of the readings either to know if they're out of spec.
I do see rpm's requested at idle are 800 but actual are 1000.

I've got some time today to do some troubleshooting so any suggestions are welcome.
 

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Check the wastegate arm on the turbo, its held on with two nuts on either side, see if they're loose.
The maf you can always disconnect, car will run fine without it.
The higher idle rpm is a bit strange, almost like its pointing to the throttle body?
 

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Discussion Starter · #3 ·
Wastegate arm looks good I think (see pics)
Tried disconnecting the MAF, gave me codes right away but the behavior didn't change. Reconnected and cleared codes, same behavior.
Noticed idle rpms are high in park, but once I'm in drive they aren't too high maybe 820-900
115383
115384
 

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Yea the wastegate arm looks good. You can also try pressurizing the waste gate actuator with an air compressor to verify. Charge it to 7 psi and see if you have very slight movement (and by very slight I mean half the width of a human hair). Go up to 10 psi if necessary to see movement.

Run a smoke test for vac leaks. A high idle is indicative of a vac leak. I have one and the car runs like crap until it heats up then it runs mostly fine. We ran a test and had a leak somewhere by the power steering pump??? Need go get it on a lift to check it. Vac leaks are a bitch to find sometimes.

Could also me the waste gate actuator solenoid going bad. This should throw a code though. Most of these should throw some kind of code but I know my vac leak isn't throwing one either.

This is not going to be something simple to find without a code.
 

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Discussion Starter · #5 ·
Yea the wastegate arm looks good. You can also try pressurizing the waste gate actuator with an air compressor to verify. Charge it to 7 psi and see if you have very slight movement (and by very slight I mean half the width of a human hair). Go up to 10 psi if necessary to see movement.

Run a smoke test for vac leaks. A high idle is indicative of a vac leak. I have one and the car runs like crap until it heats up then it runs mostly fine. We ran a test and had a leak somewhere by the power steering pump??? Need go get it on a lift to check it. Vac leaks are a bitch to find sometimes.

Could also me the waste gate actuator solenoid going bad. This should throw a code though. Most of these should throw some kind of code but I know my vac leak isn't throwing one either.
Where/how would I put the air in to pressurize the actuator?
Is there an easy to do a smoke test myself? Or will I need to take it to a shop?

This is not going to be something simple to find without a code.
Yeah I was hoping the Tech2 would tell me something but so far it hasn't.
I even have a log where the problem stopped and looking at all the data I can't see that anything is any different before & after.
Any idea how close the measured vs calculated air flow should be? They are always close but not 100%. I figure a few % off should be ok?
 

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Where/how would I put the air in to pressurize the actuator?
Is there an easy to do a smoke test myself? Or will I need to take it to a shop?


Yeah I was hoping the Tech2 would tell me something but so far it hasn't.
I even have a log where the problem stopped and looking at all the data I can't see that anything is any different before & after.
Any idea how close the measured vs calculated air flow should be? They are always close but not 100%. I figure a few % off should be ok?
Smoke test you need a smoke testor tool for. You can find them for under $200 online. Either that or take it to shop that has one.

For the actuator, you just need to unplug the vac line from the actuator that runs to it from the solenoid. (Solenoid is on the turbo and the vac line is only a couple inches long if that). Attach a longer vac kine hose to the actuator and then use that to apply pressure. You can use a hand pump or air compressor that you can accurately turn down to 7 psi.
 

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Discussion Starter · #7 · (Edited)
Ok so last week I ordered a cheap smoke machine from Amazon. Arrived Thursday and I put it to use today.
I'm seeing a fair amount of smoke come from the turbo wastegate solenoid? The one under the turbo intake.
Just want to consult with you guys first that this isn't the wastegate purging normally. It seems to leak weather I open or close the solenoid using the tech2win. I do hear it click when activating it.
It does look like it comes from the solenoid though or one of the hoses right there.
I'm guessing I'll have to teardown and inspect that area.

EDIT: turns out I was seeing smoke from the intake hose connection. When isolated, the solenoid has no smoke, it must have been coming out the underside of the intake. Going to reinstall and test again.

Also had a slight leak on the connector where my intake nipple repair is. Looks like it's the connection of the two parts. I added some silicone grease on the o-ring and it seems to have resolved it.
 

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Discussion Starter · #8 ·
Not sure why, but no matter how hard I try to clamp down the hose clamp on the turbo inlet, I still get smoke escaping. I'm going as tight as I'm comfortable with without potentially breaking or skipping a tooth on the worm clamp
Checked the hose itself and it has no cracks or leaks. I'm almost wondering if the hose itself has some warping to it or why it won't seal completely.
Anyone have any suggestions aside from replacing the worm clamp to a t-clamp?
 

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Not sure why, but no matter how hard I try to clamp down the hose clamp on the turbo inlet, I still get smoke escaping. I'm going as tight as I'm comfortable with without potentially breaking or skipping a tooth on the worm clamp
Checked the hose itself and it has no cracks or leaks. I'm almost wondering if the hose itself has some warping to it or why it won't seal completely.
Anyone have any suggestions aside from replacing the worm clamp to a t-clamp?
. Spring loaded T-bolt clamp.
 

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Not sure why, but no matter how hard I try to clamp down the hose clamp on the turbo inlet, I still get smoke escaping. I'm going as tight as I'm comfortable with without potentially breaking or skipping a tooth on the worm clamp
Checked the hose itself and it has no cracks or leaks. I'm almost wondering if the hose itself has some warping to it or why it won't seal completely.
Anyone have any suggestions aside from replacing the worm clamp to a t-clamp?
Maybe it's not pushed on far enough? In any case, given it's the intake (not pressurized) it probably won't leak enough to pass a whole lot of un-metered air in.
 

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Discussion Starter · #13 ·
So a quick update after smoke testing and putting it all back together.
I really didn't see any leaks anywhere else but I also put silicon grease on the other couplers on the hoses that connect the evap solenoid going out of the driver's side of the engine.

Last drive cycles have been like this:
1st - limp mode at start, woke up within about .5 miles and running good.
2nd - key cycled at a stoplight to test it - if it was in limp, it was only for a few blocks because when I floored it it gave me full boost
3rd - cold startup sounded very smooth, ran with full boost full drive similar to last cycle
4th-8th - warm startup - full boost.

Previous to this it had been consistently starting up in limp mode, sometimes switching out sometimes not

So perhaps I have the problem resolved? Will continue to drive and monitor and follow up with results.
 
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