Unusual starting 1998 SSE 3.8L
#1
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We've been struggling with a really odd starting problem with my wife'* 1998 SSE for some time now. The problem is intermittant and it mostly starts just fine.
This is how it goes.
Turn the key, doesn't start right away and once it starts it feels like a major drag on the engine (the crank speed seems normal).
It will start eventually but not if we give it any gas.
The idle speed will be between 500 & 1000 rpm'*.
If we give it any amount of gas, engine speed does not increase, but it feels as if the engine is fighting against stiff resistance and starts to stumble.
If we give it a little gas and hold it there, the condition never clears.
If we give it no gas, the idle will slowly increase to 1500-2000 rpm'* (30 seconds to 2 minutes) and then everything is good.
If we shut it off and restart it will sometimes start normally - but this can take more than 5 re-starts.
Doesn't matter hot or cold.
We've replaced the starter solenoid because it seems as though the starter may have been stuck engaged. So that'* not it.
Any suggestions would be appreciated.
Thanks in advance.
Dave
This is how it goes.
Turn the key, doesn't start right away and once it starts it feels like a major drag on the engine (the crank speed seems normal).
It will start eventually but not if we give it any gas.
The idle speed will be between 500 & 1000 rpm'*.
If we give it any amount of gas, engine speed does not increase, but it feels as if the engine is fighting against stiff resistance and starts to stumble.
If we give it a little gas and hold it there, the condition never clears.
If we give it no gas, the idle will slowly increase to 1500-2000 rpm'* (30 seconds to 2 minutes) and then everything is good.
If we shut it off and restart it will sometimes start normally - but this can take more than 5 re-starts.
Doesn't matter hot or cold.
We've replaced the starter solenoid because it seems as though the starter may have been stuck engaged. So that'* not it.
Any suggestions would be appreciated.
Thanks in advance.
Dave
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Sounds like your IAC (Idle air control) or MAF (mass air flow) sensors. They're easy to access and clean.
The IAC gets carbon build up over time and the pintle doesn't seat properly in the throttle body. Disconnect the electrical connection and remove the IAC. DO NOT PUSH OR PULL the pintle or spring. Use Throttle body cleaner and an old toothbrush to remove any built up carbon. Spray some TB cleaner on a cue tip and clean the cavity inside of the TB where the pintle seats itself. Put a clean cloth over your narrowest finger and insert it into the TB and clean any residue. Let it dry for about 10 minutes before reinstalling the IAC. If you have a multimeter, check the resistance on the in/out connectors for the IAC. Acceptable ranges are: between a&b - c&d....A starting from right to left with lock tab up. Resistance should be 40-80 ohms
If the resistance is not in tolerances, buy a new IAC. They're not that expensive.
Install and reconnect the electrical connector.
BEFORE you start the car, reset the IAC circuit by:
1. Turn the key to ON (without starting the engine) for 20 seconds
2. Turn the key to OFF for 10 seconds
3. Start the car. IAC is reset and your idle should be fine.
If you still have some idle issues, disconnect your MAF electrical, remove and clean the 2 filiments with ELECTRICAL CONTACT CLEANER, nothing else. Reinstall. The MAF helps control the idle of your car by detecting air flow & density going to the TB. MAF failure is not that common, but it'* an easy thing to check and clean.
One other thing you should check. Is your battery connection and alternator providing proper voltage? Clean the terminals, put on some copper kote or no corrode (petroleum jelly works too) and make sure the connections are tight.
If you need your battery and alt tested, take it to a local shop and have it tested. Usually it'* free. If you have low voltage or charging, that may contribute to your problem.
I agree with raptor660 that you might want to check your fuel filter. You may not be getting proper fuel pressure at the rails. If you decide to change the filter on your own, pull the fuel pump fuse, start the car and let it run out of gas. That will take the pressure and residual spillage out of the fuel line. Change the filter, reinstall the fuse and see if the pressure builds quickly. A partially plugged filter can create the symptoms you describe too. I'd try these things that have been outlined above before looking at a new fuel pump. That'* a lot more work to do.
Hope one of these quick fixes works for you.
The IAC gets carbon build up over time and the pintle doesn't seat properly in the throttle body. Disconnect the electrical connection and remove the IAC. DO NOT PUSH OR PULL the pintle or spring. Use Throttle body cleaner and an old toothbrush to remove any built up carbon. Spray some TB cleaner on a cue tip and clean the cavity inside of the TB where the pintle seats itself. Put a clean cloth over your narrowest finger and insert it into the TB and clean any residue. Let it dry for about 10 minutes before reinstalling the IAC. If you have a multimeter, check the resistance on the in/out connectors for the IAC. Acceptable ranges are: between a&b - c&d....A starting from right to left with lock tab up. Resistance should be 40-80 ohms
If the resistance is not in tolerances, buy a new IAC. They're not that expensive.
Install and reconnect the electrical connector.
BEFORE you start the car, reset the IAC circuit by:
1. Turn the key to ON (without starting the engine) for 20 seconds
2. Turn the key to OFF for 10 seconds
3. Start the car. IAC is reset and your idle should be fine.
If you still have some idle issues, disconnect your MAF electrical, remove and clean the 2 filiments with ELECTRICAL CONTACT CLEANER, nothing else. Reinstall. The MAF helps control the idle of your car by detecting air flow & density going to the TB. MAF failure is not that common, but it'* an easy thing to check and clean.
One other thing you should check. Is your battery connection and alternator providing proper voltage? Clean the terminals, put on some copper kote or no corrode (petroleum jelly works too) and make sure the connections are tight.
If you need your battery and alt tested, take it to a local shop and have it tested. Usually it'* free. If you have low voltage or charging, that may contribute to your problem.
I agree with raptor660 that you might want to check your fuel filter. You may not be getting proper fuel pressure at the rails. If you decide to change the filter on your own, pull the fuel pump fuse, start the car and let it run out of gas. That will take the pressure and residual spillage out of the fuel line. Change the filter, reinstall the fuse and see if the pressure builds quickly. A partially plugged filter can create the symptoms you describe too. I'd try these things that have been outlined above before looking at a new fuel pump. That'* a lot more work to do.
Hope one of these quick fixes works for you.
#4
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I will check voltage. I'd be surprised if that were the issue. It cranks fine and interior lights etc all act normally when this happens and it'* only after it actually starts that there is an issue.
The fuel filter was changed two years ago - I'll check the lines to see if maybe a leak is dropping pressure.
Not sure what the MAF is, but I'll look it up and do as you suggest.
Thanks guys, it'* all something that I will check.
Dave
The fuel filter was changed two years ago - I'll check the lines to see if maybe a leak is dropping pressure.
Not sure what the MAF is, but I'll look it up and do as you suggest.
Thanks guys, it'* all something that I will check.
Dave
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Dave,
Just a couple of quick quesions. How many miles on your Bonne? When you start it and get 1500-2000 rpms that sounds really high. Sure you don't have a vacuum leak somewhere?
Just a couple of quick quesions. How many miles on your Bonne? When you start it and get 1500-2000 rpms that sounds really high. Sure you don't have a vacuum leak somewhere?
#7
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About 93000 miles.
After starting it stays at stumbling low rpm'* for a short minute or so and then creeps to 1500 - 2000 rpm'* - then it drops back to about 1000 rpm'* (normal idle) and runs fine. That'* how I can tell it'll drive right - I watch the idle creep up and then drop back - then I can go with no problems.
If I do try to drive before this - it won't go any higher than 500 to maybe 800 rpm' no matter what I do with the gas pedal.
I can't see it being a vacuum leak - this only happens about 1 in 10 starts - it'* too inconsistant.
Once in a while, it can take 10 minutes or more to run right (maybe once every month or two). In these cases the symptoms are worse to begin with and don't recover on it'* own. Very hard to start and we have to restart 5 - 10 times before it will run right. Once it runs right, it drives like new.
I suspect it might be a bad sensor connection but don't really know where to start (other than the MAF - thanks for that). But I am open to any suggestions.
9 out of 10 times, it starts and runs like new.
Thanks
Dave
After starting it stays at stumbling low rpm'* for a short minute or so and then creeps to 1500 - 2000 rpm'* - then it drops back to about 1000 rpm'* (normal idle) and runs fine. That'* how I can tell it'll drive right - I watch the idle creep up and then drop back - then I can go with no problems.
If I do try to drive before this - it won't go any higher than 500 to maybe 800 rpm' no matter what I do with the gas pedal.
I can't see it being a vacuum leak - this only happens about 1 in 10 starts - it'* too inconsistant.
Once in a while, it can take 10 minutes or more to run right (maybe once every month or two). In these cases the symptoms are worse to begin with and don't recover on it'* own. Very hard to start and we have to restart 5 - 10 times before it will run right. Once it runs right, it drives like new.
I suspect it might be a bad sensor connection but don't really know where to start (other than the MAF - thanks for that). But I am open to any suggestions.
9 out of 10 times, it starts and runs like new.
Thanks
Dave
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My Thinking is MAF TPS IAC Or a coil pack test each one and see what happens...wont hurt anything i only suggest these as it seems similar to an issue i had with my ssei
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93000 isn't really that much for a 3800. Has your Service Engine light come on?
If you suspect a bad sensor, cleaning them with Electrical contact cleaner might help.
Have you tried using Seafoam or GM Top Engine treatment to clean the upper engine? It will get rid of carbon buildups. FYI, in the TB, the throttle plate may get a build up of carbon around the outside bore which can affect the TPS. I took my TB right off to clean it and noticed there was quite a bit of carbon there. FWIW, here are a couple of pics showing before/after. (the engine did run nice after the cleanup)
Your TB may be slightly different, but not much. Here'* some basic stuff for you. Note: The MAF, IAC and TPS have only 2 screws holding them in. The IAC and TPS have rubber O ring seals. Don't lose them or crush them putting them back in.
![Name: IMG_1157-3.jpg
Views: 470
Size: 187.3 KB](https://www.gmforum.com/attachments/1992-1999-91/20699d1501260750-unusual-starting-1998-sse-3-8l-img_1157-3.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
Now here'* the TB apart. The small 'groove' with the clean look at the top of the pic is the IAC pintle slot. It got cleaned even better once TB was off the car. BTW, if you do this, you will have to drain some antifreeze. The 3 nuts that hold the TB in place are fairly easy to get to, and the TB seal can usually be reused. It'* only 8 bucks at NAPA if you decide to replace it.
![Name: IMG_1164.jpg
Views: 387
Size: 105.1 KB](https://www.gmforum.com/attachments/1992-1999-91/20700d1501260750-unusual-starting-1998-sse-3-8l-img_1164.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
![Name: IMG_1166.jpg
Views: 305
Size: 136.5 KB](https://www.gmforum.com/attachments/1992-1999-91/20701d1501260750-unusual-starting-1998-sse-3-8l-img_1166.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
Here'* what it cleans up to:
![Name: IMG_1167.jpg
Views: 326
Size: 129.2 KB](https://www.gmforum.com/attachments/1992-1999-91/20702d1501260750-unusual-starting-1998-sse-3-8l-img_1167.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
If you suspect a bad sensor, cleaning them with Electrical contact cleaner might help.
Have you tried using Seafoam or GM Top Engine treatment to clean the upper engine? It will get rid of carbon buildups. FYI, in the TB, the throttle plate may get a build up of carbon around the outside bore which can affect the TPS. I took my TB right off to clean it and noticed there was quite a bit of carbon there. FWIW, here are a couple of pics showing before/after. (the engine did run nice after the cleanup)
Your TB may be slightly different, but not much. Here'* some basic stuff for you. Note: The MAF, IAC and TPS have only 2 screws holding them in. The IAC and TPS have rubber O ring seals. Don't lose them or crush them putting them back in.
![Name: IMG_1157-3.jpg
Views: 470
Size: 187.3 KB](https://www.gmforum.com/attachments/1992-1999-91/20699d1501260750-unusual-starting-1998-sse-3-8l-img_1157-3.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
Now here'* the TB apart. The small 'groove' with the clean look at the top of the pic is the IAC pintle slot. It got cleaned even better once TB was off the car. BTW, if you do this, you will have to drain some antifreeze. The 3 nuts that hold the TB in place are fairly easy to get to, and the TB seal can usually be reused. It'* only 8 bucks at NAPA if you decide to replace it.
![Name: IMG_1164.jpg
Views: 387
Size: 105.1 KB](https://www.gmforum.com/attachments/1992-1999-91/20700d1501260750-unusual-starting-1998-sse-3-8l-img_1164.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
![Name: IMG_1166.jpg
Views: 305
Size: 136.5 KB](https://www.gmforum.com/attachments/1992-1999-91/20701d1501260750-unusual-starting-1998-sse-3-8l-img_1166.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
Here'* what it cleans up to:
![Name: IMG_1167.jpg
Views: 326
Size: 129.2 KB](https://www.gmforum.com/attachments/1992-1999-91/20702d1501260750-unusual-starting-1998-sse-3-8l-img_1167.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
![Name: IMG_1169.jpg
Views: 268
Size: 105.3 KB](https://www.gmforum.com/attachments/1992-1999-91/20703d1501260750-unusual-starting-1998-sse-3-8l-img_1169.jpg?*=3294846884f1c6b1d2d933b56a23a2e7)
#10
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Problem solved - I cleaned the the contacts to all of the sensors with contact cleaner - it'* been well over a week with no problems. I'm pretty sure it'* cured - tried the easiest thing first and that did the trick.
Thanks guys for the feedback - definitely pointed me in the right direction.
Thanks again
Dave
Thanks guys for the feedback - definitely pointed me in the right direction.
Thanks again
Dave