surging and dies
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,453
Likes: 48
surging and dies
Hi Everybody, 1989 Corvette 6 spd. Bone stock. It has been surging. I changed the fuel pump and fuel filter. Today it got me stuck. Twenty minutes waiting and it fired up and drove m home. I bought a Fuel Pressure Regulator. Goes in this weekend. All the plugs are firing, The car stopped when it was over 210 degrees. But the surging occurs pretty much all the time. I am also buying a fuel pressure gauge. But, the regulator gets changed no matter what. Any ideas are welcome.
Thank all
Joe
Thank all
Joe
Drifting
Joined: Jan 2021
Posts: 1,311
Likes: 383
From: Northern California
Surging can be a lot of things. Is it surging at idle or while accelerating?
The FP regulator is a good step, and when there is unstable idle or engine surging I tend to suspect the IAC valve / pintle seat area in the throttle body. The reality is that it can be so many causes that you're best off getting a scan tool of some sort rather than just throwing parts at it though. That way you can see what the ECM thinks it sees from all the sensors. Just an opinion.
The FP regulator is a good step, and when there is unstable idle or engine surging I tend to suspect the IAC valve / pintle seat area in the throttle body. The reality is that it can be so many causes that you're best off getting a scan tool of some sort rather than just throwing parts at it though. That way you can see what the ECM thinks it sees from all the sensors. Just an opinion.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,453
Likes: 48
Surging can be a lot of things. Is it surging at idle or while accelerating?
The FP regulator is a good step, and when there is unstable idle or engine surging I tend to suspect the IAC valve / pintle seat area in the throttle body. The reality is that it can be so many causes that you're best off getting a scan tool of some sort rather than just throwing parts at it though. That way you can see what the ECM thinks it sees from all the sensors. Just an opinion.
The FP regulator is a good step, and when there is unstable idle or engine surging I tend to suspect the IAC valve / pintle seat area in the throttle body. The reality is that it can be so many causes that you're best off getting a scan tool of some sort rather than just throwing parts at it though. That way you can see what the ECM thinks it sees from all the sensors. Just an opinion.
Safety Car
Joined: May 2001
Posts: 4,724
Likes: 1,628
From: Fairfax Virginia
Surging is also very common when the MAF is bad or failing. Is there any air leaking in the tube between the MAF and the Throttle body? A little air leak might aggravate the situation and cause surging to happen.
You mentioned that the engine stopped when it was over 210*. Did the engine just shut off or what?
Have you measured the Coolant temperature Sensor readings and compared it to the FSM to see the ambient it represents? There is a specific temperature at which the ECM will cut off the engine. I think it is about 250* before it shuts down the fuel.
Take a look at your Knock sensor to be sure it is not triggering very often. I had a bad one that was constantly holding my spark advance back, it makes the Corvette more like a Chevette when driving it like that.
Your Tuner pro should give you an idea of what is out of wack here. I have the MT2500 but just got my ALDL Bluetooth Adapter from 1320 Electronics LLC, I can't wait to try it out!
Beware that someplace around the 1988 to 1989 Corvettes they changed the Pintle in the IAC. When you want to replace your be sure to match the pintle up at the store before buying the wrong part. Being electrical they might not take it back.. My 1988 has the 1989 newer style pintle. With the wrong pintle the IAC can't work. This is critical to match the pintle shape to ensure that your IAC works as it should.
You mentioned that the engine stopped when it was over 210*. Did the engine just shut off or what?
Have you measured the Coolant temperature Sensor readings and compared it to the FSM to see the ambient it represents? There is a specific temperature at which the ECM will cut off the engine. I think it is about 250* before it shuts down the fuel.
Take a look at your Knock sensor to be sure it is not triggering very often. I had a bad one that was constantly holding my spark advance back, it makes the Corvette more like a Chevette when driving it like that.
Your Tuner pro should give you an idea of what is out of wack here. I have the MT2500 but just got my ALDL Bluetooth Adapter from 1320 Electronics LLC, I can't wait to try it out!
Beware that someplace around the 1988 to 1989 Corvettes they changed the Pintle in the IAC. When you want to replace your be sure to match the pintle up at the store before buying the wrong part. Being electrical they might not take it back.. My 1988 has the 1989 newer style pintle. With the wrong pintle the IAC can't work. This is critical to match the pintle shape to ensure that your IAC works as it should.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,453
Likes: 48
Surging is also very common when the MAF is bad or failing. Is there any air leaking in the tube between the MAF and the Throttle body? A little air leak might aggravate the situation and cause surging to happen.
You mentioned that the engine stopped when it was over 210*. Did the engine just shut off or what?
Have you measured the Coolant temperature Sensor readings and compared it to the FSM to see the ambient it represents? There is a specific temperature at which the ECM will cut off the engine. I think it is about 250* before it shuts down the fuel.
Take a look at your Knock sensor to be sure it is not triggering very often. I had a bad one that was constantly holding my spark advance back, it makes the Corvette more like a Chevette when driving it like that.
Your Tuner pro should give you an idea of what is out of wack here. I have the MT2500 but just got my ALDL Bluetooth Adapter from 1320 Electronics LLC, I can't wait to try it out!
Beware that someplace around the 1988 to 1989 Corvettes they changed the Pintle in the IAC. When you want to replace your be sure to match the pintle up at the store before buying the wrong part. Being electrical they might not take it back.. My 1988 has the 1989 newer style pintle. With the wrong pintle the IAC can't work. This is critical to match the pintle shape to ensure that your IAC works as it should.
You mentioned that the engine stopped when it was over 210*. Did the engine just shut off or what?
Have you measured the Coolant temperature Sensor readings and compared it to the FSM to see the ambient it represents? There is a specific temperature at which the ECM will cut off the engine. I think it is about 250* before it shuts down the fuel.
Take a look at your Knock sensor to be sure it is not triggering very often. I had a bad one that was constantly holding my spark advance back, it makes the Corvette more like a Chevette when driving it like that.
Your Tuner pro should give you an idea of what is out of wack here. I have the MT2500 but just got my ALDL Bluetooth Adapter from 1320 Electronics LLC, I can't wait to try it out!
Beware that someplace around the 1988 to 1989 Corvettes they changed the Pintle in the IAC. When you want to replace your be sure to match the pintle up at the store before buying the wrong part. Being electrical they might not take it back.. My 1988 has the 1989 newer style pintle. With the wrong pintle the IAC can't work. This is critical to match the pintle shape to ensure that your IAC works as it should.
Thank you
Safety Car
Joined: May 2001
Posts: 4,724
Likes: 1,628
From: Fairfax Virginia
I like cleaning the connectors on sensors like the CTS. I use a pencil with it's eraser to do the job for me unless you have some DeOxIt nearby. I love the DeOxIt as it wipes away corrosion on light bulb sockets or anything electrical, great stuff.
The CTS uses three wires as one is a Reference Voltage used to help the accuracy of the sensor. If your CTS is telling you it is 203* on cooler mornings I would clearly replace that bad boy. Failing High like it appeared to would get your Corvette less fuel than it needs for start-up. It thinks you are living out in a desert someplace. That explains the shut down on your Corvette, it probably hit the high temperature limit and shut it down. When they fail the other way you end up with a overly rich running engine. Kind of like the old days when your electric choke was stuck "on" and that makes Hot starts really fun..
Good Luck and happy to be of help!
You are very Welcome!
Best regards,
Chris
The CTS uses three wires as one is a Reference Voltage used to help the accuracy of the sensor. If your CTS is telling you it is 203* on cooler mornings I would clearly replace that bad boy. Failing High like it appeared to would get your Corvette less fuel than it needs for start-up. It thinks you are living out in a desert someplace. That explains the shut down on your Corvette, it probably hit the high temperature limit and shut it down. When they fail the other way you end up with a overly rich running engine. Kind of like the old days when your electric choke was stuck "on" and that makes Hot starts really fun..
Good Luck and happy to be of help!
You are very Welcome!
Best regards,
Chris
