The problem and symptoms
When cold (usually after a rainfall or when moisture is present in the air), the car will drop down to a lower idle (500-600 rpm) a few minutes after starting, glug like a cammed LS, and start shaking almost like there is a misfire. The exhaust will smell very rich with fuel and the car won't rev past 2-3k RPM in gear with the throttle at full. It sputters and climbs slowly and eventually busts through this "false rev limit" and then takes off like a bat out of hell.
After a few minutes of idling, modulating the throttle, and warming up, the car runs fine and the issue goes away. This issue doesn't happen every time the car is cold started. I've also gotten the issue to go away quickly by getting into 4-5th gear and down shifting into higher rpms. Once it's in the higher rpms, it drives fine. I don't really like doing this on a cold engine.
https://www.youtube.com/watch?v=nWSimsVDDuA - sputtering until about 2800 rpm at full throttle and then it accelerates normally
https://www.youtube.com/watch?v=XInRRjsXp3M - sputtering starts at 2400 rpm at full throttle and slowly climbs to 2800-2900 rpm and accelerates normally
I'm thinking it has something to do with temperature and fuel delivery, because of the rich exhaust and the issue going away once the car is slightly warmed up.
To go into more detail. This all popped up after I did the second major maintenance and replaced a bunch of engine components. One of the things I replaced were the fuel injectors with some refurbished ones. When I got those and originally tried firing up the car, it turns out four of them were stuck and not delivering any fuel. I got those recleaned, put them in, and the issue I'm currently experiencing popped up soon after. When the issue pops up, I've listened to all the fuel injectors and they all seem to be clicking away and delivering fuel.
I changed the spark plugs in the first round of maintenance and the car ran fine for 5 months and over 1,000 miles, so I don't believe it could be that. I have not tried new ones.
Changing the MAF with one from Ebay and the original that came with the car didn't get rid of the problem.
I've replaced the crank position sensor and TPS and the issue went away for a few weeks after initially installing the components and then came back. The CPS was replaced about a year and a half ago and TPS was replaced about two months ago.
I've checked for vacuum leaks and I had one at the intake overflow tube, but that got fixed and the problem persisted. No other leaks.
I just recently did a head gasket replacement because the back of the block had a major oil leak and I thought maybe the head lifted and that was causing the problem. Cylinder 6 had very low compression. The car no longer has any oil leaks, but the issue persists.
Things I have left to try or that may be causing the issue?
Test all the coolant sensors
Test the ICV
Replace the O2 sensor
Check all my grounds
Replace the fuel injectors?
Harness or ECU problem?
It's temperature and fuel related since the issue never happens when warm, I'm almost thinking it has to be something with a sensor?
If anyone has seen this, experienced it, or can point me in the direction of solving this problem I would greatly appreciate it. It's been driving me crazy the last two years.
When cold (usually after a rainfall or when moisture is present in the air), the car will drop down to a lower idle (500-600 rpm) a few minutes after starting, glug like a cammed LS, and start shaking almost like there is a misfire. The exhaust will smell very rich with fuel and the car won't rev past 2-3k RPM in gear with the throttle at full. It sputters and climbs slowly and eventually busts through this "false rev limit" and then takes off like a bat out of hell.
After a few minutes of idling, modulating the throttle, and warming up, the car runs fine and the issue goes away. This issue doesn't happen every time the car is cold started. I've also gotten the issue to go away quickly by getting into 4-5th gear and down shifting into higher rpms. Once it's in the higher rpms, it drives fine. I don't really like doing this on a cold engine.
https://www.youtube.com/watch?v=nWSimsVDDuA - sputtering until about 2800 rpm at full throttle and then it accelerates normally
https://www.youtube.com/watch?v=XInRRjsXp3M - sputtering starts at 2400 rpm at full throttle and slowly climbs to 2800-2900 rpm and accelerates normally
I'm thinking it has something to do with temperature and fuel delivery, because of the rich exhaust and the issue going away once the car is slightly warmed up.
To go into more detail. This all popped up after I did the second major maintenance and replaced a bunch of engine components. One of the things I replaced were the fuel injectors with some refurbished ones. When I got those and originally tried firing up the car, it turns out four of them were stuck and not delivering any fuel. I got those recleaned, put them in, and the issue I'm currently experiencing popped up soon after. When the issue pops up, I've listened to all the fuel injectors and they all seem to be clicking away and delivering fuel.
I changed the spark plugs in the first round of maintenance and the car ran fine for 5 months and over 1,000 miles, so I don't believe it could be that. I have not tried new ones.
Changing the MAF with one from Ebay and the original that came with the car didn't get rid of the problem.
I've replaced the crank position sensor and TPS and the issue went away for a few weeks after initially installing the components and then came back. The CPS was replaced about a year and a half ago and TPS was replaced about two months ago.
I've checked for vacuum leaks and I had one at the intake overflow tube, but that got fixed and the problem persisted. No other leaks.
I just recently did a head gasket replacement because the back of the block had a major oil leak and I thought maybe the head lifted and that was causing the problem. Cylinder 6 had very low compression. The car no longer has any oil leaks, but the issue persists.
Things I have left to try or that may be causing the issue?
Test all the coolant sensors
Test the ICV
Replace the O2 sensor
Check all my grounds
Replace the fuel injectors?
Harness or ECU problem?
It's temperature and fuel related since the issue never happens when warm, I'm almost thinking it has to be something with a sensor?
If anyone has seen this, experienced it, or can point me in the direction of solving this problem I would greatly appreciate it. It's been driving me crazy the last two years.
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