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Discussion Starter · #1 ·
Had an interesting thing happen yesterday. All of you that were here last year know how I complained about my power issue when the car was still not up to operating temperature. We had all kind of concurred finally that it was my cat-warmup phase and unless I wanted to reprogram my ECM, I would have to learn to live with it. Well, yesterday was interesting leaving work. About 44 degrees here yesterday when I left work. My temp guage read 158 degrees. Gave it about 40% throttle, no issue…..let off gas and pushed in clutch to shift….the normal “backfire/burp” I get when it’s cold….. get back on the gas and it’s missing so bad, I’m actually slowing down…… Pulled it out of gear, tried to blip the throttle to clean it out, still missing…. At that point I started looking for an entrance to a parking lot to pull in and see what the issue was…. Put it in third gear to get me to the lot, let out the clutch to coast it down a little and it cleaned out. Didn’t have an issue the rest of the way home. I’m assuming from the way it acted that it had pushed too much fuel in the engine. I’m not sure. It did act very weird yesterday morning as well. It seemed to be burping a lot more then usual. I don’t think it was bad gas…..unless this year’s winter brew for gas has changed. I got gas from the same “good” station I always do…. Any thoughts?
 

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Discussion Starter · #3 ·
It’s my understanding that the ECM runs at a preset “rich” level until all the sensors have come up to operating temperature. The rich mode pushes more fuel into the engine, thus warming the cat up quicker during this phase. And the GXPs have this protection built in to their programs and they will also dump boost or limit boost until the engine reaches a certain temperature to protect it.
 

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Ghost, I have the exact same problem when I get going on a completely cold engine. This happens even when it is warm outside. Basically as soon as the engine is approaching 2500 RPM, I hear the turbo spinning, but power is cut dramatically so I can barely accelerate. I can only get up to speed by shifting often and early.

I thought it was normal, because it only happens when the coolant temperature is below 160-170 degrees. Once it reaches 180, everything is fine. Typical operating temperature is 200-205.

As it starts getting colder, I'm going to start leaving early so I can start the car and let it idle for 5 minutes or so to get up to operating temp.
 

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I wonder if it's actually your cat going out. (Maybe) cold weather somehow increases the blockage. Dunno - grasping at straws here.
 

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OK. Yes, most modern cars have this if not all. All 3 of my vehicles have this. If it is dumping more fuel in the motor and you let off the gas them any unburnt fuel will then exit and hit the cat and cause that backfire you are talking about. In my experience it is more common in manuals than autos especially when you run up the rpms(not saying you did this). Im sure you already know this though if it was discussed last year. My guess is as good as yours. 44 degrees outside is not cold. If it was in the single digits I could understand but not at 44. I've driven my wifes car at well below that and I start the car let it idle for about a minute and go. I've never had an issue with backfire or missing at all and yours shouldn't either and I'll run up to 4k rpms before shifting. Since you don't have a tune I would say it has to do with your exhaust and maybe CAI. If you do have a tune which isn't in your sig then you need to tell your tuner it needs tweaking and see if that helps.
 

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Ghost: I can not recall where we ending up on this last time, so please excuse me if you have already done these items:

I have had a small "cold start cough" with my car for sometime. In my case, it tends to be worse when outside/ambient temperatures warm to summer temps. When outside temps are colder, it tends not to happen. Beyond that, the problem is completely random as to how bad it is, or if it occurs at all. No other performance issues whatsoever. After the car is past the "Cold Start Warm Up Cycle", it runs perfect.

That being said: I always let my car go through the Cold Start Cycle completely, before I start driving. I wait until engine RPMs have dropped to normal idle of 900 RPMish, before taking off.

Something that I read on another thread a while back: Another forum member had cold start issues and some minor performance issues. In his case, the problem ended up being the down stream O2 sensor. So at some point, I intend to change that on my car and see if my cold start cough goes away.

Other possible causes that come to mind:

Have you replaced the "Cold Temp Sensor" on your car? Not sure where it is on our Kappas, but it will be connected to the block somewhere. I have not chased this down on my car yet because my problem is so minor and random, that I really doubt the CTS has gone bad. Typically if a CTS is bad, one will have much more severe and consistent issues at Cold Start; which your car may be presenting.

Have you gone through and checked all of the bolts on the exhaust manifold, turbo connection, down pipe and CAT? A small exhaust leak in one of these areas could account for the issue and once the system warms up; the leak seals, so the problem goes away.

Have you gone through and checked all of the electrical pigtail connections for all sensors, coil packs, etc? A marginal electrical connection will tend to fail when cold and work when warmed up.

On last idea, but you should have thrown a code for this by now: If the EVAP Purge Control Solenoid has gone bad, the the EVAP system may be blowing fuel fumes through the intake all the time and flooding the car out at inopportune times. This problem will tend to be worse at initial start, especially if outside temps are warmer. DDM has a vid posted somewhere on how to test the EVAP solenoid.
 

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The cat warm up phase is built into the ECM software. Basically the ECM sets engine paramaters to accelerate bringing the cat up to full operating temperature quickly. This phase lasts 1-2 minutes depending on conditions. It became known when the 08 braking issue was discussed. The software change modified the start up code to optimize building vacume then cat warmup.

The operation you are describing is not normal. I have never experienced that behavior on either of our turbo cars nor have I observed it in any car but for GS's special Sky.:devil:
 

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The cat warm up phase is built into the ECM software. Basically the ECM sets engine paramaters to accelerate bringing the cat up to full operating temperature quickly. This phase lasts 1-2 minutes depending on conditions. It became known when the 08 braking issue was discussed. The software change modified the start up code to optimize building vacume then cat warmup.

The operation you are describing is not normal. I have never experienced that behavior on either of our turbo cars nor have I observed it in any car but for GS's special Sky.:devil:
Good point. It shouldn't take very long. I don't understand where this misconception I've been seeing about letting a car warm up to a certain temp. Those days are long gone and oils are so much better at protection. I'm not saying fire it up and floor the piss out of it but you should be able to drive "normal" right after firing it up without any issues. If not, something is wrong.

Do you have an afermarket tune? I would guess so since you have other mods that won't do you any good unless you have one. You need to send a copy of your engine perameters back to the tuner and see what they say. It could be a simple A/F adjustment. Could your tuner wiped out the cat warm up phase?
 

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Discussion Starter · #10 ·
Okay, I am tuned. I have NO CLUE who tuned my car. I will describe the condition again for those of you that weren’t here, or don’t remember.

If I get on my car to get any boost at all under 150 degrees, even to pull out in traffic, the boost goes up, you can hear it coming out of the exhaust (so I’m guessing it’s bypassed somehow), the boost pressure increases on the DIC, and the car quits accelerating altogether. It literally feels like someone threw an anchor out the back! It gets EXTREMELY loud! Not the engine, but the exhaust note. It does tend to burp loudly and often as well until it’s up to about 150.

Yesterday when I thought it was warmed up (170+), I got on it somewhat….about 40-50% throttle. Normally this isn’t an issue, but it almost seemed like the fire mapping got all jacked up for a few seconds. Like what happens with Formula 1 cars and Top Fuel cars on occassion. It backfired pretty good….twice within less than a second. And burped it’s way down to idle. It was miss firing horribly. Put it in third and tried to give it gas but it still hadn’t cleared up. Threw it in neutral and blipped it again…still missing. Put it in fourth because it was running pretty rough and let the clutch out to try to get into a parking lot. That seemed to clear it up. Ran like a scalded rabbit today on the way in this morning….no issue at all.
 

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if your car has a custom tune, then its difficult to suggest issues based on lack of knowledge of how the tune is built.

On the stock or GMPP tune, for all but the early 08s that have the ECM software update to address the brake boost issue, the ECM goes through several stages from start up to full operating conditions.

Initially it sets for optimal starting, getting the engine running. Then it goes into cat warm up for a short period, followed by a warm up while driving which limits HP and boost until the trigger temp is reached, and finally it goes into normal operating mode. Until the temp reaches the trigger value, you will not see full boost and power is limited. My memory is that until you see 190 degrees indicated - plus or minue - the ECM limits boost.

My experience based on two cars and several years is that the only indication of the warm up states is increased black carbon "smoke" may be visible and the boost is limited. There is no other driveablility changes anything like you are experiencing.

If you have an after market tune, other than GMPP, consider going to the applicable factory tune as part of the diagnostic process. If that cures the problem then its likely the tune causing the problem. If that does not address the problem, then it at least establishes a known baseline that you can use to diagnose what the failures might be.
 

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if your car has a custom tune, then its difficult to suggest issues based on lack of knowledge of how the tune is built.

On the stock or GMPP tune, for all but the early 08s that have the ECM software update to address the brake boost issue, the ECM goes through several stages from start up to full operating conditions.

Initially it sets for optimal starting, getting the engine running. Then it goes into cat warm up for a short period, followed by a warm up while driving which limits HP and boost until the trigger temp is reached, and finally it goes into normal operating mode. Until the temp reaches the trigger value, you will not see full boost and power is limited. My memory is that until you see 190 degrees indicated - plus or minue - the ECM limits boost.

My experience based on two cars and several years is that the only indication of the warm up states is increased black carbon "smoke" may be visible and the boost is limited. There is no other driveablility changes anything like you are experiencing.

If you have an after market tune, other than GMPP, consider going to the applicable factory tune as part of the diagnostic process. If that cures the problem then its likely the tune causing the problem. If that does not address the problem, then it at least establishes a known baseline that you can use to diagnose what the failures might be.
Hmm. On the one hand, you seem to be describing exactly what is happening to me and Ghost as being normal, but then you say its not normal. I don't understand.

I always thought it was related to engine temperature, but for whatever reason, when I get going for the first time that day, I do get all kinds of limits on power and acceleration to the point where its not safe to pull into traffic.

After a couple minutes, it goes away and everything is normal. I don't have a tune, and the only mod on the car is MagnaFlow catback exhaust, but this was happening before I got the exhaust.

You're saying this is not normal behavior?
 

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Hmm. On the one hand, you seem to be describing exactly what is happening to me and Ghost as being normal, but then you say its not normal. I don't understand.

I always thought it was related to engine temperature, but for whatever reason, when I get going for the first time that day, I do get all kinds of limits on power and acceleration to the point where its not safe to pull into traffic.

After a couple minutes, it goes away and everything is normal. I don't have a tune, and the only mod on the car is MagnaFlow catback exhaust, but this was happening before I got the exhaust.

You're saying this is not normal behavior?
Are you not getting any boost when cold? You don't need much boost to pull into traffic safely. 4-5psi is all it should take and your ECM should not be limiting it that low. I have driven this cars many times when the temps are low and I have never had any power or boost reduction at all. I don't get in and run the living daylights out of it right away but I have never been afraid to pull into traffic and I know for a fact the coolant temps were no where near 190 degrees and I usually run it up to 3-4k rpms from the get go.

I am very interested in where this goes. I hope you and Ghost get this figured out.
 

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Are you not getting any boost when cold? You don't need much boost to pull into traffic safely. 4-5psi is all it should take and your ECM should not be limiting it that low. I have driven this cars many times when the temps are low and I have never had any power or boost reduction at all. I don't get in and run the living daylights out of it right away but I have never been afraid to pull into traffic and I know for a fact the coolant temps were no where near 190 degrees and I usually run it up to 3-4k rpms from the get go.

I am very interested in where this goes. I hope you and Ghost get this figured out.
Actually I will see it higher if I gun it, up to 10 PSI at least, but I can hear the air being released too. I don't think its going into the intake.

Basically I hear the turbo spool and then as the RPMs break 2k, power just falls away completely and pretty dramatically. I can barely accelerate at all. My 0-60 time in this state would be about 12-15 seconds, which I don't consider safe to pull into traffic.

Something is keeping the engine from making power, but it comes back to normal after a couple minutes. I thought it was related to engine temp, but it may be this warm-up cycle they've mentioned, or it could be something else entirely.

I haven't run the car today so I'll try to get some video of what I'm talking about when I go to the store. Not sure if you'll be able to tell from the vid or not, but you should at least be able to see the Speed-o, RPMs and boost gauge (assuming steering wheel buttons are working today) when the problem occurs.
 

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Sorry for any confusion

When starting from a cold start, the car runs normally. The only directly observable is limitation on boost. If you drive with the traffic, you do not notice any limitations or unusual behavior. If, for example, you go to high power demand, again the feeling and observables are a normally running engine but with the boost level limited until it hits minimum operating tempearture. No odd sounds, no sense of miss fire or rich running.
 

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Discussion Starter · #16 ·
Are you not getting any boost when cold? You don't need much boost to pull into traffic safely. 4-5psi is all it should take and your ECM should not be limiting it that low. I have driven this cars many times when the temps are low and I have never had any power or boost reduction at all. I don't get in and run the living daylights out of it right away but I have never been afraid to pull into traffic and I know for a fact the coolant temps were no where near 190 degrees and I usually run it up to 3-4k rpms from the get go.

I am very interested in where this goes. I hope you and Ghost get this figured out.
My car will show the full 23psi of boost on the DIC, but I go nowhere...as a matter of fact, if I floor it and get into boost, I slow down!!! It seems to blow all the boost out the exhaust. Or at least it sounds like it....
 

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Discussion Starter · #17 ·
Actually I will see it higher if I gun it, up to 10 PSI at least, but I can hear the air being released too. I don't think its going into the intake.

Basically I hear the turbo spool and then as the RPMs break 2k, power just falls away completely and pretty dramatically. I can barely accelerate at all. My 0-60 time in this state would be about 12-15 seconds, which I don't consider safe to pull into traffic.

Something is keeping the engine from making power, but it comes back to normal after a couple minutes. I thought it was related to engine temp, but it may be this warm-up cycle they've mentioned, or it could be something else entirely.

I haven't run the car today so I'll try to get some video of what I'm talking about when I go to the store. Not sure if you'll be able to tell from the vid or not, but you should at least be able to see the Speed-o, RPMs and boost gauge (assuming steering wheel buttons are working today) when the problem occurs.
Seltz....I have THE EXACT SAME ISSUE!!!! I can make full boost when cold (23psi), but the car literrally accelerates slower then if I were to use no boost!!!
 

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Discussion Starter · #18 ·
I'll get a recording of the vitals from my OBDII device off of the car and post it later. I'm almost scared though since I'm afraid I might be pressing my luck and the misfire might just stay there....but I'll try.
 

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I always let the engine on this car get up to 170 or higher before I drive it.
I know a lot of people do not want to wait, but then I do not have any issues.
Just like 100% of the time my shifts are always at 4K RPM or it will never go to the next gear.
 
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